Electronic currents in anodic polarization of oxide-covered valve metals

A model for the electron current in anodic oxidation of valve metals is presented by considering the film-forming electrolyte solution as a doped semiconductor which injects electrons into the oxide layer. The model enables us to explain the available experimental facts concerning the dependence of the current on the field in the oxide and the nature and concentration of the solution.     

Numerical investigation of quenching for a nonlinear diffusion equation with a singular Neumann boundary condition

For a nonlinear diffusion equation with a singular Neumann boundary condition, we devise a difference scheme which represents faithfully the properties of the original continuous boundary value problem. We use non‐uniform mesh in order to adequately represent the spatial behavior of the quenching solution near the boundary. © 2002 Wiley Periodicals, Inc. Numer Methods Partial Differential Eq 18: 429–440, 2002; Published online in Wiley InterScience (www.interscience.wiley.com). DOI 10.1002/num.10013     

Spatial Entanglement of Fermions in One-Dimensional Quantum Dots

The time-dependent quantum Monte Carlo method for fermions is introduced and applied in the calculation of the entanglement of electrons in one-dimensional quantum dots with several spin-polarized and spin-compensated electron configurations. The rich statistics of wave functions provided by this method allow one to build reduced density matrices for each electron, and to quantify the spatial entanglement using measures such as quantum entropy by treating the electrons as identical or distinguishable particles. Our results indicate that the spatial entanglement in parallel-spin configurations is rather small, and is determined mostly by the spatial quantum nonlocality introduced by the ground state. By contrast, in the spin-compensated case, the outermost opposite-spin electrons interact like bosons, which prevails their entanglement, while the inner-shell electrons remain largely at their Hartree–Fock geometry. Our findings are in close correspondence with the numerically exact results, wherever such comparison is possible.     

Conformational Dynamics Underlies Different Functions of Human KDM7 Histone Demethylases

The human KDM7 subfamily histone H3 Nϵ-methyl lysine demethylases PHF8 (KDM7B) and KIAA1718 (KDM7A) have different substrate selectivities and are linked to genetic diseases and cancer. We describe experimentally based computational studies revealing that flexibility of the region linking the PHD finger and JmjC domains in PHF8 and KIAA1718 regulates interdomain interactions, the nature of correlated motions, and ultimately H3 binding and demethylation site selectivity. F279S an X-linked mental retardation mutation in PHF8 is involved in correlated motions with the iron ligands and second sphere residues. The calculations reveal key roles of a flexible protein environment in productive formation of enzyme-substrate complexes and suggest targeting the flexible KDM7 linker region is of interest from a medicinal chemistry perspective.     

Effect of electric-field-induced capillary attraction on the motion of particles at an oil-water interface

Here, we investigate experimentally and theoretically the motion of spherical glass particles of radii 240-310 microm attached to a tetradecane-water interface. Pairs of particles, which are moving toward each other under the action of lateral capillary force, are observed by optical microscopy. The purpose is to check whether the particle electric charges influence the particle motion, and whether an electric-field-induced capillary attraction could be detected. The particles have been hydrophobized by using two different procedures, which allow one to prepare charged and uncharged particles. To quantify the hydrodynamic viscous effects, we developed a semiempirical quantitative approach, whose validity was verified by control experiments with uncharged particles. An appropriate trajectory function was defined, which should increase linearly with time if the particle motion is driven solely by the gravity-induced capillary force. The analysis of the experimental results evidences for the existence of an additional attraction between two like-charged particles at the oil-water interface. This attraction exceeds the direct electrostatic repulsion between the two particles and leads to a noticeable acceleration of their motion.     

Thermodynamic Modeling of Aqueous Aluminum Chemistry and Solid-Liquid Equilibria to High Solution Concentration and Temperature. I. The Acidic H-Al-Na-K-Cl-H2O System from 0 to 100 °C

In this paper, we describe the development of a thermodynamic model that calculates solute/solvent activities and solid-liquid equilibria in the acidic aluminum system, H-Al³⁺-Na-K-Cl-H₂O, to high molality from 0?° to ≈100?°C. The model incorporates the concentration-dependent, specific interaction equations for aqueous solutions of Pitzer (Activity Coefficients in Electrolyte Solutions, 2nd edn., pp. 75–153, CRC Press, Boca Raton, 1991). Parameterization of this model adds Al³⁺ specific interactions in the binary Al-Cl-H₂O and ternary Al-H-Cl-H₂O, Al-Na-Cl-H₂O and Al-K-Cl-H₂O systems as well as the standard chemical potentials of AlCl₃?6H₂O(s) and Al(OH)₃(s) (gibbsite) in the 0?° to 100?°C range to our variable temperature (0–250?°C) model of acid-base reactions in the H-Na-K-OH-Cl-HSO₄-SO₄-H₂O system (Christov and Moller in Geochim. Cosmochim. Acta 68:1309, 2004). In constructing our aluminum model, we used Emf, osmotic, equilibrium constant and solubility data. New Emf measurements using the cell Pt|H₂(g, 101.325 kPa)|HCl(m ₁), AlCl₃(m ₂)|AgCl(s)|Ag|Pt at temperatures ranging from 0 to 45?°C and at total ionic strength ranging from 0.1 to 3 mol?kg^?1 are presented. Gibbsite and boehmite, AlOOH(s), solubility data are used in testing the model. Limitations of the model due to data insufficiencies are discussed.     

Exploring quantum non-locality with de Broglie-Bohm trajectories

Here in this paper, it is shown how the quantum nonlocality reshapes probability distributions of quantum trajectories in configuration space. By variationally minimizing the ground state energy of helium atom, we show that there exists an optimal nonlocal quantum correlation length which also minimizes the mean integrated square error of the smooth trajectory ensemble with respect to the exact many-body wave function. The nonlocal quantum correlation length can be used for studies of both static and driven many-body quantum systems.     

Stokes’ first problem for some non-Newtonian fluids: Results and mistakes

The well-known problem of unidirectional plane flow of a fluid in a half-space due to the impulsive motion of the plate it rests upon is discussed in the context of the second-grade and the Oldroyd-B non-Newtonian fluids. The governing equations are derived from the conservation laws of mass and momentum and three correct known representations of their exact solutions given. Common mistakes made in the literature are identified. Simple numerical schemes that corroborate the analytical solutions are constructed.     

Shock and traveling wave phenomena on an externally damped, non-linear string

We examine the propagation of shocks and traveling wave phenomena on a one-dimensional string that is executing finite-amplitude, transverse vibrations in a resisting medium. As part of our study, we develop an approach that allows us to describe, albeit approximately, the evolution and propagation of a shock front using analytical methods. In addition, exact traveling wave solutions, one of which involves the Lambert W-function, of the string's equation of motion are determined and analyzed. Lastly, a possible new form of the solution to the linearized problem is presented and extensions and other applications of the present work are briefly discussed.