Collisional quantum interference effect on rotational energy transfer in an atom-diatom system

The theoretical model of collisional quantum interference (CQI) in intramolecular rotational energy transfer is described in an atom-diatom system, based on the first Born approximation of time-dependent perturbation theory and considering a long-range interaction potential. The relation between differential and integral interference angles is obtained. For the CO A(1)Pi (v = 0)/e(3)Sigma (-)(v = 1)-He collision system, the calculated integral interference angles are consistent with the experimental values. The physical significance of interference angle and the essential factors it depends on as well as the influence of the short-range interaction on CQI are discussed. (C) 2001 Elsevier Science B.V. All rights reserved.

Multipolar model for collisional quantum interference on rotational energy transfer

A theoretical model of collisional quantum interference (CQI) is developed in a diatom-diatom system based on the first-order Born approximation of time-dependent perturbation theory and the multipolar interaction potential. The transition cross section is obtained. The relations between the differential and integral interference angles are discussed. The key factors on the determination of the differential and integral interference angles are obtained. The changing tendency of the interference angles with the experimental temperatures is obtained.

Interference effects in the extraction of trace metals from estuarine waters

We have found that a commonly used complexation and solvent extraction technique (using mixed dithiocarbamates/Freon/HNO3) does not always extract Cd, Co, Cu and Ni from estuarine samples with the same efficiency as from Milli-Q water. For samples collected from the Derwent Estuary (Australia), the reduced extraction efficiency only occurred for unfiltered samples, but low extraction efficiencies were also observed for a (filtered) riverine certified reference material (SLRS-3) suggesting that the effect may be widespread. We have not been able to identify the reason for the low extraction efficiency and, although it is strongly correlated with the presence of high concentrations of suspended solids, dissolved organic matter and particulate iron, we have no experimental evidence to directly link any of these parameters to the effect. It is possible that similar effects may occur in other techniques which rely on a preconcentration step prior to analysis and that some literature values of heavy metals in estuarine waters may be low. We propose a modification of the standard complexation/solvent extraction method which overcomes these difficulties without adding significantly to the time taken for analyses.

面向网状信息的Radial+Focus可视化

针对当前网状信息可视化技术忽略了网状信息节点的可视信息的问题,提出一种面向网状信息的Radial+Focus可视化技术。首先介绍网状信息节点的信息详细度与先验重要度,并研究通过节点的交互历史计算节点的先验重要度的方法;然后研究了基于节点先验重要度的Radial+Focus布局算法;最后,给出了Radial+Focus可视化技术的应用实例和实验评估。实验评估表明,该技术能自然、高效地可视化网状信息,为用户对网状信息关系及网状信息节点的可视信息的分析提供有力的支持。

Rhythmic Growth-Induced Ring-Banded Spherulites with Radial Periodic Variation of Thicknesses Grown from Poly(epsilon-caprolactone) Solution with Constant Concentration

Birefringent ring-banded spherulites with radial periodic variation of thicknesses were grown from poly(epsilon-caprolactone) (PCL) solutions under conditions for which the Solution concentration was held constant during the whole development of the morphology. The as-grown ring-banded spherulites were investigated by optical (OM) and atomic force (AFM) microscopies, by transmission electron microscopy (TEM) of samples sectioned parallel to the plane of film, and also by electron diffraction (ED) and grazing incidence X-ray diffraction (GIXD) techniques.

Targeted RNA interference of cyclin A(2) mediated by functionalized single-walled carbon nanotubes induces proliferation arrest and apoptosis in chronic myelogenous leukemia K562 cells

Cyclin A(2) plays critical role in DNA replication, transcription, and cell cycle regulation. Its overexpression has been detected and related to many types of cancers including leukemia, suggesting that suppression of cyclin A(2) would be an attractive strategy to prevent tumor progression. Herein, we apply functionalized single wall carbon nanotubes (f-SWNTs) to carry small interfering RNA (siRNA) into K562 cells and determine whether inhibition of cyclin A(2) would be a potential therapeutic target for chronic myelogenous leukemia.

Application of a New Cyclic Guanidinium Ionic Liquid on Dye-Sensitized Solar Cells (DSCs)

A new cyclic guanidinium ionic liquid OGI (1,3-dimethyl-2-N ''-methyl-N ''-octylimidazoguanidinium iodide) has been used as a quasi-solid-state electrolyte for dye-sensitized solar cells (DSCs), and 6.38% conversion efficiency was achieved at AM 1.5 simulated sunlight (9.81 mW cm(-2)). Further gelation with SiO2 nanoparticles afforded the solid-state electrolyte, which presented overall conversion efficiency of 5.85%. The diffusion properties of these OGI-based electrolytes were investigated. In the meantime, the optimal structure and ion-pairing interaction in OGI have been proposed by density functional theoretical calculation (DFT) at the B3LYP/6-21G(d,p) level.

Why [6,6]- and 1,2-Benzal-3-N-4-O-Cyclic Phenylimidate C-60 Undergo Electrochemically Induced Retro-Addition Reactions while 1,4-Dibenzyl-2,3-Cyclic Phenylimidate C-60 Does Not? C-H center dot center dot center dot X (X = N, O) Intramolecular Interactions in Organofullerenes

The electrochemical properties of a series of structurally related fullerooxazoles, [6,6] cyclic phenylimidate C-60 (1), 1,2-benzal-3-N-4-O-cyclic phenylimidate C-60 (2), and 1,4-dibenzyl-2,3-cyclic phenylimidate C-60 (3), are described, and the spectroscopic characterizations of their anionic species are reported. The results show that compounds I and 2 undergo retro-cycloaddition reactions that lead to the formation of C-60 and C61HPh, respectively, upon two-electron-transfer reduction. However, compound 3 demonstrates much more electrochemical stability as no retro-cycloaddition reaction occurs under similar conditions. Natural bond orbital (NBO) calculations on charge distribution show there is no significant difference among the dianions of 1, 2, and 3, indicating that the electrochemical stability of 3 is unlikely to be caused by the charge distribution difference of the dianions of three compounds. Examination on the crystal structure of compound 3 reveals close contacts of the C-H group with the heteroatoms (N and O) of cyclic phenylimidate, suggesting the existence of C-H center dot center dot center dot X (X = N, O) intramolecular hydrogen bonding among the addends, which is further confirmed by NBO analysis.

An ionic liquid based on a cyclic guanidinium cation is an efficient medium for the selective oxidation of benzyl alcohols

A novel room temperature ionic liquid (RTIL) has been prepared containing a cyclic hexaalkylguanidinium cation. The selective oxidation of a series of substituted benzyl alcohols has been carried out in it, with sodium hypochlorite as the oxidant. The RTIL acts as both phase transfer catalyst (PTC) and solvent. The ionic liquid could be recycled after extraction of the benzaldehyde product with ether.