Meshless formulation to two-dimensional nonlinear problem of generalized Benjamin–Bona–Mahony–Burgers through singular boundary method: Analysis of stability and convergence

In this study, the singular boundary method (SBM) is employed for the simulation of nonlinear generalized Benjamin–Bona–Mahony–Burgers problem with initial and Dirichlet-type boundary conditions. The θ-weighted finite difference method is used to discretize the time derivatives. Then the original equations are split into a system of partial differential equations. A splitting scheme is applied to split the solution of the inhomogeneous governing equation into homogeneous solution and particular solution. To solve this system, the method of particular solution (MPS) in combination with the SBM is used where the SBM is used for homogeneous solution and MPS is used for particular solution. Furthermore, the stability and convergence of the proposed method is conducted. Finally, several numerical examples with different domains are provided and compared with the exact analytical solutions to show the accuracy and efficiency in comparison with existing other methods.     

Particle trapping using dielectrophoretically patterned carbon nanotubes

This study presents the dielectrophoretic (DEP) assembly of multi‐walled carbon nanotubes (MWCNTs) between curved microelectrodes for the purpose of trapping polystyrene microparticles within a microfluidic system. Under normal conditions, polystyrene particles exhibit negative DEP behaviour and are repelled from microelectrodes. Interestingly, the addition of MWCNTs to the system alters this situation in two ways: first, they coat the surface of particles and change their dielectric properties to exhibit positive DEP behaviour; second, the assembled MWCNTs are highly conductive and after the deposition serve as extensions to the microelectrodes. They establish an array of nanoelectrodes that initiates from the edge of microelectrodes and grow along the electric field lines. These nanoelectrodes can effectively trap the MWCNT‐coated particles, since they cover a large portion of the microchannel bottom surface and also create a much stronger electric field than the primary microelectrodes as confirmed by our numerical simulations. We will show that the presence of MWCNT significantly changes performance of the system, which is investigated by trapping sample polystyrene particles with plain, COOH and goat anti‐mouse IgG surfaces.     

Interfacial tension and wetting behavior of air/oil/ionic liquid systems

We measured the interfacial tension and the density of air/n-hexane, n-decane, 1-perfluorohexane/1-hexyl-3-methyl-imidazolium hexafluorophosphate systems as a function of temperature. From the air/ionic liquid surface tension values, it was suggested that Coulombic interaction between imidazolium cations and counter anions are not so much different between the surface and bulk. The density values indicated that the decrease of surface tension by saturating organics was closely correlated to the mutual solubility between ionic liquid and organics. Interfacial tension at the oil/ionic liquid interfaces suggested that ionic liquid molecules were more ordered at the oil/ionic liquid interfaces compared to the air/ionic liquid interfaces, but the decrease of the entropy due to the interfacial orientation of ionic liquid was compensated by the increase of the entropy due to the contact of different chemical species. The initial spreading coefficients and the Hamaker constants indicated that all the oil phases spread at the air/ionic liquid interfaces spontaneously, and form the complete wetting films.     

An imidazoacridine-based TADF material as an effective organic photosensitizer for visible-light-promoted [2 + 2] cycloaddition

Energy transfer (EnT) is a fundamental activation process in visible-light-promoted photocycloaddition reactions. This work describes the performance of imidazoacridine-based TADF materials for visible-light mediated triplet–triplet EnT photocatalysis. The TADF material ACR-IMAC has been discovered as an inexpensive, high-performance organic alternative to the commonly used metal-based photosensitizers for visible-light EnT photocatalysis. The efficiency of ACR-IMAC as a photosensitizer is comparable with Ir-based photosensitizers in both intra- and intermolecular [2 + 2] cycloadditions. ACR-IMAC mediated both dearomative and non-dearomative [2 + 2] cycloadditions in good yields, with high regio- and diastereocontrol. Cyclobutane-containing bi- tri- and tetracylic scaffolds were successfully prepared, with broad tolerance toward functional groups relevant to drug discovery campaigns. Fluorescence quenching experiments, time-correlated single-photon counting, and transient absorption spectroscopy were also conducted to provide insight into the reaction and evidence for an EnT mechanism.

This work describes the performance of imidazoacridine-based TADF materials for visible-light mediated triplet–triplet EnT photocatalysis.     

Uptake monitoring of anilines and phenols using modified zeolites

Uptake monitoring of a group of environmentally important phenolic and aniline compounds including aniline, phenol, 4-methylaniline, 4-aminophenol, 2-aminophenol, 4-nitrophenol, 2-nitrophenol and 2-methyl-4-nitrophenol was carried out using micellar electrokinetic capillary chromatography. For the removal of tested pollutants, the natural zeolites natrolite and clinoptilolite were examined in which the latter showed better uptakes ranging from 45 to 64% of pollutants from aqueous solution in 4 h. Modification of zeolites with cyclodextrins (CDs), especially, α-CD, considerably improves the uptake efficiency to 65-74% for clinoptilolite. The effects of equilibrium time, type and concentration of CDs were also investigated. The versatility of micellar electrokinetic capillary chromatography was shown for this type of study owing to its speed, resolution ability, and simplicity.     

Effect of surface polarity on wettability and friction coefficient of silicone rubber/poly(acrylic acid) hydrogel composite

Water absorption, surface energetic, and friction coefficient of filled silicone rubber composites containing different amounts of a superadsorbent hydrogel, poly(acrylic acid) (PAA), were investigated. Measurements were performed in two different time windows, 1 and 5 weeks, to study the effect of hydration time on surface polarity of the samples. It was shown that water absorption increased consistently with hydrogel content and that prolongation of hydration time led to a marked increase in surface tension and polarity. Friction, as measured by a solid–solid contact method in phosphate buffer saline, showed strong dependence on polarity of the composite surface. Results demonstrate that the surface of the composite continued to evolve after the bulk had reached equilibrium swelling and the surface tension reached that of PAA after 5 weeks of hydration time.     

Surface properties of diluted solutions of cyclohexanol and cyclopentanol in ethylene glycol

The surface tension, sigma, of dilute solutions of cyclohexanol and cyclopentanol in ethylene glycol was measured in the temperature range between 293.15 and 323.15 K by means of the ring detachment method. The surface entropies and enthalpies were calculated. The surface excess values were obtained using the Gibbs equation. The surface tension data were analyzed using the extended Langmuir (EL) model and the surface composition were obtained from this model. It was shown that clathrate-like solvates (hydrophobic-like solvation) are forming in the dilute solution of cyclohexanol in ethylene glycol.     

Preparation,magnetic properties and microwave absorption of Zr–Zn–Co substituted strontium hexaferrite and its nanocomposite with polyaniline

Russian Journal of Applied Chemistry - M-type strontium hexaferrite substituted by Zr4+, Zn2+, and Co2+ was firstly synthesized by a sol-gel auto combustion method. Then the polyaniline/hexaferrite...