Understanding secondary particles in a regional site of Yangtze River Delta: Insights from mass spectrometric measurement

Submicron particulate matter (PM1) poses significant risks to health risks and global climate. In this study, secondary organic aerosols (SOA) and inorganic compositions were examined for their physicochemical characteristics and evolution using high-resolution aerosol instruments in Changzhou over one-month period. The results showed that transport accompanied by regional static conditions leaded to the occurrence of heavy pollution. In addition, regional generation and local emissions also leaded to the occurrence of light and moderate pollution during the observation period in Changzhou. Organic aerosols (OA) and nitrate (NO3-) accounted for 45 % and 23 % of PM1, respectively. The increase in PM1 was dominated by the contribution of NO3- and OA. SOA was dominance in OA (63 % with 40 % MO-OOA), which was higher than primary organic aerosols (POA). Besides, photochemical reactions and the high oxidizing nature of the urban atmosphere promoted the production of OA, especially MO-OOA in Changzhou. Our results highlight that secondary particles contribute significantly to PM pollution in Changzhou, underlining the importance of controlling emissions of gaseous precursors, especially under high oxidation conditions.

A phase II study of retifanlimab, a humanized anti-PD-1 monoclonal antibody, in patients with solid tumors (POD1UM-203)

BACKGROUND

POD1UM-203, an open-label, multicenter, phase II study, evaluated retifanlimab, a humanized monoclonal antibody targeting programmed cell death protein-1 (PD-1) in patients with selected solid tumors where immune checkpoint inhibitor therapies have previously shown efficacy.

PATIENTS AND METHODS

Eligible patients (≥18 years) had measurable disease and included unresectable or metastatic melanoma, treatment-naive metastatic non-small-cell lung cancer (NSCLC) with high programmed death-ligand 1 (PD-L1) expression (tumor proportion score ≥50%), cisplatin-ineligible locally advanced/metastatic urothelial carcinoma (UC) with PD-L1 expression (combined positive score ≥10%), or treatment-naive locally advanced/metastatic clear-cell renal cell carcinoma (RCC). Retifanlimab 500 mg was administered intravenously every 4 weeks as a 30-min infusion. The primary endpoint was investigator-assessed overall response rate.

RESULTS

Overall, 121 patients (35 melanoma, 23 NSCLC, 29 UC, 34 RCC) were enrolled and treated. The overall response rate [95% confidence interval (CI)] was 40.0% (23.9-57.9) in the melanoma cohort, 34.8% (16.4-57.3) in the NSCLC cohort, 37.9% (20.7-57.7) in the UC cohort, and 23.5% (10.7-41.2) in the RCC cohort. Median duration of response was 11.5 months (95% CI 2.2-not reached) in the UC cohort, and was not reached in the other cohorts. Retifanlimab safety was consistent with previous experience for PD-(L)1 inhibitors.

CONCLUSIONS

Retifanlimab demonstrated durable antitumor activity in patients with melanoma, NSCLC, UC, or RCC. The efficacy and safety of retifanlimab were as expected for a PD-(L)1 inhibitor. These data support further study of retifanlimab in solid tumors.

Insights into the Peroxide-Bicyclic Intermediate Pathway of Aromatic Photooxidation: Experimental Yields and NOx-Dependency of Ring-Opening and Ring-Retaining Products

Aromatic hydrocarbons are important contributors to the formation of ozone and secondary organic aerosols in urban environments. The different parallel pathways in aromatic oxidation, however, remain inadequately understood. Here, we investigated the production yields and chemical distributions of gas-phase tracer products during the photooxidation of alkylbenzenes at atmospheric OH levels with NOx present using high-resolution mass spectrometers. The peroxide-bicyclic intermediate pathway emerged as the major pathway in aromatic oxidation, accounting for 52.1 ± 12.6%, 66.1 ± 16.6%, and 81.4 ± 24.3% of the total OH oxidation of toluene, m-xylene, and 1,3,5-trimethylbenzene, respectively. Notably, the yields of bicyclic nitrates produced from the reactions of bicyclic peroxy radicals (BPRs) with NO were considerably lower (3-5 times) than what the current mechanism predicted. Alongside traditional ring-opening products formed through the bicyclic pathway (dicarbonyls and furanones), we identified a significant proportion of carbonyl olefinic acids generated via the 1,5-aldehydic H-shift occurring in subsequent reactions of BPRs + NO, contributing 4-7% of the carbon flow in aromatic oxidation. Moreover, the observed NOx-dependencies of ring-opening and ring-retaining product yields provide insights into the competitive nature of reactions involving BPRs with NO, HO2, and RO2, which determine the refined product distributions and offer an explanation for the discrepancies between the experimental and model-based results.

Direct identification of total and missing OH reactivities from light-duty gasoline vehicle exhaust in China based on LP-LIF measurement

Considerable efforts have been devoted to characterising the chemical components of vehicle exhaust. However, these components may not accurately reflect the contribution of vehicle exhaust to atmospheric reactivity because of the presence of species not accounted for ("missing species") given the limitations of analytical instruments. In this study, we improved the laser photolysis-laser-induced fluorescence (LP-LIF) technique and applied it to directly measure the total OH reactivity (TOR) in exhaust gas from light-duty gasoline vehicles in China. The TOR for China I to VI-a vehicles was 15.6, 16.3, 8.4, 2.6, 1.5, and 1.6 × 10⁴ sec^-1, respectively, reflecting a notable drop as emission standards were upgraded. The TOR was comparable between cold and warm starts. The missing OH reactivity (MOR) values for China I to IV vehicles were close to zero with a cold start but were much higher with a warm start. The variations in oxygenated volatile organic compounds (OVOCs) under different emission standards and for the two start conditions were similar to those of the MOR, indicating that OVOCs and the missing species may have similar production processes. Online measurement revealed that the duration of the stable driving stage was the primary factor leading to the production of OVOCs and missing species. Our findings underscore the importance of direct measurement of TOR from vehicle exhaust and highlight the necessity of adding OVOCs and other organic reactive gases in future upgrades of emission standards, such that the vehicular contribution to atmospheric reactivity can be more effectively controlled.

Direct Observation of HONO Emissions from Real-World Residential Natural Gas Heating in China

Atmospheric nitrous acid (HONO) is an important precursor of atmospheric hydroxyl radicals. Vehicle emissions and heterogeneous reactions have been identified as major sources of urban HONO. Here, we report on HONO emissions from residential natural gas (RNG) for water and space heating in urban areas based on in situ measurements. The observed HONO emission factors (EFs) of RNG heating vary between 6.03 and 608 mg·m^-3 NG, which are highly dependent on the thermal load. The highest HONO EFs are observed at a high thermal load via the thermal NO homogeneous reaction. The average HONO EFs of RNG water heating in winter are 1.8 times higher than that in summer due to the increased thermal load caused by the lower inlet water temperatures in winter. The power-based HONO EFs of the traditional RNG heaters are 1085 times and 1.7 times higher than those of gasoline and diesel vehicles that meet the latest emission standards, respectively. It is estimated that the HONO emissions from RNG heaters in a typical Chinese city are gradually close to emissions from on-road vehicles when temperatures decline. These findings highlight that RNG heating is a non-negligible source of urban HONO emissions in China. With the continuous acceleration of coal-to-gas projects and the continuous tightening of NOx emission standards for vehicle exhaust, HONO emissions from RNG heaters will become more prominent in urban areas. Hence, it is urgently needed to upgrade traditional RNG heaters with efficient emission reduction technologies such as frequency-converted blowers, secondary condensers, and low-NOx combustors.

Women and partners' experience of major postpartum haemorrhage: a qualitative study

OBJECTIVE

To examine women and their partners' experience of major postpartum haemorrhage (PPH).

DESIGN

A qualitative interview study.

SETTING

Two Labour and Delivery Units in Denmark.

POPULATION

Women who experienced major PPH (≥1 litre within 2 hours after vaginal birth).

METHODS

Semi-structured interviews were conducted with 15 women and nine partners (nine joint interviews, six individual interviews). Interviews were analysed using thematic analysis.

MAIN OUTCOME MEASURES

A qualitative description of women and their partners' experiences.

RESULTS

Three major themes were identified. (1) 'From birth to emergency' included factors that increased concern in women and their partners, such as 'incomprehensible' medical terminology, a tense atmosphere, and alarm call. Transfer to the operating theatre was experienced as the most devastating part of major PPH. (2) 'Feeling safe during an emergency' described factors that supported the women and their partners' management of the situation such as brief explanations from a few healthcare professionals and reassurance that the healthcare professionals were in control of the situation. The pain was experienced as severe, but acceptable. (3) 'Family unity challenged' described how family bonding was supported by positioning the partner at the head of the bed and by keeping the baby on the woman's chest.

