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991.
Ma B Chen Y Hao H Wu M Wang B Lv H Zhang G 《Colloids and surfaces. B, Biointerfaces》2005,41(2-3):197-201
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%. 相似文献
992.
Jönsson B Nonat A Labbez C Cabane B Wennerström H 《Langmuir : the ACS journal of surfaces and colloids》2005,21(20):9211-9221
The main source of cohesion in cement paste is the nanoparticles of calcium silicate hydrate (C-S-H), which are formed upon the dissolution of the original tricalcium silicate (C(3)S). The interaction between highly charged C-S-H particles in the presence of divalent calcium counterions is strongly attractive because of ion-ion correlations and a negligible entropic repulsion. Traditional double-layer theory based on the Poisson-Boltzmann equation becomes qualitatively incorrect in these systems. Monte Carlo (MC) simulations in the framework of the primitive model of electrolyte solution is then an alternative, where ion-ion correlations are properly included. In addition to divalent calcium counterions, commercial Portland cement contains a variety of other ions (sodium, potassium, sulfate, etc.). The influence of high concentrations of these ionic additives as well as pH on the stability of the final concrete construction is investigated through MC simulations in a grand canonical ensemble. The results show that calcium ions have a strong physical affinity (in opposition to specific chemical adsorption) to the negatively charged silicate particles of interest (C-S-H, C(3)S). This gives concrete surprisingly robust properties, and the cement cohesion is unaffected by the addition of a large variety of additives provided that the calcium concentration and the C-S-H surface charge are high enough. This general phenomenon is also semiquantitatively reproduced from a simple analytical model. The simulations also predict that the affinity of divalent counterions for a highly and oppositely charged surface sometimes is high enough to cause a "charge reversal" of the apparent surface charge in agreement with electrophoretic measurements on both C(3)S and C-S-H particles. 相似文献
993.
Starting from the para‐phenylenediamine derivative HN(SiMe3)‐C6H4‐NH(SiMe3), a lithiation and subsequent borylation give [(MeO)2B]N(SiMe3)‐C6H4‐N(SiMe3)[B(OMe)2] ( 1 ), the hydridation of which yields Li2[(H3B)N(SiMe3)‐C6H4‐N(SiMe3)(BH3)] ( 2 ). Applying ZrCl4 upon 2 initiates a condensation to give the title compound [‐N(SiMe3)‐p‐C6H4‐N(SiMe3)‐BH‐]2, a hetero[3, 3]paracyclophane with two N‐B‐N chains that connect the para‐phenylene units. The product 3 crystallizes in the orthorhombic space group P212121. 相似文献
994.
Tingmin Wang Jerald S. Bradshaw Janet C. Curtis Peter Huszthy Reed M. Izatt 《Journal of inclusion phenomena and macrocyclic chemistry》1993,16(2):113-122
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. 相似文献
995.
996.
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. 相似文献
997.
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. 相似文献
998.
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。 相似文献
999.
Xiao Zhen Liu Fei Wang Dong Dong Luo Xing Guo Guang Qing Lei 《中国化学快报》2007,18(11):1339-1341
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. 相似文献
1000.