Localization or tunneling in asymmetric double-well potentials

An asymmetric double-well potential is considered, assuming that the wells are parabolic around the minima. The WKB wave function of a given energy is constructed inside the barrier between the wells. By matching the WKB function to the exact wave functions of the parabolic wells on both sides of the barrier, for two almost degenerate states, we find a quantization condition for the energy levels which reproduces the known energy splitting formula between the two states. For the other low-lying non-degenerate states, we show that the eigenfunction should be primarily localized in one of the wells with negligible magnitude in the other. Using Dekker’s method (Dekker, 1987), the present analysis generalizes earlier results for weakly biased double-well potentials to systems with arbitrary asymmetry.     

Resonant equations with the Neumann p-Laplacian plus an indefinite potential

We consider a nonlinear Neumann problem driven by the p  -Laplacian plus an indefinite potential and a Carathéodory reaction which at ±∞ is resonant with respect to any nonprincipal variational eigenvalue of the differential operator. Using critical point theory and Morse theory (critical groups), we show that the problem has at least three nontrivial smooth solutions, two of which have constant sign. In the process we prove some results of independent interest concerning the unique continuation property of eigenfunctions and the critical groups at infinity of a C¹$C^1$-functionals.     

Integral representation of a solution to the Stokes–Darcy problem

With methods of potential theory, we develop a representation of a solution of the coupled Stokes–Darcy model in a Lipschitz domain for boundary data in H^?1/2. Copyright © 2014 John Wiley & Sons, Ltd.     

Dried Biomass of Activated Sludge for Cu2+ Adsorption: Behaviors and Mechanisms

Activated sludge was tested for its ability to remove Cu²⁺ from aqueous solution. The effects of various experimental parameters (initial pH, initial Cu²⁺ concentration, adsorbent dosage, and temperature) on Cu²⁺ adsorption were evaluated. The Langmuir isotherm model well described the adsorption of Cu²⁺ onto activated sludge. The pseudo-second-order kinetic equation was appropriate for describing the kinetic performance of the sorption. Furthermore, Webber–Morris models indicated that the sorption of Cu²⁺ was generally found to involve with the intraparticle diffusion process. Parameters of adsorption thermodynamic suggested that the interaction of Cu²⁺ adsorbed by sludge was spontaneous and exothermic. Activated sludge was characterized by Fourier transform infrared spectroscopy analysis and results showed that active groups such as –OH, –COOH, –NH₂ were involved in Cu²⁺ adsorption. Zeta potential analysis demonstrated inner-sphere adsorption for Cu²⁺ adsorption on sludge.     

Relevance between the Chemical Structure Modifications and Physicochemical Descriptors of Chemical Reactivity for Series of Nitroxide Radicals

This work presents an experimental and theoretical study to address the chemical reactivity of series of nitroxide radicals. For that purpose two physicochemical properties: the half-wave potential and the hyperfine coupling constants of the nitrogen nuclei, were analyzed. Experimental values are compared with electronic structure calculations at the BHandHLYP/6-311++G(2d,2p) level. E_1/2 values were in good agreement with the adiabatic ionization potential when including the solvent effects by the Cramer and Truhlar Solvation Model. Preeliminar experimental electron spin deslocalization studies suggest that structural hindrance plays an important role in their deslocatization mechanism.     

低能C36团簇在金刚石(100)晶面沉积时的影响因素

"使用Brenner-LJ拟合势描述了金刚石与C36团簇原子间的相互作用,并用分子动力学模拟的方法研究单个C36(D6h)在金刚石(100)晶面的沉积机制．通过仿真实验分析了C36团簇的入射能量、入射点位置、入射姿势、入射角度等因素对其成核初期化学吸附过程以及沉积后其稳定性的影响．研究发现：由于C36入射点位置及入射姿势的不同,其在金刚石(100)晶面沉积时的沉积阈值最小值为20 eV,最大值为60 eV;在入射角不超过60o斜射时,由于水平运动分量的存在,C36可能翻滚及平滑至成键能量较小的区域后再成键     

Monitoring of the Proton Electrochemical Gradient in Reconstituted Vesicles: Quantitative Measurements of Both Transmembrane Potential and Intravesicular pH by Ratiometric Fluorescent Probes

Proteoliposomes carrying reconstituted yeast plasma membrane H⁺-ATPase in their lipid membrane or plasma membrane vesicles are model systems convenient for studying basic electrochemical processes involved in formation of the proton electrochemical gradient (Δμ_H ⁺) across the microbial or plant cell membrane. Δψ- and pH-sensitive fluorescent probes were used to monitor the gradients formed between inner and outer volume of the reconstituted vesicles. The Δψ-sensitive fluorescent ratiometric probe oxonol VI is suitable for quantitative measurements of inside-positive Δψ generated by the reconstituted H⁺-ATPase. Its Δψ response can be calibrated by the K⁺/valinomycin method and ratiometric mode of fluorescence measurements reduces undesirable artefacts. In situ pH-sensitive fluorescent probe pyranine was used for quantitative measurements of pH inside the proteoliposomes. Calibration of pH-sensitive fluorescence response of pyranine entrapped inside proteoliposomes was performed with several ionophores combined in order to deplete the gradients passively formed across the membrane. Presented model system offers a suitable tool for simultaneous monitoring of both components of the proton electrochemical gradient, Δψ and ΔpH. This approach should help in further understanding how their formation is interconnected on biomembranes and even how transport of other ions is combined to it.