CONCLUSIONS

Several factors such as small gestures from healthcare professionals and appropriate organisation of the PPH can make a difference to the woman and her partner's experience of major PPH. Particularly, efforts that support family bonding are greatly valued by women and their partners.

Observation-based sources evolution of non-methane hydrocarbons (NMHCs) in a megacity of China

Both concentrations and emissions of many air pollutants have been decreasing due to implement of control measures in China, in contrast to the fact that an increase in emissions of non-methane hydrocarbons (NMHCs) has been reported. This study employed seven years continuous NMHCs measurements and the related activities data of Shanghai, a megacity in China, to explore evolution of emissions and effectiveness of air pollution control measures. The mixing ratio of NMHCs showed no statistical interannual changes, of which their compositions exhibited marked changes. This resulted in a decreasing trend of ozone formation potential by 3.8%/year (p < 0.05, the same below), which should be beneficial to ozone pollution mitigation as its production in Shanghai is in the NMHCs-limited regime. Observed alkanes, aromatics and acetylene changed by +3.7%/year, -5.9%/year and -7.4%/year, respectively, and alkenes showed no apparent trend. NMHCs sources were apportioned by a positive matrix factorization model. Accordingly, vehicular emissions (-5.9%/year) and petrochemical industry emissions (-7.1%/year) decreased significantly, but the decrease slowed down; significant reduction in solvent usage (-9.0%/year) appeared after 2010; however, emissions of natural gas (+12.6%/year) and fuel evaporation (with an increasing fraction) became more important. The inconsistency between observations and inventories was found in interannual trend and speciation as well as source contributions, emphasizing the need for further validation in NMHCs emission inventory. Our study confirms the effectiveness of measures targeting mobile and centralized emissions from industrial sources and reveals a need focusing on fugitive emissions, which provided new insights into future air policies in polluted region.

Enigma of Urban Gaseous Oxygenated Organic Molecules: Precursor Type, Role of NOx, and Degree of Oxygenation

Oxidation of volatile organic compounds (VOCs) forms oxygenated organic molecules (OOMs), which contribute to secondary pollution. Herein, we present measurement results of OOMs using chemical ionization mass spectrometry with nitrate as the reagent ion in Shanghai. Compared to those in forests and laboratory studies, OOMs detected at this urban site were of relatively lower degree of oxygenation. This was attributed to the high NO_x concentrations (∼44 ppb), which overall showed a suppression on the propagation reactions. As another result, a large fraction of nitrogenous OOMs (75%) was observed, and this fraction further increased to 84% under a high NO/VOC ratio. By applying a novel framework on OOM categorization and supported by VOC measurements, 50 and 32% OOMs were attributed to aromatic and aliphatic precursors, respectively. Furthermore, aromatic OOMs are more oxygenated (effective oxygen number, nO_eff = 4-6) than aliphatic ones (nO_eff = 3-4), which can be partly explained by the difference in initiation mechanisms and points to possible discrimination in termination reactions. This study highlights the roles of NO_x in OOM formation in urban areas, as well as the formation of nitrogenous products that might show discrimination between aromatic and aliphatic VOCs.

The interplays among meteorology, source, and chemistry in high particulate matter pollution episodes in urban Shanghai, China

High particulate matter (PM) pollution episodes still occur occasionally in urban China, despite of improvements in recent years. Investigating the influencing factors of high-PM episodes is beneficial in the formulation of effective control measures. We herein present the effects of weather condition, emission source, and chemical conversion on the occurrence of high-PM episodes in urban Shanghai using multiple online measurements. Three high-PM episodes, i.e., locally-accumulated, regionally-transported, and dust-affected ones, as well as a clean period were selected. Stagnant air with temperature inversion was found in both locally-accumulated and regionally-transported high-PM episodes, but differences in PM evolution were observed. In the more complicated dust-affected episode, the weather condition interacted with the emission/transport sources and chemical conversion, resulting in consecutive stages with different PM characteristics. Specifically, there were (1) stronger local accumulation in the pre-dust period, (2) dust-laden air with aged organic aerosol (OA) upon dust arrival, (3) pollutants being swept into the ocean, and (4) back to the city with aged OA. Our results suggest that (a) local emissions could be rapidly oxidized in some episodes but not all, (b) aged OA from long-range transport (aged in space) had a similar degree of oxygenation compared to the prolonged local oxidation (aged in time), and (c) OA aged over land and over the ocean were similar in chemical characteristics. The findings help better understand the causes and evolution of high-PM episodes, which are manifested by the interplays among meteorology, source, and chemistry, providing a scientific basis for control measures.

Intercomparison of OH radical measurement in a complex atmosphere in Chengdu, China

Atmospheric oxidation is a driving force of complex air pollution, and accurate hydroxyl radical (OH) measurement is helpful in investigating the radical-cored photooxidation mechanism in the troposphere. A self-developed laser-induced fluorescence instrument by the Anhui Institute of Optics Fine Mechanics, Chinese Academy of Sciences (AIOFM-LIF), was able to measure OH concentration with high sensitivity and good time resolution, and a detection limit of 1.7 × 10⁵ cm^-3 (1σ, 30 s). A long-period, multi-level intercomparison of hydroxyl radical (OH) measurements between AIOFM-LIF and PKU-LIF (the Peking University laser-induced fluorescence system) was conducted in Chengdu, China. The measurement between two instruments was in excellent agreement in the 5-min time resolution. Linear regression analysis reported a linear slope of 0.96 with a 0.68 × 10⁶ cm^-3 offset, and the correlation coefficient R² was 0.85. The overall linearity with only a slight offset indicated a negligible influence on OH measurement. No noticeable artifacts from ozonolysis were observed under the condition of high ozone and ozonolysis-related compound concentrations. In addition to the subtraction of background signal through wavelength modulation, the dynamic correction on ozone photolysis interference ensured high intercomparison quality in both relatively constant and rapidly varying periods. Based on the reliability of OH_AIOFM and OH_PKU, comparisons under different oxidation-related species (NOx, VOCs, O₃, PM_2.5) levels and typical scenarios (rich-BVOC and high-reactivity) were carried out to evaluate the performance under complex atmospheres. A slightly higher drift was observed in a certain scenario, but the general data variability due to environmental changes did not affect the measurement accuracy. The intercomparison demonstrated that both systems are able to achieve reliable OH data under typical conditions of complex atmospheric pollution in China. Additional improvements are necessary for future intercomparisons in order to enhance the confidence in OH detection accuracy.

Modeling particulate nitrate in China: Current findings and future directions

Particulate nitrate (pNO3) is now becoming the principal component of PM2.5 during severe winter haze episodes in many cities of China. To gain a comprehensive understanding of the key factors controlling pNO3 formation and driving its trends, we reviewed the recent pNO3 modeling studies which mainly focused on the formation mechanism and recent trends of pNO3 as well as its responses to emission controls in China. The results indicate that although recent chemical transport models (CTMs) can reasonably capture the spatial-temporal variations of pNO3, model-observation biases still exist due to large uncertainties in the parameterization of dinitrogen pentoxide (N2O5) uptake and ammonia (NH3) emissions, insufficient heterogeneous reaction mechanism, and the predicted low sulfate concentrations in current CTMs. The heterogeneous hydrolysis of N2O5 dominates nocturnal pNO3 formation, however, the contribution to total pNO3 varies among studies, ranging from 21.0% to 51.6%. Moreover, the continuously increasing PM2.5 pNO3 fraction in recent years is mainly due to the decreased sulfur dioxide emissions, the enhanced atmospheric oxidation capacity (AOC), and the weakened nitrate deposition. Reducing NH3 emissions is found to be the most effective control strategy for mitigating pNO3 pollution in China. This review suggests that more field measurements are needed to constrain the parameterization of heterogeneous N2O5 and nitrogen dioxide (NO2) uptake. Future studies are also needed to quantify the relationships of pNO3 to AOC, O3, NOx, and volatile organic compounds (VOCs) in different regions of China under different meteorological conditions. Research on multiple-pollutant control strategies involving NH3, NOX, and VOCs is required to mitigate pNO3 pollution, especially during severe winter haze events.

