In this work, we are interested in effects of a simple profile of permanent charges on ionic flows. We determine when a permanent charge produces current reversal. We adopt the classical Poisson-NernstPlanck models of ionic flows for this study. The starting point of our analysis is the recently developed geometric singular perturbation approach for Poisson-Nernst-Planck models. Under the setti...

A 3d electron topological insulator (ETI) is a phase of matter protected by particle-number conservation and time-reversal symmetry. It was previously believed that the surface of an ETI must be gapless unless one of these symmetries is broken. A well-known symmetry-preserving, gapless surface termination of an ETI supports an odd number of Dirac cones. In this paper we deduce a symmetry-respec...

Recent results suggest that during evolution certain substitutions at protein sites may occur in a coordinated manner due to interactions between amino acid residues. Information on these coordinated substitutions may be useful for analysis of protein structure and function. CRASP is an Internet-available software tool for the detection and analysis of coordinated substitutions in multiple alig...

accurate quantum chemical computations based on density functional theory (dft) were performed on the series of 2-(4-(naphthalen-2-yl)-1,2,3-thiadiazol-5-ylthio)-n-acetamide (tta) derivatives. the local reactivity of the acetamide derivatives as anti-hiv drugs were studied in terms of fukui functions in the framework of dft. the results based on the basis set superposition error (bsse) correcti...

The charge of bubbles in aqucous solution is important in detemlining their interactions with particles, droplets, and other bubbles. While bubbles are known to be negatively charged in such media as water and sodium chloride solutions, they are found here to exhibit unusual positive surface charge chamcteristics in solutions of trivalent aluminum cations. Analysis of the results indicates that...

We report charge inversion, the sign reversal of the effective surface charge in the presence of multivalent counterions, for the biologically relevant regimes of divalent ions and mixtures of monovalent and multivalent ions. Using streaming currents, the pressure-driven transport of countercharges in the diffuse layer, we find that charge inversion occurs in rectangular silica nanochannels at ...