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Abstract Background Heart failure (HF) is one of the diseases that seriously threaten human health today and its mechanisms are very complex. Our study aims to confirm the optimal dose ISO-induced chronic heart failure mice model for better study of HF-related mechanisms and treatments in the future. Methods C57BL/6 mice were used to establish mice model of chronic heart failure. We injected isoproterenol subcutaneously in a dose gradient of 250 mg/kg, 200 mg/kg, 150 mg/kg, 100 mg/kg and 50 mg/kg. Echocardiography and ELISA were performed to figure out the occurrence of HF. We also supplemented the echocardiographic changes in mice over 30 days. Results Except group S and group E, echocardiographic abnormalities were found in other groups, suggesting a decrease in cardiac function. Except group S, myofibrolysis were found in the hearts of mice in other groups. Brain natriuretic peptide was significantly increased in groups B and D, and C-reactive protein was significantly increased in each group. Conclusion Our research finally found that the HFrEF mice model created by injection at a dose of 100 mg/kg for 7 days was the most suitable and a relatively stable chronic heart failure model could be obtained by placing it for 21 days.

To study the full sound field distribution characteristics of full ceramic ball bearings, reduce the radiation noise of the bearings, and improve their service performance. In this paper, the sound field distribution characteristics of 6206 silicon nitride ceramic deep groove ball bearings are studied under different oil supplies. A mathematical model of the sound field distribution of full ceramic ball bearings under oil lubrication is established, and the validity of the model is verified by experimental data. The bearing cavity simulation model of the full ceramic ball bearing is established, and the influence of oil supply on the operation characteristics of the full ceramic ball bearing is studied. Through theoretical and experimental research, the circular distribution law of the noise signal of ceramic ball bearings under different oil supplies is revealed. It is found that there is an optimal fuel supply when the speed and load are constant. Under optimal oil supply lubrication conditions, the full ceramic ball bearing has the minimum radiation noise, and the bearing exhibits optimal lubrication state, vibration and temperature rise characteristics. The new contribution of this paper: with the increase in oil supply, the sound pressure level of radiation noise of full ceramic ball bearings decreases and then increases. The research results reveal the radiation noise mechanism of full ceramic ball bearings, which is of great significance for enriching its theory and method.