Mechanism of copper underpotential deposition at Pt(<Emphasis Type="Italic">hkl</Emphasis>)-electrodes: Quantum-chemical modelling

Mechanism of copper underpotential deposition at stepped faces of platinum single crystals Pt(hkl) is studied using cyclic voltammetry, scanning probe microscopy, and quantum-chemical modelling. It is shown that the first stage of UPD is one-dimensional decoration of the (100)- or (110)-orientated steps, then copper monolayer forms at (111)-terraces. The final stage is the secondary step decoration. Quantum-chemical modelling, with the using of long-distance potentials of the Cu-Pt and Cu-Cu pair interactions, allows estimating the energy of copper adsorption at different structure elements of the substrate (steps, kinks, terraces) and revealing the succession of the adatom monolayer formation; it also provides additional information for the identifying of the nature of voltametric peaks for different stages of the copper adsorption-desorption.     

求解复杂湍流的非线性涡黏性系数模型和代数应力模型

非线性涡黏性系数模型和代数应力模型联系了线性涡黏性系数湍流模型和完整的微分 雷诺应力模型.随着它们受到日益关注,其形式也越来越多样化.本篇综述的目的是对这些模 型加以总结并比较它们之间的共同点及不同之处,指出它们与完整微分雷诺应力模型之间的 关系,以及相对于线性涡黏性系数模型而言它们在预报流场上所具有的优势.     

Fusion around the barrier for 7Li+12C

Fusion cross-sections for the ⁷Li + ¹²C reaction have been measured at energies above the Coulomb barrier by the direct detection of evaporation residues. The heavy evaporation residues with energies below 3 MeV could not be separated out from the α-particles in the spectrum and hence their contribution was estimated using statistical model calculations. The present work indicates that suppression of fusion cross-sections due to the breakup of ⁷Li may not be significant for ⁷Li + ¹²C reaction at energies around the barrier.     

Microfluorometric study of oxygen dependence of (1"-pyrene butyl)-2-rhodamine ester probe in mitochondria of living cells

The access to oxygen concentration is of importance in various organelles of living cells, especially in mitochondria. A new probe, (1"-pyrene butyl)-2-rhodamine ester, was designed to target this organelle. We present here the properties of the probe in such an environment. Microspectrofluorometry confirms the localization of the probe in the mitochondrial environment at low doses (1 microM). At these doses, the cell toxicity experiments show no effect on the cell growth. The emission spectrum measured at an excitation wavelength of 340 nm (pyrene centered) indicates energy transfer from the pyrene to the rhodamine chromophore, as also observed in an ethanol solution. With excitation at 337 nm, the excited state decays biexponentially with lifetime decays of 6-9 ns and 90 ns. The first corresponds to the intrinsic fluorescence of the cell and the latter corresponds to the pyrene chromophore. In degassed conditions the pyrene lifetime decay increases up to 130 ns. Under an oxygen atmosphere the lifetime decays decrease to 62 ns. The lifetime changes with the oxygen concentration were compared with the range obtained during our previous study in ethanol solution (5-220 ns). The observed differences were interpreted by studying the lifetime of the probe in simplified environments, liposome suspensions and protein solutions. In this paper we show that the new probe can be used to measure the fluctuation of oxygen concentration in the surroundings of mitochondria.