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During the oil and gas drilling process, inefficient cuttings transport may elevate cuttings concentration, leading to higher Equivalent Circulating Density (ECD) and easily triggering a series of wellbore stability issues. In this paper, a new type of annulus cleaning tool is developed, incorporating the H- B non-Newtonian fluid model and a coupled CFD-DEM to construct a numerical model for analyzing the cuttings transport behavior within the multi-layer wellbore annulus using the cleaning tool. The model, validated against experiments, reveals factors affecting Cuttings Transport Ratio (CTR). Through Box- Behnken Design (BBD), Response Surface Methodology (RSM), and Analysis of Variance (ANOVA), a correlation function for CTR is derived to optimize the cleaning tool parameters. Findings show an initial increase then decrease in CTR with nozzle quantity, diameter, and angle. Decreasing hydraulic diameter enhances CTR, whereas nozzle diameter variation has minimal impact at smaller diameters. After optimization, CTR reaches 95.76% with 4 nozzles of 10mm diameter, 32° angle, and 57mm hydraulic diameter. These results guide cleaning tool optimization design , improving cuttings transport efficiency, and ensuring safe oil and gas production.

Abstract Aiming at the near-clogging boundary condition of a certain type of transonic compressor rotor, a numerical simulation method is used to systematically study the influence of different droplet diameters on its performance under the condition of moisture content of 3%. The results show that humidifying the intake air of the transonic compressor near the blockage boundary can reduce the exhaust temperature, the mass flow rate, and the total pressure ratio. In the axial direction, the mass fraction of water vapor increases slowly and linearly under the large droplet condition, while the mass fraction of water vapor under the medium and the small droplet conditions presents a two-stage parabolic growth. The mass fraction of water vapor under the three conditions increases by 0.002, 0.0055, and 0.0072 from inlet to outlet, respectively. On the radial section with the axial span = 0.7, the difference in water vapor mass fraction between the shroud and the hub under the small droplet condition is 0.00329, and that under the medium and the large droplet condition are 46.81% and 27.96% of the small droplet condition. The research results can provide theoretical guidance for the analysis of droplet evaporation at different positions in compressor near-plugging conditions. [ABSTRACT FROM AUTHOR]

New drugs for the treatment of bacterial vaginosis (BV) are yet to be developed due to concerns that they may contribute to the increase in antibiotic resistance in BV. Antimicrobial peptides (AMPs) are one of the most promising options for next-generation antibiotics. In this study, we investigated the bacteriostatic activity of the AMPs Pexiganan, plectasin, melittin, and cathelicidin-DM against Gram-negative and Gram-positive bacteria both in vitro and in a mouse model of BV infection. The results showed that Pexiganan, melittin, and cathelicidin-DM had significant antibacterial activity against both Gram-negative and Gram-positive bacteria. AMPs have great potential for clinical application in the treatment of vaginitis, and this study provides an experimental basis for their use in the active immunoprophylaxis of BV.