UO2、UC2和UCO分子的结构和热力学性质

用密度泛函B3LYP方法,计算了UO2、UC2和UCO分子的结构和热力学函数,计算了固体U的振动内能Ev、振动和电子熵Sev,以及U在不同气氛（O2、C2、CO）中形成UO2、UC2和UCO晶体的ΔHfΘ、ΔSfΘ和ΔGfΘ.结果表明,UO2晶体最稳定.     

Influence of ultrasonic field on microcystins produced by bloom-forming algae

Under the background of algae removal and growth inhibition by ultrasonic irradiation, the effects of ultrasonic irradiation on removal of Microcystis, the concentration variation of microcystins (MC) produced by Microcystis in Microcystis suspension, and sonochemical degradation of microcystins in water, were studied in the paper. The results showed that ultrasonic irradiation could efficiently inhibit the growth of Microcystis, and ultrasonic irradiation shorter than 5 min would not introduce the increase of microcystins dissolved in Microcystis suspension simultaneity. Also, microcystins dissolved in Microcystis suspension would not increase as ultrasonic power increasing. Further research showed that microcystins were effectively degraded in ultrasonic fields. After 20 min ultrasonic irradiation at 150 kHz and 30 W, the removal rate of microcystins reached 70%.     

A structural analysis of the complexes of (S,S)-dimethylpyridino-18-crown-6 with (R) and (S)-[α-(1-naphthyl)ethyl]ammonium perchlorate by NMR techniques and molecular modeling

Significant - interaction is found in the complexes of (S, S)-dimethylpyridino-18-crown-6 with (R)- and (S)-[-(1-naphthyl)ethyl]ammonium perchlorate. This finding is supported by the¹H NOESY NMR spectral technique, greater chemical shift changes of aromatic protons in both host and guest molecules upon complexation, and by molecular mechanics calculations. Because of the flexibility of the ligand, the tripod hydrogen bonding causes¹³C relaxation times of all periphery carbons to decrease without significant selectivity. Rotational energy barrier calculations of the methyl groups of the complexed ligand also show that the (S, S)-host-(R)-guest is the more stable complex.     

超大孔磷酸铝分子筛的合成及性能

1988年Davis等首次报道了以二正丙胺和四丁基氢氧化铵为结构导向剂合成出一种命名为VPI-5的新型磷酸铝超大孔分子筛。它是一族具有相同三维拓朴学骨架的磷酸铝系分子筛,该结构的对称性属六方晶系,P6_3cm空间群,单位晶胞由36个TO_2组成,晶胞参数α=1.8989nm,c=0.8112nm,其主孔道由18员环构成,孔直径约为1.2-1.3nm。     

Recent progress in two-photon small molecule fluorescent probes for enzymes

This review aims to provide a summary of the progress in TP small molecule fluorescent probes for enzymes in recent years and displays the main fluorescent mechanisms that have been applied to design probes.     

Fourth-derivative spectrophotometric determination of neodymium in mixed rare earths with methyl thymol blue and cetylpyridinium chloride

A sensitive and selective method is described for the determination of neodymium in mixed rare earths using fourth-derivative spectrophotometry. The method is based on the absorption spectra of 4f electron transitions of the complex of neodymium with methyl thymol blue and cetylpyridinium chloride. The influence of various instrumental parameters and reaction conditions for maximum colour development are investigated. The calibration curve is linear over the range 0–3.5 g ml^–1 neodymium. The relative standard deviation for determination of 1.4 g ml^–1 neodymium (n = 7) is 1.6%. The detection limit (signal-to-noise ratio = 3) is 0.2 g ml^–1.     

杂多酸的固载化Ⅲ.溶剂对H4Siw12O40.24H2O在活性炭上吸附的影响

研究了Ｈ４ＳｉＷ１２Ｏ４０．２４Ｈ２Ｏ（ＳｉＷ１２）在水，乙醇，乙酸，乙酸丁酯中在活性炭上的吸附得出，活性炭微孔结构对ＳｉＷ１２在其表面的吸附起着分子筛作用，水溶剂化的ＳｉＷ１２分子可顺利进行活性１．７ｎｍ左右的微孔，而其它溶剂化的ＳｉＷ１２分子，则需较大的孔径，提出了ＳｉＷ１２在活性炭表面吸附的微孔中孔扩散模型。     

A new method for inversion of hydroxyl group of carbocyclic nucleosides

The hydroxyl group of carbocyclic nucleosides was inversed when the compounds were treated with Me_3SiCl,KCN and a catalytic amount of NaI in DMF/CH_3CN.     

Er:Yb:KGW激光晶体生长及缺陷研究

采用顶部籽晶(TSSG)法生长ErYbKGW晶体.通过研究助熔剂的种类、组成与溶质的比例关系对晶体生长的影响,设计了合理的工艺条件转速30～40 r·min-1;拉速1～2 mm·d-1;降温生长速率0.05 ℃·h-1;降温速率15 ℃·h-1;生长周期15～20 d.通过对晶体缺陷的观察分析认为,晶体裂缝及包裹物等缺陷与生长工艺条件密切相关,应尽量减少生长过程中的温度、浓度及生长速度的波动,保持晶体的稳态生长.     

聚乙撑二氧噻吩膜在氧化态的充电过程及电容研究

In this paper, the chronoamperometry was used to study the charging processes of polyethylenedioxythiophene (PEDOT) modified electrodes in the potential range where PEDOT was in the oxidized state. The results show that the charging behaviors of the PEDOT films are well agreed with the exhausted finite diffusion model. The dependence of the capacitance values of the films on potential and concentration of solution was also studied in this potential range.