RESUMO
A novel fourth-generation nickel-based single crystal superalloy was brazed with Co-based filler alloy. The effects of post-weld heat treatment (PWHT) on the microstructure and mechanical properties of brazed joints were investigated. The experimental and CALPHAD simulation results show that the non-isothermal solidification zone was composed of M3B2, MB-type boride and MC carbide, and the isothermal solidification zone was composed of γ and γ' phases. After the PWHT, the distribution of borides and the morphology of the γ' phase were changed. The change of the γ' phase was mainly attributed to the effect of borides on the diffusion behavior of Al and Ta atoms. In the process of PWHT, stress concentration leads to the nucleation and growth of grains during recrystallization, thus forming high angle grain boundaries in the joint. The microhardness was slightly increased compared to the joint before PWHT. The relationship between microstructure and microhardness during the PWHT of the joint was discussed. In addition, the tensile strength and stress fracture life of the joints were significantly increased after the PWHT. The reasons for the improved mechanical properties of the joints were analyzed and the fracture mechanism of the joints was elucidated. These research results can provide important guidance for the brazing work of fourth-generation nickel-based single crystal superalloy.
RESUMO
In this work, the effect of the Ru element on the γ'-phase evolution and deformation mechanism in the fourth-generation Ni-based single-crystal superalloy was investigated. Results show that the Ru element alters the distribution coefficient of other elements in the alloy to produce reverse partitioning behavior, which leads to a difference in microstructure between 0Ru and 3Ru. The addition of Ru triggered the incubation period before the beginning of the primary creep stage, which depends on the creep temperature and stress during creep deformation. TEM results revealed that Ru addition inhibits the slip system {111}<112> at medium-temperature (760-1050 °C) and high-stress (270-810 MPa) creep, which brings a considerably low creep rate and high creep life to the Ru-containing alloy.
RESUMO
CD147, a type I transmembrane glycoprotein, is highly expressed in various cancer types and plays important roles in tumor progression, especially by promoting the motility and invasion of hepatocellular carcinoma (HCC) cells. These crucial roles make CD147 an attractive target for therapeutic intervention in HCC, but no small-molecule inhibitors of CD147 have been developed to date. To identify a candidate inhibitor, we used a pharmacophore model derived from the structure of CD147 to virtually screen over 300,000 compounds. The 100 highest-ranked compounds were subjected to biological assays, and the most potent one, dubbed AC-73 (ID number: AN-465/42834501), was studied further. We confirmed that AC-73 targeted CD147 and further demonstrated it can specifically disrupt CD147 dimerization. Moreover, molecular docking and mutagenesis experiments showed that the possible binding sites of AC-73 on CD147 included Glu64 and Glu73 in the N-terminal IgC2 domain, which two residues are located in the dimer interface of CD147. Functional assays revealed that AC-73 inhibited the motility and invasion of typical HCC cells, but not HCC cells that lacked the CD147 gene, demonstrating on-target action. Further, AC-73 reduced HCC metastasis by suppressing matrix metalloproteinase (MMP)-2 via down-regulation of the CD147/ERK1/2/signal transducer and activator of transcription 3 (STAT3) signaling pathway. Finally, AC-73 attenuated progression in an orthotopic nude mouse model of liver metastasis, suggesting that AC-73 or its derivatives have potential for use in HCC intervention. We conclude that the novel small-molecule inhibitor AC-73 inhibits HCC mobility and invasion, probably by disrupting CD147 dimerization and thereby mainly suppressing the CD147/ERK1/2/STAT3/MMP-2 pathways, which are crucial for cancer progression.