Evaluating vehicular exhaust and evaporative emissions via VOC measurement in an underground parking garage

Vehicular emissions, including both tailpipe exhaust and evaporative emissions, are major anthropogenic sources of volatile organic compounds (VOCs) in urban cities. Current knowledge on vehicle tailpipe and evaporative emissions was mainly obtained via laboratory tests on very few vehicles under experimental conditions. Information on fleet gasoline vehicles emission features under real-world conditions is lacking. Here, VOC measurement was conducted in a large residential underground parking garage in Tianjin, China, to reveal the feature of the exhaust and evaporative emissions from real-world gasoline vehicle fleets. The VOC concentration in the parking garage was on average 362.7 ± 87.7 μg m-3, significantly higher than that in the ambient atmosphere at the same period (63.2 μg m-3). Aromatics and alkanes were the mainly contributors on both weekdays and weekends. A positive correlation between VOCs and traffic flow was observed, especially in the daytime. Source apportionment through the positive matrix factorization model (PMF) revealed that the tailpipe and evaporative emissions accounted for 43.2% and 33.7% of VOCs, respectively. Evaporative emission contributed 69.3% to the VOCs at night due to diurnal breathing loss from numerous parked cars. In contrast, tailpipe emission was most remarkable during morning rush hours. Based on the PMF results, we reconstructed a vehicle-related VOCs profile representing the combination of the tailpipe exhaust and evaporative emission from fleet-average gasoline vehicles, which could benefit future source apportionment studies.

Brake wear-derived particles: Single-particle mass spectral signatures and real-world emissions

Brake wear is an important but unregulated vehicle-related source of atmospheric particulate matter (PM). The single-particle spectral fingerprints of brake wear particles (BWPs) provide essential information for understanding their formation mechanism and atmospheric contributions. Herein, we obtained the single-particle mass spectra of BWPs by combining a brake dynamometer with an online single particle aerosol mass spectrometer and quantified real-world BWP emissions through a tunnel observation in Tianjin, China. The pure BWPs mainly include three distinct types of particles, namely, Ba-containing particles, mineral particles, and carbon-containing particles, accounting for 44.2%, 43.4%, and 10.3% of the total BWP number concentration, respectively. The diversified mass spectra indicate complex BWP formation pathways, such as mechanical, phase transition, and chemical processes. Notably, the mass spectra of Ba-containing particles are unique, which allows them to serve as an excellent indicator for estimating ambient BWP concentrations. By evaluating this indicator, we find that approximately 4.0% of the PM in the tunnel could be attributable to brake wear; the real-world fleet-average emission factor of 0.28 mg km^-1 veh^-1 is consistent with the estimation obtained using the receptor model. The results presented herein can be used to inform assessments of the environmental and health impacts of BWPs to formulate effective emissions control policies.

Characteristics, sources, and health risks of inorganic elements in PM2.5 and PM10 at Tianjin Binhai international airport

To study air pollution from aircraft activity at airport and its risks to human health, we conducted an experiment near Tianjin Binhai International Airport from November 11 to November 24, 2017. The characteristics, source apportionment, and health risk of inorganic elements in particles were determined in the airport environment. The mean mass concentrations of inorganic elements in PM₁₀ and PM_2.5 were 17.1 and 5.0 μg/m³, accounting for 19.0% of PM₁₀ mass and 12.3% of PM_2.5 mass, respectively. Inorganic elements, including arsenic, chromium, lead, zinc, sulphur, cadmium, potassium, sodium, and cobalt, were mainly concentrated in fine particulate matter. The particle number concentration within the 60-170 nm particle size range was significantly higher under polluted than non-polluted conditions. A principal component analysis revealed important contributions of Cr, Fe, K, Mn, Na, Pb, S, and Zn originating from airport activities, including aircraft exhaust, braking, tire wear, ground service equipment, and airport vehicles. Based on analyses of the non-carcinogenic and carcinogenic risks of heavy metal elements in PM₁₀ and PM_2.5, there were notable human health impacts, emphasising the importance of relevant research.

