Large Eddy Simulation and Acoustic Analysis of Combustion Instability in an Annular Combustor with Low-Swirl Flames.

Self-excited combustion instability in an annular combustor with low-swirl flames is studied with a combination of large eddy simulation (LES) and acoustic solvers. Acoustic analysis with a Helmholtz solver provides an estimate of frequencies and modal structures in the annular combustor. LES gives detailed modal dynamics for specific instability modes. Combustion instabilities in the annular combustor including longitudinal, spinning, and standing modes are successfully captured in a single LES. Numerical results show that the instability modes are not constant; they switch among these modes randomly and rapidly. The flow oscillates back and forth in phase with the largest pressure amplitude located near the outlet of the injectors for the longitudinal mode. The azimuthal instability oscillates in the 1A2L mode of the annular system. In the spinning mode, the pressure antinodes move forward while the modal structure keeps constant. For the standing mode, the locations of pressure antinodes are fixed in the annular combustor and the fluctuations at the pressure antinodes keep out of phase. The near-zero value of the mean spin ratio indicates that the dominant azimuthal mode is the standing mode. The azimuthal modes captured by LES are in good agreement with that predicted by Helmholtz solver in terms of frequency and modal structure. The maximum deviation of the predicted frequency is less than 5%. This adds values before the low-swirl injector is placed into the actual annular combustor.

Sanshimao formula inhibits the hypoxia-induced pro-angiogenesis of hepatocellular carcinoma cells partly through regulating MKK6/p38 signaling pathway.

OBJECTIVES: Sanshimao (SSM) is a traditional Chinese medicine formula for advanced hepatocellular carcinoma (HCC). This study was designed to investigate the effect of SSM on HCC-induced angiogenesis and to explore the potential mechanism. METHODS: The endothelial cells were cultured with HCC cells conditioned medium in the 1% oxygen atmosphere to imitate tumor hypoxia microenvironment. EA.hy926 cells migration and tubulogenesis were detected by tube formation and scratch-wound assay. The protein microarray was employed to explore SSM-targeted proteins in Huh7 cells. We also established an animal model to observe the effects of SSM on angiogenesis in vivo. RESULTS: The data indicated that SSM reduced HCC-induced migration and tube formation of EA.hy926 cells at low dose under hypoxic conditions. These effects might be partly owing to suppression of HIF-1α-induced vascular endothelial growth factorα expression in Huh7 cells. Moreover, this inhibition was in an MKK6/P38-dependent way. Besides, Huh7 subcutaneous tumor models in nude mice further demonstrated the inhibition of SSM on tumor weight might be exerted partly by reduction of angiogenesis via blocking MKK6/P38 signaling pathways. CONCLUSION: SSM inhibits HCC-induced pro-angiogenesis under hypoxic conditions via suppression of MKK6/P38 signaling pathways, which is favorable for HCC tumor growth.

Contributions of Emphysema and Functional Small Airway Disease on Intrapulmonary Vascular Volume in COPD.

Background: Previous studies have demonstrated that there is a certain correlation between emphysema and changes in pulmonary small blood vessels in patients with chronic obstructive pulmonary disease (COPD), but most of them were limited to the investigation of the inspiratory phase. The emphysema indicators need to be further optimized. Based on the parametric response mapping (PRM) method, this study aimed to investigate the effect of emphysema and functional small airway disease on intrapulmonary vascular volume (IPVV). Methods: This retrospective study enrolled 63 healthy subjects and 47 COPD patients, who underwent both inspiratory and expiratory CT scans of the chest and pulmonary function tests (PFTs). Inspiratory and expiratory IPVV were measured by using an automatic pulmonary vessels integration segmentation approach, the ratio of emphysema volume (Emph%), functional small airway disease volume (fsAD%), and normal areas volume (Normal%) were quantified by the PRM method for biphasic CT scans. The participants were grouped according to PFTs. Analysis of variance (ANOVA) and Kruskal-Wallis H-test were used to analyze the differences in indicators between different groups. Then, Spearman's rank correlation coefficients were used to analyze the correlation between Emph%, fsAD%, Normal%, PFTs, and IPVV. Finally, multiple linear regression was applied to analyze the effects of Emph% and fsAD% on IPVV. Results: Differences were found in age, body mass index (BMI), smoking index, FEV1%, FEV1/forced vital capacity (FVC), expiratory IPVV, IPVV relative value, IPVV difference value, Emph%, fsAD%, and Normal% between the groups (P<0.05). A strong correlation was established between the outcomes of PFTs and quantitative CT indexes. Finally, the effect of Emph% was more significant than that of fsAD% on expiratory IPVV, IPVV difference value, and IPVV relative value. Conclusion: IPVV may have a potential value in assessing COPD severity and is significantly affected by emphysema.