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AbstractIn this study, the potential utilization of PAN (Polyacrylonitrile) type fibers, typically discarded during the production of wigs, as a reinforcement material in cement-based composites is explored. Fibers measuring 80 microns in diameter and with lengths of 3, 6, and 12 mm are incorporated into the mortar at varying ratios of 0.5, 1, and 1.5% relative to the composite volume. The flexural tensile strength, compressive strength, and shrinkage behavior of the resulting PAN-type recycled fiber-reinforced mortars are examined. Comparative analysis is conducted with a control sample, which consists of a fiber-free specimen. Moreover, the impacts of fiber length and dosage on performance are scrutinized. The findings of the investigation reveal notable alterations in flexural strength and shrinkage due to the integration of recycled fibers in cementitious composites. Enhanced flexural tensile strength is observed with increasing fiber length in the fiber-reinforced composites. Optimal fiber content is determined to be 0.5% for all fiber lengths. Despite the control sample exhibiting a compressive strength of 53 MPa, the fiber-reinforced mortars demonstrate no adverse effects on compressive strength. Notably, fibers measuring 3 mm in length enhance the compressive strength of the composite to ∼67 MPa. Shrinkage test results indicate reduced dimensional changes in fiber-reinforced composites with higher fiber lengths and content. These outcomes align with weight loss measurements, suggesting that decreased water loss contributes to diminished shrinkage. [ABSTRACT FROM AUTHOR]

Background: Vaccination is one of the most effective measures to prevent influenza illness and its complications. Since the 1980s, countries and territories in the Americas have progressively implemented influenza vaccination operations in high-risk priority groups—such as older adults, pregnant persons, persons with comorbidities and health workers. Methods: In this review, we present the history and progress of the seasonal influenza program in the Americas, how the program contributed to the efficient and timely roll-out of the COVID-19 vaccines during the pandemic, and how the program can be used to promote immunization operations across the life span for existing and future vaccines. Results: The influenza A(H1N1)pdm09 pandemic in 2009 and the COVID-19 pandemic in 2020–2023 underscored the importance of having a robust seasonal influenza vaccination program for pandemic preparedness and response. Overall, countries with existing seasonal influenza vaccination programs were better prepared and rolled out the delivery of COVID-19 vaccines more quickly and effectively compared to other countries where the influenza vaccination platform was weak or non-existent. Conclusions: Traditionally, national immunization programs of developing countries have been predominately focused on newborns, children younger than five years and school-aged children while often limiting their investment in effective adult vaccination programs; these programs are typically isolated to high-income countries. Countries in Latin America have been the exception, with strong influenza vaccination programs for adults regardless of national income level. The presence of functional and effective adult influenza vaccination programs can also facilitate the acceptance and uptake of other adult vaccines targeting priority groups at higher risk for severe illness or complications. [ABSTRACT FROM AUTHOR]