Optical properties of vehicular brown carbon emissions: Road tunnel and chassis dynamometer tests

Brown carbon (BrC), as an important light-absorbing aerosol, significantly impacts regional and global climate. Vehicle emission is a nonnegligible source of BrC, but the optical properties of BrC emitted from vehicles remain poorly understood. This study evaluates the absorption Ångström exponent (AAE) of traffic-related light-absorbing aerosols (i.e., AAE_Tr) and the absorption emission factor (EF_abs) of vehicular BrC via chassis dynamometer tests and a road tunnel measurement in Tianjin, China. AAE_Tr are estimated as 0.98-1.33 and 1.11 ± 0.001 for tested vehicles and on-road vehicle fleet, respectively. The AAE of vehicular BrC (AAE_BrC) is 3.83 ± 0.092 for on-road vehicle fleet. The vehicle technology updates effectively reduce the EF_abs of vehicular BrC. Among the four tested China 5 and China 6 gasoline vehicles in the chassis dynamometer tests, BrC EF_abs of China 5 gasoline direct injection vehicle is the highest, while China 6 mixing fuel injection vehicle exhibits the lowest EF_abs. The BrC EF_abs of on-road vehicle fleet at 370 nm wavelength are 0.081 ± 0.0058 m² kg^-1 for mixed fleet, 0.074 ± 0.018 m² kg^-1 for gasoline vehicles (GVs), and 1.66 ± 0.71 m² kg^-1 for diesel vehicles (DVs) in the tunnel measurement. EF_abs of GV fleet in the road tunnel is higher than China 5 and China 6 vehicles, as China 1-4 vehicles accounted for 26.8% of the total vehicle fleet in the tunnel. EF_abs of vehicular BrC are lower than those from biomass burning and coal combustion emissions. The light absorption of BrC from GVs and DVs accounts for 7.2 ± 2.1% and 1.5 ± 0.77% of total traffic-related absorption at 370 nm, respectively. Our study provides optical features of BrC from vehicle source and could contribute to estimating the impacts of vehicular aerosol emissions on global and regional climate change.

HISMD: A Novel Immune Subtyping System for HNSCC

Immune subtyping is an important way to reveal immune heterogeneity, which may contribute to the diversity of the progression and treatment in head and neck squamous cell carcinoma (HNSCC). However, reported immune subtypes mainly focus on levels of immune infiltration and are mostly based on a mono-omics profile. This study aimed to identify a comprehensive immune subtype for HNSCC via multi-omics clustering and build a novel subtype prediction system for clinical application. Data were obtained from The Cancer Genome Atlas database and our independent multicenter cohort. Multi-omics clustering was performed to identify 3 clusters of 499 patients in The Cancer Genome Atlas based on immune-related gene expression and somatic mutations. The immune characteristics and biological features of the obtained clusters were revealed by bioinformatics, and 3 immune subtypes were identified: 1) adaptive immune activation subtype predominantly enriched in T cells, 2) innate immune activation subtype predominantly enriched in macrophages, and 3) immune desert subtype. Subsequently, the clinical implications of each subtype were analyzed per clinical epidemiology. We found that adaptive immune activation showed better survival outcomes and had a similar response to chemotherapy with innate immune activation, whereas immune desert might be relatively resistant to chemotherapy. Moreover, a subtype prediction system was developed by deep learning with whole slide images and named HISMD: HNSCC Immune Subtypes via Multi-omics and Deep Learning. We endowed HISMD with interpretability through image-based key feature extraction. The clinical implications, biological significances, and predictive stability of HISMD were successfully verified by using our independent multicenter cohort data set. In summary, this study revealed the immune heterogeneity of HNSCC and obtained a novel, highly accurate, and interpretable immune subtyping prediction system. For clinical implementation in the future, additional validation and utility studies are warranted.

The impact of the metabolic score for insulin resistance on cardiovascular disease: a 10-year follow-up cohort study

PURPOSE

To investigate whether the metabolic score for insulin resistance (METS-IR) is associated with an increased risk of cardiovascular disease (CVD).

METHODS

A total of 6489 participants aged 35-70 years without a history of CVD were included in this prospective cohort study. The median follow-up time was 10.6 years. The METS-IR was calculated as ln [2 × FPG (mg/dL) + fasting TG (mg/dL)] × BMI (kg/m²)/ln [HDL-C (mg/dL)]. The primary outcome was CVD, defined as the composite of coronary heart disease (CHD) and stroke.

