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In this paper, we propose a phase field-lattice Boltzmann (LB) model with an equation of state (EOS) inputting for two-phase flow containing soluble surfactants. In this model, both the order parameter for the phase field and the surfactant concentration are described by second-order partial differential equations, along with Navier–Stokes equations for the flow field. Changes in surfactant concentration do not affect the order parameter distribution; hence, an unwanted sharpening effect cannot arise. Most importantly, in the existing models, the EOS of surface tension is determined by posterior simulation tests instead of being directly set as an input parameter before the simulations. Hence, it is difficult to determine the model parameters in practical applications. To address this issue, we systematically develop a fully analytical EOS for surface tension based on the Gibbs–Duhem equation. Subsequently, an approximate explicit form for EOS is provided by utilizing the Jacobi–Gauss quadrature rule. Furthermore, a multiple-relaxation-time LB scheme is utilized to numerically solve the governing equations of three physical fields. Two benchmark examples are simulated to validate the accuracy of the present model. The consistency between the numerical results and the analytical EOS is verified. Moreover, the dynamics of droplets with surfactant in simple shear flow is investigated, unveiling the profound impact of various factors, such as surfactant bulk concentration, capillary number, and viscosity ratio, on single droplet deformation and two equal-sized droplets interaction. A detailed exploration of the fluid mechanism involved in two-phase flow with soluble surfactants is presented. [ABSTRACT FROM AUTHOR]

A diffuse interface-lattice Boltzmann model is proposed for modeling conjugate heat transfer problems with imperfect interfaces. According to the continuity condition of heat flux and jump condition of temperature across the imperfect interface, a unified sharp interface equation of the temperature field with a singular source term in the composite media domain is established. Then a diffuse interface equation is obtained by making a smoothed approximation of the unified sharp interface equation. The novel diffuse interface equation is restructured into a second-order heat diffusion equation with an anisotropic diffusion coefficient tensor. To numerically solve the second-order anisotropic diffusion equation, a multiple-relaxation-time (MRT) lattice Boltzmann (LB) scheme is employed. Several numerical simulations of benchmark test examples with analytical solutions are carried out to demonstrate the accuracy of the present model, including the steady-state heat diffusion in a two-layer medium with a flat interface, steady heat diffusion in a square domain with a curved interface and unsteady-state temperature diffusion with two-layer media. The numerical results show that the phenomenon of temperature jump across the imperfect interface can be successfully and correctly captured. Moreover, as an example of practical application, the new proposed diffuse interface model is utilized to predict the effective thermal conductivity of porous media with thermal contact resistance at pore scale. The variation law of the effective thermal conductivity is obtained for each parameter by studying the effects of thermal conductivity ratios of the dual-component material, the shape and volume fraction of blocks in the material, the interfacial thermal conductance coefficient, and the number of blocks on the effective thermal conductivity. Both uniform and random pore structures are considered. The previous theoretical equations strongly support the validity of the present model. [ABSTRACT FROM AUTHOR]

In this paper, the dynamical mechanism and a general deformation law of a ferrofluid droplet suspended between the air and a liquid substrate under the action of the applied vertical uniform magnetic field are investigated by a numerical model. A generalized conservative phase-field simplified multiphase lattice Boltzmann model is adopted to solve the flow field and phase field, which has a good ability to simulate the problems of ternary fluid flows with large density ratios. Subsequently, the Maxwell equation of static magnetic field is used to solve the magnetic field using a self-correcting scheme. We used this model to numerically study the dynamic evolvement process of ferrofluid droplets placed between the air and a liquid substrate, which are exposed in a vertical uniform magnetic field. Some typical characteristics are employed to characterize the droplet shape, and it is found that the aspect ratio, the elongated velocity, and the height of the mass center of the ferrofluid droplet are related to the magnetic Bond number. Furthermore, the numerical results obtained with the model are in good agreement with the experimental results available in the literature. Finally, the quantitative power law relation between the magnetic Bond number and the aspect ratio of ferrofluid droplets is obtained by using the method of scaling law, which provides a theoretical basis for the study of the deformation mechanism and the universal laws of a ferrofluid droplet placed between the air and a liquid substrate under the action of the vertical uniform magnetic fields with different intensities. [ABSTRACT FROM AUTHOR]

There are several numerical approaches to define a permanent magnet in terms of mathematical equations, and each approach has progressed since its inception, but still endures some limitations on specific numerical phenomena. This study seeks to propose a novel numerical representation of a permanent magnet without incorporating its effect through boundary conditions, which overcomes the limitations of previous studies and enables us to introduce a magnetic field of desired strength at any location. A self-correcting method is modified to incorporate the magnetic field effects, while a simplified lattice Boltzmann method is utilized to solve the governing equations for flow field and interface. The validity of the proposed method is ensured by simulating some benchmark phenomena with and without the external magnetic field. This study also investigates the wetting dynamics of a sessile ferrofluid droplet deposited on solid substrates with different wettabilities. The influence of uniform and non-uniform magnetic fields on droplet spreading is discussed in detail. It is observed that for a non-uniform magnetic field in vertical direction, the ferrofluid droplet on a hydrophilic surface does not observe the spherical cap approximation unless the magnetic field strength is below saturation magnetization. Moreover, if the magnet is located above, the droplet undergoes large deformations and achieves pointy shapes with sharp tips on less wettable surfaces. [ABSTRACT FROM AUTHOR]

