A lattice Boltzmann method for axisymmetric thermocapillary flows

In this work, we develop a two-phase lattice Boltzmann method (LBM) to simulate axisymmetric thermocapil- lary flows. This method simulates the immiscible axisymmetric two-phase flow by an improved color-gradient model, in which the single-phase collision, perturbation and recoloring operators are all presented with the axisymmetric effect taken into account in a simple and computational consistent manner. An additional lattice Boltzmann equation is introduced to describe the evolution of the axisymmetric temperature field, which is coupled to the hydrodynamic equations through an equation of state. This method is first validated by simulations of Rayleigh-B ́enard convection in a vertical cylinder and thermocapillary migration of a de- formable droplet at various Marangoni numbers. It is then used to simulate the thermocapillary migration of two spherical droplets in a constant applied temperature gradient along their line of centers, and the influence of the Marangoni number (Ca), initial distance between droplets (S0), and the radius ratio of the leading to trailing droplets (Λ) on the migration process is systematically studied. As Ma increases, the thermal wake behind the leading droplet strengthens, resulting in the transition of the droplet migration from coalescence to non-coalescence; and also, the final distance between droplets increases with Ma for the non-coalescence cases. The variation of S0 does not change the final state of the droplets although it has a direct impact on the migration process. In contrast, Λ can significantly influence the migration process of both droplets and their final state: at low Ma, decreasing Λ favors the coalescence of both droplets; at high Ma, the two droplets do not coalesce eventually but migrate with the same velocity for the small values of Λ, and decreasing Λ leads to a shorter equilibrium time and a faster migration velocity

A lattice Boltzmann method for axisymmetric multicomponent flows with high viscosity ratio

A color-gradient lattice Boltzmann method (LBM) is proposed to simulate ax- isymmetric multicomponent flows. This method uses a collision operator that is a combination of three separate parts, namely single-component collision op- erator, perturbation operator, and recoloring operator. A source term is added into the single-component collision operator such that in each single-component region the axisymmetric continuity and momentum equations can be exactly re- covered. The interfacial tension effect is realized by the perturbation operator, in which an interfacial force of axisymmetric form is derived using the concept of continuum surface force. A recoloring operator proposed by Latva-Kokko and Rothman is extended to the axisymmetric case for phase segregation and maintenance of the interface. To enhance the method’s numerical stability for handling binary fluids with high viscosity ratio, a multiple-relaxation-time mod- el is used for the collision operator. Several numerical examples, including static droplet test, oscillation of a viscous droplet, and breakup of a liquid thread, are presented to test the capability and accuracy of the proposed color-gradient LB- M. It is found that the present method is able to accurately capture the phase interface and produce low spurious velocities. Also, the LBM results are all in good agreement with the analytical solutions and/or available experimental data for a very broad range of viscosity ratios

MicroRNA-101 Exerts Tumor-Suppressive Functions in Non-small Cell Lung Cancer through Directly Targeting Enhancer of Zeste Homolog 2

Introduction:Overexpression of the enhancer of zeste homolog 2 (EZH2) protein has been found in broad range of cancer types, including non-small cell lung cancer (NSCLC). Nevertheless, the mechanisms by which EZH2 becomes overexpressed in NSCLC remain unclear. MicroRNAs (miRNAs) can regulate target gene expression through translational control. In this study, we investigate whether miRNA (miR-101) regulates EZH2 expression in NSCLC.Methods:We evaluated the expression of miR-101 and EZH2 in 20 matched NSCLC and adjacent nontumor lung tissues by reverse-transcriptase polymerase chain reaction and immunohistochemistry, respectively. Luciferase reporter assay was used to determine whether miR-101 directly targets EZH2. To assess the effect of miR-101 on NSCLC biological behavior, cell proliferation, invasion, and response to chemotherapy were analyzed using NSCLC cells transfected with miR-101 mimics or transfected with specific small interfering RNA to deplete EZH2 (small interfering RNA-EZH2).Results:Reduced expression of miR-101 was associated with overexpression of EZH2 in NSCLC tumor tissues. Transfection of miR-101 mimics significantly suppressed the activity of the luciferase reporter containing wild type but not mutant EZH2 3′-UTR and decreased EZH2 expression in NSCLC cell lines. Furthermore, enforced expression of miR-101 or knockdown of EZH2 led to reduced NSCLC cell proliferation and invasion and sensitized cancer cells to paclitaxel-mediated apoptosis through inducing expression of the proapoptotic protein Bim.Conclusions:miR-101 inhibits cell proliferation and invasion and enhances paclitaxel-induced apoptosis in NSCLC cells, at least in part, by directly repressing EZH2 expression. Therapeutic strategies to rescue miR-101 expression or silence EZH2 may be beneficial to patients with NSCLC in the future

Constraining the equation of state with heavy quarks in the quasi-particle model of QCD matter

In a quasi-particle model of QCD matter at finite temperature with thermal masses for quarks and gluons from hard thermal loops, the equation of state (EOS) can be described by an effective temperature dependence of the strong coupling $g(T)$. Assuming the same effective coupling between the exchanged gluon and thermal partons, the EOS can also be related to parton energy loss.} Based on the quasi-particle linear Boltzmann transport (QLBT) model coupled to a (3+1)-dimensional viscous hydrodynamic model of the quark-gluon plasma (QGP) evolution and a hybrid fragmentation-coalescence model for heavy quark hadronization, we perform a Bayesian analysis of the experimental data on $D$ meson suppression $R_{\rm AA}$ and anisotropy $v_2$ at RHIC and the LHC. We achieve a simultaneous constraint on the QGP EOS and the heavy quark transport coefficient, both consistent with the lattice QCD results.Comment: 8 pages, 5 figure