RESULTS

During follow-up, 396 individuals developed CVD. Kaplan-Meier survival curves by quintiles of METS-IR showed statistically significant differences (log-rank test, P < 0.001). Multivariate Cox regression analysis showed that the hazard ratio [95% confidence interval (95% CI)] of CVD was 1.80 (1.24-2.61) in quintile 5 and 1.17 (1.05-1.31) for per standard deviation (SD) increase in METS-IR. In subgroup analysis, the significant association between METS-IR and CVD was mainly observed among females and subjects without diabetes mellitus. A significant interaction was found between gender and METS-IR (P-interaction = 0.001). Moreover, adding METS-IR to models with traditional risk factors yielded a significant improvement in discrimination and reclassification of incident CVD.

CONCLUSION

The elevated METS-IR was independently associated with incident CVD, suggesting that the METS-IR might be a valuable indicator for risk stratification and early intervention of CVD.

Evaluating traffic emission control policies based on large-scale and real-time data: A case study in central China

The traffic control policies, including "Odd and Even" (OAE) and "One Day Per Week" (ODPW), were adopted in Zhengzhou, China. In this study, we use the bottom-up policy evaluation framework to capture the temporal-spatial characteristics of traffic conditions and vehicle emissions under various traffic restriction scenarios. Moreover, we use the street-scale simulation model to evaluate the effectiveness of improving air quality. Results showed that the improvements in traffic conditions led to the emission decrease by about 28.3 % for carbon monoxide (CO), 16.2 % for nitrogen oxide (NOx), 21.3 % for particulate matter (PM_2.5), and 23.2 % for total hydrocarbon (THC) under OAE. During ODPW, total vehicle emissions decreased by 14.1 % for CO, 10.2 % for NOx, 13.7 % for PM_2.5, and 12.4 % for THC. However, the spatial analysis indicates traffic restrictions could not significantly reduce those emissions caused by high traffic volume; besides, buses, middle-duty trucks, and heavy-duty trucks have partly offset the reduction benefit from restrictions. The air quality simulation results reveal no significant concentration decrease of CO and nitrogen dioxide (NO₂) in most areas. With the update of vehicles, stricter management of high-emission vehicles, and limited coverage for implementation of policies, the traffic control policies were not as effective as before. The limitations of the restriction policies are gradually prominent, and upgrade policies are urgently needed to continuously improve urban air quality in the future.

Dosimetric comparison of different intensity-modulated radiotherapy techniques for whole-breast irradiation of right-breast cancer

PURPOSE

This study compared the dosimetric parameters of field-in-field forward intensity-modulated radiotherapy (FIF-IMRT) and fixed-field inversely optimized intensity-modulated radiotherapy (FFIO-IMRT) for the whole-breast irradiation of patients undergoing right-breast lumpectomy.

MATERIAL AND METHODS

A total of 30 patients with pT1-2N0M0 right-breast invasive ductal carcinoma were enrolled in this study. Two different treatment plans, i.e., FIF-IMRT and FFIO-IMRT, were designed for each patient. The dosimetric parameters of the two treatment plans were compared including ipsilateral lung and heart, conformity index (CI), and the homogeneity index (HI) of the planning target volume (PTV).

RESULTS

Fixed-field inversely optimized intensity-modulated radiotherapy was found to significantly improve CI (83.302% vs. 60.146%) and HI (11.837% vs. 19.280%), and significantly reduced V₂₅ (18.038% vs. 19.653%) and V₃₀ (15.790% vs. 18.492%) of the ipsilateral lung. It also significantly increased V₅ (69.791% vs. 32.615%) of the ipsilateral lung and V₅ (61.579% vs. 3.829%), V₁₀ (14.130% vs. 0.381%), V₂₀ (1.843% vs. 0.051%), and D_mean (5.211Gy vs. 1.870Gy) of the heart.

CONCLUSION

Regardless of improving the conformity and homogeneity of PTV and reducing the ipsilateral lung irradiation volume at high doses, FFIO-IMRT significantly raised the ipsilateral lung irradiated volume at low doses, as well as the irradiation volume and mean radiation doses to the heart. This limits its use in patients with early-stage right breast cancer.

