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The semi-solid slurry of 6061 aluminum alloy was prepared by the serpentine channel pouring process. The influence of graphite serpentine channel and copper serpentine channel on the slurry was comparative analyzed. The effect of pouring temperature on the slurry microstructure was also investigated. The results indicate that both copper and graphite serpentine channel can be used to prepare semi-solid slurry with spherical primary grains. Compared with a permanent casting, the microstructure of the semi-solid slurry was significantly improved and refined. With the increase of pouring temperature, the average equivalent grain diameter of the primary phase grains in the semi-solid slurry increases gradually, but the shape factor decreases gradually. When the pouring temperature increased from 675 °C to 690 °C, a high quality semi-solid slurry can be obtained. Comparing the two kinds of serpentine channel, it is found that the copper serpentine channel can make the primary grains finer, and the average equivalent grain size was 63 μm. However, the solidified shell near the inner graphite serpentine channel surface was thinner than that of the copper serpentine channel. In conclusion, the graphite serpentine channel is more suitable for preparing semi-solid 6061 aluminum alloy slurry.

Semi-solid 6061 aluminum alloy slurry was prepared by a graphite serpentine channel and its rheo-diecasting experiment was carried out on the slurry. The influence of pouring temperature on the microstructure evolution and mechanical properties of the rheo-diecasting were investigated. The microstructure and fracture mechanism of traditional die cast tensile specimens and rheo-diecast tensile specimens were compared and investigated. The results indicate that the microstructure of rheo-diecast tensile specimens is composed of spherical primary α-Al grains and fine secondary solidified α2-Al grains. When the pouring temperature increased from 660 °C to 720 °C, the average equivalent grain diameter of primary α-Al grains increased from 42 μm to 58 μm, and the shape factor decreased from 0.82 to 0.73. As the pouring temperature increases, the as-cast tensile strength and elongation of tensile specimens both increase first and then decrease. When the pouring temperature was 690 °C, the best mechanical properties were obtained, with as-cast tensile strength of 142.93 MPa and as-cast elongation of 4.86%. The fracture mechanism of traditional die casting is mainly ductile fracture, and the fracture mechanism of rheo-diecasting is a mixed fracture of intergranular fracture and ductile fracture.

s: The semi-solid slurry of Al-25%Si hypereutectic aluminum alloy was prepared through a copper serpentine pouring channel, the effect of pouring temperature and numbers of channel bend on the slurry microstructure was investigated. The results show that the primary silicon grains in Al-25%Si hypereutectic alloy solidified at a traditional condition are very large and the average silicon grain size is about 65.3μm, however, when the liquid Al-25%Si alloy is poured through a copper serpentine pouring channel, the primary silicon grains are fined obviously. If the channel has three bends and the pouring temperature is 747°C,the average silicon grain size in the slurry is about 33.7μm. If the channel has four bends and the pouring temperature is 747°C, the average silicon grain size in the slurry is about 30.9μm. If the channel has seven bends and the pouring temperature is 747°C, the average silicon grain size in the slurry is about 28.6μm. The analysis shows that the chilling effect of the inner channel wall precipitates primary silicon nuclei, and so the primary silicon grains of Al-25%Si alloy are fined greatly. Meanwhile, the subsequent washing of the alloy melt also promotes the separation of primary silicon grains from the inner wall and the primary silicon grains are further fined. The above research work demonstrates eventually that the copper serpentine pouring channel process is a good method for fining the primary silicon grains in hypereutectic Al-25%Si alloy rather than using chemical fining agent phosphorus as in traditional process.

In order to study the possibility of refining the primary silicon grains in the microstructure of hypereutectic Al-Si alloy through a serpentine pouring channel, the semi-solid slurry of A390 aluminum alloy was prepared through a water-cooled copper serpentine pouring channel, which is a new method proposed recently for semi-solid forming process, and the effect of pouring temperature on the slurry microstructure was investigated. The results show that the slurry of A390 aluminum alloy with refined primary silicon grains can be prepared under given conditions and especially when the pouring temperatures is 690°C, the primary silicon grains can be refined obviously, the equivalent silicon grain size is 19.7mm and the average shape factor is about 0.7. The analysis shows that the chilling effect of the inner channel wall precipitates a large number of primary silicon nuclei, and so the primary silicon grains are refined greatly. Meanwhile, the subsequent alloy melt washing also promotes the separation of primary silicon grains from the inner wall and the primary silicon grains are further refined. The work undertaken demonstrates eventually that the serpentine pouring channel process is a good method for refining the primary silicon grains in hypereutectic A390 alloy rather than using chemical fining agent phosphorus as in traditional process, and provides an alternative process choice.

E2F8, one of the E2F transcription factor family members, has been demonstrated to be involved in the development and progression of several human cancers; however, the physiological and functional roles of E2F8 in colorectal cancer are not fully elucidated.Our results suggest that E2F8 expression is induced in several colon cancer cell lines. The forced downregulation of E2F8 expression inhibits the growth of colon cancer cells. Our findings indicate that knocking down E2F8 can suppress nuclear factor kappa B (NF-κB) activation. We further determine that knocking down E2F8 decreased the expression of cell cycle regulators.These results demonstrate that E2F8 modulates the growth of human colon cancer cells through promoting the NF-κB pathway.