The effect of melt superheating treatment on the solidification microstructure and mechanical properties of theγ'phase precipitation-strengthened K424 superalloy was investigated.Differential scanning calorimetry...The effect of melt superheating treatment on the solidification microstructure and mechanical properties of theγ'phase precipitation-strengthened K424 superalloy was investigated.Differential scanning calorimetry(DSC)experiments were conducted to explore the influence of melt treatment temperature on the undercooling of the superalloy.Additionally,pouring experiments were carried out to assess how alterations in both the temperature and duration of melt treatment impacted the grain size,secondary dendrite arm spacing(SDAS),elemental segregation,and mechanical properties of the alloy.Metallographic analysis,scanning electron microscopy,energy dispersive spectroscopy(EDS)and Thermo-Calc software were employed for microstructure characterization.The test specimens were subjected to tensile testing at room temperature and stress rupture testing at 975℃ under 196 MPa.The findings reveal that appropriate melt treatment conditions result in decreased grain size,refined SDAS,minimized elemental segregation,and significant improvements in mechanical properties.Specifically,the study demonstrates that a melt treatment at 1,650℃ for 5 min results in the smallest average grain size of 949μm and the smallest SDAS of 25.38μm.Furthermore,the room temperature tensile properties and creep resistance are notably affected by the melt treatment parameters.It is shown that specific melt treatment conditions,such as holding at 1,650℃ for 5 min,result in superior room temperature strength and extended stress rupture life of the K424 superalloy,while a balance between strength and stability is achieved at 1,600℃ with a holding time of 10 min.These findings offer guidance for optimizing the melt treatment parameters for the K424 superalloy,laying a foundation for further investigations.展开更多
Objectives:Melanoma is a highly aggressive and metastatic form of cancer,and the role of exosomal microRNAs(miRNAs)in its progression remains largely unexplored.This study aimed to investigate the effects of melanoma ...Objectives:Melanoma is a highly aggressive and metastatic form of cancer,and the role of exosomal microRNAs(miRNAs)in its progression remains largely unexplored.This study aimed to investigate the effects of melanoma cell-derived exosomal miR-424-5p on angiogenesis and its underlying mechanisms.Methods:Exosomes were isolated from melanoma cell lines A375 and A2058,and their effects on the proliferation,migration,and angiogenesis of human umbilical vein endothelial cells(HUVECs)were examined.The interaction between miR-424-5p and its target gene,large tumor suppressor kinase 2(LATS2),was analyzed using luciferase reporter assays and functional experiments.In vivo,tumor growth and angiogenesis were studied in a xenograft model using nude mice.Results:Melanoma cell-derived exosomes could be internalized by HUVECs,which promoted proliferation,migration,and angiogenesis.miR-424-5p was highly expressed in melanoma cells and their exosomes,and its inhibition in exosomes suppressed HUVEC proliferation,migration,and angiogenesis.LATS2 was identified as a direct target of miR-424-5p,and its silencing reversed the inhibitory effects of miR-424-5p inhibition on HUVEC functions.In vivo,exosomes derived from miR-424-5p-inhibited melanoma cells suppressed tumor growth and angiogenesis in xenograft models.Conclusions:Melanoma cell-derived exosomal miR-424-5p promotes angiogenesis by targeting LATS2,contributing to melanoma progression.Targeting the exosomal miR-424-5p/LATS2 axis could be a potential therapeutic strategy for melanoma.展开更多
基金financially supported by the Natural Science Foundation Joint Fund of Liaoning Province,China(No.2023-MSLH-342).
文摘The effect of melt superheating treatment on the solidification microstructure and mechanical properties of theγ'phase precipitation-strengthened K424 superalloy was investigated.Differential scanning calorimetry(DSC)experiments were conducted to explore the influence of melt treatment temperature on the undercooling of the superalloy.Additionally,pouring experiments were carried out to assess how alterations in both the temperature and duration of melt treatment impacted the grain size,secondary dendrite arm spacing(SDAS),elemental segregation,and mechanical properties of the alloy.Metallographic analysis,scanning electron microscopy,energy dispersive spectroscopy(EDS)and Thermo-Calc software were employed for microstructure characterization.The test specimens were subjected to tensile testing at room temperature and stress rupture testing at 975℃ under 196 MPa.The findings reveal that appropriate melt treatment conditions result in decreased grain size,refined SDAS,minimized elemental segregation,and significant improvements in mechanical properties.Specifically,the study demonstrates that a melt treatment at 1,650℃ for 5 min results in the smallest average grain size of 949μm and the smallest SDAS of 25.38μm.Furthermore,the room temperature tensile properties and creep resistance are notably affected by the melt treatment parameters.It is shown that specific melt treatment conditions,such as holding at 1,650℃ for 5 min,result in superior room temperature strength and extended stress rupture life of the K424 superalloy,while a balance between strength and stability is achieved at 1,600℃ with a holding time of 10 min.These findings offer guidance for optimizing the melt treatment parameters for the K424 superalloy,laying a foundation for further investigations.
基金Natural Science Foundation of Xinjiang Uygur Autonomous Region(2022D01C803).
文摘Objectives:Melanoma is a highly aggressive and metastatic form of cancer,and the role of exosomal microRNAs(miRNAs)in its progression remains largely unexplored.This study aimed to investigate the effects of melanoma cell-derived exosomal miR-424-5p on angiogenesis and its underlying mechanisms.Methods:Exosomes were isolated from melanoma cell lines A375 and A2058,and their effects on the proliferation,migration,and angiogenesis of human umbilical vein endothelial cells(HUVECs)were examined.The interaction between miR-424-5p and its target gene,large tumor suppressor kinase 2(LATS2),was analyzed using luciferase reporter assays and functional experiments.In vivo,tumor growth and angiogenesis were studied in a xenograft model using nude mice.Results:Melanoma cell-derived exosomes could be internalized by HUVECs,which promoted proliferation,migration,and angiogenesis.miR-424-5p was highly expressed in melanoma cells and their exosomes,and its inhibition in exosomes suppressed HUVEC proliferation,migration,and angiogenesis.LATS2 was identified as a direct target of miR-424-5p,and its silencing reversed the inhibitory effects of miR-424-5p inhibition on HUVEC functions.In vivo,exosomes derived from miR-424-5p-inhibited melanoma cells suppressed tumor growth and angiogenesis in xenograft models.Conclusions:Melanoma cell-derived exosomal miR-424-5p promotes angiogenesis by targeting LATS2,contributing to melanoma progression.Targeting the exosomal miR-424-5p/LATS2 axis could be a potential therapeutic strategy for melanoma.