Comparison of CO2, NOx, and VOCs emissions between CNG and E10 fueled light-duty vehicles

In China, natural gas (NG) is the main vehicle fuel after gasoline and diesel, and the number of NG vehicles ranks first in the world. At present, there are many studies on the conventional gaseous pollutants and particulate matter of NG vehicles, but very few studies on their VOCs. In this study, the chassis dynamometer is used to test CNG/E10 bi-fuel light-duty vehicles, analyze the advantages of CNG in CO₂, fuel thermal efficiency, and cost, and discuss its disadvantages in NO_x emission. Most importantly, the emission characteristics and ozone formation potential of VOCs in the exhaust of CNG vehicles were analyzed in the study. Compared with E10, CNG fuel can reduce CO₂ emission by about 20 %, improve thermal efficiency by about 13 %, and save fuel costs by about 50 %. However, it will increase NO_x and NO₂ emissions by about 10 % and 13 % respectively. As for VOCs, the emission factor of VOCs from CNG fuel is about 54 % of E10 fuel. The VOCs group with the highest proportion in the exhaust of CNG-fueled vehicles is alkanes, >80 %. while the alkanes and alkenes with the highest proportion in E10 fuel are 30 % and 23 % respectively. C2 VOCs emitted by CNG account for >70 %, while C2 VOCs emitted by E10 are <60 %, followed by C4 VOCs, about 10 % - 30 %. The OFPs of VOCs in CNG exhaust is about 13.7 % of E10. Alkenes contribute the most to ozone, and the OFPs of alkenes in CNG and E10 vehicle exhaust accounts for about 55.3 % and 78.8 % of TVOCs respectively. The results of this study are helpful to improve people's understanding of the environmental value of using NG vehicles.

Adaptations to water stress and pastoralism in the Turkana of northwest Kenya

The Turkana people inhabit arid regions of east Africa-where temperatures are high and water is scarce-and they practice subsistence pastoralism, such that their diet is primarily composed of animal products. Working with Turkana communities, we sequenced 367 genomes and identified 8 regions putatively involved in adaptation to water stress and pastoralism. One of these regions includes a putative enhancer for STC1-a kidney-expressed gene involved in the response to dehydration and the metabolism of purine-rich foods such as red meat. We show that STC1 is induced by antidiuretic hormone in humans, is associated with urea levels in the Turkana themselves, and is under strong selection in this population (s∼0.041). This work highlights that partnerships with subsistence-level groups can lead to new models of human physiology with biomedical relevance.

Tunnel measurements reveal significant reduction in traffic-related light-absorbing aerosol emissions in China

Light-absorbing aerosols (LAA), including black carbon (BC) and brown carbon (BrC), profoundly impact regional and global climate. Vehicle emission is an important source of LAA in urban areas, but real-world emission features of LAA from the urban vehicle fleet are not fully understood. This study evaluates traffic-related BC and BrC emission factors (EFs) and their vehicular emission inventories via road tunnel measurements in Tianjin, China, in 2017 and 2021. The distance-based and fuel-based EFs of BC for the mixed fleet were 1.05 ± 1.28 mg km^-1 veh^-1 and 0.057 ± 0.057 g (kg-fuel)^-1, respectively, in 2021, with a dramatic decrease of 80.6 % compared to those in 2017. The BC EFs for gasoline vehicles (GVs, including traditional gasoline and hybrid vehicles) and diesel vehicles (DVs) were 0.55 ± 0.065 mg km^-1 veh^-1 and 10.5 ± 2.52 mg km^-1 veh^-1, respectively, in 2021. Compared to 2017, the BrC EFs also decreased significantly in 2021, by 10.8-53.6 %, with 0.32 ± 0.45 mg km^-1 veh^-1 and 0.018 ± 0.020 g (kg-fuel)^-1 of distance-based and fuel-based EFs for mixed fleet. The BrC EFs for GVs and DVs were 0.091 ± 0.024 mg km^-1 veh^-1 and 3.06 ± 0.91 mg km^-1 veh^-1, respectively, in 2021. Based on the BC and BrC EFs for GVs and DVs and annual mileage for each vehicle category, the annual vehicular LAA emission inventories were estimated. From 2017 to 2021, the annual vehicular LAA emissions in Tianjin have been significantly reduced, by 69 % for BC and 10 % for BrC. DVs account for a small amount of the vehicle population (8.4 %), but contribute to most of the BC (83 %) and BrC (86 %). Our study demonstrates the significant reduction of vehicular light-absorbing aerosols emission due to vehicle pollution prevention and control in China.