Upgrading Emission Standards Inadvertently Increased OH Reactivity from Light-Duty Diesel Truck Exhaust in China: Evidence from Direct LP-LIF Measurement

Vehicular exhaust is an important source of reactive gases responsible for the formation of ozone and secondary organic aerosols (SOAs) in the atmosphere. Although significant efforts have been made to characterize the chemical compounds associated with vehicular exhaust, there is still a wealth of compounds that are unable to be detected, posing uncertainties in estimating their contribution to atmospheric reactivity. In this study, by improving laser-induced fluorescence techniques, we achieved the first-ever direct measurement of the total OH reactivity (TOR) from light-duty diesel truck (LDDT) exhaust with different emission standards. We found that the TOR from the LDDT exhaust was 80-130 times the TOR from the gasoline exhaust measured in Japan. Unexpectedly, we discovered increased TOR emissions along with upgrading emission standards, possibly as a collective result of high combustion temperature in the engine and the oxidation catalysts in the exhaust after-treatment that favor production of highly oxidized organics in the stricter emission standard. Most of these oxidized organics are unable to be speciated by routine measurements, resulting in the missing OH reactivity increasing rapidly from 1.91% for China III to 42.0% for China V LDDT. Upgrading the emission standard failed to reduce the TOR from LDDT exhaust, which may inadvertently promote the contribution of LDDT to the formation of ozone and SOA pollution in China.

Field Detection of Highly Oxygenated Organic Molecules in Shanghai by Chemical Ionization-Orbitrap

Secondary organic aerosol, formed through atmospheric oxidation processes, plays an important role in affecting climate and human health. In this study, we conducted a comprehensive campaign in the megacity of Shanghai during the 2019 International Import Expo (EXPO), with the first deployment of a chemical ionization─Orbitrap mass spectrometer for ambient measurements. With the ultrahigh mass resolving power of the Orbitrap mass analyzer (up to 140,000 Th/Th) and capability in dealing with massive spectral data sets by positive matrix factorization, we were able to identify the major gas-phase oxidation processes leading to the formation of oxygenated organic molecules (OOM) in Shanghai. Nine main factors from three independent sub-range analysis were identified. More than 90% of OOM are of anthropogenic origin and >60% are nitrogen-containing molecules, mainly dominated by the RO₂ + NO and/or NO₃ chemistry. The emission control during the EXPO showed that even though the restriction was effectual in significantly lowering the primary pollutants (20-70% decrease), the secondary oxidation products responded less effectively (14% decrease), or even increased (50 to >200%) due to the enhancement of ozone and the lowered condensation sink, indicating the importance of a stricter multi-pollutant coordinated strategy in primary and secondary pollution mitigation.

Nocturnal atmospheric chemistry of NO3 and N2O5 over Changzhou in the Yangtze River Delta in China

Comprehensive observations of the nocturnal atmospheric oxidation of NO₃ and N₂O₅ were conducted at a suburban site in Changzhou in the YRD using cavity ring-down spectroscopy (CRDS) from 27 May to 24 June, 2019. High concentrations of NO₃ precursors were observed, and the nocturnal production rate of NO₃ was determined to be 1.7 ± 1.2 ppbv/hr. However, the nighttime NO₃ and N₂O₅ concentrations were relatively low, with maximum values of 17.7 and 304.7 pptv, respectively, illustrating the rapid loss of NO₃ and N₂O₅. It was found that NO₃ dominated the nighttime atmospheric oxidation, accounting for 50.7%, while O₃ and OH only contributed 34.1% and 15.2%, respectively. For the reactions of NO₃ with volatile organic compounds (VOCs), styrene was found to account for 60.3%, highlighting its dominant role in the NO₃ reactivity. In general, the contributions of the reactions between NO₃ and VOCs and the N₂O₅ uptake to NO₃ loss were found to be about 39.5% and 60.5%, respectively, indicating that N₂O₅ uptake also played an important role in the loss of NO₃ and N₂O₅, especially under the high humidity conditions in China. The formation of nitrate at night mainly originated from N₂O₅ uptake, and the maximum production rate of NO₃^- reached 6.5 ppbv/hr. The average NO_x consumption rate via NO₃ and N₂O₅ chemistry was found to be 0.4 ppbv/h, accounting for 47.9% of the total NO_x removal. The predominant roles of NO₃ and N₂O₅ in nitrate formation and NOx removal in the YRD region was highlighted in this study.

Observation and simulation of HOx radicals in an urban area in Shanghai, China

A continuous wintertime observation of ambient OH and HO₂ radicals was first carried out in Shanghai, in 2019. This effort coincided with the second China International Import Expo (CIIE), during which strict emission controls were implemented in Shanghai, resulting in an average PM_2.5 concentration of less than 35 μg/m³. The self-developed instrument based on the laser-induced fluorescence (LIF) technique reported that the average OH radical concentration at noontime (11:00-13:00) was 2.7 × 10⁶ cm^-3, while the HO₂ concentration was 0.8 × 10⁸ cm^-3. A chemical box model utilizing the Regional Atmospheric Chemical Mechanism 2 (RACM2), which is used to simulate pollutant reactions and other processes in the troposphere and which incorporates the Leuven isoprene mechanism (LIM1), reproduced the OH concentrations on most days. The HO₂ concentration was underestimated, and the observed-to-modelled ratio demonstrated poor performance by the model, especially during the elevated photochemistry period. Missing primary peroxy radical sources or unknown behaviors of RO₂ for high-NOx regimes are possible reasons for the discrepancy. The daytime ROx production was controlled by various sources. HONO photolysis accounted for more than one half (0.83 ppb/h), and the contribution from formaldehyde, OVOCs and ozone photolysis was relatively similar. Active oxidation paths accelerated the rapid ozone increase in winter. The average ozone production rate was 15.1 ppb/h, which is comparable to that of a Beijing suburb (10 ppb/h for the 'BEST-ONE') but much lower than that of Beijing's center (39 ppb/h in 'PKU' and 71 ppb/h in 'APHH') in wintertime. Cumulative local ozone based on observed peroxy radicals was five times higher than the value simulated by the current model due to the underprediction of HO₂ and RO₂ under the high-NOx regime. This analysis provides crucial information for subsequent pollution control policies in Shanghai.

Intermediate volatile organic compounds emissions from vehicles under real world conditions

Real-world vehicle emission factors (EFs) for the total intermediate volatile organic compounds (total-IVOCs) and volatile organic compounds (VOCs) from mixed fleets of vehicles were quantified in the Yangtze tunnel in Shanghai. Relationships of EFs of IVOCs with fleet compositions and vehicle speed as well as secondary organic formation potentials (SOAFPs) from IVOCs and VOCs were studied. Multiple linear regression (MLR) was used to estimate EFs of total-IVOCs for gasoline and diesel vehicles. IVOCs were classified into unresolved complex mixtures (unspeciated cyclic compounds and branched alkanes (b-alkanes)) and speciated targets (11 n-alkanes and ten polycyclic aromatic hydrocarbons (PAHs)). The results showed that the average EF of total-IVOCs was 24.9 ± 7.8 mg/(km·veh), which was comparable to that of VOCs. Unspeciated cyclic compounds and b-alkanes dominated the main composition (~77% and ~19%), followed by n-alkanes (~4%) and PAHs (~1%). EFs of IVOCs showed a significant, positive relationship with diesel vehicle fractions (p < 0.05). EFs of IVOCs dropped notably with the decrease of the diesel vehicle fractions. SOAFP produced by the total organic compounds (IVOCs + VOCs) was 8.9 ± 2.5 mg/(km·veh), in which up to 86% of SOAFP was from IVOCs. Estimated EFs of total-IVOCs for gasoline vehicles and diesel vehicles were 15.3 and 219.8 mg/(km·veh) respectively. Our results demonstrate that IVOCs emitted from diesel vehicles are the main emission sources under real world conditions and significant contributions of IVOCs emissions to SOA formation is evident, which indicates the necessity of making control policies to reduce IVOCs emissions from vehicles.

Identification of two main origins of intermediate-volatility organic compound emissions from vehicles in China through two-phase simultaneous characterization

Intermediate-volatility organic compounds (IVOCs) emitted from vehicles are generally in the gas phase but may partly partition into particle phase when measured under ambient temperature. To have a complete and accurate picture of IVOC emissions from vehicles, gas- and particle-phase IVOCs from a fleet of gasoline and diesel vehicles were simultaneously characterized by dynamometer testing in Guangzhou, China. The total IVOC emission factors of the diesel vehicles were approximately 16 times those of the gasoline vehicles, and IVOCs were mainly concentrated in the particle phase in the form of the unresolved complex mixture (UCM). The chemical compositions and volatility distributions of the gas-phase IVOCs differed much between gasoline and diesel vehicles, but were similar to those of their respective fuel content. This indicated that vehicle fuel is the main origin for the gas-phase IVOC emissions from vehicles. In comparison, the chemical compositions of the particle-phase IVOCs from gasoline and diesel vehicles were similar and close to lubricating oil content, implying that lubricating oil plays an important role in contributing to particle-phase IVOCs. The highest IVOC fraction in the particle phase occurred from B₁₆-B₁₈ volatility bins, overall accounting for more than half of the particle-phase IVOCs for both the gasoline and diesel vehicles. A conceptual model was developed to articulate the distributions of lubricating oil contents and their evaporation and nucleation/adsorption capabilities in the different volatility bins. The IVOCs-produced secondary organic aerosol (SOA) were 1.4-2.6 and 3.9-11.7 times POAs emitted from the gasoline and diesel vehicles, respectively. The tightening of emission standards had not effectively reduced IVOC emissions and the SOA production until the implementation of China VI emission standard. This underscores the importance of accelerating the promotion of the latest emission standard to alleviate pollution from vehicles in China.

