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This paper presents a multi-material topology optimisation (MMTO) process for the lightweight design of an electric bus roof structure including the self-weight. The usage of electric buses is increasing owing to environmental issues. However, it is challenging to design a lightweight structure, because the heavy battery pack mounted on the roof increases the deformation and reduces the safety. In a design including the self-weight, the appropriate distribution of multiple materials improves the performance more than that of a single material. The MMTO method has been applied to identify the optimal distribution of multiple materials. However, in the real-engineering problem, only a simple objective function such as compliance and a single constraint function such as the volume of material have been considered, whereas the mass reduction is the most important factor. In this paper, an MMTO process is proposed for the lightweight design of the bus roof structure to consider multiple displacement constraints including the self-weight. To control the complexity of the distribution of multiple materials for improving the manufacturability, the welding surface function is proposed. An optimisation process was constructed that can handle the complex finite-element model and multiple load cases, and it was validated according to the well-known compliance minimisation problem. Mass reduction was achieved via the lightweight optimisation, and the interfacial area between the different materials was reduced by employing the welding surface function.

The impact of microplastics (MPs) on the metabolic functions of the liver is currently unclear and not completely understood. To investigate the effects of the administration of MPs on the hepatic metabolism of normal and obese mice, alterations in the lipid, glucose (Glu), and amino acid regulation pathways were analyzed in the liver and adipose tissues of C57BL/6Korl (wild type, WT) or C57BL/6-Lepem1hwl/Korl mice (leptin knockout, Lep KO) orally administered polystyrene (PS) MPs for 9 weeks. Significant alterations in the lipid accumulation, adipogenesis, lipogenesis, and lipolysis pathways were detected in the liver tissue of MP-treated WT and Lep KO mice compared to the vehicle-treated group. These alterations in their liver tissues were accompanied by an upregulation of the serum lipid profile, as well as alterations in the adipogenesis, lipogenesis, and lipolysis pathways in the adipose tissues of MP-treated WT and Lep KO mice. Specifically, the level of leptin was increased in the adipose tissues of MP-treated WT mice without any change in their food intake. Also, MP-induced disruptions in the glycogenolysis, Glu transporter type 4 (GLUT4)-5′ AMP-activated protein kinase (AMPK) signaling pathway, levels of lipid intermediates, and the insulin resistance of the liver tissues of WT and Lep KO mice were observed. Furthermore, the levels of seven endogenous metabolites were remarkably changed in the serum of WT and Lep KO mice after MP administrations. Finally, the impact of the MP administration observed in both types of mice was further verified in differentiated 3T3-L1 adipocytes and HepG2 cells. Thus, these results suggest that the oral administration of MPs for 9 weeks may be associated with the disruption of lipid, Glu, and amino acid metabolism in the liver tissue of obese WT and Lep KO mice.

This study investigates the reduction in thermal residual stress during the powder bed fusion (PBF) process in a non-standardized shape generated by topology optimization method in lightweight automotive part of brake caliper. While the caliper of the braking system for reducing the CO2 consumption in vehicle systems undergoes a redesign to increased strength and reduced weight, challenges arise due to biased melting area ratios in the topologically optimized design, causing the thermal deformation. To address this, our research proposes an efficient PBF scan strategy aimed at minimizing anisotropy and residual stress—a critical consideration for successful manufacturing. The effectiveness of the laser scan strategy is validated through testing on a brake dynamometer, following the JASO C406 test procedure, an authorized standard for commercial brake calipers. Furthermore, a comparative analysis between the conventional product and the proposed brake caliper highlights superior performance, particularly under lightweight conditions. This comprehensive approach contributes valuable insights to the field, offering a potential solution for overcoming manufacturing challenges associated with topologically optimized designs in automotive components.

