Ni-based alloy was transient liquid phase bonded using a BNi-2 interlayer. The effect of bonding parameters on the microstructures and mechanical properties of the joints was investigated. With the increase of bonding...Ni-based alloy was transient liquid phase bonded using a BNi-2 interlayer. The effect of bonding parameters on the microstructures and mechanical properties of the joints was investigated. With the increase of bonding temperature or time, the number of Ni-rich and Cr-rich borides and the grain size of precipitation zone decrease. Higher bonding temperature or longer bonding time is beneficial to the diffusion of melting point depressant elements （B and Si） from the PZ to the base metal and atomic interdiffusion between the base metal and the joint. The chemical composition and microstructure of the joints bonded at 1170 ℃ for 24 h are comparable to the base metal. The shear test results show that both the room and elevated temperature shear-strengths of the joints increase with increasing bonding time. However, the effect of bonding time on elevated temperature tensile-shear strength is greater than on room temperature tensile-shear strength.展开更多
Diffusion bonding of TC21 titanium alloy was carried out at temperature ranging from 780 ℃ to 980 ℃ for 5-90 min.The interfacial bonding ratio,deformation ratio,microstructures and microhardness of the diffusion bon...Diffusion bonding of TC21 titanium alloy was carried out at temperature ranging from 780 ℃ to 980 ℃ for 5-90 min.The interfacial bonding ratio,deformation ratio,microstructures and microhardness of the diffusion bonded joints were investigated.Results show that joints with high bonding quality can be obtained when bonded at 880 ℃ for 15？30 min.The microhardness increases with increasing the bonding temperature,while it has a peak value（HV367） when bonding time is prolonged up to 90 min.Fully equiaxed microstructures,bi-modal microstructures and fully lamellar microstructures were observed when bonded in temperature range of 780-880 ℃,at 930 ℃ or 980 ℃,respectively.The volume fraction of α phase first increases and achieves the maximum when bonded at 880 ℃ for 60 min,and then descended.展开更多
Upon growth factor stimulation, the scaffold protein, Gabl, is tyrosine phosphorylated and subsequently the adaptor protein, Crk, transmits signals from Gabl. We have previously shown that Crk overexpression, which is...Upon growth factor stimulation, the scaffold protein, Gabl, is tyrosine phosphorylated and subsequently the adaptor protein, Crk, transmits signals from Gabl. We have previously shown that Crk overexpression, which is detectable in various human cancers, induces tyrosine phosphorylation of Gabl without extracellular stimuli. In the present study, the underlying mechanisms were further investigated. Mutational analyses of CrkII demonstrated that the SH2 domain, but not the SH3（N） or the regulatory Y221 residue of CrkII, is critical for the induction of Gabl- Y307 phosphorylation. SH2 mutation of CrkII also decreased the interaction with Gabl. In GST pull-down assay, Crk-SH2 bound to wild-type Gahl, whereas Crk-SH3（N） interacted with the Gabl mutant, which lacks the clus- tered tyrosine region （residues 242-410）. Tyrosine phosphorylation of Gabl was induced by all Crk family proteins, but not other SH2-containing signalling adaptors. Src-family kinase inhibitor, PP2, abrogates Crk-induced tyrosine phosphorylations of Gabl. Y307 phosphorylation was undetectable in fibroblasts lacking Src, Yes, and Fyn, even upon overexpression of Crk, whereas cells lacking only Yes and Fyn still contained Gabl with phosphorylated Y307. Furthermore, Crk induced the phosphorylation of Src-Y416; accordingly the interaction between Crk and Csk was increased. The Gabl-Y307F mutant failed to localize near the plasma membrane even upon HGF stimulation and decreased cell migration. Moreover, Gabl-Y307F disturbed the localization of Crk, FAK, and paxillin, which are the typical components of focal adhesions. Taken together, these results indicate that Crk facilitates tyrosine phosphory- lation of Gabl-Y307 through Src, contributing to the organization of focal adhesions and enhanced cell migration, thereby possibly promoting human cancer development.展开更多
The dissimilar joining of CP-copper to 304 stainless steel was performed by gas tungsten arc welding process using different filler materials. The results indicated the formation of defect free joint by using copper f...The dissimilar joining of CP-copper to 304 stainless steel was performed by gas tungsten arc welding process using different filler materials. The results indicated the formation of defect free joint by using copper filler material. But, the presence of some defects like solidification crack and lack of fusion caused decreasing tensile strength of other joints. In the optimum conditions, the tensile strength of the joint was 96% of the weaker material. Also, this joint was bent till to 180° without any macroscopic defects like separation, tearing or fracture. It was concluded that copper is a new and good candidate for gas tungsten arc welding of copper to 304 stainless steel.展开更多
