[Transport Influence and Potential Sources of PM2.5 Pollution for Nanjing].

In this study, 24-hour backward trajectories of the air mass in Nanjing were calculated by using the HYSPLIT model with the NCEP global reanalysis data from March 2019 to February 2020. The backward trajectories combined with the hourly concentration data of PM2.5 were then utilized in the trajectory clustering analysis and potential pollution source analysis. The results showed that the average concentration of PM2.5 in Nanjing was(36±20) µg·m-3 during the study period, with 17 days exceeding the grade Ⅱ national ambient air quality standards (75 µg·m-3). PM2.5 concentration exhibited clear seasonal variation, with winter (49 µg·m-3)>spring (42 µg·m-3)>autumn (31 µg·m-3)>summer (24 µg·m-3). PM2.5 concentration was significantly positively correlated with surface air pressure but significantly negatively correlated with air temperature, relative humidity, precipitation, and wind speed. Based on the trajectories, seven transport routes were identified in spring, and six routes for the other seasons. The northwest and south-southeast routes in spring, southeast route in autumn, and southwest route in winter were the main pollution transport routes in each season, with the characteristics of short transport distance and slow air mass movement, indicating that local accumulation was one of the main reasons for the high value of PM2.5 in quiet and stable weather. The distance of the northwest route in winter was large, and the PM2.5 concentration was 58 µg·m-3, which was the 2nd highest concentration in all routes, indicating that the cities in the northeast of Anhui had a great transport influence on Nanjing PM2.5. The distribution of PSCF and CWT was relatively consistent, and the main potential source areas were mainly local and adjacent areas of Nanjing, indicating that PM2.5 control is needed to strengthen local control and carry out joint prevention and control with adjacent areas. Winter was most affected by transport, its main potential source area was located at the junction of northwest Nanjing and Chuzhou, and the main source origin was in Chuzhou; therefore joint prevention and control should be expanded to Anhui.

Short-term efficacy of pipeline embolization device for treating complex intracranial aneurysms.

OBJECTIVE: To observe the short-term efficacy of Pipeline embolization divice (PED) for the treatment of complex intracranial aneurysms. METHODS: The clinical data of 29 consecutive patients with 32 intracranial aneurysms treated with PED between April 2015 to September 2016 were analyzed retrospectively. There were 3 small aneurysm, 15 large aneurysms, 8 giant aneurysms, 5 fusiform ayneurysms and 1 recidivation. The vessels include 25 anterior circulation and 4 posterior circulation. RESULTS: We treated 31 aneurysms with 30 PEDs and all of the stents were implanted successfully. 1 case of single aneurysm was multiple divices implanted and 1 case of 3 aneurysms were treated by single PED. 12 of the 29 patients were implanted PED only, 17 were implanted PED with coils, 2 underwent balloon remodeling after the PED implanted. The ostia of 19 ophthalmic arteries, 10 posterior communicating arteries, 4 posterior inferior cerebellar arteries and 1 anterior cerebral artery were covered by PED during procedures; 1 ophthalmic arteries and 1 posterior communicating artery disappeared, no branch vessels occlusion and parent artery stenosis occurred.Hemorrhagic complacations occurred in 2 patients, 2 hours and 5 days after procedure respectively. Radiographic follow-up examnations were carried out in 24 patients and revealed complete occlusion in 21 patients, uncomplete occlusion in 3 patients. No neurological injure occurred in 27 patients who received a clinical follow-up. CONCLUSION: PED provide a safe and effective methord for the treatment of intracranial complex aneurysms like wide-neck aneurysms, fusiform aneurysms, giant aneurysms in low risk of procedural complications and high rates of aneurysm occlusion.