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A series of MXene/MnCo2O4.5 nanocomposites was successfully prepared by hydrothermal, ice crystal template and physical blend methods, respectively. Various characterizations indicated that hydrothermal method could successfully loaded MnCo2O4.5 nanoparticles on the surface of MXene nanosheets to obtain MMC-W nanocomposites with 3D flower-like structure, which could give MMC-W large specific surface area. The HTD temperature and decomposition heat of AP with adding 2.0 wt% MMC-W could significantly decrease to 304.7 °C and increase to 1310.9 J g-1, respectively. The lowest decomposition temperature (286.1 °C) and the highest heat release (1427.6 J g-1) of AP could be obtained by adding 8.0 wt% and 4.0 wt% of MMC-W, respectively. Moreover, MMC-W (2.0 wt%) could also significantly reduce the Ea of pure AP by 118.3 kJ mol-1 and increase the k value for AP by 11.2 times. The excellent catalytic performance of MMC-W was owing to the synergistic effect of nano-sized MnCo2O4.5 and MXene nanosheets. Owing to its high catalytic activity, MMC-W would be used as an excellent catalyst for ameliorating AP decomposition and supply an idea for the preparation of novel metal oxide nanoparticles.

Soybean processing waste (SPW) has potential as a sustainable source of phytochemicals and functional foods. A variety of phytochemicals, nutrients, and minerals have been characterized from SPW using various analytical methods. SPW utilization strategies may provide a new way to increase production of bioactive compounds, nutritional supplements, and cosmetic ingredients. SPW has the potential for value-added processing, to improve commercial use, and to lower environmental pollution through proper use. Okara, a byproduct generated during soybean processing of tofu and soy milk, is rich in dietary fiber, isoflavones, and saponins. Isoflavones, an important class of biologically active compounds owing to their multifunctional and therapeutic effects, are extracted from SPW. Further, studies have shown that okara has potential prebiotic and therapeutic value in lowering the risk of noncommunicable diseases. Therefore, in this review, we focus on several extraction methods and pharmacotherapeutic effects of different SPWs. Their effective uses in functional foods, nutraceuticals, and health applications, as biocatalysts, and as value-added resources have been discussed.

Photolysis of oxygenated volatile organic compounds (OVOCs) produces a primary source of free radicals, including OH and inorganic and organic peroxy radicals (HO2 and RO2), consequently increasing photochemical ozone production. The amplification of radical cycling through OVOC photolysis provides an important positive feedback mechanism to accelerate ozone production. The large production of OVOCs near the surface helps promote photochemistry in the whole boundary layer. This amplifier effect is most significant in regions with high nitrogen oxides (NOx) and VOC concentrations such as Wangdu, China. Using a 1-D model with comprehensive observations at Wangdu and the Master Chemical Mechanism (MCM), we find that OVOC photolysis is the largest free-radical source in the boundary layer (46%). The condensed chemistry mechanism we used severely underestimates the OVOC amplifier effect in the boundary layer, resulting in a lower ozone production rate sensitivity to NOx emissions. Due to this underestimation, the model-simulated threshold NOx emission value, below which ozone production decreases with NOx emission decrease, is biased low by 24%. The underestimated OVOC amplifier effect in a condensed mechanism implies a low bias in the current 3-D model-estimated efficacy of NOx emission reduction on controlling ozone in polluted urban and suburban regions of China.