Observations and modeling of OH and HO2 radicals in Chengdu, China in summer 2019

This study reports on the first continuous measurements of ambient OH and HO₂ radicals at a suburban site in Chengdu, Southwest China, which were collected during 2019 as part of a comprehensive field campaign 'CompreHensive field experiment to explOre the photochemical Ozone formation mechaniSm in summEr - 2019 (CHOOSE-2019)'. The mean concentrations (11:00-15:00) of the observed OH and HO₂ radicals were 9.5 × 10⁶ and 9.0 × 10⁸ cm^-3, respectively. To investigate the state-of-the-art chemical mechanism of radical, closure experiments were conducted with a box model, in which the RACM2 mechanism updated with the latest isoprene chemistry (RACM2-LIM1) was used. In the base run, OH radicals were underestimated by the model for the low-NO regime, which was likely due to the missing OH recycling. However, good agreement between the observed and modeled OH concentrations was achieved when an additional species X (equivalent to 0.25 ppb of NO mixing ratio) from one new OH regeneration cycle (RO₂ + X → HO₂, HO₂ + X → OH) was added into the model. Additionally, in the base run, the model could reproduce the observed HO₂ concentrations. Discrepancies in the observed and modeled HO₂ concentrations were found in the sensitivity runs with HO₂ heterogeneous uptake, indicating that the impact of the uptake may be less significant in Chengdu because of the relatively low aerosol concentrations. The ROx (= OH + HO₂ + RO₂) primary source was dominated by photolysis reactions, in which HONO, O₃, and HCHO photolysis accounted for 34%, 19%, and 23% during the daytime, respectively. The efficiency of radical cycling was quantified by the radical chain length, which was determined by the NO to NO₂ ratio successfully. The parameterization of the radical chain length may be very useful for the further determinations of radical recycling.

Seasonal variation of aerosol compositions in Shanghai, China: Insights from particle aerosol mass spectrometer observations

The variations of non-refractory submicron aerosol (NR-PM₁) were characterized using an high-resolution time-of-flight aerosol mass spectrometer (HR-ToF-AMS) and other online instruments measurements sampled at an urban site in Shanghai from 2016 to 2017. Spring (from 18 May to 4 June 2017), summer (from 23 August to 10 September 2017) and winter (from 28 November 2016 to 23 January 2017) seasons were chosen for detail investigating the seasonal variations in the aerosol chemical characteristics. The average PM₁ (NR-PM₁ + BC) mass concentration showed little difference in the three seasons in Shanghai. The average mass concentrations of total PM₁ during spring, summer, and winter observations in Shanghai were 23.9 ± 20.7 μg/m³, 28.5 ± 17.6 μg/m³, and 31.9 ± 22.7 μg/m³, respectively. The seasonal difference on chemical compositions was more significant between them. Organic aerosol (OA) and sulfate were dominant contributor of PM₁ in summer, whereas OA and nitrate primarily contribution to the increase of PM₁ mass loading in spring and winter. As an abundant component in PM₁ (accounting for 39%-49%), OA were resolved into two primary organic aerosol (POA) factors and two secondary aerosol (SOA) factors by using positive matrix factorization (PMF), of which OA was overwhelmingly dominated by the SOA (50-60%) across the three seasons in Shanghai. Correlation analysis with relative humidity and odd oxygen indicated that aqueous-phase processing and played an important role in more aged SOA formation in summer and winter. In spring, both aqueous-phase and photochemical processing contributed significantly to fresh SOA formation. Our results suggest the significant role of secondary particles in PM pollution in Shanghai and highlight the importance of control measures for reducing emissions of gaseous precursors, especially need to consider seasonal characteristics.

A novel algorithm to determine the scattering coefficient of ambient organic aerosols

In the present work, we propose a novel algorithm to determine the scattering coefficient of OA by evaluating the relationships of the MSEs for primary organic aerosol (POA) and secondary organic aerosol (SOA) with their mass concentrations at three distinct sites, i.e. an urban site, a rural site, and a background site in China. Our results showed that the MSEs for POA and SOA increased rapidly as a function of mass concentration in low mass loading. While the increasing rate declined after a threshold of mass loading of 50 μg/m³ for POA, and 15 μg/m³ for SOA, respectively. The dry scattering coefficients of submicron particles (PM₁) were reconstructed based on the algorithm for POA and SOA scattering coefficient and further verified by using multi-site data. The calculated dry scattering coefficients using our reconstructing algorithm have good consistency with the measured ones, with the high correlation and small deviation in Shanghai (R² = 0.98; deviations: 2.9%) and Dezhou (R² = 0.90; deviations: 4.7%), indicating that our algorithms for OA and PM₁ are applicable to predict the scattering coefficient of OA and Submicron particle (PM₁) in China.

Transport and boundary layer interaction contribution to extremely high surface ozone levels in eastern China

Vertical measurements of ozone (O₃) within the 3000-m lower troposphere were obtained using an O₃ lidar to investigate the contribution of the interactions between the transport and boundary layer processes to the surface O₃ levels in urban Shanghai, China during July 23-28, 2017. An extremely severe pollution episode with a maximum hourly O₃ mixing ratio of 160.4 ppb was observed. In addition to enhanced local photochemical production, both downward and advection transport in the lower troposphere may have played important roles in forming the pollution episode. The O₃-rich air masses in the lower free troposphere primarily originated from central China and the northern Yangtze River Delta (YRD) region. The downward transport of O₃ from the lower free troposphere may have an average contribution of up to 49.1% to the daytime (09:00-16:00 local time) surface O₃ in urban Shanghai during the pollution episode (July 23-26, 2017). As for the advection transport, large amounts of O₃ were transported outward from Shanghai in the planetary boundary layer under the influence of southeasterly winds during the field study. In this condition, the boundary-layer O₃ that was transported downward from the free troposphere in Shanghai could be transported back to the northern YRD region and accumulated therein, leading to the occurrence of severe O₃ pollution events over the whole YRD region. Our results indicate that effective regional emission control measures are urgently required to mitigate O₃ pollution in the YRD region.

Tracer-based characterization of source variations of PM2.5 and organic carbon in Shanghai influenced by the COVID-19 lockdown

Air quality in megacities is significantly impacted by emissions from vehicles and other urban-scale human activities. Amid the outbreak of Coronavirus (COVID-19) in January 2020, strict policies were in place to restrict people's movement, bringing about steep reductions in pollution activities and notably lower ambient concentrations of primary pollutants. In this study, we report hourly measurements of fine particulate matter (i.e., PM_2.5) and its comprehensive chemical speciation, including elemental and molecular source tracers, at an urban site in Shanghai spanning a period before the lockdown restriction (BR) (1 to 23 Jan. 2020) and during the restriction (DR) (24 Jan. to 9 Feb. 2020). The overall PM_2.5 was reduced by 27% from 56.2 ± 40.9 (BR) to 41.1 ± 25.3 μg m^-3 (DR) and the organic carbon (OC) in PM_2.5 was similar, averaged at 5.45 ± 2.37 (BR) and 5.42 ± 1.75 μgC m^-3 (DR). Reduction in nitrate was prominent, from 18.1 (BR) to 9.2 μg m^-3 (DR), accounting for most of the PM_2.5 decrease. Source analysis of PM_2.5 using positive matrix factorization modeling of comprehensive chemical composition, resolved nine primary source factors and five secondary source factors. The quantitative source analysis confirms reduced contributions from primary sources affected by COVID-19, with vehicular emissions showing the largest drop, from 4.6 (BR) to 0.61 μg m^-3 (DR) and the percentage change (-87%) in par with vehicle traffic volume and fuel sale statistics (-60% to -90%). In the same time period, secondary sources are revealed to vary in response to precursor reductions from the lockdown, with two sources showing consistent enhancement while the other three showing reductions, highlighting the complexity in secondary organic aerosol formation and the nonlinear response to broad primary precursor pollutants. The combined contribution from the two secondary sources to PM_2.5 increased from 7.3 ± 6.6 (BR) to 14.8 ± 9.3 μg m^-3 (DR), partially offsetting the reductions from primary sources and nitrate while their increased contribution to OC, from 1.6 ± 1.4 (BR) to 3.2 ± 2.0 μgC m^-3 (DR), almost offset the decrease coming from the primary sources. Results from this work underscore challenges in predicting the benefits to PM_2.5 improvement from emission reductions of common urban primary sources.

