Embryonic stem (ES) cells have the potential to differentiate into all three germ layers, providing new perspectives not only for embryonic development but also for the application in cell replacement therapies. Even though the formation of an embryoid body (EB) in a suspension culture has been the most popular method to differentiate ES cells into a wide range of cells, not much is known about the characteristics of EB cells. To this end, we investigated the process of EB formation in the suspension culture of ES cells at weekly intervals for up to 6 weeks. We observed that the central apoptotic area is most active in the first week of EB formation and that the cell adhesion molecules, except β-catenin, are highly expressed throughout the examination period. The sequential expression of endodermal genes in EBs during the 6-week culture correlated closely with that of normal embryo development. The outer surface of EBs stained positive for α-fetoprotein and GATA-4. When isolated from the 2-week-old EB by trypsin treatment, these endodermal lineage cells matured in vitro into hepatocytes upon stimulation with various hepatotrophic factors. In conclusion, our results demonstrate that endodermal cells can be retrieved from EBs and matured into specific cell types, opening new therapeutic usage of these in vitro differentiated cells in the cell replacement therapy of various diseases. Stem Cells 2005;23:817-827

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In order to obtain thinner and brighter backlight units (BLU), we simulated a new-type backlight unit. A micro-lens array sheet was formed on the upper plane of the light guide plate (LGP) comprising the backlight unit. Also, in order to match with the LGP, we simulated a functional optical sheet. The conventional BLU uses one LGP and four optical sheets, but we simulated a BLU that uses one optical sheet. Simulation results have revealed that our BLU can achieve the same luminance and 30% better view angle as compared with conventional ones.

A ZrO 2 thin film as a corrosion protective layer was deposited on Zircaloy-4 (Z-4) clad material using N 2 O as a reactive gas by RF reactive magnetron sputtering at room temperature. The Z-4 substrate was located in plasma or out of plasma during the ZrO 2 deposition process to investigate mechanical and corrosive properties for the plasma immersion. Tetragonal and monoclinic phases were existed in ZrO 2 thin film immersed in plasma. We observed that a grain size of the ZrO 2 thin film immersed in plasma state is larger than that of the ZrO 2 thin film out of plasma state. In addition, the corrosive property of the ZrO 2 thin films in the plasma was characterized using the weight gains of Z-4 after the corrosion test. Compared with the ZrO 2 thin film immersed out of plasma, the weight gains of ZrO 2 thin film immersed in plasma were larger. These results indicate that the ZrO 2 film with the tetragonal phase in the ZrO 2 can protect the Z-4 from corrosive phenomena.

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