Autoimmune thrombocytopenia (ITP) and autoimmune hemolytic anemia (AIHA) can be observed in Waldenström macroglobulinemia (WM). The autoimmune disorders are primarily mediated by autoimmune monoclonal gammopathy, but drug-induced hemolysis should also be considered. Herein, we presented the case of a 63-year-old female WM patient complicated with ITP, who was admitted to our department with a complaint of abdominal pain. After first half of bortezomib/dexamethasone/rituximab (BRD) chemotherapy, her platelet level recovered, but subsequently decreased to extremely low level (around 1–2×109/L), and the patient suffered from platelet transfusion refractoriness. During the management of refractory thrombocytopenia, the patient developed severe hemolytic anemia, and further tests confirmed warm AIHA. FcγRIIα polymorphism test showed that the patient had FcγRIIα-131RH, which implied that the AIHA may not be WM-related. Given the effects of ibrutinib in controlling WM, secondary AITP and AIHA, ibrutinib single treatment was started, which quickly corrected the thrombocytopenia within five days, but not hemolysis. With a relatively safe platelet level, eltrombopag was stopped, and the hemolysis relieved three days after eltrombopag withdrawal. This is the first report on eltrombopag-induced AIHA in the management of WM-associated ITP.

Wintertime episodes of high aerosol concentrations occur frequently in urban and agricultural basins and valleys worldwide. These episodes often arise following development of persistent cold-air pools (PCAPs) that limit mixing and modify chemistry. While field campaigns targeting either basin meteorology or wintertime pollution chemistry have been conducted, coupling between interconnected chemical and meteorological processes remains an insufficiently studied research area. Gaps in understanding the coupled chemical–meteorological interactions that drive high-pollution events make identification of the most effective air-basin specific emission control strategies challenging. To address this, a September 2019 workshop occurred with the goal of planning a future research campaign to investigate air quality in western U.S. basins. Approximately 120 people participated, representing 50 institutions and five countries. Workshop participants outlined the rationale and design for a comprehensive wintertime study that would couple atmospheric chemistry and boundary layer and complex-terrain meteorology within western U.S. basins. Participants concluded the study should focus on two regions with contrasting aerosol chemistry: three populated valleys within Utah (Salt Lake, Utah, and Cache Valleys) and the San Joaquin Valley in California. This paper describes the scientific rationale for a campaign that will acquire chemical and meteorological datasets using airborne platforms with extensive range, coupled to surface-based measurements focusing on sampling within the near-surface boundary layer, and transport and mixing processes within this layer, with high vertical resolution at a number of representative sites. No prior wintertime basin-focused campaign has provided the breadth of observations necessary to characterize the meteorological–chemical linkages outlined here, nor to validate complex processes within coupled atmosphere–chemistry models.

Sulfate is one of the main components of haze fine particles, and its formation mechanism remains controversial. A lack of detailed and comprehensive field data hinders the accurate evaluation of relative roles of prevailing sulfate formation pathways. Here, we analyzed the sulfate production rates using a state-of-the-art multiphase model constrained to the observed concentrations of transition metal, nitrogen dioxide, ozone, hydrogen peroxide and other important parameters in winter and summer in the North China Plain. Our results showed that aqueous transition metal ion (TMI)-catalyzed oxidation was the most important pathway followed by the surface oxidation of Mn in both winter and summer while the hydroxyl and Criegee radical oxidations contribute significantly in summer. In addition, we also modeled the published cases for the fog and cloud conditions. It is found that nitrogen dioxide oxidation is the dominant pathway for the fog in a higher pH range while hydroperoxide and ozone oxidations dominated for the cloud.

The lockdown due to COVID-19 created a rare opportunity to examine the nonlinear responses of secondary aerosols, which are formed through atmospheric oxidation of gaseous precursors, to intensive precursor emission reductions. Based on unique observational data sets from six supersites in eastern China during 2019-2021, we found that the lockdown caused considerable decreases (32-61%) in different secondary aerosol components in the study region because of similar-degree precursor reductions. However, due to insufficient combustion-related volatile organic compound (VOC) reduction, odd oxygen (Ox = O3 + NO2) concentration, an indicator of the extent of photochemical processing, showed little change and did not promote more decreases in secondary aerosols. We also found that the Chinese provinces and international cities that experienced reduced Ox during the lockdown usually gained a greater simultaneous PM2.5 decrease than other provinces and cities with an increased Ox. Therefore, we argue that strict VOC control in winter, which has been largely ignored so far, is critical in future policies to mitigate winter haze more efficiently by reducing Ox simultaneously.

