During hot-dipping in molten Zn-55Al, the forming of “floating” dross is closely re- lated with the interaction between the Al and the Fe atoms. Utilizing the thita-thita X-ray diffraction and the Percus-Yevick hard sphere model, this paper investigates the structure of molten Al3Fe that is an approximant of partial melt in practical Zn-55Al alloy melt. It is found that in the melt there exist clusters that resemble the structure of intermetallic compound Al3Fe. The strong in- teraction between Al and Fe atoms is also indicated by the deficiency of the coordination number from 12 and the shrinkage of averaged atomic diameter. Based on such information, it is specu- lated that in the molten Zn-55Al, with the accumulation of Fe, Al3Fe-like clusters form with priority, then grow into dross. On the other hand, after deflating of the effective hard sphere diameter of pure Al atom and enlarging that of the pure Fe atom, the modified model can achieve reasonable fit to the experimental structure factor. Hard sphere modeling also gave a good estimation of the mass density 3.65 g/cm3 of liquid Al3Fe alloy at 1550℃. Compared with the density of 3.7 g/cm3 of Zn-55Al, the reason for dross floating is satisfactorily understood.
WEI Yunhe1, ZHANG Changqiao1, QIN Jingyu2 & LIU Chengbu1 1. School of Chemistry and Chemical Engineering, Shandong University, Jinan 250100, China
Introduction Electron transfer oxidation of DNA by triplet artificial photonuclease reveals a bright prospect of its application in biology and medicine. Both molecular orbital calculation and laser experiments have indicated that the homo guanine sequence should be the final localization site of photoexcited hole via long range migration within DNA. However, the direct observation of the produced ion pairs of biomolecules especially the stabilized radical cation DNA or its components is hampered by the overwhelming transient absorption of protonated radical anion of photosensitizers, such as 2-methyl-1,4-naphthaguinonel （MQ）.
MA Jian-huaLIN Wei-zhenHAN Zhen-huiYAO Si-deLIN Nian-yun
