RESUMO
In order to study the pollution characteristics of volatile organic compounds ï¼VOCsï¼ï¼ continuous monitoring of VOCs in two pollution processes was conducted in June and December 2021 in Zhengzhou. Combined with meteorological conditionsï¼ the pollution characteristicsï¼ source contributionsï¼ and reactivity of VOCs in winter and summer were compared and analyzed. The results showed that the volume fraction of atmospheric VOCs in two episodes were ï¼27.92±12.68ï¼×10-9 and ï¼24.30±5.93ï¼×10-9ï¼ respectively. The volume fraction of atmospheric VOCs in the haze pollution process in winter was larger than that in the ozone pollution process in summer. The analysis results of winter sources were as followsï¼ industrial source ï¼27.0%ï¼ï¼ motor vehicle source ï¼22.5%ï¼ï¼ combustion source ï¼20.1%ï¼ï¼ solvent use source ï¼16.3%ï¼ï¼ and oil and gas volatilization source ï¼14.1%ï¼. The analysis results of summer sources were as followsï¼ motor vehicle source ï¼24.8%ï¼ï¼ industrial source ï¼24.1%ï¼ï¼ solvent source ï¼17.4%ï¼ï¼ oil and gas volatilization source ï¼14.2%ï¼ï¼ combustion source ï¼11.2%ï¼ï¼ and plant source ï¼8.4%ï¼. The results of the smog production model showed that the proportion of days in the synergistic control zone of VOCs during the two pollution processes in summer ï¼66.7%ï¼ was smaller than that in winter ï¼100.0%ï¼. The secondary reaction activity results showed that the average ·OH loss rate ï¼L·OHï¼ values in winter and summer were 4.12 s-1 and 4.75 s-1ï¼ respectively. The average ozone formation potential ï¼OFPï¼ values in summer were 108.36 µg·m-3. The olefins were dominant in the top ten species due to L·OH and OFP contributions in summer. The total SOAFP values in winter in Zhengzhou were 54.38 µg·m-3. Among the top ten species contributing to SOAFP in winterï¼ nine were aromatic hydrocarbons.
RESUMO
OBJECTIVE: Temporary vascular access (TVA) is frequently used during the first dialysis in patients with chronic kidney disease (CKD), and it is associated with an increased risk of infection, central vein stenosis, and mortality. Here, factors associated with TVA in patients with CKD were explored. METHODS: This study included patients in a single-center CKD care program who initiated long-term renal replacement therapy. The primary outcome was TVA use at first dialysis. Factors possibly associated with TVA use were analyzed using Cox regression. RESULTS: Temporary vascular access was used in 53.2% of the patients at first dialysis. In total, 73.2% (n = 865) and 26.8% (n = 317) of the patients were on hemodialysis and peritoneal dialysis, respectively. Multivariate Cox regression analysis showed that TVA use in patients with CKD was associated with diabetes (hazard ratio [HR] 1.52, 95% confidence interval [CI] 1.28-1.81, p < 0.001), lower albumin (HR 0.82, 95% CI 0.75-0.91, p < 0.001), lower education level (HR 0.75, 95% CI 0.56-1.00, p = 0.055), and total care dependency (HR 1.92, CI 1.44-3.43, p = 0.003). CONCLUSION: Diabetes, education level, and care dependency are associated with TVA at dialysis initiation in patients with CKD.