ABSTRACT
Limited observation sites and insufficient monitoring of atmospheric CO2 in urban areas restrict our comprehension of urban-suburban disparities. This research endeavored to shed light on the urban-suburban differences of atmospheric CO2 in levels, diurnal and seasonal variations as well as the potential sources and impact factors in the megacity of Hangzhou, China, where the economically most developed region in China is. The observations derived from the existing Hangzhou Atmospheric Composition Monitoring Center Station (HZ) and Lin'an Regional Atmospheric Background Station (LAN) and the newly established high-altitude Daming Mountain Atmospheric Observation Station (DMS), were utilized. From November 2020 to October 2021, the annual averages of HZ, LAN and DMS were 446.52 ± 17.01 ppm, 441.56 ± 15.42 ppm, and 422.02 ± 10.67 ppm. The difference in atmospheric CO2 mole fraction between HZ and LAN was lower compared to the urban-suburban differences observed in other major cities in China, such as Shanghai, Nanjing, and Beijing. Simultaneous CO2 enhancements were observed at HZ and LAN, when using DMS observations as background references. The seasonal variations of CO2 at LAN and DMS exhibited a high negative correlation with the normalized difference vegetation index (NDVI) values, indicating the strong regulatory of vegetation canopy. The variations in boundary layer height had a larger influence on the low-altitude HZ and LAN stations than DMS. Compared to HZ and LAN, the atmospheric CO2 at DMS was influenced by emissions and transmissions over a wider range. The potential source area of DMS in autumn covered most areas of the urban agglomeration in eastern China. DMS measurements could provide a reliable representation of the background level of CO2 emissions in the Yangtze River Delta and a broader region. Conventional understanding of regional CO2 level in the Yangtze River Delta through LAN measurements may overestimate background concentration by approximately 10.92 ppm.
ABSTRACT
OBJECTIVE: To investigate the effectiveness of modified mechanical percussion for eliminating upper urinary tract stone fragments after extracorporeal shock wave lithotripsy. MATERIALS AND METHODS: We assigned patients aged 18-60 years with upper urinary tract calculi to the modified mechanical percussion (trial) or observation (control) group. Kidney-ureter-bladder radiography and ultrasound were used for diagnostic evaluation. The primary outcome was the stone-expulsion rate (SER) at 6 hours. The first stone-expulsion time, the SER at 3, 12, and 24 hours, the stone-free rate, additional interventions, and adverse events (AEs) were recorded. RESULTS: A total of 120 patients underwent randomization: 60 for each group. The mean first stone-expulsion time in the trial and control groups was 6.75 and 13.58 hours, respectively (P = .001). The SERs at 3, 6, and 12 hours in the trial group were 51.8%, 75.4%, and 76.8%, respectively, which were higher than the control group (all P <.05). Among patients who expelled fragments within 6 hours, the stone-free rates were improved at 1 week (P = .002) and at 2 weeks (P = .000). Patients needed fewer additional interventions in the trial group (P = .035). AEs occurred in 42.9% (24 of 56) and 67.9% (38 of 56) of the patients in the trial and control groups, respectively (P = .008). Age, gender, stone size and location, and SER at 24 hours did not differ significantly among the groups. CONCLUSION: Modified mechanical percussion significantly improved SERs and accelerated stone passage after shock wave lithotripsy, resulting in a stone-free status with a lower risk of AEs and reduced need for additional interventions.
