Al-3Ti-1B master alloys were prepared at different processing parameters by the reaction of halide salts,and the grain refining response of Al-7Si alloy was investigated with Al-3Ti-B master alloy.The microstructure o...Al-3Ti-1B master alloys were prepared at different processing parameters by the reaction of halide salts,and the grain refining response of Al-7Si alloy was investigated with Al-3Ti-B master alloy.The microstructure of master alloy and its grain refining effect on Al-7Si alloy were investigated by means of OM,XRD and SEM.Experimental results show that,the size of Al3Ti particles presented in Al-3Ti-1B master alloys increases with the increase of reaction temperature and decreases with the increase of cooling rate.The grain refining efficiency of Al-3Ti-1B master alloy on Al-7Si alloy is mainly attributed to heterogeneous nucleation of Al3Ti particles,and the morphology ofα(Al)changes from coarse dendritic to fine equiaxed.As a result,Al-3Ti-1B master alloy is prepared by permanent mold,and holding at 800 ℃for 30min,which has better grain refining performance on Al-7Si alloy.展开更多
背景:诱导骨髓基质干细胞成骨条件的优化与探讨是再生医学研究的热点。前期实验发现Wnt7b在骨发育中的作用,此次实验是前期工作的延续。目的:构建Wnt7b重组反转录病毒载体,观察其在C3H10T1/2中的表达。设计、时间及地点:细胞学体外观察,...背景:诱导骨髓基质干细胞成骨条件的优化与探讨是再生医学研究的热点。前期实验发现Wnt7b在骨发育中的作用,此次实验是前期工作的延续。目的:构建Wnt7b重组反转录病毒载体,观察其在C3H10T1/2中的表达。设计、时间及地点:细胞学体外观察,于2005-01/2008-08在华盛顿大学医学院和同济大学附属第十人民医院中心实验室完成。材料:pXy-Wnt7b购于ATCC公司,载体pCIG-IRES-EGFP,pLef-Luciferase,pCMV-Rennilla,反转录病毒载体pSFG和包装细胞GP293由华盛顿大学医学院提供。方法:用多步亚克隆技术构建目的基因Wnt7b和标记基因加强型绿色荧光蛋白(enhanced green fluorescent protein,EGFP)双表达重组反转录病毒载体pSFG-Wnt7b-IRES-EGFP,在条件培养液中经GP293包装,并在常规培养液中释放出假病毒并将其转染C3H10T1/2细胞,检测成骨活性诱导中的作用和荧光素酶报告基因检测信号转导通路。主要观察指标:①Wnt7b重组反转录病毒转染C3H10T1/2细胞的表达。②Wnt7b诱导C3H10T1/2碱性磷酸酶生成分析。③Wnt7b信号转导分析。结果:构建目的基因的Wnt7b和标记基因EGFP双表达重组反转录病毒载体能够高效地表达,转染C3H10T1/2细胞后能诱导碱性磷酸酶的生成。Wnt7b信号转导分析可见Wnt7b成骨作用通过Noncanonical途径。结论:Wnt7b在C3H10T1/2中能高效表达,能显著诱导骨发育的重要标志--碱性磷酸酶的生成,Noncanonical途径在其中起重要作用。展开更多
文摘Al-3Ti-1B master alloys were prepared at different processing parameters by the reaction of halide salts,and the grain refining response of Al-7Si alloy was investigated with Al-3Ti-B master alloy.The microstructure of master alloy and its grain refining effect on Al-7Si alloy were investigated by means of OM,XRD and SEM.Experimental results show that,the size of Al3Ti particles presented in Al-3Ti-1B master alloys increases with the increase of reaction temperature and decreases with the increase of cooling rate.The grain refining efficiency of Al-3Ti-1B master alloy on Al-7Si alloy is mainly attributed to heterogeneous nucleation of Al3Ti particles,and the morphology ofα(Al)changes from coarse dendritic to fine equiaxed.As a result,Al-3Ti-1B master alloy is prepared by permanent mold,and holding at 800 ℃for 30min,which has better grain refining performance on Al-7Si alloy.
文摘背景:诱导骨髓基质干细胞成骨条件的优化与探讨是再生医学研究的热点。前期实验发现Wnt7b在骨发育中的作用,此次实验是前期工作的延续。目的:构建Wnt7b重组反转录病毒载体,观察其在C3H10T1/2中的表达。设计、时间及地点:细胞学体外观察,于2005-01/2008-08在华盛顿大学医学院和同济大学附属第十人民医院中心实验室完成。材料:pXy-Wnt7b购于ATCC公司,载体pCIG-IRES-EGFP,pLef-Luciferase,pCMV-Rennilla,反转录病毒载体pSFG和包装细胞GP293由华盛顿大学医学院提供。方法:用多步亚克隆技术构建目的基因Wnt7b和标记基因加强型绿色荧光蛋白(enhanced green fluorescent protein,EGFP)双表达重组反转录病毒载体pSFG-Wnt7b-IRES-EGFP,在条件培养液中经GP293包装,并在常规培养液中释放出假病毒并将其转染C3H10T1/2细胞,检测成骨活性诱导中的作用和荧光素酶报告基因检测信号转导通路。主要观察指标:①Wnt7b重组反转录病毒转染C3H10T1/2细胞的表达。②Wnt7b诱导C3H10T1/2碱性磷酸酶生成分析。③Wnt7b信号转导分析。结果:构建目的基因的Wnt7b和标记基因EGFP双表达重组反转录病毒载体能够高效地表达,转染C3H10T1/2细胞后能诱导碱性磷酸酶的生成。Wnt7b信号转导分析可见Wnt7b成骨作用通过Noncanonical途径。结论:Wnt7b在C3H10T1/2中能高效表达,能显著诱导骨发育的重要标志--碱性磷酸酶的生成,Noncanonical途径在其中起重要作用。