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This paper investigated the optimization of the hardness and oscillation mode of flexible hydrofoils using bidirectional fluid–structure interaction (FSI) to address the issue of insufficient guidance in engineering applications. A two-dimensional flexible symmetric hydrofoil model of NACA0012 with a chord length of 1 m was constructed for this research. The hydrodynamic characteristics of low-frequency flexible hydrofoils with varying hardness and oscillation modes were analyzed through numerical simulation. The results indicated that the flexible hydrofoil with a Shore hardness of D50 exhibited the most optimal hydrodynamic performance under low-frequency conditions across the five groups of hardness tests. Among the three commonly utilized oscillation modes, the inboard oscillation mode demonstrated the most favorable performance. The hydrodynamic performance of the flexible hydrofoil surpassed that of the rigid hydrofoil in both inward and outward oscillation motions; however, it was inferior in pure pitching motions. Comparative analysis of the vortex structure and velocity distribution in the flow field revealed that the inward oscillation motion effectively enhanced the kinetic energy of the wake vortex and slowed down vortex dissipation, thereby improving the overall flow velocity. These findings provide theoretical support for the study of flexible hydrofoils and contribute to their advancement in pumping applications under actual ultra-low head conditions.

To investigate the influence of the chord length and frequency of an oscillating hydrofoil device on the discharge characteristics of floating particulate matter, in this study, we take raceway aquaculture as an example and systematically compare and analyze the flow field characteristics of the hydrofoil device with different chord lengths and frequencies, as well as the sewage discharge performance of the raceway based on Computational Fluid Dynamics (CFD). The results indicate that in the particulate matter discharge process of raceway aquaculture, when the chord length and motion frequency of the hydrofoil device are 0.1 W (W is the width of the raceway) and 1.0 Hz, respectively, the anti-Karman vortex streets produced by the hydrofoil device are less affected by the wall, the flow field is the most uniform, the particulate matter discharge performance is the best, and the final floating particulate matter discharge rate reaches up to 99.09%. Adjusting the chord length of the hydrofoil can effectively ameliorate flow field reflux issues, enhancing the uniformity and flow performance of the flow field. When the chord length is 0.1 W, the uniformity of the flow field is optimal. When the chord length is 0.2 W, the flow performance of the flow field is superior. Increasing the frequency enhances the flow performance of the flow field, with an average increase of 0.1 Hz in motion frequency leading to a 19.42% improvement in the average velocity at the outlet. Based on this, we recommend the use of a hydrofoil device with a chord length of 0.1 W and a motion frequency of 1.0 Hz in the raceway aquaculture system to achieve optimal particulate matter discharge performance, providing a theoretical basis and practical guidance for using hydrofoil devices to improve the efficiency of floating particulate matter treatment in raceway aquaculture environments.

Abstract Background Bone marrow mesenchymal stem cell-derived extracellular vesicles (BMSC-EVs) have been highly studied with their critical roles as carriers of therapeutic targets such as microRNAs (miRNAs) in the treatment of human diseases, including pulmonary arterial hypertension (PAH). Herein, we tried to study the potential of BMSC-EVs to deliver miR-200b for the regulation of macrophage polarization in PAH. Methods Rat models of PAH were induced with monocrotaline treatment, followed by miR-200b expression detection in lung tissues, pulmonary artery smooth muscle cells (PASMCs) and macrophages. miR-200b-containing BMSCs or miR-200b-deficient BMSCs were selected to extract EVs. Then, we assessed the changes in rats with PAH-associated disorders as well as in vitro macrophage polarization and the functions of PASMCs after treatment with BMSC-EVs. Moreover, the interaction between miR-200b, phosphodiesterase 1 A (PDE1A) was identified with a luciferase assay, followed by an exploration of the downstream pathway, cAMP-dependent protein kinase (PKA). Results miR-200b was reduced in lung tissues, PASMCs and macrophages of rats with PAH-like pathology. BMSC-EVs transferred miR-200b into macrophages, and subsequently accelerated their switch to the M2 phenotype and reversed the PAH-associated disorders. Furthermore, miR-200b carried by BMSC-EVs induced PKA phosphorylation by targeting PDE1A, thereby expediting macrophage polarization. Conclusion Our current study highlighted the inhibitory role of BMSC-EV-miR-200b in PAH formation.

In order to study the effect of the pumping depth and pumping frequency of the flapping hydrofoil device on suspended solids in the waters, this paper takes raceway aquaculture as an example, and introduces a flapping hydrofoil device to improve the discharge of suspended solids in the raceway, in response to the problem of the deposition of suspended solids from fish faeces and bait residues in water. The CFD method was used to compare and analyze the discharge of suspended solids at different pumping depths, and the combined effect of the two was studied according to different combinations of pumping frequency and pumping depth. The results proved that the flapping hydrofoil motion can improve the bottom hydrodynamic insufficiency in ecological waters and thus enhance the discharge effect of suspended particles in water. In addition, the pumping depth of the flapping hydrofoil is too deep for the movement to be disturbed by the bottom surface, while the thrust generated by the flapping hydrofoil is weakened if the depth is too shallow. When the pump water depth is 1.1 H, the reversed Kármán vortex street is more stable under the balancing effect of the bottom surface and gravity, and the rate curve of the flapping hydrofoil acting on the discharge of suspended particles is better. From our comprehensive consideration of the joint effect of the pumping depth and pumping frequency, we recommend the use of a 1.1 H of pumping depth and 2.0 Hz pumping frequency in combination to achieve the best effect of discharging suspended particles. This study provides valuable insights into the actual engineering applications of flapping hydrofoil devices for improving water quality and ecological sustainability in raceway aquaculture.

Abstract Background Asthma is a heterogeneous chronic inflammatory disease of the airway, involving reversible airflow limitation and airway remodeling. T helper 17 (Th17) cells play an important role in the pathogenesis of allergic asthma. However, there is limited understanding of the signaling pathways controlling Th17 cell differentiation in asthma. The aim of this study was to investigate if the Yes-associated protein (YAP)/hypoxia inducible factor-1α (HIF-1α)/microRNA-182 (miR-182)/early growth response 2 (EGR2) axis is involved in mediating Th17 cell differentiation and disease severity in asthma. Methods The study included 29 pediatric patients with asthma, 22 healthy volunteers, ovalbumin-induced murine asthma models, and mouse naive CD4+ T cells. The subpopulation of Th17 cells was examined by flow cytometry. The levels of interleukin-17A were determined by enzyme linked immunosorbent assay. Chromatin immunoprecipitation-quantitative polymerase chain reaction assays and dual-luciferase reporter gene assays were performed to examine interactions between HIF-1α and miR-182, and between miR-182 and EGR2. Results YAP, HIF-1α, and miR-182 were upregulated but EGR2 was downregulated in human and mouse peripheral blood mononuclear cells from the asthma group. Abundant expression of YAP and HIF-1α promoted miR-182 expression and then inhibited EGR2, a target of miR-182, thus enhancing Th17 differentiation and deteriorating asthma and lipid metabolism dysfunction. In addition, in vivo overexpression of EGR2 countered the promoting effect of the YAP/HIF-1α/miR-182 axis on asthma and lipid metabolism dysfunction. Conclusion These results indicate that activation of the YAP/HIF-1α/miR-182/EGR2 axis may promote Th17 cell differentiation, exacerbate asthma development, and aggravate lipid metabolism dysfunction, thus suggesting a potential therapeutic target for asthma.