Lead-rich and antimony-rich oxidizing slag was subjected to regular HCl-NaCl leaching, with the experimental conditions optimized under which ultrasound was introduced. After only 15 min of ultrasound-assisted leaching, the leaching rate of Sb resembled that after 45 min of regular leaching. Ultrasonic treatment considerably elevated the leaching rates of Sb and Pb, and shortened the leaching time. With the decrease of particle size, the leaching rate of Sb and Pb increased gradually. Especially, as the particle size of the slag was greater than 0.217 mm, the ultrasonic leaching effects of Sb and Pb were significantly higher than that of regular leaching effects. The temperature exhibited great effect on ultrasonic leaching performance. As the temperature increased, the leaching rates of Sb and Pb increased step by step. In case the temperature was higher than 85°C, the increasing speed of the leaching rates for Sb and Pb tended to be slow. Increasing ultrasonic power could augment the leaching rate or accelerate the procedure till the same leaching rate. However, since ultrasound failed to energize the formation of new reaction pathways, the maximum leaching rates of Sb and Pb were determined by their phase compositions rather than by ultrasonic field.

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Objective: To study the active sites of podophyllotoxin derivatives. Methods: Some podophyllotoxin derivatives were analyzed by quantum and mechanics method. Results: Some information was given according to the calculation results about HOMO and LUMO electron density. The C-4 position is the position for effective modification. The B ring and E ring are important active centers. Conclusion: The hole of positive charge in B ring easily combines with an acceptor within the molecular. Some quinolones with similar electronic construction to podophyllotoxin may have antitumor activity.Podophyllotoxin is a natural substance with strong antitumor activity m. But due to its toxic side effects, structural modification is essential. It is believed that podophyllotoxin derivatives exert their antitumor activity by forming a stable covalent complex between DNA and Biography: HE Feng (1969-), assistant professor, master of chemistry, Department of Chemistry, Sun Yat-sen University of Medical Sciences, majors in research of anticancer drugs. type II DNA topoisomerase. This leads to inhibition of DNA catenation activity C21.On the basis of our previous studies C3-61, we undertook quantum chemistry calculation and threedimensional quantitative structure-activity analysis for the compounds in literatures Iv-91. Furthermore, we investigated their structural characteristics and structure -activity according to their relationship inhibition of L12~0 leukemia cell lines in vitro. This study would help searching for compounds with more ideal structure and activity.In the process of molecular modeling construction, the trans ring-D juncture is required (Figure 1).Generally, the activities of the drugs are always associated with their HOMO and LUMO orbits. Compared to their ICso (Table 1), compounds whose LUMO components are mainly in the ring-B and HOMO's principal components in the ring-E, have relatively high activity. Therefore, it can be postulated that the parent structure has two functioning regions: one in the ring-E (including the 4'-hydroxyl), the other one in the ring-B.Moreover, the energy of the LUMO and LUMO (+1) is negative, different from that of general compounds which is positive. It becomes clear that the LUMO is responsible for the interaction of the molecular orbit. It suggests that the active compounds' LUMO is quite low. In addition, as the principal components of LUMO are in ring-B, so, it is the ring-B that is responsible for maintaining sufficient activity.Many studies indicated that C-4 position is suitable for modification I1°1. When the C-4 position is substituted by different groups, the density of electronic in ring-B changes. The migration of LUMO from ring-B leads to diminished activity. However, according to the analysis