Using a distributed air sensor network to investigate the spatiotemporal patterns of PM2.5 concentrations

Spatiotemporal variations in PM_2.5 are a key factor affecting personal pollution exposure levels in urban areas. However, fixed-site monitoring stations are so sparsely distributed that they hardly capture the dynamic and fine-scale variations in PM_2.5 in urban areas with complex geographical features and urban forms. Recently, a distributed air sensor network (DASN) was deployed in Dezhou city, China, to monitor fine-scale air pollution information and obtain deep insight into variations in PM_2.5. Based on the data collected by the DASN, this paper investigated the spatiotemporal patterns of PM_2.5 using the time-series clustering method. The results demonstrated that there were four stages of PM_2.5 daily variations, i.e., accumulation, continuous pollution, dispersion, and cleaning. Generally, the stage of dispersion occurred more rapidly than the stage of accumulation, and PM_2.5 accumulated easily in warm and humid weather with low wind speeds. However, the stage of dispersion was affected mainly by high wind speeds and precipitation. Additionally, the results suggested that four variation stages did not strictly correspond to seasonal divisions. The spatial distributions of PM_2.5 revealed that the main pollution source was located in a southeastern industrial park, which exhibited a significant impact throughout the four stages. Considering both the temporal and spatial characteristics of PM_2.5, this study successfully identified pollution hotspots and confirmed the effect of industrial parks. The study demonstrates that the DASN has high prospective applicability for assessing the fine-scale spatial distribution of PM_2.5, and the time-series clustering method can also assist environmental researchers in further exploring the spatiotemporal characteristics of urban air pollution.

Smog chamber study of the effects of NOx and NH3 on the formation of secondary organic aerosols and optical properties from photo-oxidation of toluene

Secondary organic aerosols (SOAs) have been receiving significant attention because of their significant impacts on air quality and human health. In this study, the influences of nitrogen oxides (NOx) and ammonia (NH₃) on SOA formation from photooxidation of toluene was investigated in the Shanghai university smog chamber. The chemical and physical characteristics of gas-phase products and SOAs from toluene photo-oxidation were characterized using laboratory-developed single photon ionization time-of-flight mass spectrometry, single particle aerosol mass spectrometry, and cavity ring-down aerosol extinction albedo spectroscopy instruments. It was observed that increasing the initial nitrogen oxides ([NOx]₀) under low-[NOx]₀ conditions enhanced the SOA yield, while increasing [NOx]₀ under high-[NOx]₀ conditions suppressed the SOA yield. After adding NH₃, the number concentration, average SOA diameter, and extinction and scattering coefficients showed an immediate and rapid increase due to the formation of significant amounts of condensable ammonium nitrate and nitrogen-containing (NOC) compounds. Moreover, a simplified reaction mechanism for the photooxidation of toluene initiated by the hydroxyl radical (OH) was believed to follow two reaction channels: minor H abstraction, and major OH addition, which continuously induced the subsequent reactions. The results of this study presented rapid analytical method for the joint use of a smog chamber with on-line analytical instruments to immediately characterize the effects of SOA formation, which will help in understanding the new particle formation and particle growth, and thus provides a new insight for in-depth understanding of the haze pollution in China.

Percutaneous vertebroplasty versus non-operative treatment for osteoporotic vertebral compression fractures: a meta-analysis of randomized controlled trials

PURPOSE

Osteoporotic vertebral compression fractures (OVCFs) are common in the elderly population and are often treated using percutaneous vertebroplasty (PVP). However, the effectiveness of PVP reported by various randomized controlled trials (RCTs) is inconclusive. This study aimed to analyze, from published literature, the efficacy and safety of PVP for OVCFs.

METHODS

A search was conducted in Medline, EMBASE, and Cochrane Libraries since their respective inception on January 1, 2019, for RCTs of OVCFs treated with PVP compared with non-operative treatment. The primary outcomes were pain relief at 1 to 2 weeks, 1 to 3 months, and 6 to 12 months. The secondary outcome was the rate of occurrence of new vertebral fractures. Meta-analysis was performed using a random effect model.

RESULTS

A total of 13 RCTs comprising 1624 patients were included. For the blinded studies, statistical differences were found between PVP and the sham injection group for the 3 primary outcomes in the subgroup of the Vertebroplasty for Acute Painful Osteoporotic fractURes (VAPOUR) trial. Although pain scores were similar between the PVP group and the sham injection group for the VAPOUR trial at each period, the effect size of PVP increased over time. For the open-label studies, PVP significantly reduced pain at all time points. The risk of new vertebral fractures was similar between the PVP groups and control groups.

CONCLUSIONS

Application of PVP was effective and safe only in patients with acute OVCFs having persistent and severe pain. No benefits were recorded, among patients with older fractures or those bearing non-severe symptoms.

Real-time analysis of the homogeneous and heterogeneous reactions of pyrene with ozone by SPAMS and CRD-EAS

Single particle aerosol mass spectrometry (SPAMS) and Cavity ring-down aerosol extinction albedo spectroscopy (CRD-EAS) were applied in this work to real-time investigate the chemical and physical characteristics of the homogeneous and heterogeneous reactions of O₃ with pyrene in a Teflon reaction chamber. Suspended pyrene coated polystyrene latex spheres (PSLs) were generated by vaporization-condensation. Ozonation products and particle size distribution during the reactions were detected in real-time using a SPAMS instrument. Among these products, the peaks at m/z of 262 and 278, assigned to 4,5,9,10-dipyrenequinone and 1-hydroxy-4,5,9,10-dipyrenequinone, respectively, were first detected to our knowledge. The mechanism for the formation of reaction product was also proposed based on the real time monitoring. With increasing the ozone concentration, the size growth of the original pyrene-coated particles and the formation of new fine particles and size growth were observed continuously. The optical characteristics were also investigated using a laboratory-developed CRD-EAS instrument. The extinction and scattering coefficients were observed to increase approximately five and four times, respectively. The absorption coefficient also increased because more polar oxidation products coated on the particles exhibiting higher light absorption ability than pyrene, and meanwhile, the single scattering albedo reduced from 0.88 to 0.77 which indicated the reactions could cause positive climate forcing. Using the on-line mass spectrometry and optic spectroscopy instruments, a systematic analysis method was developed to characterize the chemical and physical properties of homogeneous and heterogeneous reactions in real-time, which will help to investigate and understand the formation of new particles and particle growth in the atmosphere.

Reconstructed algorithm for scattering coefficient of ambient submicron particles

Ambient submicron particles (PM₁) exert significant impacts on visibility degradation during severe pollution episodes of urban China. The U.S. IMPROVE algorithms are widely used for assessing the extinction effect of atmospheric aerosols, but only suitable for fine particulate matter. A proper algorithm for PM₁ extinction estimation is lacking and becomes urgent, especially after the online measurement of PM₁ species is routine by aerosol mass spectrometers. Here we conducted three-month in-situ measurements to explore mass scattering efficiencies (MSE) of PM₁ major species at a supersite of eastern China. Results indicated that MSEs of ammonium sulfate and nitrate increase quickly and then keep stable with the mass accumulation, while those of organic matter keep at ∼5.5 m²/g but with a large vibration in the whole mass range. The algorithm for reconstructing PM₁ dry scattering coefficient was derived from the integral of the variation patterns for the three PM₁ species. The algorithm was then validated and compared with other empirical algorithms through separate field measurements. Good correlations between the reconstructed and measured dry scattering coefficient were observed with R square higher than 0.9 and slope of 1.01-1.05, indicating that the reconstructed algorithm can predict the dry scattering coefficient well based on PM₁ chemical composition measurements in urban China. Our study is expected to provide observed insights on the variation of MSE in the wide mass range especially in the high region, as well as accurate formulas for ambient PM₁ dry scattering apportionment.

