Curing of epoxy resins by complex based on monoamide of phosphonic acid and ammonium chloride

Reaction of epoxy-diane resin with complex based on monoamide of phosphonic acid and ammonium chloride (MODAF) is studied. It is established that the MODAF equivalent in the reaction with epoxy resin is equal to 1/5 of its molecular weight. Epoxy resin is cured via the reactions of both monoamide and ammonium chloride. The dependence of the epoxide and hydroxyl groups has a stepped character over time, which is probably due to the existence of certain threshold concentrations of the curing coefficients. The investigated reaction is a new example of macroscopic coherence manifestation.     

Regioselective Benzoylation of Glycopyranosides by Benzoyl Chloride in the Presence of MoO2(acac)2

Benzoylation of methyl and benzyl glycopyranosides by benzoyl chloride in the presence of MoO₂(acac)₂ as a catalyst resulted in 3-benzoates with good yield and high regioselectivity. Simple synthesis of the monobenzoates of some glycopyranosides is suggested.     

Effect of Adsorption of Neutral Molecules on the EDL Capacitance of a Rough Electrode

The perturbation theory is used to design a theoretical model for the Frumkin–Melik-Gaikazyan impedance of a sine electrode with a perturbation parameter equal to the ratio between the amplitude of surface oscillations and its period for a diffusion-controlled adsorption stage. The unequal diffusion access to the interface increases its capacitance. At higher frequencies, the electrode capacitance is defined by its geometric roughness factor. At lower frequencies, the capacitance depends on the adsorption conditions. The adsorption of electroactive substances results in a constant phase angle; the electrode roughness alters it and the frequency range where it remains constant.     

An analytical continuum-based model of time-of-flight distributions for pulsed laser ablation

An analytical model for time-of-flight (TOF) distributions of particles produced by pulsed laser ablation in vacuum has been proposed. The model takes into account the hydrodynamic expansion stage of the ablation plume and is based on a ‘sudden freeze’ model developed previously for steady-state supersonic jets. It is assumed that a continuum-like expansion of the plume takes place until a freezing time moment t _free (or, alternatively, until a ‘freezing distance’ x _free) whereupon the collisionless expansion begins. The proposed model is applied for analysis of experimental data on graphite ablation with nanosecond laser pulses. For verification, the analytical distributions are compared with calculated results obtained using a hybrid model combining a thermal model of laser-induced material heating with calculations of the plume dynamics by the direct simulation Monte Carlo (DSMC) method. It is shown that the proposed model can accurately estimate the surface temperature for conditions when the common approach fails.     

Locally Polynomial Method for Solving Systems of Linear Inequalities

Computational Mathematics and Mathematical Physics - A numerical method combining a gradient technique with the projection onto a linear manifold is proposed for solving systems of linear...     

Approximating a solution set of nonlinear inequalities

In this paper we propose a method for solving systems of nonlinear inequalities with predefined accuracy based on nonuniform covering concept formerly adopted for global optimization. The method generates inner and outer approximations of the solution set. We describe the general concept and three ways of numerical implementation of the method. The first one is applicable only in a few cases when a minimum and a maximum of the constraints convolution function can be found analytically. The second implementation uses a global optimization method to find extrema of the constraints convolution function numerically. The third one is based on extrema approximation with Lipschitz under- and overestimations. We obtain theoretical bounds on the complexity and the accuracy of the generated approximations as well as compare proposed approaches theoretically and experimentally.     

Influence of Annealing Temperature on the Microstructure and Morphology of TiN Films Synthesized by Dual Magnetron Sputtering

TiN films synthesized on leucosapphire substrates by dual magnetron sputtering have been annealed in vacuum at 600, 700, 800, and 900°C for 2 min. The microstructure and morphology of the films have been studied by X-ray diffraction and scanning electron microscopy at different temperatures. It has been found that annealing changes the microstructure, texture, grain size, and surface roughness of the TiN films.