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Poor air quality is often experienced in densely populated areas located alongside large rivers. The presence of a river valley can modify local meteorology, potentially interfering with the formation of air pollutants such as PM2.5. However, the mechanisms behind PM2.5 formation in river valleys and its impacts on surrounding regions remain poorly understood. This study investigates the formation mechanisms of PM2.5 in the Nanjing reach of the Yangtze River, considering its complex terrain and anthropogenic emissions, through numerical simulation. Simulated results revealed higher PM2.5 concentrations along the Yangtze River compared to the average concentrations in Nanjing, primarily driven by elevated nitrate level. Factors such as higher humidity, wind speed, ageostrophic wind field, and shallow boundary layer were identified as key contributors to the increased PM2.5 concentrations along the river. Our study demonstrates significant impact of local thermal circulations on PM2.5 formation, resulting from the interaction between the large water body of the Yangtze River and the urban area. This phenomenon was confirmed through sensitivity experiments, which showed attenuated local thermal circulations in the absence of the Yangtze River. Source apportionment and process analysis results confirm the dominant roles of local thermal circulation related horizontal and vertical advections, with diurnal fluctuations, in shaping PM2.5 variations along the river. Inorganic chemistry processes also played a non‐negligible role, particularly during polluted conditions. Local thermal circulations in river valleys are crucial for PM2.5 formation, highlighting the need for comprehensive strategies to tackle air pollution in similar regions. Plain Language Summary: Throughout history, civilizations have thrived along major rivers across the globe. However, these densely populated areas often suffer from poor air quality due to high anthropogenic emissions. Notably, fine particulate matter (PM2.5) tends to be higher along rivers than in surrounding urban areas, raising questions about the mechanisms behind PM2.5 formation in river valleys and its impacts on neighboring regions. Using numerical experiments, this study focuses on the Nanjing reach of the Yangtze River as an example to model PM2.5 air quality. We observed a noticeable diurnal pattern of source regions for PM2.5 along the Yangtze River. The findings uncover that the topography of river valleys, coupled with urban terrain, can induce a unique small‐scale thermal circulation embedded within the conventional urban heat island circulation. This local thermal circulation acts as a physical barrier, trapping air pollutants within the valley during the daytime, and aggravating PM2.5 air quality along the river. Understanding the role of local thermal circulation is essential for developing comprehensive strategies for combatting air pollution in urban areas near major rivers. Key Points: The PM2.5 concentration along the Yangtze River is higher than in the neighboring Nanjing urban areasThe contribution from regions outside the Yangtze River to PM2.5 along the river shows a pronounced diurnal patternLocal thermal circulations, induced by the Yangtze River's water body and the urban terrains, interfere with PM2.5 formation [ABSTRACT FROM AUTHOR]

The reinforcing effect of short carbon fibers (CFs) in Ti−6Al−4V (TC4) matrix composites fabricated by powder metallurgy is investigated by mechanical testing at room/high temperatures. Different mass fractions of CFs (0−3%) are dispersed into TC4 matrix by high‐energy ball milling. CFs/TC4 powder mixtures are then consolidated by hot isostatic pressing to obtain CFs/TC4 composites. Microscopic morphology, phase composition, and interfacial microstructure of CFs/TC4 composites are thoroughly characterized by various electron microscopies and Raman spectra. It is found that all composites fail before yielding at room‐temperature tensile tests, which is due to the unpleasant bonding condition between CFs and TC4. However, the 1% CFs/TC4 composite fractures in a ductile mode at elevated temperatures. The reinforcing effect of CFs becomes more prominent with the increase in testing temperature. At 700 °C, the 1% CFs/TC4 composite registers 74% improvement in the yield strength compared with the TC4 matrix, which suggests the excellent reinforcing effect of CFs among available reinforcements in the literature. The results suggest that short CFs might be a suitable reinforcement candidate for high‐temperature applications of titanium matrix composites. [ABSTRACT FROM AUTHOR]

Background: This study aimed to investigate the anesthetic effect of butorphanol with different doses in patients undergoing gastroscopy and colonoscopy.Methods: 480 patients undergoing gastroscopy and colonoscopy were recruited and randomly divided into four groups to receive different doses of butorphanol (Group A = 2.5 μg/kg, Group B = 5 μg/kg, Group C = 7.5 μg/kg and Group D = 10 μg/kg). Butorphanol was administered 5 min before propofol infusion. The primary outcome was the incidence of body movement. Secondary outcomes were postoperative recovery time, length of stay in the Post-Anesthesia Care Unit (PACU), the total dose of propofol, and the incidence of intraoperative hypoxemia, propofol injection pain, cough, postoperative nausea and vomiting, drowsiness, and dizziness.Results: The incidence of body movement and the dose of propofol in Group C and D were lower than those in Group A and B (P < 0.05). The incidence and intensity of propofol injection pain and the incidence of cough in Group B, C, and D were lower than those in Group A (P < 0.05). The length of stay in PACU and the incidence of postoperative drowsiness and dizziness were higher in Group D than in Group A, B, and C (P < 0.05).Conclusion: Intravenous pre-injection of 7.5 μg/kg butorphanol with propofol can be the optimal dosage for patients undergoing gastroscopy and colonoscopy.Trial Registration: Trial registration: Chinese Clinical Trial Registry, ChiCTR2000031506. Registered 3 April 2020-Retrospectively registered, http://www.medresman.org.cn . [ABSTRACT FROM AUTHOR]