Graphene nanoplatelets(GNPs)have attracted tremendous interest due to their unique properties and bonding capabilities.This study focuses on the effect of GNP dispersion on the mechanical,thermal,and morphological beh...Graphene nanoplatelets(GNPs)have attracted tremendous interest due to their unique properties and bonding capabilities.This study focuses on the effect of GNP dispersion on the mechanical,thermal,and morphological behavior of GNP/epoxy nanocomposites.This study aims to understand how the dispersion of GNPs affects the properties of epoxy nanocomposite and to identify the best dispersion approach for improving mechanical performance.A solvent mixing technique that includes mechanical stirring and ultrasonication was used for producing the nanocomposites.Fourier transform infrared spectroscopy was used to investigate the interaction between GNPs and the epoxy matrix.The measurements of density and moisture content were used to confirm that GNPs were successfully incorporated into the nanocomposite.The findings showed that GNPs are successfully dispersed in the epoxy matrix by combining mechanical stirring and ultrasonication in a single step,producing well-dispersed nanocomposites with improved mechanical properties.Particularly,the nanocomposites at a low GNP loading of 0.1 wt%,demonstrate superior mechanical strength,as shown by increased tensile properties,including improved Young's modulus(1.86 GPa),strength(57.31 MPa),and elongation at break(4.98).The nanocomposite with 0.25 wt%GNP loading performs better,according to the viscoelastic analysis and flexural properties(113.18 MPa).Except for the nanocomposite with a 0.5 wt%GNP loading,which has a higher thermal breakdown temperature,the thermal characteristics do not significantly alter.The effective dispersion of GNPs in the epoxy matrix and low agglomeration is confirmed by the morphological characterization.The findings help with filler selection and identifying the best dispersion approach,which improves mechanical performance.The effective integration of GNPs and their interaction with the epoxy matrix provides the doorway for additional investigation and the development of sophisticated nanocomposites.In fields like aerospace,automotive,and electronics where higher mechanical performance and functionality are required,GNPs'improved mechanical properties and successful dispersion present exciting potential.展开更多
Recent studies have shown that fibrotic scar formation following cerebral ischemic injury has varying effects depending on the microenvironment.However,little is known about how fibrosis is induced and regulated after...Recent studies have shown that fibrotic scar formation following cerebral ischemic injury has varying effects depending on the microenvironment.However,little is known about how fibrosis is induced and regulated after cerebral ischemic injury.Sonic hedgehog signaling participates in fibrosis in the heart,liver,lung,and kidney.Whether Shh signaling modulates fibrotic scar formation after cerebral ischemic stroke and the underlying mechanisms are unclear.In this study,we found that Sonic Hedgehog expression was upregulated in patients with acute ischemic stroke and in a middle cerebral artery occlusion/reperfusion injury rat model.Both Sonic hedgehog and Mitofusin 2 showed increased expression in the middle cerebral artery occlusion rat model and in vitro fibrosis cell model induced by transforming growth factor-beta 1.Activation of the Sonic hedgehog signaling pathway enhanced the expression of phosphorylated Smad 3 and Mitofusin 2 proteins,promoted the formation of fibrotic scars,protected synapses or promoted synaptogenesis,alleviated neurological deficits following middle cerebral artery occlusion/reperfusion injury,reduced cell apoptosis,facilitated the transformation of meninges fibroblasts into myofibroblasts,and enhanced the proliferation and migration of meninges fibroblasts.The Smad3 phosphorylation inhibitor SIS3 reversed the effects induced by Sonic hedgehog signaling pathway activation.Bioinformatics analysis revealed significant correlations between Sonic hedgehog and Smad3,between Sonic hedgehog and Mitofusin 2,and between Smad3 and Mitofusin 2.These findings suggest that Sonic hedgehog signaling may influence Mitofusin 2 expression by regulating Smad3 phosphorylation,thereby modulating the formation of early fibrotic scars following cerebral ischemic stroke and affecting prognosis.The Sonic Hedgehog signaling pathway may serve as a new therapeutic target for stroke treatment.展开更多