Lattice distortions and the metal-insulator transition in pure and Ti-substituted Ca3Ru2O7

We report pair distribution function studies on the relationship between the metal-insulator transition (MIT) and lattice distortions in pure and Ti-substituted bilayer Ca₃Ru₂O₇. Structural refinements performed as a function of temperature, magnetic field and length scale reveal the presence of lattice distortions not only within but also orthogonal to the bilayers. Because of the distortions, the local and average crystal structure differ across a broad temperature region extending from room temperature to temperatures below the MIT. The coexistence of distinct lattice distortions is likely to be behind the marked structural flexibility of Ca₃Ru₂O₇under external stimuli. This observation highlights the ubiquity of lattice distortions in an archetypal Mott system and calls for similar studies on other families of strongly correlated materials.

[Thirty-year changes in disability adjusted life years for colorectal cancer in China: a screening perspective analysis]

Objective: From a screening-focused perspective, to analyze the 30-year changes in disability adjusted life years (DALYs) caused by colorectal cancer (CRC) in China and in some other selected populations, to inform extent of burden of CRC and future related prevention and control in populations in China. Methods: Based on the data of Global Burden of Disease 2019 (GBD 2019), the DALYs, world standardized DALY rate, and the composition of different subgroups in China were collected. Joinpoint regression model was used to analyze the trend during 1990-2019, and comparison was made with the international data and population screening situation. The trend of DALY burden caused by CRC in China was predicted. Results: In 2019, the DALYs due to CRC in China was 6.395 million person-years, accounting for 26.3% of the global burden and 9.5% of all cancers burden in China; the DALYs in men accounted for 65.2%, in those aged ≥65 years old accounted for 44.8%, in the age group recommended by local screening guidelines (40-75 years) accounted for 73.7%. The years lived with disability accounted for 4.8%. Compared with 1990, the CRC-caused DALYs in China increased by 181.5% in 2019. Factors with the largest increase in the attributable percentage were high Body Mass Index (151.1%), diet high in red meat (86.4%) and diet high in processed meat (78.8%), etc. For DALY rate, it was 245.6/100 000 in 1990 and 320.6/100 000 in 2019, an increase of 30.5%. For reference, Australia (began in 2006), the UK (2006), and Japan (1992), where CRC population-wide screening has been conducted, had decreases in DALY rate of 36.0%, 28.6%, and 17.8%, respectively. The predication of DALYs suggested that without continued expansion of population-based screening, the DALYs in China would reach 7.7 million person-year-9.1 million person-year by 2030, an increase of 19.9%-41.8% compared with 2019. Conclusions: The burden of CRC-caused DALYs in China increased over the past 30 years, and would become more serious because of population aging and the concomitant disability problem. The age range recommended by the current local screening guideline could theoretically include 70% of the population from which the DALYs burden originates, however, the real-world population screening coverage is still limited. The observed decline in CRC-related DALY rate in selected countries was substantially due to the implementation of mass screening, indicating the importance of speedily expanding the population coverage of CRC screening in China.

Diagnostic accuracy of ultrasonography for detecting gastric tube placement: an updated meta-analysis

OBJECTIVE

This study aimed at reviewing the diagnostic accuracy of ultrasonography for detecting correct nasogastric tube placement compared with X-ray imaging as the reference standard.

MATERIALS AND METHODS

This was a systematic review and meta-analysis of observational studies published between 1961 and 2022. We included studies that compared the diagnostic accuracy of ultrasound detection for nasogastric tube placement with that of X-ray imaging in adult patients who were undergoing nasogastric tube placement for any reason. We searched for published studies in the following electronic databases: Cochrane Library, PubMed, EMBASE, and Web of Science. The risk of bias was assessed using a standard procedure according to the Quality Assessment of Diagnostic Accuracy Studies-2 criteria. The results were analyzed using RevMan or Meta-Disc software to determine the adequacy and conclusiveness of the available evidence.