ABSTRACT Fibrotic disease involves excessive fibrous connective tissue accumulation in organs, leading to dysfunction and irreversible damage. Metabolic alterations can sometimes contribute to fibrosis development. This study aimed to develop dual agonists for farnesoid X receptor (FXR) and peroxisome proliferator‐activated receptor alpha (PPARα), targeting anti‐fibrosis and metabolic regulation. Benzoxazole derivatives were found to potently activate both FXR and PPARα in hepatocytes. Among them, MHY5396 showed the most potent effects with low EC50 values. MHY5396 reduced lipid synthesis and enhanced beta‐oxidation in hepatocytes, decreasing lipid accumulation. It also suppressed TGFβ‐induced fibrosis in hepatic stellate cells. In a methionine/choline‐deficient diet mouse model, MHY5396 reduced lipid accumulation, liver damage, and fibrosis. In a thioacetamide‐induced liver fibrosis model, MHY5396 had an anti‐fibrotic effect comparable to obeticholic acid, a potent FXR agonist. MHY5396 also significantly reduced inflammation and fibrosis in renal cells and a folic acid‐induced renal fibrosis mouse model. Pharmacokinetic studies showed that orally administered MHY5396 was well absorbed (F = 98.6%) and primarily metabolized by hepatic CYP1A2 with negligible urinary excretion. Overall, MHY5396, with dual FXR and PPARα agonist activity, exhibited significant anti‐fibrotic and metabolic regulatory properties in liver and kidney fibrosis models, presenting a novel therapeutic potential for fibrotic diseases. MHY5396, a benzoxazole derivative, functions as a potent dual FXR and PPARα agonist. It exhibits significant anti‐fibrotic and metabolic regulatory effects, effectively improving liver and kidney fibrosis in experimental models. These findings highlight its potential as a therapeutic candidate for fibrosis and metabolic disorders.

The impact of microplastics (MPs) on the metabolic functions of the liver is currently unclear and not completely understood. To investigate the effects of the administration of MPs on the hepatic metabolism of normal and obese mice, alterations in the lipid, glucose (Glu), and amino acid regulation pathways were analyzed in the liver and adipose tissues of C57BL/6Korl (wild type, WT) or C57BL/6-Lep[sup.em1hwl]/Korl mice (leptin knockout, Lep KO) orally administered polystyrene (PS) MPs for 9 weeks. Significant alterations in the lipid accumulation, adipogenesis, lipogenesis, and lipolysis pathways were detected in the liver tissue of MP-treated WT and Lep KO mice compared to the vehicle-treated group. These alterations in their liver tissues were accompanied by an upregulation of the serum lipid profile, as well as alterations in the adipogenesis, lipogenesis, and lipolysis pathways in the adipose tissues of MP-treated WT and Lep KO mice. Specifically, the level of leptin was increased in the adipose tissues of MP-treated WT mice without any change in their food intake. Also, MP-induced disruptions in the glycogenolysis, Glu transporter type 4 (GLUT4)-5′ AMP-activated protein kinase (AMPK) signaling pathway, levels of lipid intermediates, and the insulin resistance of the liver tissues of WT and Lep KO mice were observed. Furthermore, the levels of seven endogenous metabolites were remarkably changed in the serum of WT and Lep KO mice after MP administrations. Finally, the impact of the MP administration observed in both types of mice was further verified in differentiated 3T3-L1 adipocytes and HepG2 cells. Thus, these results suggest that the oral administration of MPs for 9 weeks may be associated with the disruption of lipid, Glu, and amino acid metabolism in the liver tissue of obese WT and Lep KO mice.

The launch vehicle with a liquid propulsion system requires pressurization during the propellant discharge. While the launch vehicle is flying through the air layer, a process in which frictional heat is generated between the liquid propellant tank and the air layer can be assumed. External heat inflow occurs during the liquid discharging process, and it is necessary to investigate how the external heat influx affects the liquid pressurized discharge process. A test device was constructed to determine the effect of pressurization of external heat inflow. The test device consisted of a liquid tank located in a vacuum chamber and a heating device to simulate external heat inflow. The heating device is a halogen lamp. The cryogenic liquid discharge with and without external heat inflow was compared. It was confirmed that the amount of pressurant gas used was decreased when there was external heat inflow. External heat inflow contributes to the evaporation of the liquid, and the evaporated gas increases the pressure of the ullage.

The impact of microplastics (MPs) on the metabolic functions of the liver is currently unclear and not completely understood. To investigate the effects of the administration of MPs on the hepatic metabolism of normal and obese mice, alterations in the lipid, glucose (Glu), and amino acid regulation pathways were analyzed in the liver and adipose tissues of C57BL/6Korl (wild type, WT) or C57BL/6-Lep /Korl mice (leptin knockout, Lep KO) orally administered polystyrene (PS) MPs for 9 weeks. Significant alterations in the lipid accumulation, adipogenesis, lipogenesis, and lipolysis pathways were detected in the liver tissue of MP-treated WT and Lep KO mice compared to the vehicle-treated group. These alterations in their liver tissues were accompanied by an upregulation of the serum lipid profile, as well as alterations in the adipogenesis, lipogenesis, and lipolysis pathways in the adipose tissues of MP-treated WT and Lep KO mice. Specifically, the level of leptin was increased in the adipose tissues of MP-treated WT mice without any change in their food intake. Also, MP-induced disruptions in the glycogenolysis, Glu transporter type 4 (GLUT4)-5' AMP-activated protein kinase (AMPK) signaling pathway, levels of lipid intermediates, and the insulin resistance of the liver tissues of WT and Lep KO mice were observed. Furthermore, the levels of seven endogenous metabolites were remarkably changed in the serum of WT and Lep KO mice after MP administrations. Finally, the impact of the MP administration observed in both types of mice was further verified in differentiated 3T3-L1 adipocytes and HepG2 cells. Thus, these results suggest that the oral administration of MPs for 9 weeks may be associated with the disruption of lipid, Glu, and amino acid metabolism in the liver tissue of obese WT and Lep KO mice.