Ozone (O3) pollution has a negative effect on the public health and crop yields. Accurate diagnosis of O3 production sensitivity and targeted reduction of O3 precursors [i.e., nitrogen oxides (NOx) or volatile organic compounds (VOCs)] are effective for mitigating O3 pollution. This study assesses the indicative roles of the surface formaldehyde-to-NO2 ratio (FNR) and glyoxal-to-NO2 ratio (GNR) on surface O3-NOx-VOC sensitivity based on a meta-analysis consisting of multiple field observations and model simulations. Thresholds of the FNR and GNR are determined using the relationship between the relative change of the O3 production rate and the two indicators, which are 0.55 ± 0.16 and 1.0 ± 0.3 for the FNR and 0.009 ± 0.003 and 0.024 ± 0.007 for the GNR. The sensitivity analysis indicated that the surface FNR is likely to be affected by formaldehyde primary sources under certain conditions, whereas the GNR might not be. As glyoxal measurements are becoming increasingly available, using the FNR and GNR together as O3 sensitivity indicators has broad potential applications.

New particle formation (NPF) is thought to contribute half of the global cloud condensation nuclei. A better understanding of the NPF at different altitudes can help assess the impact of NPF on cloud formation and corresponding physical properties. However, NPF is not sufficiently understood in the upper mixing layer because previous studies mainly focused on ground-level measurements. In this study, the developments of aerosol size distribution at different altitudes are characterized based on the field measurement conducted in January 2019 in Beijing, China. We find that the partition of nucleation-mode particles in the upper mixing layer is larger than that at the ground, which implies that the nucleation processing is more likely to happen in the upper mixing layer than that at the ground. Results of the radiative transfer model show that the photolysis rates of the nitrogen dioxide and ozone increase with altitude within the mixing layer, which leads to a higher concentration of sulfuric acid in the upper mixing layer than that at the ground. Therefore, the nucleation processing in the upper mixing layer should be stronger than that at the ground, which is consistent with our measurement results. Our study emphasizes the influence of aerosol–radiation interaction on the NPF. These results have the potential to improve our understanding of the source of cloud condensation nuclei on a global scale due to the impacts of aerosol–radiation interaction.

As Volatile Organic Compounds (VOCs) are one of the precursors of ozone, their distribution and variable concentrations are highly related to local ozone pollution control. In this study, we obtained vertical profiles of VOCs in Shanghai’s Jinshan district on 8 September and 9 September in 2016 to investigate their distribution and impact on local atmospheric oxidation in the near surface layer. Vertical samples were collected from heights between 50 m and 400 m by summa canisters using an unmanned aerial vehicle (UAV). Concentrations of VOCs (VOCs refers to the 52 species measured in this study) varied minimally below 200 m, and decreased by 21.2% from 100 m to 400 m. The concentrations of VOCs above 200 m decreased significantly in comparison to those below 200 m. The proportions of alkanes and aromatics increased from 55.2% and 30.5% to 57.3% and 33.0%, respectively. Additionally, the proportion of alkenes decreased from 13.2% to 8.4%. Toluene and m/p-xylene were the key species in the formation of SOA and ozone. Principal component analysis (PCA) revealed that the VOCs measured in this study mainly originated from industrial emissions.

We developed thermal dissociation cavity-enhanced absorption spectroscopy (TD-CEAS) for the in situ measurement of NO2, total peroxy nitrates (PNs, RO2NO2), and total alkyl nitrates (ANs, RONO2) in the atmosphere. PNs and ANs were thermally converted to NO2 at the corresponding pyrolytic temperatures and detected by CEAS at 435–455 nm. The instrument sampled sequentially from three channels at ambient temperature, 453 and 653 K, with a cycle of 3 min, to measure NO2, NO2+ PNs, and NO2+ PNs + ANs. The absorptions between the three channels were used to derive the mixing ratios of PNs and ANs by spectral fitting. The detection limit (LOD, 1σ) for retrieving NO2 was 97 parts per trillion by volume (pptv) in 6 s. The measurement uncertainty of NO2 was 9 %, while the uncertainties of PN and AN detection were larger than those of NO2 due to chemical interferences that occurred in the heated channels, such as the reaction of NO (or NO2) with the peroxy radicals produced by the thermal dissociation of organic nitrates. Based on laboratory experiments and numerical simulations, we created a lookup table method to correct these interferences in PN and AN channels under various ambient organic nitrates, NO, and NO2. Finally, we present the first field deployment and compare it with other instruments during a field campaign in China. The advantages and limitations of this instrument are outlined.

