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The effect of microstructural features on the toughness of 2091 A1-Li alloys processed with various thermomechanical schemes was analyzed. Grain size and the distribution of precipitates were varied by thermomechanical processing. Dynamic fracture toughness tests were done to evaluate the toughness of these materials using a Computer Aided Instrumented testing system. The 6' (A13Li) and S' (AI,CuMg) precipitates, which are primary strengthening precipitates, were confirmed by TEM analysis in the under-aged 2091 AILi alloy. From analysis of the relation between toughness and the microstructural lhctors induced by thermomechanical processing, the toughening of the alloy was found to be associated with the refinement of the subgrains. The strength and toughness parameters were well related to subgrain size.

Background: In a pandemic situation such as the one of the COVID-19 pandemic, nosocomial transmissions attempted to be prevented by initially classifying them in triage. Therefore, emergency departments (EDs) installed isolation rooms at their entrance. Additionally, a system for pre-emptive quarantine at the triage stage was established nationwide for patients with COVID-19-related symptoms. Methods: Data were retrospectively collected from 28,609 patients who visited the regional emergency medical center of Yeungnam University Hospital in Daegu Metropolitan City in 2021. The study population was divided into experimental and control groups comprising patients with and without COVID-19-related symptoms, respectively. The difference in the percentage of patients visiting from outside the city was investigated between the two groups. The critically ill patient (CP) ratio was analyzed in the experimental group to verify the appropriateness of visiting a higher-level ED and was further divided into sub-regions to determine their reason for visiting an ED beyond their residential region. Results: Most lower-level EDs did not have isolation rooms. About 20.1% and 17.3% of patients in the experimental and control groups visited a higher-level ED with an isolation room beyond their residential region, respectively. The absence of an isolation room in the ED in their residential region was one reason for traveling beyond their residential region, with an odds ratio of 4.44 (95% confidence interval: 0.53–8.35). Conclusion: In the process of implementing the “pre-emptive quarantine” system, it was revealed that the cooperation of the lower-level EDs was not effective during the implementation of the “pre-emptive quarantine” system. Consequently, a higher number of patients with COVID-19-related symptoms had to locate an ED with an isolation room and travel a longer distance than general patients. The participation of more EDs is required.