Taraxacum Officinale, commonly called dandelion, is herbaceous perennial belonging to the family of Asteraceae, having good antibacterial effects which are related to its phenolic substances. In this study, the effect of phenolic contents as well as the antibiofilm activity against Staphylococcus aureus of phenolic extract from T. Officinale were evaluated in vitro. With 70% metha- nol-water (v/v) as a solvent, the dandelion was extracted by ultrasonic assisted extraction method. Subsequent identification and quantification of phenol in extract was carried out using High Performance Liquid Chromatography (HPLC). The minimum inhibitory concentration and anti- bacterial kinetic curve of dandelion phenolic extract were analyzed by spectrophotometry. Changes in extracellular alkaline phosphatase (AKP) contents, electrical conductivity, intracellular protein contents, and DNA of S. aureus after the action of dandelion phenolic extract were determined to study its effect on the permeability of S. aureus cell wall and cell membrane. The results showed that chlorogenic acid (1.34 mg/g) was present in higher concentration, followed by luteolin (1.08 mg/g), ferulic acid (0.22 mg/g), caffeic acid (0.21 mg/g), and rutin (0.19 mg/g) in the dandelion phenolic extract. The minimum inhibitory concentration (MIC) of dandelion phenolic extract against S. aureus was 12.5 mg/mL. The antibacterial kinetic curve analysis showed that the inhibitory effect of dandelion phenolic extract on S. aureus was mainly in the exponential growth phase. After applying the dandelion phenolic extract, the growth of S. aureus was signifi- cantly inhibited entering into the decay phase early. Furthermore, after the action of dandelion, the extracellular AKP contents of S. aureus, the electrical conductivity and the extracellular protein contents were all increased. The phenolic extract also affected the normal reproduction of S. aureus. These results suggest that dandelion has an inhibitory effect on S. aureus, and the mechanism of its action was to destroy the integrity of the cell walls and cell membranes.

Based on the electromagnetic thermal coupling analysis method, the cooling performance of different motor cooling models and the influence of key parameters of the cooling system on the cooling effect of the motor are investigated. First, the losses of various parts of the permanent magnet synchronous motors are obtained through electromagnetic calculations; the analysis results show that the stator core loss, winding copper loss, and eddy current loss of permanent magnets exceed 95% of the total loss of the motor. Second, the cooling performance of the three motor was compared and analyzed. The axial housing liquid cooling and oil spray cooling (Model B) has a better cooling performance and a higher cooling efficiency. Compared with the other two motor models, Model B can reduce the time to reach steady-state temperature by about 81.8%.Then the effects of coolant volume flow rate, coolant inlet temperature, and ambient temperature on the cooling effect of the motor are investi-gated. The results show that within a certain range, the rate of coolant inlet temperature change is approximately proportional to the internal temperature rise of the motor. The oil spray cooling system of Model B is less affected by ambient temperature and can be used for motor cooling in complex environments. The results of this study can provide a useful guidance for the design of the cooling system and the selection of coolant volume flow rate for oil-cooling motor with hairpin windings.