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In this work, X90 pipeline steel was welded by shielded metal arc welding with root and submerged arc welding with calk and cap. After that, the joint was tempered at 550 °C and 600 °C. Subsequently, the microstructure and mechanical properties were investigated by optical microscope, scanning electron microscope (SEM) and Vickers hardness tester. The fracture surface of welded joint was analyzed by SEM. The experiments show that: After high-temperature tempering treatment, the Widmanstatten structure disappears in coarse-grained region. The number of lath martensite in the original structure of the welded joint decreases, and the quantity of granular bainite increases. The acicular ferrite disappears gradually and the polygonal ferrite grains increase, and the M/A island components decompose into fine grains with the increase in tempering temperature. The mechanical properties of the joints also change and the hardness rises because of the disappearance of Widmanstatten structure improves after heat treatment, and yield strength and tensile strength of the specimens have the lowest values after tempering at 550 °C. After tempering at 600 °C, the hardness decreases and strength–ductility reaches 11,571 MPa%. The tensile fracture of 600 °C sample presents delamination and ductile fracture. Through comparative analysis, it can be concluded that the plasticity and toughness of multilayer welded joints after tempering at 600 °C is improved, and they have better comprehensive mechanical properties. [ABSTRACT FROM AUTHOR]

Genistein, a natural isoflavonoid found in soybean products, has been proposed to be associated with a lower rate of breast cancer in Asian women. Studies from our laboratory and others have shown that genistein can induce apoptosis by regulating the expression of apoptosis-related genes in breast cancer cells. However, the precise molecular mechanism(s) by which genistein induces apoptotic cell death is not clear. In order to investigate such mechanism, we tested the role of Akt and NF-?B in genistein-treated MDA-MB-231 breast cancer cells. We found that inhibition of cell growth and induction of apoptosis by genistein are partly mediated through the downregulation of Akt and NF-?B pathways. Gel shift assay showed that NF-?B DNA-binding activity in MDA-MB-231 cells transfected with Akt cDNA was induced, suggesting that there is a cross-talk between NF-?B and Akt signaling pathway. Moreover, we found that genistein could abrogate EGF and Akt induced NF-?B activation. From these results, we conclude that the inactivation of NF-?B by genistein in MDA-MB-231 breast cancer cells is partly mediated via Akt pathway, which could be useful for rational design of strategies for the prevention and/or treatment of breast cancer.Oncogene (2003) 22, 4702-4709. doi:10.1038/sj.onc.1206583 [ABSTRACT FROM AUTHOR]