Damage characteristics and surface description of near-wall materials subjected to ultrasonic cavitation.

For the analysis of ultrasonic cavitation erosion on the surface of materials, the ultrasonic cavitation erosion experiments for AlCu4Mg1 and Ti6Al4V were carried out, and the changes of surface topography, surface roughness, and Vickers hardness were explored. Cavitation pits gradually expand and deepen with the increase of experiment time, and Ti6Al4V is more difficult to erode by cavitation than AlCu4Mg1. After experiments, the cavitation damage characteristics such as the single pit, the rainbow ring area, the fisheye pit, and some small pits were observed, which can be considered to be induced by a single micro-jet impact, ablation effect caused by the high temperature, micro-jet impingement with a sharp angle, and multibeam micro-jets coupling impact or negative pressure in the local area produced by micro-jet impact, respectively.

Ultrasonic cavitation damage characteristics of materials and a prediction model of cavitation impact load based on size effect.

High-speed micro-jet produced by cavitation collapse near the wall is the main mechanism of material damage, and cavitation pit is the most typical damage feature. The reason why high-pressure and high-speed micro-jet can only cause nano- and microscale cavitation pit is that the micro-jet is a short-term impact load of nano- and microscale, and the material shows size effect during the formation of pits. To further explore the cavitation damage characteristics and deformation mechanism of materials, the theoretical framework of indentation test and J-C constitutive model were adopted, and the size effect of materials during the process of cavitation pit formation was mainly considered, and the prediction models of cavitation impact load, impact pressure and velocity of micro-jet were established.

Switching on the activity of 1,5-diaryl-pyrrole derivatives against drug-resistant ESKAPE bacteria: Structure-activity relationships and mode of action studies.

Antibiotic resistance represents a major threat worldwide. Gram-positive and Gram-negative opportunistic pathogens are becoming resistant to all known drugs mainly because of the overuse and misuse of these medications and the lack of new antibiotic development by the pharmaceutical industry. There is an urgent need to discover structurally innovative antibacterial agents for which no pre-existing resistance is known.