A new Cd‐MOF containing the nucleobase adenine and multicarboxylates, Cd2(tdc)2(1H‐ade)2(H2O) (H2tdc = 2,5‐thiophene carboxylic acid, 1H‐ade = adenine), was synthesized successfully under hydrothermal condition and characterized by single‐crystal X‐ray diffraction, infrared spectrum, thermogravimetric analysis and photoluminescence. The two crystallographically unsymmetrical Cd atoms are bridged by 2,5‐tdc ligands with (κ1‐κ1)‐(κ1)‐μ3 and (κ1–κ1)–μ2 modes into two dimensional extended layers, which are further pillared with the neutral ade molecules to form a 3D frameworks stabilized by extensive π···π interactions between imidazole‐, pyrimidine‐ and thiophene‐rings. Inspection of the structure reveals that the architecture can be simplified as a 3,4,5‐ connected networks with a Schläfli symbol of (62·8)(42·63·8)(42·65·83). The photochemical property shows that the luminescent emission can be significantly quenched by aromatic azo compounds. The quenching effect coefficient (Ksv) for bis(4‐imidazol‐1‐yl‐phenyl)diazene is determined to be 4.1 × 104m–1, indicating the title compound as a potential fluorescent sensing materials. [ABSTRACT FROM AUTHOR]

Abstract: In this work, a luminescent probe (RuE, the abbreviation of Ru(bpy)2(E)Cl2, where bpy=2,2′‐bipyridine, E=N,N′‐5,6‐(1,10‐phenanthroline)‐bis(2‐hydroxy benzaldehyde)diamine) based on the ruthenium(II) bipyridyl complex conjugated with functionalized Schiff bases, which revealed a highly selective luminescence quenching by Cu2+ in aqueous solution was prepared. Because of the quenching effect of copper ions, the luminescence of RuE−Cu(II) solution was weak. However, in the presence of pyrophosphate (P 2O4‐ 7, PPi), the strong binding ability of PPi to Cu2+ can promote the break up of RuE−Cu(II) complex and then recover the luminescence. Most of other potential interfering anions, including strong interfering substance, like phosphate, ATP, ADP and AMP can not enhance the luminescence apparently. Therefore, the RuE−Cu(II) ensemble can act as an excellently selective and sensitive turn‐on probe for the sequential determination of PPi in aqueous solution. The detection limit of the probe for PPi was 0.58 nM and the linear concentration range was 0−16 μM. In addition, the potential applicability of this probe has been demonstrated by the successful detection of PPi in human urine samples. [ABSTRACT FROM AUTHOR]

A ruthenium(II) bipyridyl complex conjugated with functionalized Schiff base (RuA) has been synthesized and functioned as a luminescent probe. The luminescence of RuA was greatly quenched by Cu 2+ due to its molecular coordination with paramagnetic Cu 2+ . Subsequently, the addition of l -Histidine can turn on the luminescence of the RuA-Cu(II) ensemble, which can be attributed to the replacement of RuA in RuA-Cu(II) ensemble by l -Histidine. On the basis of the quenching and recovery of the luminescence of RuA, we proposed a rapid and highly sensitive on-off-on luminescent assay for sensing Cu 2+ and l -Histidine in aqueous solution. Under the optimal conditions, Cu 2+ and l -Histidine can be detected in the concentration range of 5 nM–9.0 μM and 50 nM–30 μM, respectively, and the corresponding detection limits were calculated to be 0.35 and 0.44 nM (S/N=3), separately. The proposed luminescent probe has been successfully utilized for the analysis of Cu 2+ and l -Histidine in real samples (drinking water and biological fluids). Furthermore, the probe revealed good photostability, low cytotoxicity and excellent permeability, making it a suitable candidate for cell imaging and labeling in vitro. [ABSTRACT FROM AUTHOR]

• The method can be applied to both miscible and immiscible ternary flow problems. • The method can deal with ternary flows with reduction consistency and conservation of mass. • The method can effectively simulate the ternary flows with a large density ratio up to 1200. In this paper, a generalized conservative phase-field simplified lattice Boltzmann method is proposed, which is suitable for both miscible and immiscible ternary flow problems. This method extends our earlier simplified multiphase lattice Boltzmann method (SMLBM) (Chen et al., 2018a) for two-phase flows to the ternary flows by using a generalized conservative equation with Lagrange multiplier to control the evolution of the interface and ensures the conservations of the volume and total mass of each phase. Moreover, the good stability of the SMLBM is utilized for solving the interface problems with large gradients induced by large density ratios between different fluid components. To validate the present method, several ternary flow examples are simulated. The numerical results show that the method can effectively simulate the ternary flows with a density ratio up to 1200 and can be applied to accurately simulate the miscible ternary flows with satisfying the reduction consistency conditions. [ABSTRACT FROM AUTHOR]

Seed shape and seed volume are functionally important traits which are associated with seed germination. To study the ecological and evolutionary significance of seed shape and volume in relation to germination, a database comprising seed information for 383 species within 50 families from an alpine meadow on the eastern Qinghai-Tibet plateau was compiled. The independent and interactive effects of seed traits on germination and whether these effects are controlled by phylogeny are discussed. The results show the following: (1) Elongated seeds had higher percentage and faster speed of germination than compact seeds whereas smaller seeds tended to have higher germinability compared to larger ones; (2) Seed volume and shape evolved together but had independent effects on seed germination. Seed volume had no significant influence on seed germination among species with compact seeds, but had a significant effect on those among species with elongated seeds; seed germination of larger seeded species was affected by seed shape, but not by seed volume. These results might be related to their predation pressure and ability to germinate from deeper soil layers. Lastly, (3) Phylogenetic conservation plays an important role in the co-evolution of seed traits and germination characteristics. Species with similarly shaped seeds on a large scale might reflect a common selective pressure, but related species within a family might be more dependent on phylogenetic conservation. [ABSTRACT FROM AUTHOR]