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To cite this article: Nader Kazemi (2019) Reasons for crack propagation and strength loss in refractory castables based on changes in their chemical compositions and micromorphologies with heating: special focus on the large blocks,

Background: Stomach cancer is one of the most common cancers in modern societies. B-Cell Lymphoma-2 (Bcl-2) family members are classified to anti-apoptotic and pro-apoptotic groups, based on structural and functional features. The Bcl-2 inhibits apoptosis, while Bax (BCL-2 associated X protein) induces the apoptosis process. Saffron has anti-cancer properties and inhibits tumor genesis. The aim of this study was to investigate the anti-cancer properties of saffron extract and its effect on expression of Bcl-2 and Bax genes in gastric adenocarcinoma cell line (AGS) by real-time polymerase chain reaction (PCR). Methods: In this experiment, aqueous extract of saffron was made and MTT test was performed on AGS cells at concentrations of 0, 200, 400, 800, 1200, and 2000 µg/mL from saffron extract at 48 and 72 hours. The 50% inhibitory concentration (IC50) was calculated for saffron extract at specific doses and times. The AGS cancer cell line was treated by saffron extract with concentrations of 800, 1200, and 2000 µg/mL at 48 and 72 hours. Total RNA was extracted from AGS cells and its concentration and purity was determined. Then, cDNA was synthesized and evaluating the expression of Bcl-2 and Bax genes was performed by real-time PCR. Finally, the obtained results were analyzed by a statistical software. Results: The results of MTT test showed that with increasing concentration of extract and time, disappearance of cancer cells is increased. Thus, saffron extract has high cytotoxicity at high concentrations and in the long-term. The expression of Bax and Bcl-2 genes was also associated with significant increase (P < 0.05) in 800, 1200, and 2000 µg/mL extract doses and at 48 and 72 hours, compared to cells that were not treated with the saffron extract. The overall result of this experiment showed that the ratio of Bax on Bcl-2 expression (Bax/Bcl-2) increased with increasing extract concentration and time. This results in the apoptosis of cancerous cells. Conclusions: Treatment of AGS cells with saffron extract caused an increase in the expression rate of Bax gene in comparison with Bcl-2 gene, and AGS cells were driven towards cell death. According to the obtained results, this effect is dependent on dose and time.

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The active power-virtual frequency (P-ω′) and reactive power-virtual voltage (Q-V′) droop control scheme has been suggested for coordinated control of distributed energy resources (DERs) in islanded microgrids. While this method mitigates the issue of active and reactive power coupling in the droop controller, its main limitation is power-sharing error. Due to the local property of the virtual frequency and voltage, significant steady-state errors occur for both active and reactive power sharing. In this paper, a decentralized method is proposed to eliminate the mentioned errors without utilization of communication links. In the proposed scheme, P-ω′ and Q-V′ droops are realized at the microgrid point of common coupling (PCC). By employing the PCC virtual frequency/voltage for the active/reactive power sharing of all DERs, the sharing errors caused by the local property are eliminated. Small signal stability of the proposed scheme is studied, and Hardware-in-the-Loop (HIL) experimental results are presented to validate the proposed method and highlight the improvements compared with the conventional P-ω′/Q-V′ scheme. The results verify the efficacy of the proposed method for providing accurate active and reactive power sharing while regulating the frequency and voltage close to the rated values.