Results 1 - 10 of 9088
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[en] The fundamentals of the theory of formation of surface complexes (or the surface complexation theory, SCT), which is used in processing the results of studies on the equilibria in multicomponent ion exchange sorption systems, are outlined. The advantage of the theory is the use of the sorption characteristics of binary ion exchange systems for the description and calculation of multicomponent equilibria with allowance for the medium pH value. The solutions to some problems of nonlinear sorption dynamics theory obtained using the description of multicomponent equilibria in the framework of the SCT model are considered. Experimental data on the concentration distributions of components in frontal and displacement chromatograms are compared with the results of corresponding numerical calculations using various sets of parameters of the SCT model (including versions with allowance for the effect of complexation reactions in the mobile phase).
[en] Modern trends in studies of solutions of surfactant mixtures are discussed. The emphasis is placed on thermodynamic and molecular-statistical modelling of the phase behaviour and self-assembly patterns. The methods for prediction of properties of mixed micellar solutions based on the data for solutions of individual surfactants and the methods for calculation of the size, shape and composition distribution of micelles using the quasichemical models that take into account the molecular characteristics of components are analysed. Recent studies of surfactant solutions using computer experiments are surveyed. Theoretical approaches to the description of self-assembly phenomena in solutions of amphiphilic polymers and of their mixtures with low-molecular-mass surfactants are discussed.
[en] In order to produce only a pH-controlled solution without discharging any unused solution, has developed a continuous electrolytic system with a pH-adjustment reservoir being placed before an ion exchange membrane-equipped electrolyzer, where as a target solution was fed into the pH-adjustment reservoir, some portion of the solution in the pH-adjustment reservoir was circulated through the cathodic or anodic chamber of the depending on the type of the ion exchange membrane used, and some other the solution in the pH-adjustment reservoir was discharged from the electrolytic system through other counter chamber with its pH being controlled as acid or base. The of the pH being controlled in the system could be explained by the electro-migration of the ion species in the solution through the ion exchange membrane under a cell potential difference between anode and cathode and its consequently-occurring non-charge equilibriums and electrolytic water- split reactions in the anodic and cathodic chambers
[en] A theory-based model is presented for correlating viscosity of polymer solutions and is based on the segment-based Eyring mixture viscosity model as well as the segment-based Wilson model for describing deviations from ideality. The model has been applied to several polymer solutions and the results show that it is reliable both for correlation and prediction of the viscosity of polymer solutions at different molar masses and temperature of the polymer
[en] The critical concentration(CMC) and the counterion binding constant(B) for the mixed micellization of sodium n-octanoate(SOC) with n-octylammonium chloride(OAC) were determined as a function of the overall mole fraction of SOC(α1). Various thermodynamic parameters(Xi, γi, Ci, aiM, and ΔHmix) for the mixed micellization of the SOC/OAC systems have been calculated and analyzed by means of the equations derived from the nonideal mixed micellar model. The results show that there are great deviations from the ideal behavior for the mixed micellization of these systems. And other thermodynamic parameters(ΔGmo, ΔHmo, and ΔSmo) associated with the micellization of SOC, OAC, and their mixture(α1=0.5) have been also estimated from the temperature dependence of CMC and B values, and the significance of these parameters and their relation to the theory of the micelle formation have been considered and analyzed by comparing each other
[en] The paper shows two possibilities obtain first systems of solid phase in the case of growing single-crystals from solutions. These systems, obtained from a supersaturated solution or by a preferential cutting from a single-crystal previously grown, are thermodynamically stable and were used as seeds for further growing under controlled conditions. The paper also mentioned the method used for the growing Kdp single-crystals from solution, the slow cooling method, using seeds obtained by the help of the two methods previously mentioned. In addition, the paper shows two Kdp single-crystals grown from the liquid phase from the two types of seeds
[en] With the recent advances in nanoscale science and engineering, materials containing reinforcement with superior mechanical properties can be found in many advanced products. The accurate prediction of the mechanical properties of this class of composite materials is important to ensure the reliability of the products. Characterization methods based contact probe such as nano-indentation and scratch tests have been developed in recent years to measure the mechanical properties of the new class of nanomaterials. This paper presents a constitutive modeling framework for predicting the mechanical properties of nanoparticle reinforced composite materials. The formulation directly considers the effects of inter-nanoparticle interaction and performs a statistical averaging to the solution of the problem of two-nanoparticle interaction. Final constitutive equations are obtained in analytical closed form with no additional material parameters. The predictions from the proposed constitutive model are compared with experimental measurement from nano-indentation tests. This constitutive model for nanoparticle reinforced composites can be used to determine the volume concentration of the reinforcing nanoparticles in nano-indentation test
[en] We examine theoretically the structural behaviour of dilute solutions of multiarm star polymers under the addition of smaller homopolymer chains. The approach is based on effective interactions, for which the star-polymer centres and the centres of mass of the linear chains are used as effective coordinates. We find that addition of linear chains first leads to a softening of the star-polymer repulsions and, at higher chain concentrations, to the formation of stable, multi-star clusters. We accompany the theoretical approach with dynamical light scattering measurements in real systems, finding agreement between theory and experiment. We rationalize our findings by deriving the chain-induced, one-component effective potential between stars, which features an attractive well followed by a repulsive barrier. We discuss the dependence of these characteristics on the size and concentration of the homopolymer additives and relate the present system to recent models that also display cluster formation
[en] Starting from BPS solutions to Yang-Mills which define a stable holomorphic vector bundle, we investigate its deformations. Assuming slowly varying fieldstrengths, we find in the abelian case a unique deformation given by the abelian Born-Infeld action. We obtain the deformed Donaldson-Uhlenbeck-Yau stability condition to all orders in α'. This result provides strong evidence supporting the claim that the only supersymmetric deformation of the abelian d=10 supersymmetric Yang-Mills action is the Born-Infeld action