Defect-free butt joints of 3003 Al alloy to mild steel plates with 3 mm thickness were performed using friction stir welding （FSW）. A heat input model reported for similar FSW was simplified and used to investigate ...Defect-free butt joints of 3003 Al alloy to mild steel plates with 3 mm thickness were performed using friction stir welding （FSW）. A heat input model reported for similar FSW was simplified and used to investigate the effects of welding speed, rotation speed and tool shoulder diameter on the microstructure and properties of dissimilar welds. The comparison between microstructure, intermetallics and strength of welds shows the good conformity between the results and the calculated heat input factor （HIF） achieved from the model. The joint strength is controlled by Al/Fe interface at HIF of 0.2-0.4, by TMAZ at HIF of 0.4-0.8 and by intermetallics and/or defects at HIF0.8.展开更多
The Ti−6Al−4V(TC4)alloy powder and forged solid were diffusion bonded by hot isostatic pressing(HIP)to fabricate a powder−solid part.The microstructure of the powder−solid part was observed by scanning electron micros...The Ti−6Al−4V(TC4)alloy powder and forged solid were diffusion bonded by hot isostatic pressing(HIP)to fabricate a powder−solid part.The microstructure of the powder−solid part was observed by scanning electron microscope(SEM).The microhardness and tensile tests were conducted to investigate the mechanical properties.The results showed that the powder compact was near-fully dense,and the powder/solid interface was tight and complete.The microhardness of the interface was higher than that of the powder compact and solid.The fractures of all powder−solid tensile specimens were on the solid side rather than at the interface,which indicated that a good interfacial strength was obtained.The tensile strength and elongation of the powder compact were higher than those of the solid.It is concluded that the HIP process can successfully fabricate high-quality Ti−6Al−4V powder−solid parts,which provides a novel near net shape technology for titanium alloys.展开更多
In order to investigate the regulatory role of connective tissue growth factor （CTGF） on production of RANTES （regulated on activation, normal T cell expressed and secreted） in rat glomerular mesangial cells, and ...In order to investigate the regulatory role of connective tissue growth factor （CTGF） on production of RANTES （regulated on activation, normal T cell expressed and secreted） in rat glomerular mesangial cells, and the modulatory effect of lipoxin A4 （ LXA4 ） on action of CTGF, and to explore the mechanisms of action of CTGF and LXA4, cultured rat mesangial cells were treated with CTGF, with or without preincubation with LXA4. Expression of mRNA was analyzed by RT-PCR. Protein of RANTES in the supematants was determined by ELISA. Monocyte transmigration was assessed by in vitro chemotaxis assay. Expression of p42/44 mitogen-activated protein kinase （MAPK）, phosphoinositide 3-kinase （ PI3- K） and protein kinase B （PKB） was assessed by Western blotting. DNA-binding activity of nuclear factor-roB （NF-kB） was determined by electrophoretic mobility shift assay （EMSA）. To observe whether transfection of LXA4 receptor homologue gene （LRHg） into mesangial cells intensified these modulatory effects of LXA4, mesangial cells were transfected with pcDNA3.1/LRHG vector. The results showed that CTGF enhanced the mRNA expression and protein release of RANTES, and the expression of phospho （P）-p42/44 MAPK, P-PI3-K, P-PKB and NF-kB. P-p42/44 MAPK blockade inhibited the CTgF-induced expression of P-p42/44 MAPK and partially decreased the level of RANTES in supematants. P- PI3-K blockade downregulated the CTGF-stimulated expression of P-PI3-K, P-PKB and NF-kB, and partially decreased the release of RANTES. NF-kB blockade abrogated the CTGF-activated NF-kB and partially decreased the secretion of RANTES. LXA4 dose-dependently inhibited the CTGF-stimulated above action. Transfection of LRHG into mesangial cells intensified these inhibitory effects of LXA4 on CTGFinduced release of RANTES and expression of the P-p42/44 MAPK. In conclusion, LXA4 inhibits CTGFinduced production of RANTES via PI3-K/PKB/NF-kB and p42/44 MAPK-dependent signal pathway, which is mediated by LRHG in rat mesangial cells.展开更多
基金Projects (50975062, 51105107, 51275135, 51021002) supported by the National Natural Science Foundation of ChinaProject (QC2011C044) supported by the Natural Science Foundation of Heilongjiang Province, China+1 种基金Project (20112302130005) supported by Specialized Research Fund for the Doctoral Program of Higher Education, ChinaProject (20100471027) supported by the Postdoctoral Science Foundation of China
文摘Ni-based alloy was transient liquid phase bonded using a BNi-2 interlayer. The effect of bonding parameters on the microstructures and mechanical properties of the joints was investigated. With the increase of bonding temperature or time, the number of Ni-rich and Cr-rich borides and the grain size of precipitation zone decrease. Higher bonding temperature or longer bonding time is beneficial to the diffusion of melting point depressant elements （B and Si） from the PZ to the base metal and atomic interdiffusion between the base metal and the joint. The chemical composition and microstructure of the joints bonded at 1170 ℃ for 24 h are comparable to the base metal. The shear test results show that both the room and elevated temperature shear-strengths of the joints increase with increasing bonding time. However, the effect of bonding time on elevated temperature tensile-shear strength is greater than on room temperature tensile-shear strength.
