Advances in emission control of diesel vehicles in China.

Diesel vehicles have caused serious environmental problems in China. Hence, the Chinese government has launched serious actions against air pollution and imposed more stringent regulations on diesel vehicle emissions in the latest China VI standard. To fulfill this stringent legislation, two major technical routes, including the exhaust gas recirculation (EGR) and high-efficiency selective catalytic reduction (SCR) routes, have been developed for diesel engines. Moreover, complicated aftertreatment technologies have also been developed, including use of a diesel oxidation catalyst (DOC) for controlling carbon monoxide (CO) and hydrocarbon (HC) emissions, diesel particulate filter (DPF) for particle mass (PM) emission control, SCR for the control of NOx emission, and an ammonia slip catalyst (ASC) for the control of unreacted NH3. Due to the stringent requirements of the China VI standard, the aftertreatment system needs to be more deeply integrated with the engine system. In the future, aftertreatment technologies will need further upgrades to fulfill the requirements of the near-zero emission target for diesel vehicles.

Influence of Perioperative COVID-19 Infection on Surgical Outcomes and Risk Adjustment for Quality Assessment in the American College of Surgeons NSQIP.

BACKGROUND: Surgical patients with perioperative coronavirus disease 19 (COVID-19) infection experience higher rates of adverse events than those without COVID-19, which may lead to imprecision in hospital-level quality assessment. Our objectives were to quantify differences in COVID-19-associated adverse events in a large national sample and examine distortions in surgical quality benchmarking if COVID-19 status is not considered. STUDY DESIGN: Data included 793,280 patient records from the American College of Surgeons NSQIP from April 1, 2020, to March 31, 2021. Models predicting 30-day mortality, morbidity, pneumonia, and ventilator dependency greater than 48 hours, and unplanned intubation were constructed. Risk adjustment variables were selected for these models from standard NSQIP predictors and perioperative COVID-19 status. RESULTS: A total of 5,878 (0.66%) had preoperative COVID-19, and 5,215 (0.58%) had postoperative COVID-19. COVID-19 rates demonstrated some consistency across hospitals (median preoperative 0.84%, interquartile range 0.14% to 0.84%; median postoperative 0.50%, interquartile range 0.24% to 0.78%). Postoperative COVID-19 was always associated with increased adverse events. For postoperative COVID-19 among all cases, there was nearly a 6-fold increase in mortality (1.07% to 6.37%) and15-fold increase in pneumonia (0.92% to 13.57%), excluding the diagnosis of COVID-19 itself. The effects of preoperative COVID-19 were less consistent. Inclusion of COVID-19 in risk-adjustment models had minimal effects on surgical quality assessments. CONCLUSIONS: Perioperative COVID-19 was associated with a dramatic increase in adverse events. However, quality benchmarking was minimally affected. This may be the result of low overall COVID-19 rates or balance in rates established across hospitals during the 1-year observational period. There remains limited evidence for restructuring ACS NSQIP risk-adjustment for the time-limited effects of the COVID-19 pandemic.