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As the inlet temperature of the gas turbine exceeds the high temperature limit of the blade materials, efficient leading edge cooling technologies are crucial for the further development of gas turbines. Therefore, this paper reviews the research progress on external cooling technology, internal cooling technology, and composite cooling technology for gas turbine rotating blade leading edge cooling. It focuses on the impact of the geometric shape, arrangement, and flow parameters of film cooling holes on external cooling performance, the influence of jet hole design, configuration, crossflow, ribs on internal cooling efficiency, and the characteristics and influencing factors of composite cooling technologies are also discussed. Among the most promising composite cooling techniques, the impingement jet film composite cooling technology and swirl film composite cooling technology stand out. For impingement jet film composite cooling technology, this paper explores the effects of blowing ratio, nozzle parameters, jet hole characteristics, and flow field parameters on the overall cooling performance of the rotating blade leading edge. Impingement jet film composite cooling technology has been shown to significantly improve the cooling performance of the leading edge compared to traditional single cooling techniques. For applications requiring large area cooling or maintaining film integrity, swirl film composite cooling technology not only enhances heat transfer efficiency but also improves the uniformity of heat transfer. The design of swirl nozzles, coolant flow rate, Reynolds number, and jet temperature all have significant effects on the heat transfer efficiency of swirl film composite cooling. To further advance the development of gas turbine rotating blade leading edge cooling technologies, it is recommended to focus on the study of film composite cooling techniques, particularly investigating the effects of various parameters of impingement, swirl on composite cooling performance. [ABSTRACT FROM AUTHOR]

Particulate matter (PM), particularly fine (PM2.5) and ultrafine (PM0.1) particles, originates from both natural and anthropogenic sources, such as biomass burning and vehicle emissions. These particles contain harmful compounds that pose significant health risks. Upon inhalation, ingestion, or dermal contact, PM can penetrate biological systems, inducing oxidative stress, inflammation, and DNA damage, which contribute to a range of health complications. This review comprehensively examines the protective potential of natural products against PM-induced health issues across various physiological systems, including the respiratory, cardiovascular, skin, neurological, gastrointestinal, and ocular systems. It provides valuable insights into the health risks associated with PM exposure and highlights the therapeutic promise of herbal medicines by focusing on the natural products that have demonstrated protective properties in both in vitro and in vivo PM2.5-induced models. Numerous herbal medicines and phytochemicals have shown efficacy in mitigating PM-induced cellular damage through their ability to counteract oxidative stress, suppress pro-inflammatory responses, and enhance cellular defense mechanisms. These combined actions collectively protect tissues from PM-related damage and dysfunction. This review establishes a foundation for future research and the development of effective interventions to combat PM-related health issues. However, further studies, including in vivo and clinical trials, are essential to evaluate the safety, optimal dosages, and long-term effectiveness of herbal treatments for patients under chronic PM exposure. [ABSTRACT FROM AUTHOR]

It is known that ultrashort echo time (UTE) magnetic resonance imaging (MRI) sequences can detect signals from water protons but not collagen protons in short T2 species such as cortical bone and tendons. However, whether collagen protons are visible with the zero echo time (ZTE) MRI sequence is still unclear. In this study, we investigated the potential of the ZTE MRI sequence on a clinical 3T scanner to directly image collagen protons via D2O exchange and freeze-drying experiments. ZTE and UTE MRI sequences were employed to image fully hydrated bovine cortical bone (n = 10) and human patellar tendon (n = 1) specimens. Then, each specimen was kept in a 30 mL syringe filled with D2O solution for two days. Fresh D2O was flushed every 2 h to reach a more complete D2O–H2O exchange. Later, the samples were lyophilized for over 40 h and then sealed in tubes. Finally, the samples were brought to room temperature and visualized using the identical 3D ZTE and UTE sequences. All hydrated bone and tendon specimens showed high signals with ZTE and UTE sequences. However, all specimens showed zero signal after the D2O exchange and freeze-drying procedures. Therefore, similar to UTE imaging, the signal source in ZTE imaging is water. The ZTE sequence cannot directly detect signals from collagen protons in bone and tendons. [ABSTRACT FROM AUTHOR]