基金Project(2010CB731704)supported by the National Basic Research Program of Chinathe Northwest Institute for Non-ferrous Metal Research of China for the support
文摘Diffusion bonding of TC21 titanium alloy was carried out at temperature ranging from 780 ℃ to 980 ℃ for 5-90 min.The interfacial bonding ratio,deformation ratio,microstructures and microhardness of the diffusion bonded joints were investigated.Results show that joints with high bonding quality can be obtained when bonded at 880 ℃ for 15？30 min.The microhardness increases with increasing the bonding temperature,while it has a peak value（HV367） when bonding time is prolonged up to 90 min.Fully equiaxed microstructures,bi-modal microstructures and fully lamellar microstructures were observed when bonded in temperature range of 780-880 ℃,at 930 ℃ or 980 ℃,respectively.The volume fraction of α phase first increases and achieves the maximum when bonded at 880 ℃ for 60 min,and then descended.
基金Acknowledgments We thank M Hamaguchi （Nagoya Univ., Japan） and T Iwahara （Osaka Bioscience Institute, Japan） forJak null MEFs, and N Gotoh （Tokyo Univ., Japan）, H Higashi （Hokkaido Univ., Japan）, N Mochizuki （National Cardiovascular Cent. Res. Inst., Japan）, H Hanafusa （Prof. emeritus, The Rockefeller Univ., USA and Direc- tor em., OBI, Japan）, SK Hanks （Vanderbilt Univ., USA）, and M Matsuda （Kyoto Univ., Japan） for plasmids. We also thank K Sasai （Hokkaido Univ., Japan） and Y Ohba （Hokkaido Univ., Japan） for valuable discussion. This work was supported in part by grants-in- aid from the Ministry of Education, Science, Culture, and Sports, and the Ministry of Health, Labor, and Welfare, Japan, as well as Suhara Memorial Foundation （Sapporo, Japan）, and the Mochida Medical Science Foundation （Tokyo, Japan）. The work of SF and TK is supported by grants from Cancer Research UK and the Brit- ish Cancer Charity ＂Heads Up＂. We dedicate this work to our great mentor Hidesaburo Hana- fusa, professor emeritus of the Rockefeller University, who passed away on March 15, 2009 at the age of 79. He devoted his life to science and in particular to creating the oncogene research field, to teaching and to providing profound affection to his students and postdocs. All of the alumni of Saburo＇s laboratory pride them- selves in having been his apprentices and we would like to hereby express our deeply felt gratitude to Saburo.
文摘Upon growth factor stimulation, the scaffold protein, Gabl, is tyrosine phosphorylated and subsequently the adaptor protein, Crk, transmits signals from Gabl. We have previously shown that Crk overexpression, which is detectable in various human cancers, induces tyrosine phosphorylation of Gabl without extracellular stimuli. In the present study, the underlying mechanisms were further investigated. Mutational analyses of CrkII demonstrated that the SH2 domain, but not the SH3（N） or the regulatory Y221 residue of CrkII, is critical for the induction of Gabl- Y307 phosphorylation. SH2 mutation of CrkII also decreased the interaction with Gabl. In GST pull-down assay, Crk-SH2 bound to wild-type Gahl, whereas Crk-SH3（N） interacted with the Gabl mutant, which lacks the clus- tered tyrosine region （residues 242-410）. Tyrosine phosphorylation of Gabl was induced by all Crk family proteins, but not other SH2-containing signalling adaptors. Src-family kinase inhibitor, PP2, abrogates Crk-induced tyrosine phosphorylations of Gabl. Y307 phosphorylation was undetectable in fibroblasts lacking Src, Yes, and Fyn, even upon overexpression of Crk, whereas cells lacking only Yes and Fyn still contained Gabl with phosphorylated Y307. Furthermore, Crk induced the phosphorylation of Src-Y416; accordingly the interaction between Crk and Csk was increased. The Gabl-Y307F mutant failed to localize near the plasma membrane even upon HGF stimulation and decreased cell migration. Moreover, Gabl-Y307F disturbed the localization of Crk, FAK, and paxillin, which are the typical components of focal adhesions. Taken together, these results indicate that Crk facilitates tyrosine phosphory- lation of Gabl-Y307 through Src, contributing to the organization of focal adhesions and enhanced cell migration, thereby possibly promoting human cancer development.
