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Boron carbide (B4C) is an essential material in various high-performance applications due to its light weight and hardness. In this work, B4C-based composites were fabricated via a powder route consisting of powder mixing, precursor preparation, and hot-pressing under vacuum. The composites' mechanical properties and microstructure were analyzed to investigate the effect of adding minor second-phase particles. In addition to homogenizing the grain size, the addition of SiC (≤10 wt%) to B4C increased its strength and improved its fracture toughness, with values reaching 551 MPa and 3.22 MPa m1/2, respectively. Meanwhile, the addition of TiB2 (≤10 wt%) significantly improved the strength and fracture toughness only, with values reaching 548 MPa and 3.92 MPa m1/2, respectively, with only a minimal decrease in hardness. Microstructural analysis revealed that the second-phase particles were uniformly distributed and reduced the average grain size, contributing to the increase in strength. Additionally, the TiB2 particles impeded crack propagation and induced crack deflection at the interface, indicating the formation of an intergranular fracture mode. On the contrary, the addition of SiC primarily resulted in transgranular fracture behavior, though it still improved the toughness of the B4C. These results suggest that small amounts of SiC and TiB2 can effectively enhance the mechanical properties of B4C ceramics while maintaining the lightweight characteristics critical for military and aerospace applications. [ABSTRACT FROM AUTHOR]

This study aims to provide basic data for establishing strategies to maintain the core functions of health centers, and enable an effective response to emergency tasks in the event of future infectious disease disasters. Methods: The participants were 41 workers from two public health centers in Seoul. They all had prior experience in responding to the early and middle stages of the COVID-19 pandemic. Data were collected through Focus Group Discussions, and then analyzed using the deductive method of content analysis. Results: The participants' experiences during the infectious disease disaster crisis were examined through ten categories: governance and coordination, information management, human resources, essential medical supplies and equipment, infrastructure, administration, finance and logistics, community engagement and risk communication, delivery of essential services, security, and additional considerations for vulnerable populations. The analysis of the results made it apparent that new systems and policies were imperative for responding appropriately to the concerns and experiences of the public healthcare center staff, and for improving the response to future epidemics. Conclusion: We found that to prepare for infectious disaster situations in the future, it is necessary for health centers to establish a mid- to long-term business continuity plan to ensure the continuation and stability of their operations. Additionally, it was found that health professionals in public health centers also believe in the necessity of education and training programs on disaster preparedness, based on Business Continuity Planning proposed by the World Health Organization. They deem these essential to sustain routine tasks for the management of the health of local community residents during outbreaks of novel infectious diseases in the future. [ABSTRACT FROM AUTHOR]

Background and Aim Metachronous recurrence often occurs after endoscopic submucosal dissection for early gastric cancer, and a method for preventing recurrence is unknown. We aimed to identify risk factors for metachronous lesions, and the effects of aspirin use and Helicobacter pylori eradication on preventing recurrence. Methods A total of 1041 consecutive patients who underwent endoscopic submucosal dissection for early gastric cancer between January 2007 and December 2011 were retrospectively analyzed. Every patient was examined endoscopically at 2, 6, and 12 months after endoscopic submucosal dissection, and then annually. Patients were classified into the metachronous group or non-metachronous group according to the existence of metachronous lesions and subdivided by Helicobacter pylori status into three groups: not infected, eradicated after infection, and not eradicated. Results At 39 months' median follow-up, metachronous gastric lesions had developed in 35 patients (3.4%), including 16 with dysplasia and 19 cancers. Metachronous group were significantly older than non-metachronous group ( P = 0.02). Although non-metachronous group took aspirin more frequently than metachronous group (15.5% vs 5.7%), the difference was statistically insignificant ( P = 0.11). In the not eradicated group, the odds ratio of metachronous lesion was 7.762 compared with the not infected group (95% confidence interval, 1.483-60.854; P = 0.02). In the eradicated group, the odd ratio of metachronous lesion was 8.120 compared with not infected group (95% confidence interval, 1.950-58.985; P = 0.01). Conclusion Helicobacter pylori infection was an independent risk factor for metachronous gastric lesions. However, eradication of Helicobacter pylori alone does not prevent all metachronous lesions in an inflamed stomach. [ABSTRACT FROM AUTHOR]