In-situ synchrotron radiation photoemission spectroscopy study of the initial atomic layer deposition of Al2O3 film on Si(001) substrate.

In-situ synchrotron radiation photoemission spectroscopy and X-ray photoemission spectroscopy have been used to investigate the initial stages of Al2O3 growth on a Si(001) substrate by atomic layer deposition (ALD). The core level spectra of Si 2p, O 1s, and Al 2p as well as the valence band spectra were measured at every half reaction in the trimethylaluminum (TMA)-H2O ALD process. The line shape changes and binding energy shifts of the core level spectra reveal that Al2O3 is predominantly formed with a small amount of Si oxide in the initial stages without the formation of Al silicate. All core level spectra were alternately shifted toward higher and lower binding energies sides at every half ALD reaction. This can be explained by the band bending effect induced by different chemical species on the surface during the TMA-H2O ALD reaction. The valence band spectra showed that four cycles of ALD reactions were necessary to complete the electronic structure of the Al2O3 film with a valence band offset of 3.73 eV.

Tanshinone IIA, an ingredient of Salvia miltiorrhiza BUNGE, induces apoptosis in human leukemia cell lines through the activation of caspase-3.

Tanshinone II-A is a derivative of phenanthrene-quinone isolated from Salvia miltiorrhiza BUNGE, a traditional herbal medicine that is known to induce antiinflammatory, anti-oxidative and cytotoxic activity. We have examined cellular effects of Tanshione II-A on HL60 human promyelocytic leukemic cells and K562 human erythroleukemic cells. Tanshione II-A induced a dose- and time-dependent DNA fragmentation into the multiples of 180 bp and specific proteolytic cleavage of poly(ADP-ribose) polymerase in both cell lines. PI-staining and flow cytometry analysis of K562 cells following Tanshione II-A treatment showed an increase of the cells possessing hypodiploid DNA indicative of apoptotic state of cells. Caspase-3 activity was significantly increased during Tanshinone II-A treatment of both HL60 and K562 cells, whereas caspase-1 activity was not changed. These results suggest that Tanshione II-A induced HL60 and K562 cellular apoptosis that may be associated with the selective members of caspase family.

Anticomplementary activity of stilbenes from medicinal plants.

The anticomplementary activity of stilbenes from medicinal plants in Korea was investigated in vitro. 3,5-Dihydroxy-4'-methoxystilbene (3) was most potent with IC50 value of 1.5 x 10(-4) M followed by rhapontigenin (4), oxyresverastrol (2), 2,3,4',5-tetrahydroxystilbene-2-O-beta-glucoside (9), rhaponticin (8), resverastrol (1), and piceid (7). The activity was found to be increased by a methylation on a hydroxy group of C-4' of 1, but decreased by further methylation on hydroxy groups of C-3 and C-5 and glucosylation on any hydroxy group of 1. Addition of hydroxy group on C-2' of 1 or C-3' of 3 was little affected on the anticomplementary activity but the activity was increased by O-glucosylation on C-2 of 1.