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In this letter, a modified series-capacitor (SC) high conversion ratio (HCR) dc–dc converter is proposed. The proposed converter inherits most of the advantages of the existing SC HCR dc–dc converter and can eliminate the problem of high switch-voltage stress of the existing converter encountered during start-up using a simple circuit modification. Although an extra capacitor is required in the proposed converter, total series capacitance of the proposed converter is the same as that of the conventional SC converter. In addition, input capacitance of the proposed converter can be reduced by less than half of that of the SC buck converter. A 1-kW prototype converter is built and tested to verify the performance of the proposed converter.

The feasibility of the industrial application of kapok fiber for the removal of lead (II) ions from aqueous stream was evaluated in this study. The fiber was modified using NaOH solution and also was oxidized with NaClO2 solution. Both of the chemically enhanced kapok fibers showed a high adsorption efficiency, which was 23.4 and 34.6 mg/g, respectively, while unmodified kapok fibers had 4.70 mg/g. Kinetic reactions and their rate constants exhibited that the removal of lead was linearly correlated with adsorption capacity of the modified and oxidized kapok fibers. Adsorption isotherm of the experiment fitted very well with the Langmuir model for the chemically enhanced kapok fibers. Adsorption capacity decreased with a decrease in the pH. The recycling process of the used kapok fibers was also carried out and the results found that kapok fibers were reusable with relatively high regeneration rate.

This paper proposes a novel dual output boost converter with output voltage balancing capability. The proposed converter can achieve zero voltage switching (ZVS) without additional components or complex techniques. It has low switch current stress when compared to the conventional counterpart converter. A 1kW prototype converter is built and tested to verify the performance of the proposed converter.

The new anthracycline analogues (2–10) as potential anticancer agents were synthesized from daunomycin (1a) and doxorubicin (1b). Compounds 2, 6, and 7 were prepared by the nucleophilic displacement type esterification of a 14-bromodaunomycin (1c) with a sodium pyruvate, aspartate, and N-acetylaspartic acid, respectively. Whereas compounds (3, 8) and (4, 9) were prepared by the reaction of daunomycin (1a) or doxorubicin (1b) with one equivalent of the corresponding acids in the presence of EDCI/PP, compounds (5, 10) were obtained from 1b by reaction with two equivalents of the corresponding acids in the same manner.

As a biopolymer-modified building block, a poly-dopamine layer can be utilized with a wide range of inorganic and organic materials for an adsorptive and microbial remediation. In this study, dopamine (DOPA) was used as a structural platform to bind silver onto the surface of kapok fibers, and a composite of surface-modified kapok fibers coated with DOPA along with silver were successfully manufactured. After a silver-coating process, a very strong antibacterial property was exhibited against Staphylococcus aureus with a high antibacterial efficiency, over 99 %, which could last for 48 h in peptone water. Enumeration determination was carried out in a spread plate method. For a comparative study, the antibacterial activity of raw kapok fibers and chemically enhanced kapok fibers with DOPA and silver was also evaluated. The results indicated that the chemically enhanced kapok fibers were very useful in controlling a microbial activity on a surface environment.

Department of Chemistry, Woosuk University, Wanju 565-701, KoreaReceived January 30, 2001The potential anticancer agents, new anthracycline analogues ( 2-9) have been synthesized from the glycosidesdaunomycin (1a) and doxorubicin (1b). Compounds 2 and 6 were prepared by nucleophilic displacement es-terification of a 14-bromodaunomycin ( 1c) with sodium or potassium salts of butyric and all trans retinoic acid,respectively. Compounds 3 and 7 were obtained from daunomycin ( 1a) by direct amidation with a butyric andall trans retinoic acid in the presence of EDCI and PP, respectively. Compounds 4 and 8 were obtained fromdoxorubicin (1b) by reaction with the corresponding acids in the same manner. Compounds 5 and 9 were pre-pared from doxorubicin (1b) by acylation with two equivalents of the corresponding acids under the same re-action conditions.Keywords : Daunomycin, Doxorubicin, Anthracycline derivatives, Butyric and retinoic acid, Acylation.IntroductionThe anthracycline antibiotics daunomycin (1a) and adria-mycin (1b) (Figure 1) are clinically effective anticancerchemotherapeutic agents against several types of humancancers as well as various experimental tumors.

Department of Chemistry, Woosuk University, Wanju 565-701, KoreaReceived March 6, 2001The potential anticancer agents new anthracycline derivatives (2-9) have been synthesized from daunomycin(1a) and doxorubicin (1b) as starting materials. Compounds 2 and 6 were prepared by the nucleophilic dis-placement type esterification of a 14-bromodaunomycin ( 1c) with a acetylsalicylic and palmitic acid in triethyl-amine, respectively. Compounds 3 and 7 were obtained from daunomycin (1a) by direct amidation with thecorresponding acids in the presence of EDCI and PP as esterification reagents. Whereas 4 and 8 were preparedby reaction of doxorubicin (1b) with one equivalent of acetylsalicylic and palmitic acid using DCC/DMAP,respectively, 5 and 9 were obtained from 1b by acylation with two equivalents of the corresponding acids usingEDCI/PP reagents.Keywords : Daunomycin, Doxorubicin, Anthracycline, Acetylsalicyclic acid, Palmitic acid.IntroductionThe substitution of one hydrogen atom in the daunorubicin(daunomycin, DM, 1a) acetyl side chain with a hydroxylgroup gives adriamycin (doxorubicin, DX, 1b) (Figure 1).These anthracycline antibiotics, in particular, are the power-ful antitumor agents in the treatment of a wide range ofhuman cancers.

The new anthracycline analogues (2–10) as potential anticancer agents were synthesized from daunomycin (1a) and doxorubicin (1b). Compounds 2, 6, and 7 were prepared by the nucleophilic displacement type esterification of a 14-bromodaunomycin (1c) with a sodium pyruvate, aspartate, and N-acetylaspartic acid, respectively. Whereas compounds (3, 8) and (4, 9) were prepared by the reaction of daunomycin (1a) or doxorubicin (1b) with one equivalent of the corresponding acids in the presence of EDCI/PP, compounds (5, 10) were obtained from 1b by reaction with two equivalents of the corresponding acids in the same manner.