A type of supramolecular polyampholyte hydrogel with salt-mediated triple shape-memory effect, ionic conductivity, high stretchability and self-healing property was fabricated, which can be applied for strain sensors to monitor human health.
Paper-based composite friction material is a kind of key functional material for automatic transmission. In this study, five types of paper-based composite friction materials with different compound mineral fiber contents were prepared using the paper-making process. The effect of compound mineral fiber content on the properties such as shear strength, thermal property, friction torque curves, dynamic friction coefficient and wear resistance was studied. Meanwhile, the sensitivity of the friction coefficients was also investigated. Worn surfaces of samples were analyzed using scanning electron microscope. Experimental results revealed that the thermal properties of the samples were improved as the compound mineral fiber content increased and the shear strength increased initially and then decreased. The friction torque curve of the sample with 20% compound mineral fiber contents was the highest among all the samples and the sample with higher compound mineral fiber contents possessed the more flat friction torque curve during the mixed asperity contact phase of the engagement process. The dynamic friction coefficient increased with the increase of compound mineral fiber content and decreased as contact pressure and rotating speed increased. The wear resistance of the sample was highest when the compound mineral fiber content was about 15%.
The coronavirus disease 2019 (COVID-19) brought a healthy crisis all around the world. It's not only affected healthcare utilization, but also some disease's incidence. We collected pre-hospital emergency data in Chengdu from January 2016 to December 2021, and studied the demand for emergency medical services (EMSs), emergency response times (ERTs), and the disease spectrum in the city proper of Chengdu as a whole. A total of 1,122,294 prehospital emergency medical service (EMS) instances met the inclusion criteria. Under the influence of COVID-19, notably in 2020, the epidemiological characteristics of prehospital emergency services in Chengdu were considerably altered. However, as the pandemic was brought under control, they returned to normal or even earlier in 2021.The COVID-19 pandemic had an effect on people's medical care-seeking behavior and the performance of prehospital emergency services. Although the indicators associated with prehospital emergency services eventually recovered as the epidemic was brought under control, they remained marginally different from before the outbreak.
In this study, CaSO 4 whisker was applied to the paper-based composite friction material as the friction layer (secondary layer) by the paper-making process. The tribological and thermal properties were analyzed. Three-dimensional surface profiles were observed to discuss the wear mechanism. The results showed that the samples with higher CaSO 4 whisker contents owned better thermal resistance. The sample with 4% CaSO 4 whisker content had the highest dynamic friction coefficient. As the CaSO 4 whisker content increased from 0% to 16%, the wear rate decreased first and then increased, and the sample with 8% CaSO 4 whisker content had the highest wear resistance.
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