As critical precursors of ozone (O3) and secondary organic aerosols, volatile organic compounds (VOCs) play a vital role in air quality, human health, and climate change. In this study, a campaign of comprehensive field observations and VOC grid sampling was conducted in Xi'an, China, from 20 June to 20 July 2019 to identify the spatiotemporal concentration levels, sources, and secondary transformation potential of VOCs. During the observation period, the average VOC concentrations at the Chanba (CB), Di Huan Suo (DHS), Qinling (QL), and gridded sampling sites were 27.8 ± 8.9, 33.8 ± 10.5, 15.5 ± 5.8, and 29.1 ± 8.4 ppb, respectively. Vehicle exhaust was the primary source of VOC emissions in Xi'an, and the contributions of vehicle exhaust to VOCs at the CB, DHS, and QL sites were 41.3 %, 30.6 %, and 23.6 %–41.4 %, respectively. While industrial emissions were the second-largest source of VOCs in urban areas, contributions from aging sources were high in rural areas. High potential source contribution function values primarily appeared in eastern and southern Xi'an near the sampling site, which indicates that Xi'an exhibits a strong local VOC source. Moreover, alkenes, aromatics, and oxygenated VOCs played a dominant role in secondary transformation, which is a major concern in reducing O3 pollution in Xi'an.

Herein, 3D alumina-doped magnesium oxide (Al2O3/MgO) aerogels were successfully prepared by a simple lyophilization–calcination method for the uranium (U(VI)) elimination from wastewater. Various batch experiments were used to testify that Al2O3/MgO aerogels exhibited remarkable removal performance for U(VI), especially Al2O3/MgO aerogels with Al2O3/MgO molar ratios of 1 : 1 (Al/Mg-3). Results showed that Al/Mg-3 could quickly reach the adsorption equilibrium within the contact time of 100 min, while the adsorption capacity of Al/Mg-3 for U(VI) could reach as high as 1046.9 mg g−1 at pH 6.0. The selectivity of Al/Mg-3 for U(VI) proved that Al/Mg-3 could be used to remove U(VI) from wastewater. The adsorption efficiency of Al/Mg-3 for U(VI) could still retain more than 92.5% after five cycles. Furthermore, the continuous U(VI) separation test results showed that the adsorption equilibrium time and adsorption efficiency of Al/Mg-3 could decrease to 40 min and increase to 99.7%, respectively. This work demonstrated that the remarkable U(VI) removal performance of Al/Mg-3 could make it an effective and reusable material for the adsorption of U(VI) from U(VI)-contained wastewater.

MXene-supported CuO nanocomposites (MCNs) were synthesized through an ice-crystal templating method without using any chemical modifiers. Nano-sized CuO particles were uniformly and stably attached to the surface of MXene nanosheets. The catalysis of the MCNs in ammonium perchlorate (AP) decomposition was studied and the results indicated that the MCNs as catalysts (2 wt%) could significantly decrease the high temperature decomposition (HTD) temperature of AP from 425.0 °C (pure AP) to 324.9 °C (AP with MCNs-3) and increase the exothermic heat from 295.2 J g−1 (pure AP) to 1272.9 J g−1 (AP with MCNs-3). With the increase of the mass ratio, the decomposition temperature decreased at first and then increased. When the ratio of MCNs-3 was 4 wt%, the HTD temperature of AP was reduced by as much as 114.4 °C and the exothermic heat was remarkably increased to 1360.6 J g−1. The high catalytic activity of MCNs-3 for AP thermal decomposition might be owing to the synergistic effect between MXene nanosheets and CuO nanoparticles. In other words, the results proved that the MXene in combination with CuO could be an effective way to enhance the catalytic performance of CuO in AP decomposition, which has potential application value in AP-based composite solid propellants.