Combination therapy with parathyroid hormone analogs and antiresorptive agents for osteoporosis: a systematic review and meta-analysis of randomized controlled trials

Combination therapy with parathyroid hormone (PTH) analogs and antiresorptive agents may be more effective than monotherapy for the treatment of osteoporosis. This study aimed to estimate the effectiveness and safety of this combination therapy for osteoporosis. MEDLINE, EMBASE, and Cochrane Library were searched from inception to May 1, 2018, including randomized controlled trials (RCTs) with a duration of at least 6 months on adults with osteoporosis treated with combination therapy versus monotherapy. Outcomes included fractures, bone mineral density (BMD) changes, and adverse events. A meta-analysis was performed using a random-effect model, to estimate risk ratios (RRs) for fractures, and mean differences (MDs) for BMD changes. A total of 19 RCTs and 2177 patients were included. Compared with monotherapy, combination therapy had an advantage of 36% (RR, 0.64; 95% confidence interval (CI), 0.42-0.98) regarding fracture risk reduction. It also appears to improve lumbar spine BMD by 4.06% (95%CI = 2.60-5.53) and total hip BMD by 1.89% (95%CI = 1.25-2.53). No RCT reported an increased risk of serious adverse events. Among patients with osteoporosis, combination therapy was superior to monotherapy regarding improvement of the lumbar spine and total hip BMD, without risk of serious adverse events. Combination therapy also had an advantage over monotherapy on fracture risk reduction. However, owing to the limited sample size, additional larger studies are required to confirm this benefit.

Intermediate Volatility Organic Compound Emissions from a Large Cargo Vessel Operated under Real-World Conditions

Intermediate volatility organic compound (IVOC) emissions from a large cargo vessel were characterized under real-world operating conditions using an on-board measurement system. Test ship fuel-based emission factors (EFs) of total IVOCs were determined for two fuel types and seven operating conditions. The average total IVOC EF was 1003 ± 581 mg·kg-fuel^-1, approximately 0.76 and 0.29 times the EFs of primary organic aerosol (POA) emissions from low-sulfur fuel (LSF, 0.38 wt % S) and high-sulfur fuel (HSF, 1.12 wt % S), respectively. The average total IVOC EF from LSF was 2.4 times that from HSF. The average IVOC EF under low engine load (15%) was 0.5-1.6 times higher than those under 36%-74% loads. An unresolved complex mixture (UCM) contributed 86.1 ± 1.9% of the total IVOC emissions. Ship secondary organic aerosol (SOA) production was estimated to be 546.5 ± 284.1 mg·kg-fuel^-1; IVOCs contributed 98.9 ± 0.9% of the produced SOA on average. Fuel type was the dominant determinant of ship IVOC emissions, IVOC volatility distributions, and SOA production. The ship emitted more IVOC mass, produced higher proportions of volatile organic components, and produced more SOA mass when fueled with LSF than when fueled with HSF. When reducing ship POA emissions, more attention should be paid to commensurate control of ship SOA formation potential.

Size-resolved effective density of submicron particles during summertime in the rural atmosphere of Beijing, China

Particle density is an important physical property of atmospheric particles. The information on high time-resolution size-resolved particle density is essential for understanding the atmospheric physical and chemical aging processes of aerosols particles. In the present study, a centrifugal particle mass analyzer (CPMA) combined with a differential mobility analyzer (DMA) was deployed to determine the size-resolved effective density of 50 to 350nm particles at a rural site of Beijing during summer 2016. The measured particle effective densities decreased with increasing particle sizes and ranged from 1.43 to 1.55g/cm³, on average. The effective particle density distributions were dominated by a mode peaked at around 1.5g/cm³ for 50 to 350nm particles. Extra modes with peaks at 1.0, 0.8, and 0.6g/cm³ for 150, 240, and 350nm particles, which might be freshly emitted soot particles, were observed during intensive primary emissions episodes. The particle effective densities showed a diurnal variation pattern, with higher values during daytime. A case study showed that the effective density of Aitken mode particles during the new particle formation (NPF) event decreased considerably, indicating the significant contribution of organics to new particle growth.

Emission factors of particulate and gaseous compounds from a large cargo vessel operated under real-world conditions

On-board emissions measurements were performed on a Handysize-class bulk carrier operating under real-world conditions. Emission factors (EFs) were determined for criteria pollutants such as NO_x, CO, total hydrocarbons (THC), and PM; PM composition, including organic and elemental carbon (OC and EC), inorganic species, and a variety of organic compounds and VOC species (including alkanes, alkenes, single-ring aromatics, and oxygenated VOCs) were also analyzed. To investigate the impacts of engine type, fuel, and operating conditions on emissions, measurements were conducted on one main and one auxiliary engines using low- and high-sulfur fuels (LSF and HSF) under actual operating conditions, including at-berth, maneuvering, and cruising at different engine loads. OC was the most abundant PM component (contributing 45-65%), followed by sulfate (2-15%) and EC (1-20%). Compounds with 3 or 4 aromatic rings, including phenanthrene, fluoranthene, pyrene, and benzo[b+k]fluoranthene, dominated the particulate polycyclic aromatic hydrocarbons (PAHs) emitted from the ship, accounting for 69-89% of the total PAHs. Single-ring aromatics constituted 50-78% of the emitted VOCs and were dominated by toluene. In this study, switching from HSF (1.12% S) to LSF (0.38% S) reduced emitted PM by 12%, OC by 20%, sulfate by 71%, and particulate PAHs by 94%, but caused an increase in single-ring aromatics. The power-based EFs generally decreased with increasing engine loads. However, decreasing the ship engine load also reduced the vessel speed and, thus, decreased emissions over a given voyage distance. Herein, a Vessel Speed Reduction (VSR) from 11 to 8-9 knots decreased NO_x and PM emissions by approximately 33% and 36%, respectively, and OC, EC, sulfate, and particulate PAHs in PM emissions by 34%, 83%, 29%, and 11%. These data can be used to minimize uncertainty in the emission factors used in ship emissions calculations.

Ammonia Emission Measurements for Light-Duty Gasoline Vehicles in China and Implications for Emission Modeling

Motor vehicle ammonia (NH₃) emissions have attracted increasing attention for their potential to form secondary aerosols in urban atmospheres. However, vehicle NH₃ emission factors (EFs) remain largely unknown due to a lack of measurements. Thus, we conducted detailed measurements of NH₃ emissions from 18 Euro 2 to Euro 5 light-duty gasoline vehicles (LDGVs) in Shanghai, China. The distance- and fuel-based NH₃ EFs average 29.2 ± 24.1 mg·km^-1 and 0.49 ± 0.41 g·kg^-1, respectively. The average NH₃-to-CO₂ ratio is 0.41 ± 0.34 ppbv·ppmv^-1. The measurements reveal that NH₃ emissions from LDGVs are strongly correlated with both vehicle specific power (VSP) and the modified combustion efficiency (MCE); these relationships were used to predict LDGV NH₃ EFs via a newly developed model. The predicted LDGV NH₃ EFs under urban and highway driving cycles are 23.3 mg·km^-1 and 84.5 mg·km^-1, respectively, which are consistent with field measurements. The NH₃ EF has decreased by 32% in average since the implementation of vehicle emission control policies in China five years ago. The model presented herein more accurately predicts LDGV NH₃ emissions, contributing substantially to the compilation of NH₃ emission inventories and prediction of future motor vehicle emissions in China.

Emissions of volatile organic compounds (VOCs) from cooking and their speciation: A case study for Shanghai with implications for China

Cooking emission is one of sources for ambient volatile organic compounds (VOCs), which is deleterious to air quality, climate and human health. These emissions are especially of great interest in large cities of East and Southeast Asia. We conducted a case study in which VOC emissions from kitchen extraction stacks have been sampled in total 57 times in the Megacity Shanghai. To obtain representative data, we sampled VOC emissions from kitchens, including restaurants of seven common cuisine types, canteens, and family kitchens. VOC species profiles and their chemical reactivities have been determined. The results showed that 51.26%±23.87% of alkane and 24.33±11.69% of oxygenated VOCs (O-VOCs) dominate the VOC cooking emissions. Yet, the VOCs with the largest ozone formation potential (OFP) and secondary organic aerosol potential (SOAP) were from the alkene and aromatic categories, accounting for 6.8-97.0% and 73.8-98.0%, respectively. Barbequing has the most potential of harming people's heath due to its significant higher emissions of acetaldehyde, hexanal, and acrolein. Methodologies for calculating VOC emission factors (EF) for restaurants that take into account VOCs emitted per person (EF_person), per kitchen stove (EF_{kitchen stove}) and per hour (EF_hour) are developed and discussed. Methodologies for deriving VOC emission inventories (S) from restaurants are further defined and discussed based on two categories: cuisine types (S_type) and restaurant scales (S_scale). The range of S_type and S_scale are 4124.33-7818.04t/year and 1355.11-2402.21t/year, respectively. We also found that S_type and S_scale for 100,000 people are 17.07-32.36t/year and 5.61-9.95t/year, respectively. Based on Environmental Kuznets Curve, the annual total amount of VOCs emissions from catering industry in different provinces in China was estimated, which was 5680.53t/year, 6122.43t/year, and 66,244.59t/year for Shangdong and Guangdong provinces and whole China, respectively. Large and medium-scaled restaurants should be paid more attention with respect to regulation of VOCs.

