Lattice Boltzmann method for simulation of wettable particles at a fluid-fluid interface under gravity

A computational technique was developed to simulate wettable particles trapped at a fluid-fluid interface under gravity. The proposed technique combines the improved smoothed profile-lattice Boltzmann method (iSP-LBM) for the treatment of moving solid-fluid boundaries and the free-energy LBM for the description of isodensity immiscible two-phase flows. We considered five benchmark problems in two-dimensional systems, including a stationary drop, a wettable particle trapped at a fluid-fluid interface in the absence or presence of gravity, two freely moving particles at a fluid-fluid interface in the presence of gravity (i.e., capillary floatation forces), and two vertically constrained particles at a fluid-fluid interface (i.e., capillary immersion forces). The simulation results agreed well with theoretical estimations, demonstrating the efficacy of the proposed technique

Acoustic pressure pulses from laser-irradiated suspensions containing gold nanospheres in water: Experimental and theoretical study

We present a physical model that describes the acoustic pressure pulses from diluted suspensions of metal nanospheres in a liquid medium irradiated by laser pulses. The experimental measurements of the photoacoustic signals are also reported, where the suspensions of 8-nm gold nanospheres in water at different concentrations and different temperatures were irradiated by 0.8-ns laser pulses. We mainly investigate how the nanosphere concentration and the suspension temperature influence the photoacoustic responses. The estimations from our model are found to be in good agreement with the results from the experiments

Effect of internal mass in the lattice Boltzmann simulation of moving solid bodies by the smoothed-profile method

A computational method for the simulation of particulate flows that can efficiently treat the particle-fluid boundary in systems containing many particles was developed based on the smoothed-profile lattice Boltzmann method (SPLBM). In our proposed method, which we call the improved SPLBM (iSPLBM), for an accurate and stable simulation of particulate flows, the hydrodynamic force on a moving solid particle is exactly formulated with consideration of the effect of internal fluid mass. To validate the accuracy and stability of iSPLBM, we conducted numerical simulations of several particulate flow systems and compared our results with those of other simulations and some experiments. In addition, we performed simulations on flotation of many lightweight particles with a wide range of particle size distribution, the results of which demonstrated the effectiveness of iSPLBM. Our proposed model is a promising method to accurately and stably simulate extensive particulate flows

Lattice Boltzmann model for capillary interactions between particles at a liquid-vapor interface under gravity

A computational technique based on the lattice Boltzmann method (LBM) is developed to simulate the wettable particles adsorbed to a liquid-vapor interface under gravity. The proposed technique combines the improved smoothed-profile LBM for the treatment of moving solid particles in a fluid and the free-energy LBM for the description of a liquid-vapor system. Five benchmark two-dimensional problems are examined: (A) a stationary liquid drop in the vapor phase; a wettable particle adsorbed to a liquid-vapor interface in (B) the absence and (C) the presence of gravity; (D) two freely moving particles at a liquid-vapor interface in the presence of gravity (i.e., capillary flotation forces); and (E) two vertically constrained particles at a liquid-vapor interface (i.e., capillary immersion forces). The simulation results are in good quantitative agreement with theoretical estimations, demonstrating that the proposed technique can reproduce the capillary interactions between wettable particles at a liquid-vapor interface under gravity

Characterization of the DIMS system based on astronomical meteor techniques for macroscopic dark matter search

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Effects of valproic acid on the cell cycle and apoptosis through acetylation of histone and tubulin in a scirrhous gastric cancer cell line

<p>Abstract</p> <p>Background</p> <p>Management of peritoneal dissemination is the most critical problem in gastric cancer. This study was performed to investigate the inhibitory effects of valproic acid (VPA) on a highly peritoneal-seeding cell line of human scirrhous gastric cancer, OCUM-2MD3, and to explore the mechanism and the potential of VPA.</p> <p>Methods</p> <p>The effects of VPA on the growth of OCUM-2MD3 cells were assessed by MTT assay. In addition, paclitaxel (PTX) was combined with VPA to evaluate their synergistic effects. HDAC1 and HDAC2 expression were evaluated by western blotting in OCUM-2MD3 cells and other gastric cancer cell lines (TMK-1, MKN-28). The acetylation status of histone H3 and α-tubulin after exposure to VPA were analyzed by western blotting. The activities of cell cycle regulatory proteins and apoptosis-modulating proteins were also examined by western blotting. The effects of VPA <it>in vivo </it>were evaluated in a xenograft model, and apoptotic activity was assessed by TUNEL assay.</p> <p>Results</p> <p>OCUM-2MD3 cells showed high levels of HDAC1 and HDAC2 expression compared with TMK-1 and MKN-28. The concentration of VPA required for significant inhibition of cell viability (<it>P </it>< 0.05) was 5 mM at 24 h and 0.5 mM at 48 h and 72 h. The inhibition of VPA with PTX showed dose-dependent and combinatorial effects. VPA increased acetyl-histone H3, acetyl-α-tubulin, and p21WAF1 levels accompanied by upregulation of p27, caspase 3, and caspase 9, and downregulation of bcl-2, cyclin D1, and survivin. In the xenograft model experiment, the mean tumor volume of the VPA-treated group was significantly reduced by 36.4%, compared with that of the control group at 4 weeks after treatment (<it>P </it>< 0.01). The apoptotic index was significantly higher in the VPA-treated group (42.3% ± 3.5%) than in the control group (7.7% ± 2.5%) (<it>P </it>< 0.001).</p> <p>Conclusions</p> <p>VPA induced dynamic modulation of histone H3 and α-tubulin acetylation in relation with the anticancer effect and the enhancement of PTX in the OCUM-2MD3 cell line. Therefore, VPA in combination with PTX is expected to be a promising therapy for peritoneal dissemination of scirrhous gastric cancer.</p

Computer simulation of wetting, capillary forces, and particle-stabilized emulsions: From molecular-scale to mesoscale modeling

The present paper gives an overview of two methodologies for the computer simulation of wetting and capillary forces as well as particle-stabilized emulsions, which usually appear in a two-phase fluid system including solid bodies. One method is the molecular simulation with a coarse-grained model. The other is the computational fluid dynamics with a phase-field model. The main emphasis of this review is concerning our idea how to model the solid surfaces with wettability for the different simulation methods in the same spirit of “a simple modeling with focusing on hydrophilicity and hydrophobicity”

Adhesion of melanoma cells to the microsphere surface is reduced by exposure to nanoparticles

It is of fundamental importance to better understand the interactions of nanoparticles with mammalian cells, such as cellular uptake of nanoparticles and the resultant cellular responses. In the present study, we have measured the interaction force of single nanoparticle-treated cells with a microsphere surface, using atomic force microscopy (AFM) with colloid probes. It was found that the adhesion force of murine melanoma cells to the surface of a 6.90-μm carboxyl-modified polystyrene (PS-COOH) microsphere was significantly reduced by exposing them to the 40-nm PS-COOH nanoparticles in a serum-free culture medium for 15 min, although the nanoparticle treatment of the cells up to 180 min hardly affected their morphology, membrane integrity, and metabolic activity. Possible mechanism of this phenomenon will be discussed