AIM:To investigate the effects of Sonic hedgehog(Shh)gene-modified bone marrow mesenchymal stem cells(MSCs)on graft-induced retinal gliosis and retinal ganglion cells(RGCs)survival in diabetic mice.METHODS:Bone marrow...AIM:To investigate the effects of Sonic hedgehog(Shh)gene-modified bone marrow mesenchymal stem cells(MSCs)on graft-induced retinal gliosis and retinal ganglion cells(RGCs)survival in diabetic mice.METHODS:Bone marrow-derived MSCs were genetically modified with the Shh gene to generate a stably transfected cell line of Shh-modified MSCs(MSC-Shh).Intravitreal injections of MSC-Shh and green fluorescent protein-modified MSCs(MSC-Gfp;control)were administered in diabetic mice.After 4wk,the effects of MSC-Shh on retinal gliosis were evaluated using fundus photography,and markers of gliosis were examined by immunofluorescence and Western blotting.The neurotrophic factors expression and RGCs survival in the host retina were evaluated using Western blotting and immunofluorescence.The mechanisms underlying the effects of MSC-Shh was investigated.RESULTS:A significant reduction of proliferative vitreoretinopathy(PVR)was observed after intravitreal injection of MSC-Shh compared to MSC-Gfp.Significant downregulation of glial fibrillary acidic protein(GFAP)was demonstrated in the host retina after MSC-Shh administration compared to MSC-Gfp.The extracellular signal-regulated kinase 1/2(ERK1/2),protein kinase B(AKT)and phosphatidylin-ositol-3-kinase(PI3K)pathways were significantly downregulated after MSC-Shh administration compared to MSC-Gfp.Brain-derived neurotrophic factor(BDNF)and ciliary neurotrophic factor(CNTF)levels were significantly increased in the host retina,and RGCs loss was significantly prevented after MSC-Shh administration.CONCLUSION:MSC-Shh administration reduces graft-induced reactive gliosis following intravitreal injection in diabetic mice.The ERK1/2,AKT and PI3K pathways are involved in this process.MSC-Shh also increases the levels of neurotrophic factors in the host retina and promoted RGCs survival in diabetic mice.展开更多
After the last flight of the Concorde in 2003,sonic boom has been one of the obstacles to the return of a supersonic transport aircraft to service.To reduce the sonic boom intensity to an acceptable level,it is of gre...After the last flight of the Concorde in 2003,sonic boom has been one of the obstacles to the return of a supersonic transport aircraft to service.To reduce the sonic boom intensity to an acceptable level,it is of great significance to study the effect of lift distribution on far-field sonic boom,since lift is one of the most important contributors to an intense sonic boom.Existing studies on the longitudinal lift distribution used low-fidelity methods,such as Whitham theory,and in turn,only preliminary conclusions were obtained,such as that extending the lift distribution can reduce sonic boom.This paper uses a newly developed high-fidelity prediction method to quantitatively study the effect of longitudinal lift distribution on the sonic boom of a Canard-Wing-Stabilator-Body(CWSB)configuration.This high-fidelity prediction method combines near-feld CFD simulation with far-field propagation by solving the augmented Burgers equation.A multipole analysis method is employed for the extraction of near-field waveform in order to reduce computational cost.Seven configurations with the same total lift but different distributions are studied,and the quantitative relationship between the longitudinal lift distribution and far-field sonic boom intensity is investigated.It is observed that a small lift generated by the stabilator can prevent aft-stabilator and aft-fuselage shocks from merging,while the balanced lift generated by the canard and wing can effectively keep the corresponding shocks further apart,which is beneficial for reducing both the on-track and off-track sonic boom.In turn,the acoustic level perceived at the ground can be reduced by 5.9 PLdB on-track and 5.4 PLdB off-track,on average.展开更多
