Purpose
This paper aims to numerically investigate the nanofluid flow, heat transfer and entropy generation during natural convection in an annulus.
Design/methodology/approach
The lattice Boltzmann method is used to simulate the velocity and temperature fields. Furthermore, some special modifications are applied to make the lattice Boltzmann method capable for simulation in the curved boundary conditions. The annulus is filled with CuO-water nanofluid. The dynamic viscosity of nanofluid is estimated using KLL (Koo-Kleinstreuer-Li) model, and the nanoparticle shape effect is taken account in calculating the thermal conductivity. On the other hand, the local/volumetric entropy generation is used to show the irreversibility under influence of different parameters.
Findings
The effect of considered governing parameters including Rayleigh number (103<Ra < 106); nanoparticle concentration (0<<0.04) and configuration of annulus on the flow structure; temperature field; and local and total entropy generation and heat transfer rate are presented.
Originality/value
The originality of this work is using of lattice Boltzmann method is simulation of natural convection in a curved configuration and using of Koo–Kleinstreuer–Li correlation for simulation of nanofluid.
Orange peel contains bioactive compounds with high antioxidant properties that may exhibit pharmacological effects on cancer cells with low toxicity. This study sought to investigate the anticancer and apoptotic effects of orange peel extract (OPE) and its main flavonoid derivative, naringin (NR), on doxorubicin (Dox)-induced apoptosis in a human esophageal squamous carcinoma cell line (ESCC). The cytotoxicity and DNA fragmentation were evaluated using the methylthiazoletetrazolium (MTT) and fluorescent nuclear dye 4’,6-diamidino-2-phenylindole (DAPI) assays, respectively. The protein expression of Bax, Bcl-2, p21, p53, and caspases 8 and 9 were measured using ELISA. A dose-dependent decline was observed in the viability of YM-1 cells treated with OPE, NR, and Dox. The combination effects of Dox with OPE and NR indicated a protective effect against Dox-induced cytotoxicity. Similarly, apoptotic bodies decreased in the interaction between Dox with OPE and NR. Up-regulation of pro-apoptotic Bax gene was found in YM-1 cells subjected to treatments. Interaction between Dox+OPE and Dox+NR resulted in the down-regulation of Bax. Activation of the executioner 8 and 9 caspases was found in the YM-1 cell line exposed to Dox and its combination with OPE and NR. The overexpression of anti-tumor p21 and p53 genes were observed in the YM-1 cells subjected to the treatments. However, down-regulation of P21 and P53 anti-tumor genes were found by the interaction of Dox with OPE and NR. In conclusion, this study suggests that OPE and NR have a pro-apoptotic potential on ESCC through Bax-dependent pathways and are promising agents to attenuate the toxic effect of Dox on ESCC.
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