RESULTS

Fourteen studies met our inclusion criteria. Overall, 1,812 patients were included in these studies. The results included a pooled sensitivity of 0.96 (95% confidence interval [CI] 0.94-0.97), specificity of 0.91 (95% CI 0.85-0.96), positive likelihood ratio of 5.08 (95% CI 1.49-17.39), and negative likelihood ratio of 0.08 (95% CI 0.06-0.10). This was confirmed through a summary receiver operating characteristic curve, which showed that the area under the curve was 0.96.

CONCLUSIONS

We found evidence about validity of ultrasound as an efficient method for verifying nasogastric tube placement, although there is insufficient evidence to suggest that it can be used as a diagnostic tool for incorrect gastric tube placement.

The effect of black carbon aging from NO2 oxidation of SO2 on its morphology, optical and hygroscopic properties

Atmospheric aging of black carbon (BC) leads to changes in its physiochemical properties, exerting complex effects on environment and climate. In this study, we have conducted laboratory chamber experiments to investigate the effects of BC aging on its morphology, hygroscopicity and optical properties by exposing monodisperse fresh BC particles to ambient ubiquitous species of nitrogen dioxide (NO₂), sulfur dioxide (SO₂) and ammonia (NH₃) in absence of UV light. We show a rapid aging from highly fractal to compacted aggregates for the monodisperse BC particles with an initial diameter of 150 nm, with decline in the dynamic shape factor (χ) from about 1.8 to nearly 1. The effective density of the monodisperse BC particles increases from ∼0.54 to 1.50 g cm^-3 accordingly. The aging process leads to that the light scattering, absorption, and single scattering albedo of the monodisperse BC particles are strongly enhanced by factors of 7.0, 1.8 and 3.0 respectively. By comparing with the BC aging from other mechanisms, we reveal a critical role of the composition of the coating materials on BC in determining its light absorption enhancement. Moreover, due to strong water uptake capacity of the aged BC particles, the light absorption enhancement (E_abs) could be 40-60% higher at humid atmosphere compared with dry conditions. This BC aging process from NO₂ oxidation of SO₂ may occur commonly in polluted regions and thus considerably alter its effects on regional air quality and climate.

Applying machine learning to construct braking emission model for real-world road driving

Brake emissions from vehicles are increasing as the number of vehicles increases. However, current research on brake emissions, particularly the intensity and characteristics of emissions under real road conditions, is significantly inadequate compared to exhaust emissions. To this end, a dataset of 600 (200 unique real-world braking events simulated using three types of brake pads) real-world braking events (called brake pad segments) was constructed and a mapping function between the average brake emission intensity of PM2.5 from the segments and the segment features was established by five algorithms (multiple linear regression (MLR) and four machine learning algorithms). Based on the five algorithms, the importance of the different features of the fragments was discussed and brake energy intensity (BEI) and metal content (MC) of the brake pad emissions were identified as the most significant factors affecting brake emissions and used as the final modeling features. Among the five algorithms, categorical boosting (CatBoost) had the best prediction performance, with a mean R2 and RMSE of 0.83 and 0.039 respectively for the tenfold cross-validation. In addition, the CatBoost-based model was further compared with the MOVES model to demonstrate its applicability. The CatBoost-based model has better prediction performance than the MOVES model. The MOVES model overpredicts brake fragment emissions for urban roads and underpredicts brake fragment emissions for motorways. Furthermore, the CatBoost-based model was interpreted and visualized by an individual conditional expectation (ICE) plot to break the machine learning "black box", with BEI and MC showing nonlinear monotonic increasing relationships with braking emissions. ICE plot also provides viable technical solutions for controlling brake emissions in the future. Both avoiding aggressive braking driving behavior (e.g., the application of smart transportation technologies) and using brake pads with less metal content (e.g., using ceramic brake pads) can effectively reduce brake emissions. The construction of a machine learning-based brake emission model and the white-boxing of its model provide excellent insights for the future detailed assessment and control of brake emissions.