几种葡萄酒色素抗氧化活性的密度泛函理论分析

采用密度泛函理论,对葡萄酒中常见的锦葵色素葡萄糖苷、儿茶酸、两种通过CH_(3)—CH桥连接形成的手性异构的色素分子和直接相连而形成的色素分子的结构参数、NPA电荷、前线轨道能级以及各酚羟基对前线轨道的贡献进行了分析,得出其抗氧化活性的强弱和发生抗氧化反应的主要作用位点。结果表明,5种色素在C7和C14处均有较强的反应活性,通过CH_(3)—CH桥连接形成的色素和直接相连形成的色素在B′环的C14′、C15′处有较强的反应活性,色素B抗氧化能力远低于其他4种。引入CH_(3)—CH桥对葡萄酒色素的抗氧化能力没有较大的影响,且手性异构对其也没有影响。

Influence of intramolecular hydrogen bond formation sites on fluorescence mechanism

The fluorescence mechanism of HBT-HBZ is investigated in this work. A fluorescent probe is used to detect HClO content in living cells and tap water, and its structure after oxidation by HCl O(HBT-ClO) is discussed based on the density functional theory(DFT) and time-dependent density functional theory(TDDFT). At the same time, the influence of the probe conformation and the proton transfer site within the excited state molecule on the fluorescence mechanism are revealed. Combined with infrared vibrational spectra and atoms-in-molecules theory, the strength of intramolecular hydrogen bonds in HBT-HBZ and HBT-ClO and their isomers are demonstrated qualitatively. The relationship between the strength of intramolecular hydrogen bonds and dipole moments is discussed. The potential energy curves demonstrate the feasibility of intramolecular proton transfer. The weak fluorescence phenomenon of HBT-HBZ in solution is quantitatively explained by analyzing the frontier molecular orbital and hole electron caused by charge separation. Moreover, when strong cyan fluorescence occurs in solution, the corresponding molecular structure should be HBT-ClO(T). The influence of the intramolecular hydrogen bond formation site on the molecule as a whole is also investigated by electrostatic potential analysis.

砌体房屋裂缝原因及防治

砌体房屋的裂缝是一个急需解决的质量通病。裂缝不仅种类繁多，形态各异．而且较普遍，轻微者影响建筑物美观。造成渗漏水、严重者降低建筑结构的承载力、刚度、稳定和整体性、耐久性，甚至还会导致整体倒塌的重大质量事故，因此，正确分析原因、切实加以防治十分必要。