Velocity autocorrelations of decaying isotropic homogeneous turbulence

Velocity autocorrelations and the mean-square displacements of fluid particles are obtained for decaying, isotropic homogeneous turbulence by numerical simulation of the flow field, using 1283 and 2563 grids, and tracking several tens of thousands of fluid particles, using a third-order interpolation scheme. A self-preserving Lagrangian velocity autocorrelation coefficient is found in terms of a dimensionless time variable s, defined by ds=dt/[script T]s(t), under the observation of a power-law energy decay and the assumption that [script T]s(t) is proportional to the Lagrangian integral timescale [script T][script L]. This timescale is in turn assumed to be proportional to the length scale of the energy-containing eddies [script L]e~K3/2/epsilon divided by the turbulent velocity u[prime], where K=3/2u[prime]2 is turbulent energy and epsilon is the energy dissipation rate

Power-law decay of homogeneous turbulence at low Reynolds numbers

The decay of nominally isotropic, homogeneous incompressible turbulence is studied by direct numerical simulations for Re-lambda in the range (5-50) with 256(3) spectral coefficients. A power-law decay of the turbulent energy is observed with exponents approximately equal to 1.5 and 1.25, apparently dependent on Re-lambda. A new complete similarity form for the double and triple velocity correlation functions, f(r,t) and k(r,t), is proposed for low to intermediate Re-lambda that is consistent with the Karmia-Howarth equation and the results of the numerical experiments. The results are also consistent with Saffman's proposed asymptotic behavior of f(r,t) for large separation r for runs with a decay exponent of 1.5. The so-called final period of decay is not observed

HT2008-56339 CURVATURE EFFECT ON THE THERMAL CONDUCTIVITY OF NANOWIRES

ABSTRACT Directional preference of the ballistic phonon transport plays an important role in the effective thermal conductivity of nanostructures. Curved nanowires can have very different thermal conductivities from straight ones. In this work, a Monte-Carlo simulator is developed and used to investigate the curvature effect on the phonon transport in silicon nanowires. The results show that the curvature of geometry does not alter the phonon transport efficiency in large wires but decreases the effective thermal conductivity in their nano-sized counterparts

Design and Synthesis of 2-(3-Benzo[ b ]thienyl)-6,7-methylenedioxyquinolin-4-one Analogues as Potent Antitumor Agents that Inhibit Tubulin Assembly

As part of our continuing investigation of azo-flavonoid derivatives as potential anticancer drug candidates, a series of 2-aryl-6,7-methylenedioxyquinolin-4-one analogs was designed and synthesized. The design combined structural features of 2-(2-fluorophenyl)-6,7-methylenedioxyquinolin-4-one (CHM-1), a previously discovered compound with potent in vivo antitumor activity, and 2-arylquinolin-4-ones identified by CoMFA models. The newly synthesized analogs were evaluated for cytotoxicity against seven human cancer cell lines, and structure-activity relationship (SAR) correlations were established. Analogs 1, 37, and 39 showed potent cytotoxicity against different cancer cell lines. Compound 1 demonstrated selective cytotoxicity against Hep 3B (hepatoma) cells. Compound 37 was cytotoxic against HL-60 (leukemia), HCT-116 (colon cancer), Hep 3B (hepatoma), and SK-MEL-5 (melanoma) cells. Compound 39 exhibited broad cytotoxicity against all seven cancer cell lines, with IC50 values between 0.07–0.19 µM. Results from mechanism of action studies revealed that these new quinolone derivatives function as antitubulin agents

The novel synthesized 2-(3-(methylamino)phenyl)-6-(pyrrolidin-1-yl)quinolin-4-one (Smh-3) compound induces G2/M phase arrest and mitochondrial-dependent apoptotic cell death through inhibition of CDK1 and AKT activity in HL-60 human leukemia cells

2-Phenyl-4-quinolone series compounds have exhibited growth inhibitory influence on several human cancer cell lines. In this study, we investigated the effects of 2-(3-(methylamino)phenyl)-6-(pyrrolidin-1-yl)quinolin-4-one (Smh-3) on viability, cell cycle and apoptotic cell death which occurred in different leukemia cell lines (HL-60, U937 and K562) in a dose- and time-dependent manner, but which did not obviously impair the viability of normal human umbilical vein endothelial cells (HUVEC) in vitro. The approximate IC50 was 103.26 ± 4.59 nM for a 48 h treatment in HL-60 cells. Cell cycle analysis showed that 100 nM Smh-3 induced signi-ficant G2/M arrest in examined cells. Within 0, 12, 24 and 48 h of treatment, Smh-3 inhibited CDK1 activity and decreased protein levels of CDK1, cyclin A and cyclin B. Smh-3-induced chromatin condensation and DNA fragmentation were determined by DAPI and TUNEL staining. Cell apoptosis was significantly reduced after pretreatment with a pan-caspase inhibitor (Z-VAD-fmk) and results indicated that Smh-3-induced apoptosis was mainly mediated by activation of the caspase cascade in HL-60 cells. Results from colorimetric assays and Western blot analysis indicated that activities of caspase-9, -7 and -3 were promoted in Smh-3-treated HL-60 cells during cell apoptosis. Smh-3-induced apoptosis in HL-60 cells was accompanied by an apparent increase in ROS production, and protein levels of cytosolic cytochrome c, apoptotic protease activating factor-1 (Apaf-1) and apoptosis-inducing factor (AIF). Strikingly, Smh-3 induced apoptosis in HL-60 cells by simultaneously suppressing protein levels of AKT, p-AKT, p-mTOR and p-BAD and inducing BAD protein levels. Taken together, we conclude that Smh-3 acts against leukemia cells in vitro via G2/M phase arrest, down-regulation of AKT activity and induction of mitochondrial-dependent apoptotic pathways

Synthesis and SAR studies of novel 6,7,8-substituted 4-substituted benzyloxyquinolin-2(1 H )-one derivatives for anticancer activity: Synthesis and anticancer activity of 2-quinolones

4-Phenylquinolin-2(1H)-one (4-PQ) derivatives can induce cancer cell apoptosis. Additional new 4-PQ analogs were investigated as more effective, less toxic antitumour agents

Design and synthesis of new 2-arylnaphthyridin-4-ones as potent antitumor agents targeting tumorigenic cell lines

To develop new anticancer drug candidates from 2-arylnaphthyridin-4-one (AN), we have designed and synthesized a series of 3′-hydroxy and 6-hydroxy derivatives of AN. The results of cytotoxicity screening indicated that the replacement of the 3′-methoxy moiety on the C-ring phenyl group of AN (6a–e) with 3′-hydroxy (7a–e) made no significant effect on the inhibitory activity against HL-60, Hep3B and NCI-H460 cancer cell lines. On the other hand, replacing the 6-methoxy group on the A-ring of AN (6g–i) with a 6-hydroxy group (7g–i) resulted in reduced inhibitory activity against the above three cancer cell lines. Among the above-mentioned target compounds, 2-(3-hydroxyphenyl)-5-methyl-1,8-naphthyridin-4(1H)-one (7a) demonstrated the greatest potency and the best selectivity toward tumorigenic cancer cell lines. In a 7a preliminary mechanism of action study in Hep3B hepatoma cells, 7a showed the effects on microtubules followed by cell cycle arrest and sequentially led to apoptosis