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Accurately modeling two-phase flows involving the surfactant is of great significance for understanding the interface evolution dynamics due to the variation of surface tension. In this study, we proposed an Allen–Cahn-based lattice Boltzmann model for two-phase flows with soluble surfactants, in which a new force scheme from the view of continuous surface tension force scheme and the consistent wetting boundary condition are derived. Several numerical tests are conducted, and the results are compared with the model based on the previous potential form (PF) interfacial force scheme. The results indicate that our proposed model can model two-phase flows involving the soluble surfactants, even for high-density ratio situations. The distribution across the interface is accurately predicted. Our model also shows superior performance on two-phase dynamics involving surfactants, i.e. smaller spurious currents and larger range of contact angle. This model can be a favorable alternative for high-density-ratio two-phase flows involving soluble surfactants.

Electronic absorption spectroscopy was used to measure the molecular association of copper phthalocyanine tetrasulfonate in micellar solutions, a microemulsion made with cationic surfactant, and homogeneous solvents. Analysis of absorbance versus concentration data using a multiple-aggregation model and non-linear regression analysis gave values of association constants, molar absorptivities and estimates of average aggregation number. Microemulsions and aqueous micellar solutions made with alkylammonium surfactants inhibited aggregation, probably because of interactions between the phthalocyanine sulfonate groups and the cationic surfactant head groups at interfacial surfaces. Similar aggregation behavior was observed previously in multiple-bilayer films of cationic surfactants. Water and aqueous solutions containing tetraethylammonium bromide or anionic SDS micelles provide environments facilitating extensive aggregation of Cu^IIPcTS⁴⁻. The major species are dimers in water and acetonitrile/water, but the formation of higher aggregates is promoted by addition of SDS or TEAB. Aprotic organic solvents provide environments intermediate between these two extremes, giving relatively large aggregation numbers (i.e. five to seven) but smaller association constants than aqueous media not containing cationic surfactants.

We develop our existing two-dimensional lattice-gas model to simulate the flow of single phase, binary immiscible and ternary amphiphilic fluids. This involves the inclusion of fixed obstacles on the lattice, together with the inclusion of "no-slip" boundary conditions. Here we report on preliminary applications of this model to the flow of such fluids within model porous media. We also construct fluid invasion boundary conditions, and the effects of invading aqueous solutions of surfactant on oil-saturated rock during imbibition and drainage are described.

We report the application of the Monte Carlo simulation to phase separation dynamics. First, we deal with the phase separation under shear flow. The thermal effect on the phase separation is discussed, and the anisotropic growth exponents in the late stage are estimated. Next, we study the effect of surfactants on the three-component solvents. We obtain the mixture of macrophase separation and microphase separation, and investigate the dynamics of both phase separations.

We presented here the phase diagrams and the influence of the external electric field on the lyotropic liquid crystal phase (LLC) for some binary and pseudoternary systems based on surfactants. Binary systems are of the type surfactant/water (S/W) and the pseudoternary systems are of the type surfactant/oil/water (S/O/W). Two surfactants have been used: the lauryl alcohol ethoxilated with 11 molecules of ethylene oxide (LA11EO), which is a nonionic compound, and a mixture of LA11EO with the cationic surfactant named alkyl C₁₂–C₁₄-dimethyl-benzyl ammonium chloride. Based on these two types of surfactants, pseudoternary systems were prepared. Pine oil has been used as the oil. The region where the LLC phase appears depends on the concentration of the surfactant and that of the pine oil, respectively. It is strongly influenced by the nature of the surfactant and by the presence of the pine oil for the same type of surfactant. The influence of the external electric field, investigated by measuring the electric current appearing in the samples for different concentrations of surfactant and pine oil was found to be more important in the case of the systems based on the nonionic-cationic mixture of surfactants. The results are discussed in terms of a theoretical model based on the local thermal equilibrium approach for systems running nonstatic processes.