A novel oxidized MXene-supported MCo2O4 (oxidized MXene/MCo2O4, M = Mn, Zn, Cu and Co) nanocomposite was successfully synthesized through a facile hydrothermal assisted calcination method. Various characterization results indicated that MCo2O4 nanoparticles were successfully formed in situ on MXene nanosheets, which effectively reduce the aggregation of nanoparticles and remarkably improve the specific surface area, especially MZC (203.5 m2 g−1). Among the oxidized MXene/MCo2O4 nanocomposites, oxidized MXene/ZnCo2O4 (MZC) enormously ameliorated the performance of AP decomposition. With adding MZC (2.0 wt%), the high-temperature decomposition (HTD) temperature of AP could significantly decrease to 297.1 °C, while the decomposition heat could increase to 1409.6 J g−1, respectively. The apparent activation energy of AP decomposition decreased from 209.6 kJ mol−1 (pure AP) to 104.5 kJ mol−1 (AP mixed with MZC). The excellent catalytic performance of MZC might be due to the synergistic effect of MXene nanosheets and ZnCo2O4 nanoparticles. It could be foreseen that MZC would be an excellent material for optimizing AP decomposition and would supply an idea for the development of new catalyst materials.

Heterogeneous uptake of hydroperoxyl radicals (HO2) onto aerosols has been proposed to be a significant sink of HOx, hence impacting the atmospheric oxidation capacity. Accurate calculation of the HO2 uptake coefficient γHO2 is key to quantifying the potential impact of this atmospheric process. Laboratory studies show that γHO2 can vary by orders of magnitude due to changes in aerosol properties, especially aerosol soluble copper (Cu) concentration and aerosol liquid water content (ALWC). In this study we present a state-of-the-art model called MARK to simulate both gas- and aerosol-phase chemistry for the uptake of HO2 onto Cu-doped aerosols. Moreover, a novel parameterization of HO2 uptake was developed that considers changes in relative humidity (RH) and condensed-phase Cu ion concentrations and which is based on a model optimization using previously published and new laboratory data included in this work. This new parameterization will be applicable to wet aerosols, and it will complement current IUPAC recommendations. The new parameterization is as follows (the explanations for symbols are in the Appendix): 1γHO2=1αHO2+3×υHO24×106×RdHcorrRT×(5.87+3.2×ln⁡(ALWC/[PM]+0.067))×[PM]-0.2×Cu2+eff0.65+υHO2l4RTHorgDorgε. All parameters used in the paper are summarized in Table A1. Using this new equation, field data from a field campaign were used to evaluate the impact of the HO2 uptake onto aerosols on the ROx (= OH + HO2 + RO2) budget. Highly variable values for HO2 uptake were obtained for the North China Plain (median value

