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In the space environment, the elastic vibrations of satellite solar panels are caused by various factors that disturb satellite missions. Therefore, we propose a multi-layered high-damping yoke structure based on a passive control method. To optimize the proposed yoke structure, we performed a free vibration test on various multi-layered blade specimens and designed a yoke structure with the maximum damping performance based on the test results. This high-damping yoke structure was mounted on a dummy solar panel with flexible mode (0.79 Hz) and basic characteristic tests were performed to validate the effectiveness of the solar panel vibration suppression. The test results demonstrated that the proposed multi-layered high-damping yoke is effective in suppressing the vibrations of the first and second modes. In addition, a thermal vacuum test was performed to investigate the delamination between multi-layered structures, and the test results proved the applicability of the proposed yoke structure in an actual space environment. [ABSTRACT FROM AUTHOR]

This study investigates the tensile behavior of carbon-fiber-reinforced polymer (CFRP) and textile-reinforced mortar (TRM) under various design variables to enhance understanding and application in construction structures. TRM reinforced with CFRP grids is highly effective for strengthening existing structures due to its lightweight nature, durability, ease of installation, and corrosion resistance. The research aims to evaluate how design parameters such as the CFRP grid type, mortar matrix strength (influenced by the water-to-cement ratio), specimen length, and grid width affect TRM's mechanical properties. Through the direct tensile test using a universal testing machine, TRM specimens were subjected to load until failure, with data collected on stress–strain relationships, crack patterns, and strengths. Specimens included untreated CFRP grids (Groups KC, Q47, and Q85) and sand-coated CFRP grids (Specimens AQ47_7 and AQ85_7), each tested under controlled laboratory conditions. The results indicate that crack formation significantly influenced load transfer mechanisms within the specimens, with longitudinal strands bearing load as cracks propagated through the mortar matrix. The presence of sand-coated CFRP grids notably enhanced interfacial bond strength, leading to increased cracking strength and ultimate strength compared with their untreated counterparts. The findings underscore the importance of the surface treatment of CFRP grids for improving TRM performance, with implications for enhancing structural integrity and durability in practical applications. The results provide valuable insights into optimizing TRM design for better crack control and mechanical efficiency in infrastructure. [ABSTRACT FROM AUTHOR]

Fiber-reinforced polymers (FRPs), which are resistant to corrosion, are used as reinforcement material for concrete. However, the flexural behavior of concrete members reinforced with FRPs can vary depending on the properties of FRPs. In this study, the flexural behavior of one-way concrete slab specimens reinforced with a new grid-type carbon-fiber-reinforced polymer (CFRP) (carbon grid) manufactured by bonding pultruded CFRP strands to an adhesive was investigated. The experimental results indicated differences in the load–deflection relationships of the specimens depending on the carbon grid reinforcement amount. Specimens in which the carbon grids were over-reinforced or reinforced close to the balanced reinforcement ratio reached the maximum load due to concrete crushing and exhibited ductile failure. The specimen under-reinforced with the carbon grid exhibited brittle failure. Specimens with carbon grid reinforcement close to a balanced reinforcement ratio exhibited maximum loads ranging from 0.43 to 0.61 times the calculated flexural strength, which resulted in becoming 0.86–1.00 lower in the specimens with a wider width of the CFRP strands. This study proposes coefficients to estimate the stiffness of carbon-grid-reinforced concrete flexural members after cracking. Applying these coefficients resulted in stiffness calculations that reasonably simulated the behavior of the specimens reinforced with carbon grids after crack formation. [ABSTRACT FROM AUTHOR]

Introduction: Particulate matter (PM) air pollution is associated with an increased incidence of lung diseases, but the underlying mechanisms have not been fully elucidated. In this study, a mouse model of subacute lung inflammation was employed to investigate the cellular responses and gene expression changes induced by exposure to natural ambient air pollution. Methods: C57BL/6J mice were exposed to road dust (primarily PM10) at 150 µg/m³ for 21 days (8 h/day) through a nose-only inhalation exposure system. Lung tissues were analyzed for the expression of proinflammatory signaling, oxidative stress, and fibrosis markers. RNA-sequencing analysis was conducted to identify differentially expressed genes (DEGs). A gene ontology over-representation analysis was performed to identify the altered genetic pathways. Results: Elevated levels of proinflammatory cytokines, including IL-1β, IL-6, and TNF-α, and an increase in phosphorylated MAPK were determined in the road dust exposure group compared to the control group. Histopathological examinations revealed more severe lung inflammation and damage in the exposed mice, including fibrosis and bronchiolar hyperplasia. Gene expression profiling identified 108 DEGs, with decreases in most except genes such as Krt15 and Reg3g. The protein–protein interaction network analysis together with text-mining identified 18 key hub genes, associated with fatty acid oxidation, lipid metabolism, and peroxisomes. Conclusion: This study identified key genes, signaling pathways, and cellular responses in mouse lung affected by road dust exposure. These findings contribute to a deeper understanding of the transcriptional and cellular responses induced by subacute exposure to the PM in road dust. [ABSTRACT FROM AUTHOR]