purification of drinking and industrial water required usage of high molecular weight polymer to cause flocculation process of dispersed suspension of contaminants. polyelectrolytes, including ionic polyacrylamide are especially appropriate for these purposes, because in this case the suspension stability can be controlled by both steric and electrostatic forces. thus the influence of solution ...

The major features of a scalar property P defined on a molecular surface can be captured in the form of a directed graph derived from the gradient flow of P . These molecular surface property graphs (MSPG) have vertices at the critical points (maxima, minima and saddles) of P and edges formed by the trajectories of the gradient flow that pass through the saddles. Techniques developed for the co...

The arithmetic mean roughness, Ra, values were determined by scanning electron microscopic technique of different core models (furazolidone, nitrofurantoin and acetyl salicylic acid), coated by HPMC film forming solution containing 10 wt% of various molecular weight PEGs. The results showed that both plasticizer molecular weight and core surface free energy could have a significant influence on...

The Molecular structure, conformational stability and vibrational frequencies of succinonitrile NCCH2CH2CN have been investigated with ab initio and density functional theory (DFT) methods implementing the standard 6-311++G* basis set. The potential energy surfaces (PES) have been explored at DFT-B3LYP, HF and MP2 levels of theory. In agreements with previous experimental results, the molecule ...

A new method, non-Markovian quantum-classical approximation (NQCA), is suggested to model the photoisomerization of polyatomic molecules. The NQCA method can be successfully applied to follow the photoisomerization process for a wide class of reacting systems, namely, those for which the time scale required for the equilibration in the phase space of the potential energy surface (PESs) is short...

Recent computational efforts have shown that the current potential energy models used in molecular dynamics are not accurate enough to describe the conformational ensemble of RNA oligomers and suggest that molecular dynamics should be complemented with experimental data. We here propose a scheme based on the maximum entropy principle to combine simulations with bulk experiments. In the proposed...

Generation of equilibrium configurations is the major obstacle for numerical investigation of the slow dynamics in supercooled liquid states. The parallel tempering (PT) technique, originally proposed for the numerical equilibration of discrete spin-glass model configurations, has recently been applied in the study of supercooled structural glasses. We present an investigation of the ability of...

We have performed extensive molecular dynamics simulations to study noise-power spectra of density and potential energy fluctuations of a Lennard-Jones model of a fluid in the supercritical region. Emanating from the liquid-vapor critical point, there is a locus of isobaric specific heat maxima, called the Widom line, which is often regarded as an extension of the liquid-vapor coexistence line....

The sticking and scattering of O(2)Pt(111) has been studied by tight-binding molecular dynamics simulations based on an ab initio potential energy surface. We focus, in particular, on the sticking probability as a function of the angle of incidence and the energy and angular distributions in scattering. Our simulations provide an explanation for the seemingly paradox experimental findings that ...