Extinction coefficient per CdE （E = Se or S） unit for zinc- blende CdE nanocrystals

The extinction coefficient of semiconductor nanocrystals is a key parameter for understanding both the quantum confinement and applications of the nanocrystals. The existing extinction coefficients of CdE （E = Se, S） nanocrystals were found to have an unacceptable deviation for the zinc-blende CdE quantum dots （QDs）. The analysis reveals that, in addition to the interference of impurities, the commonly applied extinction coefficient per CdE nanocrystal is sensitive to the size, shape, and density of the surface ligands of nanocrystals. The extinction coefficient per CdE unit does not depend on accurate information of the size, shape, and number of surface ligands of the nanocrystals. A new three-step purification scheme was developed to investigate three classes of possible impurities for accurate determination of the extinction coefficient per CdE unit, including CdE clusters not considered previously. Given that the sole ligands of zinc-blende CdE nanocrystals are cadmium fatty acid salts （CdFa2）, a universal formula for the nanocrystals can be written as （CdE）,（CdFa2）,. The n：rn ratio was accurately determined for purified nanocrystals. The resulting extinction coefficients per unit for both CdSe and CdS QDs were found to decrease exponentially as the size of the QDs increases, with the corresponding bulk value as the large-size limit.

基于多目标文化差分进化算法的污水处理厂活性污泥单元多目标操作优化（英文）

污水处理厂活性污泥单元的操作优化旨在保证出水最佳水质的同时,提高过程的运行效率和经济效益。本文在活性污泥系统机理模型基础上,选取进水流量、出水生物需氧量(BOD)和运行成本作为优化目标,建立基于过程的单目标和多目标非线性规划(NLP)模型,包括一个单目标NLP模型、二个双目标NLP模型和一个三目标NLP模型。通过单目标三层混合文化差分进化算法(3LM-CDE)和基于Pareto准则的多目标三层混合文化差分进化算法(MO-3LM-CDE)对以上模型进行求解,得到单目标问题的唯一最优解和多目标问题的一组非支配解集。计算结果表明,三目标问题模型对实际工况的考量更为周全,并且在过程效率、净化质量和经济效益方面均表现出了良好的优化效果。