To quantitatively study the location errors induced by deviation of sonic speed, the line and plane location tests were carried out. A broken pencil was simulated as acoustic emission source in the rocks. The line and...To quantitatively study the location errors induced by deviation of sonic speed, the line and plane location tests were carried out. A broken pencil was simulated as acoustic emission source in the rocks. The line and plane location tests were carried out in the granite rod using two sensors and the cube of marble using four sensors, respectively. To compare the position accuracy between line and plane positions, the line poison test was also carried out on the marble surface. The results show that for line positioning, the maximum error of absolute distance is about 0.8 cm. With the speed difference of 200 m/s, the average value of absolute difference from the position error is about 0.4 cm. For the plane positioning, in the case of the sensor array of 30 cm, the absolute positioning distance is up to 8.7 cm. It can be seen that the sonic speed seriously impacts on the plane positioning accuracy. The plane positioning error is lager than the line positioning error, which means that when the line position can satisfy the need in practical engineering, it is better to use the line position instead of the plane location. The plane positioning error with the diagonal speed is the minimum one.展开更多
目的:研究大鼠胃癌前病变形成过程中胃黏膜Sonic Hedgehog(Shh)信号通路的变化。方法:72只乳鼠随机分为正常组36只,造模组36只,雌雄各半。造模组灌服800 mg/L的1-甲基-3-硝基-1-亚硝基胍(MNNG)0.1 m L/d,正常组灌服生理盐水0.1 m L/d,共...目的:研究大鼠胃癌前病变形成过程中胃黏膜Sonic Hedgehog(Shh)信号通路的变化。方法:72只乳鼠随机分为正常组36只,造模组36只,雌雄各半。造模组灌服800 mg/L的1-甲基-3-硝基-1-亚硝基胍(MNNG)0.1 m L/d,正常组灌服生理盐水0.1 m L/d,共10 d。随后在实验观察第10周、22周、34周末每组分别雌雄各处死6只。HE染色检测胃黏膜组织病理学变化,q RTPCR法检测胃黏膜组织Shh、Ptch1、Smo、Gli1、Gli2、Gli3、Su Fu、Cyclin D1、Cyclin E1、c-Myc、β-actin m RNA的表达。Western blot检测胃黏膜组织Shh、Ptch1、Smo、Gli1、Su Fu、Cyclin D1、Cyclin E1、cMyc、p-c-Myc蛋白表达。结果:随造模时间的延长,模型组大鼠胃黏膜萎缩及异型增生逐渐加重,其胃黏膜内Shh、Smo、Gli1、Cyclin D1、Cyclin E1及c-Myc m RNA表达较正常组不同程度升高,而Ptch1和Su Fu m RNA不同程度降低。模型组胃黏膜内Shh、Smo、Gli1、Cyclin D1、Cyclin E1、p-c-Myc蛋白水平较正常组增加,Ptch1和Su Fu则降低,但差异无统计学意义。结论:大鼠胃癌前病变的形成过程中存在Shh信号通路的激活,提示Shh信号通路可能参与胃癌前病变的发生与发展。展开更多
基金the Puncak RM for the project under the grant 6733204-13069 to carry out the experiments。
文摘Graphene nanoplatelets(GNPs)have attracted tremendous interest due to their unique properties and bonding capabilities.This study focuses on the effect of GNP dispersion on the mechanical,thermal,and morphological behavior of GNP/epoxy nanocomposites.This study aims to understand how the dispersion of GNPs affects the properties of epoxy nanocomposite and to identify the best dispersion approach for improving mechanical performance.A solvent mixing technique that includes mechanical stirring and ultrasonication was used for producing the nanocomposites.Fourier transform infrared spectroscopy was used to investigate the interaction between GNPs and the epoxy matrix.The measurements of density and moisture content were used to confirm that GNPs were successfully incorporated into the nanocomposite.The findings showed that GNPs are successfully dispersed in the epoxy matrix by combining mechanical stirring and ultrasonication in a single step,producing well-dispersed nanocomposites with improved mechanical properties.Particularly,the nanocomposites at a low GNP loading of 0.1 wt%,demonstrate superior mechanical strength,as shown by increased tensile properties,including improved Young's modulus(1.86 GPa),strength(57.31 MPa),and elongation at break(4.98).The nanocomposite with 0.25 wt%GNP loading performs better,according to the viscoelastic analysis and flexural properties(113.18 MPa).Except for the nanocomposite with a 0.5 wt%GNP loading,which has a higher thermal breakdown temperature,the thermal characteristics do not significantly alter.The effective dispersion of GNPs in the epoxy matrix and low agglomeration is confirmed by the morphological characterization.The findings help with filler selection and identifying the best dispersion approach,which improves mechanical performance.The effective integration of GNPs and their interaction with the epoxy matrix provides the doorway for additional investigation and the development of sophisticated nanocomposites.In fields like aerospace,automotive,and electronics where higher mechanical performance and functionality are required,GNPs'improved mechanical properties and successful dispersion present exciting potential.