Chromosomal microarray as primary diagnostic genomic tool for pregnancies at increased risk within a population-based combined first-trimester screening program

OBJECTIVE

To evaluate the performance of high-resolution chromosomal microarray (CMA) as the standard diagnostic approach for genomic imbalances in pregnancies with increased risk based on combined first-trimester screening (cFTS).

METHODS

This was a retrospective study of genomic findings in a cohort of 575 consecutive pregnancies undergoing invasive testing because of a cFTS risk ≥ 1:300 on a publicly funded population-based screening program in the Central and Northern Regions of Denmark, between September 2015 and September 2016. Women with fetal nuchal translucency thickness ≥ 3.5 mm or opting for non-invasive prenatal testing (NIPT) were excluded. Comparative genomic hybridization was performed using a 180-K oligonucleotide array on DNA extracted directly from chorionic villus/amniocentesis samples. Genomic outcomes were reported in relation to cFTS findings.

RESULTS

Of the 575 pregnancies that underwent invasive testing, CMA detected 22 (3.8% (95% CI, 2.5-5.7%)) cases of trisomies 21, 18 and 13, 14 (2.4% (95% CI, 1.4-4.0%)) cases of other types of aneuploidy and 15 (2.6% (95% CI, 1.5-4.3%)) cases with a pathogenic or probably pathogenic copy number variant (CNV). Of the 15 CNVs, three were > 10 Mb and would probably have been detected by chromosomal analysis, but the other 12 would most probably not have been detected using conventional cytogenetic techniques; therefore, the overall detection rate of CMA (8.9% (95% CI, 6.8-11.5%)) was significantly higher than that estimated for conventional cytogenetic analysis (6.8% (95% CI, 5.0-9.1%)) (P = 0.0049). Reducing the cFTS risk threshold for invasive diagnostic testing to 1 in 100 or 1 in 50 would have led, respectively, to 60% or 100% of the pathogenic CNVs being missed.

CONCLUSIONS

CMA is a valuable diagnostic technique that can identify an increased number of genomic aberrations in pregnancies at increased risk on cFTS. Limiting diagnostic testing to pregnancies with a risk above 1 in 100 or 1 in 50, as proposed in contingent NIPT/invasive testing models, would lead to a significant proportion of pathogenic CNVs being missed at first-trimester screening. Copyright © 2017 ISUOG. Published by John Wiley & Sons Ltd.

Insights into extinction evolution during extreme low visibility events: Case study of Shanghai, China

Apportionment of ambient extinction coefficient is essential for quantifying the causes of visibility degradation. Previous studies focused on either seasonal or episode-average extinction coefficients. The extinction evolution during different types of low visibility events was still unclear and seldom investigated. In this study, hourly-resolution apportionment of ambient extinction coefficient, including dry extinction coefficient and hygroscopic portion, during three low visibility events (i.e., dust storm, autumn and winter haze) and one clear episode was retrieved through online measurement in Shanghai, China. PM_2.5 soil and coarse particles contributed 90% of PM₁₀ mass and 62% of total extinction coefficient throughout the dust storm event. Secondary inorganic aerosol and organic matter dominated the autumn and winter haze events, accounting for 52% and 31% of PM_2.5 mass, 35% and 27% of extinction coefficient, respectively. Hygroscopic enhancement by inorganic particles contributed another 22-27% of extinction coefficient during the two haze events. However, higher relative humidity elevated the extinction percentage of inorganic aerosol and hygroscopic enhancement during the autumn haze, and the percentage of organic matter decreased correspondingly. In contrast, the extinction of each contributor increased proportionally and the percentages could keep at a stable level during the winter haze. Furthermore, the mass extinction efficiency of major PM_2.5 chemical components was found to increase with the accumulation of mass loading. These findings indicated the importance of reducing the mass level of organic matter and secondary inorganic aerosol during the autumn or winter haze events. The control of precursors of sulfur and nitrogen oxides seemed more effective for visibility improvement during the autumn events with higher relative humidity.

Genetic variants of microRNA processing genes and risk of non-syndromic orofacial clefts

OBJECTIVE

MicroRNA (miRNA) processing genes play important roles in the craniofacial development. The aim of this study was to explore the associations between single nucleotide polymorphisms (SNPs) of miRNA processing genes with the risk of non-syndromic orofacial clefts (NSOC).

METHODS

We genotyped 12 potentially functional SNPs from seven miRNA processing genes (GEMIN3, DROSHA, DGCR8, GEMIN4, PIWIL1, XPO5, and DICER) in a case-control study of 602 NSOC cases and 605 controls.

RESULTS

Two SNPs were associated with the susceptibility of CL/P: rs10719 in DROSHA led to an increased risk of cleft lip with or without palate (CL/P) (GA/AA: p = .024, OR = 1.33, 95% CI = [1.04, 1.70]; GG + GA/AA: p = .037, OR = 1.29, 95% CI = [1.02, 1.63]), while rs493760 in DROSHA (CC/TT: p = .049, OR = 0.58, 95% CI = [0.34, 0.99]) could reduce the risk of CL/P. In addition, rs10719 (A)-rs493760 (C) haplotype contributed to a decreased risk of CL/P (OR = 0.77, 95% CI = [0.63, 0.94]), whereas the rs10719 (G)-rs493760 (C) haplotype contributed to the increased risk of cleft palate only (CPO) (OR = 2.70, 95% CI = [1.15, 6.35]). However, there was no difference observed in these SNPs after the Bonferroni correction.

CONCLUSION

Taken together, our results provided the potential evidence that rs10719 and rs493760 might contribute to the risk of CL/P and suggested potential genetic basis and mechanisms of CL/P. The lack of association between these SNPs and CPO might be due to the limited sample size of CPO subgroup.

Chemical characteristics of fine particles and their impact on visibility impairment in Shanghai based on a 1-year period observation

In this work, a one-year observation focusing on high time resolution characteristics of components in fine particles was conducted at an urban site in Shanghai. Contributions of different components on visibility impairment were also studied. Our research indicates that the major components of PM_2.5 in Shanghai are water-soluble inorganic ions and carbonaceous aerosol, accounting for about 60% and 30% respectively. Higher concentrations of sulfate (SO₄^2-) and organic carbon (OC) in PM_2.5 occurred in fall and summer, while higher concentrations of nitrate (NO₃^-) were observed in winter and spring. The mass concentrations of Cl^- and K⁺ were higher in winter. Moreover, NO₃^- increased significantly during PM_2.5 pollution episodes. The high values observed for the sulfate oxidizing rate (SOR), nitrate oxidizing rate (NOR) and secondary organic carbon (SOC) in OC indicate that photochemical reactions were quite active in Shanghai. The IMPROVE (Interagency Monitoring of Protected Visual Environments) formula was used in this study to investigate the contributions of individual PM_2.5 chemical components to the light extinction efficient in Shanghai. Both NH₄NO₃ and (NH₄)₂SO₄ had close relationships with visibility impairment in Shanghai. Our results show that the reduction of anthropogenic SO₂, NO_x and NH₃ would have a significant effect on the improvement of air quality and visibility in Shanghai.

Do vehicular emissions dominate the source of C6-C8 aromatics in the megacity Shanghai of eastern China?

The characteristic ratios of volatile organic compounds (VOCs) to i-pentane, the indicator of vehicular emissions, were employed to apportion the vehicular and non-vehicular contributions to reactive species in urban Shanghai. Two kinds of tunnel experiments, one tunnel with more than 90% light duty gasoline vehicles and the other with more than 60% light duty diesel vehicles, were carried out to study the characteristic ratios of vehicle-related emissions from December 2009 to January 2010. Based on the experiments, the characteristic ratios of C6-C8 aromatics to i-pentane of vehicular emissions were 0.53 ± 0.08 (benzene), 0.70 ± 0.12 (toluene), 0.41 ± 0.09 (m,p-xylenes), 0.16 ± 0.04 (o-xylene), 0.023 ± 0.011 (styrene), and 0.15 ± 0.02 (ethylbenzene), respectively. The source apportionment results showed that around 23.3% of C6-C8 aromatics in urban Shanghai were from vehicular emissions, which meant that the non-vehicular emissions had more importance. These findings suggested that emission control of non-vehicular sources, i.e. industrial emissions, should also receive attention in addition to the control of vehicle-related emissions in Shanghai. The chemical removal of VOCs during the transport from emissions to the receptor site had a large impact on the apportionment results. Generally, the overestimation of vehicular contributions would occur when the VOC reaction rate constant with OH radicals (kOH) was larger than that of the vehicular indicator, while for species with smaller kOH than the vehicular indicator, the vehicular contribution would be underestimated by the method of characteristic ratios.