High concentrations of PM2.5 (particulate matter with an aerodynamic diameter less than 2.5 µm) in China have caused severe visibility degradation. Accurate simulations of PM2.5 and its chemical components are essential for evaluating the effectiveness of pollution control strategies and the health and climate impacts of air pollution. In this study, we compared the GEOS-Chem model simulations with comprehensive datasets for organic aerosol (OA), sulfate, nitrate, and ammonium in China. Model results are evaluated spatially and temporally against observations. The new OA scheme with a simplified secondary organic aerosol (SOA) parameterization significantly improves the OA simulations in polluted urban areas, highlighting the important contributions of anthropogenic SOA from semivolatile and intermediate-volatility organic compounds. The model underestimates sulfate and overestimates nitrate for most of the sites throughout the year. More significant underestimation of sulfate occurs in winter, while the overestimation of nitrate is extremely large in summer. The model is unable to capture some of the main features in the diurnal pattern of the PM2.5 chemical components, suggesting inaccuracies in the presented processes. Potential model adjustments that may lead to a better representation of the boundary layer height, the precursor emissions, hydroxyl radical concentrations, the heterogeneous formation of sulfate and nitrate, and the wet deposition of nitric acid and nitrate have been tested in the sensitivity analysis. The results show that uncertainties in chemistry perhaps dominate the model biases. The proper implementation of heterogeneous sulfate formation and the good estimates of the concentrations of sulfur dioxide, hydroxyl radical, and aerosol liquid water are essential for the improvement of the sulfate simulation. The update of the heterogeneous uptake coefficient of nitrogen dioxide significantly reduces the modeled concentrations of nitrate. However, the large overestimation of nitrate concentrations remains in summer for all tested cases. The possible bias in the chemical production and the wet deposition of nitrate cannot fully explain the model overestimation of nitrate, suggesting issues related to the atmospheric removal of nitric acid and nitrate. A better understanding of the atmospheric nitrogen budget, in particular, the role of the photolysis of particulate nitrate, is needed for future model developments. Moreover, the results suggest that the remaining underestimation of OA in the model is associated with the underrepresented production of SOA.

A low-pressure reactor (LPR) was developed for the measurement of ambient organic peroxy (RO2) radicals with the use of the laser-induced fluorescence (LIF) instrument. The reactor converts all the ROx (= RO2 + HO2 + RO + OH) radicals into HO2 radicals. It can conduct different measurement modes through altering the reagent gases, achieving the speciated measurement of RO2 and RO2# (RO2 radicals derived from the long-chain alkane, alkene and aromatic hydrocarbon). An example of field measurement results was given, with a maximum concentration of 1.88 × 108 molecule/cm3 for RO2 and 1.18 × 108 molecule/cm3 for RO2#. Also, this instrument quantifies the local ozone production rates directly, which can help to deduce the regional ozone control strategy from an experimental perspective. The new device can serve as a potent tool for both the exploration of frontier chemistry and the diagnosis of the control strategies.

Particulate nitrate (pNO3-) has often been found to be the major component of fine particles in urban air-sheds in China, the United States, and Europe during winter haze episodes in recent years. However, there is a lack of knowledge regarding the experimentally determined contribution of different chemical pathways to the formation of pNO3-. Here, for the first time, we combine ground and tall-tower observations to quantify the chemical formation of pNO3- using observationally constrained model approach based on direct observations of OH and N2O5 for the urban air-shed. We find that the gas-phase oxidation pathway (OH+NO2) during the daytime is the dominant channel over the nocturnal uptake of N2O5 during pollution episodes, with percentages of 74% in urban areas and 76% in suburban areas. This is quite different from previous studies in some regions of the US, in which the uptake of N2O5 was concluded to account for a larger contribution in winter. These results indicate that the driving factor of nitrate pollution in Beijing and different regions of the US is different, as are the mitigation strategies for particulate nitrate.

The heterogeneous hydrolysis of dinitrogen pentoxide (N2O5) plays an important role in regulating NOx. The N2O5 uptake coefficient, γ(N2O5), was determined using an iterative box model that was constrained to observational data obtained in suburban Beijing from February to March 2016. The box model determined 2289 individual γ(N2O5) values that varied from