基金supported by the National Natural Science Foundation of China,Nos.82171456(to QY)and 81971229(to QY)the Natural Science Foundation of Chongqing,Nos.CSTC2021JCYJ-MSXMX0263(to QY)and CSTB2023NSCQ-MSX1015(to XL)Doctoral Innovation Project of The First Affiliated Hospital of Chongqing Medical University,Nos.CYYY-BSYJSCXXM-202318(to JW)and CYYY-BSYJSCXXM-202327(to HT).
文摘Recent studies have shown that fibrotic scar formation following cerebral ischemic injury has varying effects depending on the microenvironment.However,little is known about how fibrosis is induced and regulated after cerebral ischemic injury.Sonic hedgehog signaling participates in fibrosis in the heart,liver,lung,and kidney.Whether Shh signaling modulates fibrotic scar formation after cerebral ischemic stroke and the underlying mechanisms are unclear.In this study,we found that Sonic Hedgehog expression was upregulated in patients with acute ischemic stroke and in a middle cerebral artery occlusion/reperfusion injury rat model.Both Sonic hedgehog and Mitofusin 2 showed increased expression in the middle cerebral artery occlusion rat model and in vitro fibrosis cell model induced by transforming growth factor-beta 1.Activation of the Sonic hedgehog signaling pathway enhanced the expression of phosphorylated Smad 3 and Mitofusin 2 proteins,promoted the formation of fibrotic scars,protected synapses or promoted synaptogenesis,alleviated neurological deficits following middle cerebral artery occlusion/reperfusion injury,reduced cell apoptosis,facilitated the transformation of meninges fibroblasts into myofibroblasts,and enhanced the proliferation and migration of meninges fibroblasts.The Smad3 phosphorylation inhibitor SIS3 reversed the effects induced by Sonic hedgehog signaling pathway activation.Bioinformatics analysis revealed significant correlations between Sonic hedgehog and Smad3,between Sonic hedgehog and Mitofusin 2,and between Smad3 and Mitofusin 2.These findings suggest that Sonic hedgehog signaling may influence Mitofusin 2 expression by regulating Smad3 phosphorylation,thereby modulating the formation of early fibrotic scars following cerebral ischemic stroke and affecting prognosis.The Sonic Hedgehog signaling pathway may serve as a new therapeutic target for stroke treatment.
基金Supported by the Natural Science Foundation of Guangdong Province(No.2018A0303130293,No.2023A1515012470).
文摘AIM:To investigate the effects of Sonic hedgehog(Shh)gene-modified bone marrow mesenchymal stem cells(MSCs)on graft-induced retinal gliosis and retinal ganglion cells(RGCs)survival in diabetic mice.METHODS:Bone marrow-derived MSCs were genetically modified with the Shh gene to generate a stably transfected cell line of Shh-modified MSCs(MSC-Shh).Intravitreal injections of MSC-Shh and green fluorescent protein-modified MSCs(MSC-Gfp;control)were administered in diabetic mice.After 4wk,the effects of MSC-Shh on retinal gliosis were evaluated using fundus photography,and markers of gliosis were examined by immunofluorescence and Western blotting.The neurotrophic factors expression and RGCs survival in the host retina were evaluated using Western blotting and immunofluorescence.The mechanisms underlying the effects of MSC-Shh was investigated.RESULTS:A significant reduction of proliferative vitreoretinopathy(PVR)was observed after intravitreal injection of MSC-Shh compared to MSC-Gfp.Significant downregulation of glial fibrillary acidic protein(GFAP)was demonstrated in the host retina after MSC-Shh administration compared to MSC-Gfp.The extracellular signal-regulated kinase 1/2(ERK1/2),protein kinase B(AKT)and phosphatidylin-ositol-3-kinase(PI3K)pathways were significantly downregulated after MSC-Shh administration compared to MSC-Gfp.Brain-derived neurotrophic factor(BDNF)and ciliary neurotrophic factor(CNTF)levels were significantly increased in the host retina,and RGCs loss was significantly prevented after MSC-Shh administration.CONCLUSION:MSC-Shh administration reduces graft-induced reactive gliosis following intravitreal injection in diabetic mice.The ERK1/2,AKT and PI3K pathways are involved in this process.MSC-Shh also increases the levels of neurotrophic factors in the host retina and promoted RGCs survival in diabetic mice.
基金sponsored by the National Natural Science Foundation of China(Nos.12072285,U20B2007)the Shaanxi Science Fund for Distinguished Young Scholars,China(No.2020JC-13)the Natural Science Funding of Shaanxi Province,China(No.2020JM-127).
