Search

The optimization of pumping station inlet channels is a key research area for improving the operation efficiency, reducing the energy consumption, and enhancing the operation reliability of pumping stations. For the elbow inlet channel of the Majinggang Pumping Station project, based on the Stress-Blended Eddy Simulation (SBES) turbulence model and entropy generation theory, an optimization design plan is proposed by altering the inclination angle of the flow channel base plate, the length of the transitional arc segment, and the length of the curved segment. Various schemes were analyzed and comprehensively compared in terms of the hydraulic loss, the velocity-weighted average angle, and the axial-velocity distribution uniformity of the channel. The results indicate that optimal hydraulic performance is achieved when the inclination angle of the base plate is between 8° and 10°. In a reasonable range of values, appropriately increasing the length of the transitional arc and reducing the section width (throat width) can improve the hydraulic performance of the inlet channel. The optimal model obtained achieved an impressive velocity-weighted average angle of 89.25°, along with an axial-velocity distribution uniformity of 97.5%. Its excellent hydraulic performance not only meets the design requirements of the pumping station in terms of functionality but also takes into account economic efficiency, and it serves as a valuable reference for similar projects, contributing to the more refined and intelligent development of the optimization of pumping station inlet flow channels. [ABSTRACT FROM AUTHOR]

Mixed-flow pumps, optimized for marine engineering, provide a balance of high efficiency and adaptability, accommodating varied flow and head demands across challenging oceanic settings and are essential for reliable operations in tidal energy and subsea applications. The primary purpose of this paper is to perform a numerical analysis of the cavitation flow characteristics of the mixed-flow pump under differing operational circumstances. The cavitation simulation was implemented to explore the cavitation bubbles evolution and the pressure pulsation characteristics in the impeller region under diverse flow rates, utilizing the Shear Stress Transport (SST) turbulence model and the Zwart-Gerber-Belamri cavitation model as a foundation. The findings indicate that cavitation bubbles initially distribute at the leading edge of blade suction surfaces at the cavitation growth stage. The bubbles spread gradually with the decline of the available net positive suction head (NPSHa). At the same time, many bubbles appear in the area below the blade and extend to the rim of the suction side of blades. As the flow rate decreases, the critical net positive suction head (NPSHc) gradually declines. The dominant pressure pulsation frequency at the impeller inlet is the blade passing frequency, and the vibration at the impeller shroud inlet is more intense than that at the hub. The dominant frequency at the impeller outlet is mainly the blade passing frequency. With the development of cavitation, it changes to impeller rotation frequency at low flow rates, while the dominant frequency remains unchanged at high flow rates. [ABSTRACT FROM AUTHOR]

Background: Didymin is a dietary flavonoid derived from citrus fruits and has been shown to have extensive biological functions, especially anti-inflammatory effects, but its mechanism is unclear. The purpose of this study was to investigate the potential mechanism of didymin that alleviates ulcerative colitis. Methods and Results: Our results indicated that didymin could alleviate the symptoms of ulcerative colitis, as it inhibited the expressions of interleukin-6 (IL-6), interleukin-1β (IL-1β) and tumor necrosis factor-α (TNF-α). Didymin also promoted the expressions of claudin-1 and zona occludens-1(ZO-1), which are closely related with restoring colon barrier function. Didymin also increased the abundance of Firmicutes and Verrucomicobiota, while decreasing the abundance of Bacteroidota and Proteobacteria. Meanwhile, didymin significantly altered the levels of metabolites related to arginine synthesis and metabolism, and lysine degradation in the colitis mice. Utilizing network pharmacology and molecular docking, our results showed that the metabolites L-ornithine and saccharin could interact with signal transducer and activator of transcription 3 (STAT3) and nuclear factor kappa-B (NF-κB). In this in vitro study, L-ornithine could reduce the expressions of transcription factors STAT3 and NF-κB, and it also inhibited the expressions of IL-6 and IL-1β in the lipopolysaccharides (LPS) induced in RAW264.7 cells, while saccharin had the opposite effect. Conclusions: Taken together, didymin can regulate gut microbiota and alter metabolite products, which can modulate STAT3 and NF-κB pathways and inhibit the expressions of inflammatory factors and inflammatory response in the DSS-induced colitis mice. [ABSTRACT FROM AUTHOR]

Excessive inflammatory reactions are the most important pathological injury factor in acute lung injury (ALI). Our recent study found that sialic acid had an anti-colitis effect. In this study, the effect of sialic acid (SA) on acute lung inflammation was investigated. A lipopolysaccharide (LPS)-induced ALI animal model and LPS-stimulated HUVEC cell model were used to evaluate the anti-inflammatory effect of SA and study its molecular mechanisms. Compared with the LPS group, the lung index of the SA group decreased from 0.79 ± 0.05% to 0.58 ± 0.06% (LPS + 50 SA) and 0.62 ± 0.02% (LPS + 100 SA), with p < 0.01, suggesting that SA could improve the pulmonary edema of mice and alleviate LPS-induced lung injury. Transcriptome research identified 26 upregulated genes and 25 downregulated genes involved in the protection of SA against ALI. These genes are mainly related to the MAPK and NF-κB signaling pathways. Our study also proved that SA markedly downregulated the expression of inflammatory factors and blocked the JNK/p38/PPAR-γ/NF-κB pathway. Meanwhile, SA treatment also upregulated the expression of HO-1 and NQO1 in ALI mice. In vitro, SA obviously repressed the expressions of inflammatory cytokines and the JNK/p38-NF-κB/AP-1 pathway. SA also regulated the expression of oxidative stress-related genes through the Nrf2 pathway. Taken together, SA exhibits a protective role by modulating the anti-inflammatory and anti-oxidation pathways in ALI, and it may be a promising candidate for functional foods to prevent ALI. [ABSTRACT FROM AUTHOR]

TiAl alloy was electrochemically anodized in ethylene glycol electrolyte containing with NH4F to prepare anodic film. The influence of anodization treatment on the oxidation behavior and mechanical properties of the anodized TiAl alloy were then characterized. Results shown that based on the halogen effect a continuous and dense Al2O3 oxide scale will generate on the anodized TiAl alloy after high temperature oxidation. After oxidation at 1000 ℃ for 100 h, the weight gain of the anodized TiAl alloy was dramatically decreased from 85.86 mg/cm2 to 0.67 mg/cm2. Moreover, it is shown that the surface hardness and elastic modulus of the anodized TiAl alloy decreased first and then increased with the prolonging of oxidation time. Meanwhile, the friction coefficient of the anodized TiAl alloy increased comparing to the bare TiAl alloy. The surface wear resistance of the anodized TiAl alloy exhibited similar phenomena. This is because that during high temperature oxidation process, aluminum fluorides selectively transport to the surface through pores or micro-cracks, and are oxidized to Al2O3 at the surface region. The influence of anodization treatment on the mechanical properties of the anodized TiAl alloy is attributed to the Al2O3 content contained in the oxide scale.