The effect of temperature on the emulsification has been investigated by discontinuous molecular dynamic simulation. When a large oil drop is put in water, on one hand the mixing entropy makes it divide into small oil drops; on the other hand the interactions among particles drives the small oil drops fowards aggregation. The evolution of the mean size of oil drops obeys the exponential delay law. There exist an active temperature, at which, the addition of surfactants has obvious effect on the emulsification. The surfactants with low HLB value (e.g. H₁T₃) make the dispersity of emulsion decrease, and the surfactants with high HLB value (e.g. H₂T₂ and H₃T₁) make a contribution to increase the dispersity of emulsion.

Phyllotaxis of plant organs, bacterial ordering and animal coat patterns are analyzed for homogeneity and density. The patterns are approximated by 15 tiles and characterized by the self-coordination numbers T₁, T₂, T₃ of the nearest, next-nearest and third neighbors of the vertices of the tiles. Homogeneous structures with integer T_i values and maximum densities are obtained for distichous, whorled or spiral growth of leaves. Similar T₁ values, such as T₁=5 and 6 of sunflower seeds or bacteriae, give rise to maximum density. Inhomogeneous structures like the striped patterns of zebras with T₁=1, 2 and 3 connections have a higher density than homogeneous stripes with T₁=2. Maximum density is also obtained in icosahedral viruses.

Nano-composite Ni-Al₂O₃ coatings due to their good wear and corrosion resistance have been widely used in different industries. The agglomeration of nano-particle ceramics in the electrolyte is a serious problem in electrodeposition process that leads to the presence of agglomerated particles in the coating and influences its properties. Using a suitable surfactant can be helpful to control the agglomeration of ceramic particles. In this research nano-composite Ni-Al₂O₃ coating has been deposited from an alumina containing Watts bath using a square pulse current and Sodium Dodecyl-Sulphate (SDS) as surfactant. It was observed that SDS addition has an important effect on the reduction of particles agglomeration and increases the incorporation of finer particles into the coating. Addition of saccharin to the electrolyte, decreases the grain size and the alumina content in the coating, and also, leads to lower agglomeration and better distribution of ceramic particles. Moreover, the synergistic addition of SDS and saccharin, decreases the grain size, increases the hardness and wear resistance, but has no effect on the crystallographic texture of the coating.

Strontium hexaferrite is a hard magnetic material and has been extensively used as a permanent magnet. In this work a novel sol-gel auto-combustion method was used to synthesize ultra fine strontium hexaferrite. The investigations show that the model of combustion changes with the change of basic agent. The XRD results show that using ammonia or trimethylamine does not change the composition of the combustion product and it also shows that the surfactant burns completely during the combustion process. The average crystallite size of hexaferrite powders was also measured by X-ray line broadening technique employing Scherrer formula. The results show that changing the basic agent makes the particle size of the final product much smaller. Basic agent also affects the formation temperature of the single phase strontium hexaferrite.

Layered titanate nanosheets were synthesized by hydrolyzing titanium tetraisopropoxide (TIPT) in hydrothermal solution using triethanolamine (TEOA), and dodecanediamine (DDA) as surfactant. The effects of synthesis conditions on the formation of layered titanate nanosheets were investigated. A layered structure of the titanate was produced under basic (pH12.8) conditions using NaOH or NH₄OH aqueous solution. The flaky forms were observed only in reaction mixtures that included DDA, and the flaky forms had multilayer structure comprising several monolayer sheets. In addition, TEOA and DDA promote control of the crystalline structure of layered titanate. The surface acidity of layered titanate nanosheets was studied by coloration with color indicator reagents. The acidity of the sample corresponds to that of dilute hydrochloric acid. It is assumed that acid sites can be formed on the surface of titanate nanosheets by elimination of NH₄⁺ caused by calcination in air.