文摘After the last flight of the Concorde in 2003,sonic boom has been one of the obstacles to the return of a supersonic transport aircraft to service.To reduce the sonic boom intensity to an acceptable level,it is of great significance to study the effect of lift distribution on far-field sonic boom,since lift is one of the most important contributors to an intense sonic boom.Existing studies on the longitudinal lift distribution used low-fidelity methods,such as Whitham theory,and in turn,only preliminary conclusions were obtained,such as that extending the lift distribution can reduce sonic boom.This paper uses a newly developed high-fidelity prediction method to quantitatively study the effect of longitudinal lift distribution on the sonic boom of a Canard-Wing-Stabilator-Body(CWSB)configuration.This high-fidelity prediction method combines near-feld CFD simulation with far-field propagation by solving the augmented Burgers equation.A multipole analysis method is employed for the extraction of near-field waveform in order to reduce computational cost.Seven configurations with the same total lift but different distributions are studied,and the quantitative relationship between the longitudinal lift distribution and far-field sonic boom intensity is investigated.It is observed that a small lift generated by the stabilator can prevent aft-stabilator and aft-fuselage shocks from merging,while the balanced lift generated by the canard and wing can effectively keep the corresponding shocks further apart,which is beneficial for reducing both the on-track and off-track sonic boom.In turn,the acoustic level perceived at the ground can be reduced by 5.9 PLdB on-track and 5.4 PLdB off-track,on average.
基金Projects (50934006, 10872218) supported by the National Natural Science Foundation of ChinaProject (2010CB732004) supported by the National Basic Research Program of ChinaProject (kjdb2010-6) supported by Doctoral Candidate Innovation Research Support Program of Science & Technology Review, China
文摘To quantitatively study the location errors induced by deviation of sonic speed, the line and plane location tests were carried out. A broken pencil was simulated as acoustic emission source in the rocks. The line and plane location tests were carried out in the granite rod using two sensors and the cube of marble using four sensors, respectively. To compare the position accuracy between line and plane positions, the line poison test was also carried out on the marble surface. The results show that for line positioning, the maximum error of absolute distance is about 0.8 cm. With the speed difference of 200 m/s, the average value of absolute difference from the position error is about 0.4 cm. For the plane positioning, in the case of the sensor array of 30 cm, the absolute positioning distance is up to 8.7 cm. It can be seen that the sonic speed seriously impacts on the plane positioning accuracy. The plane positioning error is lager than the line positioning error, which means that when the line position can satisfy the need in practical engineering, it is better to use the line position instead of the plane location. The plane positioning error with the diagonal speed is the minimum one.
文摘目的:研究大鼠胃癌前病变形成过程中胃黏膜Sonic Hedgehog(Shh)信号通路的变化。方法:72只乳鼠随机分为正常组36只,造模组36只,雌雄各半。造模组灌服800 mg/L的1-甲基-3-硝基-1-亚硝基胍(MNNG)0.1 m L/d,正常组灌服生理盐水0.1 m L/d,共10 d。随后在实验观察第10周、22周、34周末每组分别雌雄各处死6只。HE染色检测胃黏膜组织病理学变化,q RTPCR法检测胃黏膜组织Shh、Ptch1、Smo、Gli1、Gli2、Gli3、Su Fu、Cyclin D1、Cyclin E1、c-Myc、β-actin m RNA的表达。Western blot检测胃黏膜组织Shh、Ptch1、Smo、Gli1、Su Fu、Cyclin D1、Cyclin E1、cMyc、p-c-Myc蛋白表达。结果:随造模时间的延长,模型组大鼠胃黏膜萎缩及异型增生逐渐加重,其胃黏膜内Shh、Smo、Gli1、Cyclin D1、Cyclin E1及c-Myc m RNA表达较正常组不同程度升高,而Ptch1和Su Fu m RNA不同程度降低。模型组胃黏膜内Shh、Smo、Gli1、Cyclin D1、Cyclin E1、p-c-Myc蛋白水平较正常组增加,Ptch1和Su Fu则降低,但差异无统计学意义。结论:大鼠胃癌前病变的形成过程中存在Shh信号通路的激活,提示Shh信号通路可能参与胃癌前病变的发生与发展。
