Numerical simulation based on phase field method is performed to describe solidification process of pure material in a free or forced flow. The evolution of the interface is showed, and the effects of mesh grid and fl...Numerical simulation based on phase field method is performed to describe solidification process of pure material in a free or forced flow. The evolution of the interface is showed, and the effects of mesh grid and flow velocity on succinonitrite shape are studied. These results indicate that crystal grows into an equiaxial dendrite in a free flow and into an asymmetrical dendritic in a forced flow. With increasing flow velocity, the upstream dendritic arm tip grows faster and the downstream arm grows slower. However, the evolution of the perpendicular tip has no significant change. In addition, mesh grid has no influence on dendritic growth shape when mesh grid is above 300×300.展开更多
Amniotic fluid stem cells(AFSC) are noncontroversial and abundant potentially transplantable cells. They are derived from fetal and amniotic sources and show osteogenic, neuronal, and adipogenic differentiation in cul...Amniotic fluid stem cells(AFSC) are noncontroversial and abundant potentially transplantable cells. They are derived from fetal and amniotic sources and show osteogenic, neuronal, and adipogenic differentiation in culture. Clinical material must be expanded in culture and sorted if clinical use is desired. Cellular senescence and replicative potential for AFSC cultures has had limited study, with scant data on gene expression over time. We report changes in samples from 17 patients over multiple passages form 10 to 81 population doublings. Longevity was unrelated to telomere length in these cells. It was related to upregulation of TWIST1, which is highly expressed in stem cells, and downregulation of genes associated with apoptosis.展开更多
基金supported by the Major Program of the National Natural Science Foundation of China (Nos.50331040 and 60171034).
文摘Numerical simulation based on phase field method is performed to describe solidification process of pure material in a free or forced flow. The evolution of the interface is showed, and the effects of mesh grid and flow velocity on succinonitrite shape are studied. These results indicate that crystal grows into an equiaxial dendrite in a free flow and into an asymmetrical dendritic in a forced flow. With increasing flow velocity, the upstream dendritic arm tip grows faster and the downstream arm grows slower. However, the evolution of the perpendicular tip has no significant change. In addition, mesh grid has no influence on dendritic growth shape when mesh grid is above 300×300.
文摘Amniotic fluid stem cells(AFSC) are noncontroversial and abundant potentially transplantable cells. They are derived from fetal and amniotic sources and show osteogenic, neuronal, and adipogenic differentiation in culture. Clinical material must be expanded in culture and sorted if clinical use is desired. Cellular senescence and replicative potential for AFSC cultures has had limited study, with scant data on gene expression over time. We report changes in samples from 17 patients over multiple passages form 10 to 81 population doublings. Longevity was unrelated to telomere length in these cells. It was related to upregulation of TWIST1, which is highly expressed in stem cells, and downregulation of genes associated with apoptosis.