Intercalation of hydrogen phosphate (HPO₄) into Mg/Al-Layered Double Hydroxides (LDH) with DodecylBenzeneSulfonate (DBS) was investigated with regard to anion exchange, rehydration and a combination of delamination and anion exchange. HPO₄ could not be intercalated into the interlayer space of LDH with DBS when using either anion exchange or rehydration methods. However, HPO₄ was successfully intercalated into the Mg/Al-LDH using a combination of delamination and anion exchange methods.

In this study, electrorheological (ER) properties of biodegradable and conducting polyaniline-graft-chitosan (PAni-g-CS) copolymer particles were investigated. For this purpose, PAni and PAni-g-CS particles were synthesized by using in situ oxidative radicalic polymerization method. At first, PAni and PAni-g-CS/silicone oil (SO) ER suspensions (15% V/V) were subjected to external electric field and they exhibited low ER activity. When the external electric field strengths ($E)$ were increased, both the suspensions showed electrical breakdown. Therefore, virgin PAni and PAni-g-CS were first subjected to dedoping process by treating with 1.0 M NaOH(aq) and non-ionic surfactant Triton X-100 (T-X) surfactant to enhance the expected ER activity and prevent the electrical breakdown. But we observed that the addition of T-X as promoter had no significant effect on the ER activity. On the other hand, electric filed-induced viscosities of both the suspensions were observed to enhance after the dedoping (DD) process and electrical breakdown prohibited. After the DD process, DD PAni-g-CS/SO ER system exhibited the highest electric field-induced viscosity by reaching 400Pa⋅s at $E=4$kV/mm. The highest ER efficiency was also obtained for DD PAni-g-CS/SO system at 15% (V/V) as 79. Additionally, typical shear thinning non-Newtonian viscoelastic behavior was observed under externally applied E. The conduction model of DD PAni-g-CS/SO system was determined to well fit the conduction model by showing a slope of $m=1.5$ calculated from the E vb. yield stress graph. In conclusion, conducting and biodegradable-dedoped PAni-g-CS particles would be a good candidate for potential ER applications as dry-based ER materials having high colloidal stability of 76%.

Germanium was deposited onto highly oriented pyrolytic graphite (HOPG) with and without antimony in ultra-high vacuum. The surface morphology was analyzed using in situ scanning tunneling microscopy (STM) at room temperature (RT). The film grows exclusively in 3D island mode and was affected significantly by substrate defects. At initial stage, nucleation of cluster occurred at step edges and defect sites. Later, we found various types of Ge nanostructures on HOPG in different deposition conditions and stages, including cluster chains, cluster islands, nanowires, and double layer ramified islands at RT. Compact Ge islands were observed when depositing at a substrate temperature of 450 K or after an annealing at 600 K following RT deposition. In addition, the pre-deposited Sb on graphite enhances the sticking probability and suppresses the surface diffusion of Ge atoms, resulting in a significant increase in Ge cluster island density on HOPG terraces.

We have investigated the effect of Bi on the heteroepitaxial growth of Co on Cu by reflection high-energy electron diffraction (RHEED) measurements. It was found that Bi enhanced the layer-by-layer growth of Co on the Cu(111) surfaces at 100°C. The dependence of the growth on Bi layer thickness suggested that there existed a suitable amount of Bi surfactant layer that enhanced smoother layered growth. On the contrary, for the case of Co growth on Cu(100), Bi depressed the layer-by-layer growth of Co on Cu(100). The surface segregation effect of Bi was also studied by Auger electron spectroscopy (AES).

Influence of surfactants on the corrosion properties of chromium-free electroless nickel deposit were investigated on AZ91D magnesium alloy. The corrosion tests were carried out by immersion test (1 M HCl) and electrochemical polarization test (3.5 wt% NaCl). The surfactants in the electroless nickel bath increases the corrosion resistance properties of the deposit on the magnesium alloy. In addition, smoothness and amorphous plus nano-crystalline phase were increased and accounted for the significant corrosion resistance. As a consequence, the corrosion potential moved towards the positive direction and the corrosion current density decreased. The immersion tests also provided the same trend as that of electrochemical polarization test. On the whole, the study concluded that corrosion resistance was enhanced by including a surfactant in the electroless deposits on magnesium alloy.