Mathematical and statistical methods are invaluable in epidemiological investigations, enhancing our understanding of disease transmission dynamics and informing effective control measures. In this study, we presented a method to estimate transmissibility using patient-level data, with application to the 2015 MERS outbreak at Pyeongtaek St. Mary’s Hospital, the Republic of Korea. We developed a stochastic model based on individual case data to derive a likelihood function for disease transmission. Through scenario-based analysis, we explored transmission dynamics, including the role of superspreaders, and investigated how mask-wearing impacted infection control within the hospital. Our findings indicated that the superspreader during the MERS outbreak had approximately 25 times higher transmissibility compared to other patients. Under scenarios of prolonged hospital transmission periods, the number of cases could potentially increase threefold. The impact of mask-wearing in the hospital was significant, with reductions in the epidemic scale ranging from 17% to 77%, depending on the type of mask and intervention intensity. This study quantifies key risk factors in hospital-based transmission, demonstrating the effectiveness of intervention measures. The methodology developed here can be readily adapted to other infectious diseases, providing valuable insights for future outbreak preparedness and response strategies.

Middle East Respiratory Syndrome (MERS) is an endemic disease that presents a significant global health challenge characterized by a high risk of transmission within healthcare settings. Understanding both intra- and inter-hospital spread of MERS is crucial for effective disease control and prevention. This study utilized stochastic modeling simulations to capture inherent randomness and unpredictability in disease transmission. This approach provides a comprehensive understanding of potential future MERS outbreaks under various scenarios in Korea. Our simulation results revealed a broad distribution of case number, with a mean of 70 and a prediction interval of [0, 315]. Additionally, we assessed the risks associated with delayed outbreak detection and investigated the preventive impact of mask mandates within hospitals. Our findings emphasize the critical role of early detection and the implementation of preventive measures in curbing the spread of infectious diseases. Specifically, even under the worst-case scenario of late detection, if mask mandates achieve a reduction effect exceeding 55%, the peak number of isolated cases would remain below 50. The findings derived from this study offer valuable guidance for policy decisions and healthcare practices, ultimately contributing to the mitigation of future outbreaks. Our research underscores the critical role of mathematical modeling in comprehending and predicting disease dynamics, thereby enhancing ongoing efforts to prepare for and respond to MERS or other comparable infectious diseases.

In the Republic of Korea (ROK), social distancing and public behavior changes mitigated COVID-19 spread. However, a second wave of the epidemic is expected in the fall if neither vaccine nor antiviral drugs become available. This study investigated the impact of non-pharmaceutical measures on short- and long-term outbreak dynamics. A mathematical model based on Susceptible-Exposed-Infectious-Recovered model is developed considering isolated and behavior-changed groups. Using the least-squares fitting method, transmission and behavior change rates were estimated using cases reported from February 16 to April 20, 2020. The estimated transmission rate of COVID-19 was 4·6180 and behavior change rate was 2·6044. The model predicted the number of new cases to continuously decrease, with less than one case expected after May 6, 2020. Concurrently, a 25% reduction in behavioral changes during the outbreak would increase the case count by 60,000, resulting in 4,000 cases at maximum, exceeding the medical system's capacity. As behavioral restrictions are eased, local transmission will likely increase, with forecasted second wave peak in October 2020. Social distancing and public behavior changes have curbed the spread of COVID-19 in the ROK. Mathematical modeling demonstrates the importance of these measures in reducing and delaying outbreaks. Nevertheless, non-pharmaceutical interventions cannot eliminate the disease. In the future, vaccines and antiviral treatments combined with social distancing and public behavior changes will be paramount to ending COVID-19 epidemic.