Ni catalysts supported on Al2O3, ZrO2-Al2O3, CeO2-Al2O3 and ZrO2-CeO2-Al2O3 were prepared by coprecipitation method, and their catalytic performances for autothermal reforming of methane to hydrogen were investigated....Ni catalysts supported on Al2O3, ZrO2-Al2O3, CeO2-Al2O3 and ZrO2-CeO2-Al2O3 were prepared by coprecipitation method, and their catalytic performances for autothermal reforming of methane to hydrogen were investigated. The Ni-supported catalysts were characterized by XRD, TPR and XPS. The relationship between the structures and catalytic activities of the catalysts was discussed. The results showed that the catalytic activity and stability of the Ni/ZrO2-CeO2-Al2O3 catalyst was better than those of other catalysts with the highest CH4 conversion, H2/CO and H2/COx ratio at 750 ℃. The catalyst showed a little deactivation along the reaction time during its 72 h on stream with the mean deactivation rate of 0.08%/h. The catalytic performance of the Ni/ZrO2-CeO2-Al2O3 catalyst was also affected by reaction temperature, no2 ： nCH4 molar ratio and nH2O ： nCH4 molar ratio. TPR, XRD and XPS measurements indicated that the formation of ZrO2-CeO2 solid solution could improve the dispersion of NiO, and inhibit the formation of NiAl2O3, and thus significantly promoted the catalytic activity of the Ni/ZrO2-CeO2-Al2O3 catalyst.展开更多
Sall4 as one of the spalt family members contains several alternative splicing variants, which are differentially expressed and has a key role in maintaining pluripotent stem cells. However, the molecular features and...Sall4 as one of the spalt family members contains several alternative splicing variants, which are differentially expressed and has a key role in maintaining pluripotent stem cells. However, the molecular features and function of SALL4 have not been well elucidated in porcine induced pluripotent stem cells(piPSCs). In this study, we identi?ed SALL4 splice variants and found two SALL4 splicing variants through analysis of the porcine transcriptome data derived from piPSCs. SALL4 A was only detected in piPSCs but SALL4 B was globally expressed in porcine tissues and piPSCs. The level of SALL4 B was signi?cantly reduced when piPSCs differentiation occurred, however, the expression of SALL4 A was not affected, indicating that SALL4 B may be essential for the maintenance of piPSCs self-renewal. Overexpression of SALL4 A and SALL4 B in PEF cells could signi?cantly stimulated expression of endogenous pluripotent genes,when SALL4 B signi?cantly promoted OCT4 expression.Conversely, SALL4 A signi?cantly promoted KLF4 expression. Additionally, both SALL4 A and SALL4 B could repress OTX2 promoter activity in a dose-dependent manner. Conversely, OTX2 also negatively regulated SALL4 expression. These observations indicate that a negative feedback regulatory mechanism may exist between SALL4 and OTX2, which is useful for the maintenance of the self-renewal of piPSCs.展开更多
基金supported by Guangdong Provincial Natural Science Foundation of China(030514)Science and Technology Plan of Guangdong Province of China(2004B33401006)Doctoral Startup Foundation of Guang Dong Pharmaceutical University.
文摘Ni catalysts supported on Al2O3, ZrO2-Al2O3, CeO2-Al2O3 and ZrO2-CeO2-Al2O3 were prepared by coprecipitation method, and their catalytic performances for autothermal reforming of methane to hydrogen were investigated. The Ni-supported catalysts were characterized by XRD, TPR and XPS. The relationship between the structures and catalytic activities of the catalysts was discussed. The results showed that the catalytic activity and stability of the Ni/ZrO2-CeO2-Al2O3 catalyst was better than those of other catalysts with the highest CH4 conversion, H2/CO and H2/COx ratio at 750 ℃. The catalyst showed a little deactivation along the reaction time during its 72 h on stream with the mean deactivation rate of 0.08%/h. The catalytic performance of the Ni/ZrO2-CeO2-Al2O3 catalyst was also affected by reaction temperature, no2 ： nCH4 molar ratio and nH2O ： nCH4 molar ratio. TPR, XRD and XPS measurements indicated that the formation of ZrO2-CeO2 solid solution could improve the dispersion of NiO, and inhibit the formation of NiAl2O3, and thus significantly promoted the catalytic activity of the Ni/ZrO2-CeO2-Al2O3 catalyst.
基金supported by the National Natural Science Foundation of China (31571521 and 31371505)
文摘Sall4 as one of the spalt family members contains several alternative splicing variants, which are differentially expressed and has a key role in maintaining pluripotent stem cells. However, the molecular features and function of SALL4 have not been well elucidated in porcine induced pluripotent stem cells(piPSCs). In this study, we identi?ed SALL4 splice variants and found two SALL4 splicing variants through analysis of the porcine transcriptome data derived from piPSCs. SALL4 A was only detected in piPSCs but SALL4 B was globally expressed in porcine tissues and piPSCs. The level of SALL4 B was signi?cantly reduced when piPSCs differentiation occurred, however, the expression of SALL4 A was not affected, indicating that SALL4 B may be essential for the maintenance of piPSCs self-renewal. Overexpression of SALL4 A and SALL4 B in PEF cells could signi?cantly stimulated expression of endogenous pluripotent genes,when SALL4 B signi?cantly promoted OCT4 expression.Conversely, SALL4 A signi?cantly promoted KLF4 expression. Additionally, both SALL4 A and SALL4 B could repress OTX2 promoter activity in a dose-dependent manner. Conversely, OTX2 also negatively regulated SALL4 expression. These observations indicate that a negative feedback regulatory mechanism may exist between SALL4 and OTX2, which is useful for the maintenance of the self-renewal of piPSCs.