文摘The dissimilar joining of CP-copper to 304 stainless steel was performed by gas tungsten arc welding process using different filler materials. The results indicated the formation of defect free joint by using copper filler material. But, the presence of some defects like solidification crack and lack of fusion caused decreasing tensile strength of other joints. In the optimum conditions, the tensile strength of the joint was 96% of the weaker material. Also, this joint was bent till to 180° without any macroscopic defects like separation, tearing or fracture. It was concluded that copper is a new and good candidate for gas tungsten arc welding of copper to 304 stainless steel.
文摘Defect-free butt joints of 3003 Al alloy to mild steel plates with 3 mm thickness were performed using friction stir welding （FSW）. A heat input model reported for similar FSW was simplified and used to investigate the effects of welding speed, rotation speed and tool shoulder diameter on the microstructure and properties of dissimilar welds. The comparison between microstructure, intermetallics and strength of welds shows the good conformity between the results and the calculated heat input factor （HIF） achieved from the model. The joint strength is controlled by Al/Fe interface at HIF of 0.2-0.4, by TMAZ at HIF of 0.4-0.8 and by intermetallics and/or defects at HIF0.8.
基金the National Natural Science Foundation of China(No.51675029).
文摘The Ti−6Al−4V(TC4)alloy powder and forged solid were diffusion bonded by hot isostatic pressing(HIP)to fabricate a powder−solid part.The microstructure of the powder−solid part was observed by scanning electron microscope(SEM).The microhardness and tensile tests were conducted to investigate the mechanical properties.The results showed that the powder compact was near-fully dense,and the powder/solid interface was tight and complete.The microhardness of the interface was higher than that of the powder compact and solid.The fractures of all powder−solid tensile specimens were on the solid side rather than at the interface,which indicated that a good interfacial strength was obtained.The tensile strength and elongation of the powder compact were higher than those of the solid.It is concluded that the HIP process can successfully fabricate high-quality Ti−6Al−4V powder−solid parts,which provides a novel near net shape technology for titanium alloys.
文摘In order to investigate the regulatory role of connective tissue growth factor （CTGF） on production of RANTES （regulated on activation, normal T cell expressed and secreted） in rat glomerular mesangial cells, and the modulatory effect of lipoxin A4 （ LXA4 ） on action of CTGF, and to explore the mechanisms of action of CTGF and LXA4, cultured rat mesangial cells were treated with CTGF, with or without preincubation with LXA4. Expression of mRNA was analyzed by RT-PCR. Protein of RANTES in the supematants was determined by ELISA. Monocyte transmigration was assessed by in vitro chemotaxis assay. Expression of p42/44 mitogen-activated protein kinase （MAPK）, phosphoinositide 3-kinase （ PI3- K） and protein kinase B （PKB） was assessed by Western blotting. DNA-binding activity of nuclear factor-roB （NF-kB） was determined by electrophoretic mobility shift assay （EMSA）. To observe whether transfection of LXA4 receptor homologue gene （LRHg） into mesangial cells intensified these modulatory effects of LXA4, mesangial cells were transfected with pcDNA3.1/LRHG vector. The results showed that CTGF enhanced the mRNA expression and protein release of RANTES, and the expression of phospho （P）-p42/44 MAPK, P-PI3-K, P-PKB and NF-kB. P-p42/44 MAPK blockade inhibited the CTgF-induced expression of P-p42/44 MAPK and partially decreased the level of RANTES in supematants. P- PI3-K blockade downregulated the CTGF-stimulated expression of P-PI3-K, P-PKB and NF-kB, and partially decreased the release of RANTES. NF-kB blockade abrogated the CTGF-activated NF-kB and partially decreased the secretion of RANTES. LXA4 dose-dependently inhibited the CTGF-stimulated above action. Transfection of LRHG into mesangial cells intensified these inhibitory effects of LXA4 on CTGFinduced release of RANTES and expression of the P-p42/44 MAPK. In conclusion, LXA4 inhibits CTGFinduced production of RANTES via PI3-K/PKB/NF-kB and p42/44 MAPK-dependent signal pathway, which is mediated by LRHG in rat mesangial cells.