Al- and N-polar AlN have been grown by metalorganic vapor phase epitaxy (MOVPE) with the assistance of In dopant and characterized by in situ interferometry, ellipsometry, scanning electron microscopy, atomic force microscopy, and X-ray diffractometry. The growth of Al-polar AlN is faster with smoother surfaces than the N-polar ones, which is explained by theoretical calculations. The surfactant effect of In is confirmed by improving the growth rate and surface flatness without getting into the epilayer. Additionally, In is also favorable for reducing the density of dislocations and improving the crystalline quality, especially that of Al-polar AlN. The results suggest that using In surfactant to grow the Al-polar AlN epilayer leads to a better crystal quality under proper pre-growth treatments, low- and high-temperature AlN growth conditions.

Carbon nanofibers (CNFs) were coated by surfactants of polyoxyetheylene alkyl ether (AEO₉, AEO₇) and polyvinyl alcohol (PVA 1799), respectively, after being mixed with surfactant aqueous solution and then treated with ultrasonication, high shear and magnetic stirring. The CNF/epoxy composites were prepared by mixing the surfactant coated CNFs with epoxy. Tensile strength, elastic modulus and ultimate strain of the composites were studied. The tensile strength and the ultimate strain of the composites were increased by 20% and 70%, respectively, after the CNFs were coated by surfactants. However, the elastic modulus of the composite will be lowered when the CNFs were treated by too high a concentration of surfactant solution.

In this study, high purity gamma-alumina nanopowders with crystalline structures have been prepared via a sol–gel process by waste metal aluminum, HCl, NaOH, Polyethylene glycol (PEG) and polyvinyl alcohol (PVA). Polyethylene glycol and polyvinyl alcohol have been used as stabilizing agents. The characterization of the samples has been performed utilizing XRD, FTIR, SEM, N₂ adsorption/desorption techniques. Prepared samples of gamma-alumina at 800^∘C with PEG has an average crystallite size of 2.58nm, average particle size of 21nm, specific surface area (SSA) of 65.55m²/g, and pore volume of $\sim$0.06cm³/g. The average crystallite size of 3.07nm, average particle size of 31nm, specific surface area of 131.25m²/g, and pore volume of $\sim$0.14cm³/g, were obtained using PVA surfactant.

The reduced viscosity of polymer guar gum solutions containing a certain concentration of sodium dodecyl benzene sulfonate (SDBS) was measured. It has been found that the Huggins coefficient k_H of polymer solutions is very sensitive to the concentration of the surfactant, c_SDBS, in solutions. If c_SDBS is lower than CMC, the critical micelle concentration of SDBS, k_H increases rapidly with c_SDBS. On the other hand, if c_SDBS is larger than CMC, k_H decreases rapidly with c_SDBS. Comparatively, the intrinsic viscosity of polymer solution does not show a notable change with c_SDBS. The experimental results indicate that the interchain association of polymer guar gum in solution is greatly associated with SDBS interacted with polymer chains through hydrogen bonds. However, the effect of SDBS upon the intrachain association of polymer guar gum solution is negligible, presumably due to the fact that guar gum is a slightly stiffened random-coil chain polymer.

Tin porphyrin (SnTPP) was applied to two new types of photoinduced oxygen evolution systems by visible light irradiation. In microheterogeneous system, tin porphyrin was dispersed by a nonionic surfactant and the system could efficiently oxidize water to evolve oxygen when compared with the conventional system. In addition, two types of tin porphyrin fixed PVC membranes, porous and homogeneous, were prepared and applied to a photoinduced oxygen evolution membrane system. SEM images of two types of tin porphyrin fixed PVC membranes also show differences in both morphologies.