Chemical and optical properties of aerosols and their interrelationship in winter in the megacity Shanghai of China

A field campaign on air quality was carried out in Shanghai in winter of 2012. The concentrations of NO, NO2, NOx, SO2, CO, and PM2.5 increased during haze formation. The average masses of SO4(2-), NO3(-) and NH4(+) were 10.3, 11.7 and 6.7 μg/m(3) during the haze episodes, which exceeded the average (9.2, 7.9, and 3.4 μg/m(3)) of these components in the non-haze days. The mean values for the aerosol scattering coefficient (bsp), aerosol absorption coefficient (bap) and single scattering albedo (SSA) were 288.7, 27.7 and 0.91 Mm(-1), respectively. A bi-peak distribution was observed for the mass concentrations of CO, NO, NO2, and NOx. More sulfate was produced during daytime than that in the evening due to photochemical reactions. The mass concentration of NH4(+) achieved a small peak at noontime. NO3(-) showed lower concentrations in the afternoon and higher concentrations in the early morning. There were obvious bi-peak diurnal patterns for bsp and bap as well as SSA. bsp and bap showed a positive correlation with PM2.5 mass concentration. (NH4)2SO4, NH4NO3, organic mass, elemental carbon and coarse mass accounted for 21.7%, 19.3%, 31.0%, 9.3% and 12.3% of the total extinction coefficient during non-haze days, and 25.6%, 24.3%, 30.1%, 8.1% and 8.2% during hazy days. Organic matter was the largest contributor to light extinction. The contribution proportions of ammonium sulfate and ammonium nitrate to light extinction were significantly higher during the hazy time than during the non-haze days.

Blood versus crystalloid cardioplegia for pediatric cardiac surgery: a meta-analysis

OBJECTIVE

Blood and crystalloid cardioplegia are the main myocardial protective solutions used in pediatric cardiac surgery. However, the effectiveness of these two solutions on myocardial metabolism, reperfusion injury and clinical outcomes in pediatric patients is still under debate. The purpose of this meta-analysis was to compare the efficacy of these two cardioplegia solutions in pediatric cardiac surgery.

METHODS

Keyword searches were performed on PUBMED, EMBASE and The Cochrane Library for randomized, controlled, clinical studies which were primarily comparing blood and crystalloid cardioplegia in pediatric cardiac surgery and provided data of postoperative cardiac troponin I (cTnI), lactate, mechanical ventilation time, length of intensive care unit (ICU) stay and inotropic support. Databases were searched from 1966 to June 2013 and were restricted to peer-reviewed English language publications of human subjects. We summarized the combined results of the data as mean difference (MD, when outcome measurements were made on the same scale) or standard mean difference (SMD, when the studies assess the same outcome with different scales), with 95% confidence intervals.

RESULTS

Five studies were identified, with a total of 323 patients. Lactate level after cardiopulmonary bypass (CPB) was significantly lower after blood cardioplegia compared with crystalloid cardioplegia (SMD 1.09, 95%CI 0.12 to 2.06, p=0.03); cTnI release postoperatively at 4-6 h (MD 0.92 ng/ml, 95%CI -0.13 to 1.97, p=0.09), 12 h (MD 0.2 ng/ml, 95% CI -0.43 to 0.84, p=0.53) and 24 h (MD 0.98 ng/ml, 95%CI -0.26 to 2.22, p=0.12) was not significantly different between the groups; ventilation duration (MD 5.15 hours, 95%CI -7.51 to 17.81, p=0.42) and length of ICU stay (SMD -0.3, 95%CI -0.80 to 0.21, p=0.25) were not significantly different between the groups either.

CONCLUSION

Myocardial metabolism was better in the blood cardioplegia group compared with the crystalloid cardioplegia group. However, there was no evidence of improvement in myocardial damage or clinical outcome for either cardioplegia solution.

PM2.5 constituents and hospital emergency-room visits in Shanghai, China

Although ambient PM2.5 has been linked to adverse health effects, the chemical constituents that cause harm are largely unclear. Few prior studies in a developing country have reported the health impacts of PM2.5 constituents. In this study, we examined the short-term association between PM2.5 constituents and emergency room visits in Shanghai, China. We measured daily concentrations of PM2.5, organic carbon (OC), elemental carbon (EC), and eight water-soluble ions between January 1, 2011 and December 31, 2012. We analyzed the data using overdispersed generalized linear Poisson models. During our study period, the mean daily average concentration of PM2.5 in Shanghai was 55 μg/m(3). Major contributors to PM2.5 mass included OC, EC, sulfate, nitrate, and ammonium. For a 1-day lag, an interquartile range increment in PM2.5 mass (36.47 μg/m(3)) corresponded to 0.57% [95% confidence interval (CI): 0.13%, 1.01%] increase of emergency room visits. In all the three models used, we found significant positive associations of emergency room visits with OC and EC. Our findings suggest that PM2.5 constituents from the combustion of fossil fuel (e.g., OC and EC) may have an appreciable influence on the health impact attributable to PM2.5.

Source and mixing state of iron-containing particles in Shanghai by individual particle analysis

Bioavailable iron (Fe) is an essential nutrient that can control oceanic productivity, thereby impacting the global carbon budget and climate. Therefore it is of vital importance to identify chemical species and mixing state of Fe-containing particles in the air, which are demonstrated to pose substantial impact on bioavailability of Fe. Using a single particle aerosol mass spectrometer (SPAMS), ~2,000,000 individual particles with mass spectra were collected in Shanghai for nearly 22d during the winter of 2011. Number fraction of Fe-containing particles (NfFe) varied in a wide range (<1-15%) throughout the measurement. Fe-containing particles were mainly clustered into four chemical groups, comprising of Fe-rich, K-rich, Dust and V-containing particle types. Analysis of mass spectra and mixing state suggests that Fe-containing particles correspond to various sources in Shanghai, especially anthropogenic sources iron/steel industrial activities, and fly ashes from both biomass burning and coal combustion, accounting for ~55% and ~18%, respectively. However, invasion of dust from northern desert areas is suspected to be more responsible for the spikes of NfFe (>10%), when Dust particle type contributed to >50% of Fe-containing particles. It is also revealed that Fe-containing particles were internally mixed with secondary species (e.g., sulfate and nitrate). Anthropogenic K-rich and Fe-rich particles tended to associate with both sulfate and nitrate, and thus might lead to more fraction of soluble Fe, compared to Dust particles. These results imply that atmospheric processing of Fe-containing particles from various sources might vary and thus would change the bioavailability of atmospheric Fe.

Expression profiling based graph-clustering approach to determine renal carcinoma related pathway in response to kidney cancer

BACKGROUND

Renal cell carcinoma (RCC) is the most common cancer of the kidney. Despite advances in treatment, 5-year survival rate for metastatic RCC is estimated to be less than 10%. Thus, new therapeutic options for RCC are urgently needed.

AIM

In this study, our objective here was to identify a set of discriminating genes in RCC and normal kidney tissue, and predict their underlying molecular pathway in response to RCC using graph-clustering approach and gene ontology (GO) term analysis.

MATERIALS AND METHODS

The GSE6344 expression profile was used in this study and the tissues used were either de-identified or were archival tissues. Through Statistical analysis, Network analyses, graph clustering and Pathway enrichment analysis to predict underlying molecular pathway.

RESULTS

The results indicated the genes in cluster 1 and cluster 6 were involved in metabolism pathways, such as PPAR (peroxisome proliferator activated receptor) signaling pathway and Glycolysis pathway, etc. The genes in cluster 2, 3, 5, and 7 were associated with RCC progression through adhesion pathways, such as Focal adhesion, Cell adhesion molecules, and Gap junction. Besides, cluster 4 participated in MAPK (mitogen activated protein kinases) signaling pathway.

CONCLUSIONS

These results suggested these pathways play an important role in RCC progression. Further study may pay more attention to confirm the unidentified genes, explore their prognosis for RCC, and novel chemotherapeutic targets.