Ozone pollution is becoming increasingly serious in China, the accurate calculation of the volatile organic compounds (VOCs) contributions to ozone formation potential is the precondition for scientific and effective ozone control strategies. Maximum incremental reactivity (MIR) is an effective tool to evaluate VOCs’ reactivities, which may vary significantly because of different atmospheric conditions, VOCs compositions, and the relative abundances of VOCs and NO x . Nevertheless, the most widely used MIR calculated by Carter based on 39 urban areas in the United States reflected the ozone formation potential of each VOCs species under atmospheric conditions in US. Whether their MIR values are appropriate under atmospheric conditions in China or not is still under discussion. In order to calculate the real contribution of VOCs to ozone formation, we firstly calculated the indigenized MIR values for Chinese megacities. Box model based on the second Regional Atmospheric Chemistry Mechanism (RACM2) was used to calculate the indigenized MIR for China. Observed data of four megacities (Beijing-Tianjin-Hebei, Yangtze River Delta, Pearl River Delta and Chengdu-Chongqing) which represent the typical atmospheric conditions in China were used as input parameters in calculation. We set two scenarios (Base scenarios and MIR scenarios) for MIR calculation, where Base scenarios were established by selecting the fourth highest ozone day during three years’ observed data, MIR scenarios were set by adjusting the NO x availability to obtain the scenarios where ozone formation was most sensitive to VOCs. MIR values were calculated via the ratio of the change in ozone concentration due to the change in VOCs concentration divided by the change of VOCs concentrations in MIR scenarios. MIR_CHN (MIR values for four megacities) was obtained by averaging the normalized MIR values of all sites, with an uncertainty of 25%. Compared to the MIR calculated by Carter (MIR_USA in this study), our results showed a larger range values between the most active VOCs and the most inert VOCs. The MIR_CHN values of highly reactive VOCs (such as internal alkenes, butadiene, anthropogenic dienes, terminal alkenes, isoprene and o/m/p-xylene) were higher than MIR_USA values. Whereas MIR_CHN values of low reactive VOCs (HC5 and acetylene) were lower than MIR_USA values. Values of MIR_CHN and values of MIR_UAS were comparable for the moderate reactive VOCs. The differences between MIR_CHN and MIR_USA may be caused by differences in simulation time, reaction mechanism, and proportion of ozone precursors, NO x availability, and VOCs compositions. Ozone formation potential of four megacities calculated by the MIR_CHN were much higher than that calculated by the MIR_USA, which meant that using MIR_USA may not only underestimate ozone formation potential, but also miss the key VOCs species in ozone formation in China. The key VOCs were isoprene, internal alkenes and m/p-xylene in ozone formation in China based on MIR_CHN calculation.

Atmospheric particles are important reaction vessels for multiphase chemistry. We conducted a meta-analysis of previous field observations in various environments (includes ocean, urban and rural regions), showing that particle hygroscopicity inhomogeneity (PHI) is ubiquitous for the continental atmospheric particles, in which a considerable part of the particulate matters is hydrophobic (10%–33% on average). However, the effects of PHI in quantifying the uptake process of reactive gases are still unclear. Here, taking N2O5 uptake as an example, we showed that using a laboratory-based parameterization scheme without considering the PHI might result in a misestimation of uptake rate coefficient, especially under low ambient relative humidity (RH). Such misestimation may be caused by the differences of the uptake coefficients, as well as the proportion of surface area concentration (SA) between hydrophilic and hydrophobic particles. We suggested that the PHI should be well-considered in establishing the reactive traces gases heterogeneous uptake parameterizations.

In the summer of 2018, a comprehensive field campaign, with measurements on HONO and related parameters, was conducted at the foot (150 m a.s.l.) and the summit of Mt. Tai (1534 m a.s.l.) in the central North China Plain (NCP). With the implementation of a 0-D box model, the HONO budget with six additional sources and its role in radical chemistry at the foot station were explored. We found that the model default source, NO + OH, could only reproduce the observed HONO by 13 %, leading to a strong unknown source strength up to 3 ppbv h−1. Among the additional sources, the NO2 uptake on the ground surface dominated (~70 %) night-time HONO formation, and its photo-enhanced reaction dominated (~80 %) daytime HONO formation. Their contributions were sensitive to the mixing layer height (MLH) used for the parameterizations, highlighting the importance of a reasonable MLH for exploring ground-level HONO formation in 0-D models and the necessity of gradient measurements. A HONO / NOx ratio of 0.7 % for the direct emission was inferred and a new method to quantify its contribution to the observations was proposed and discussed. Aerosol-derived sources, including the NO2 uptake on the aerosol surface and the particulate nitrate photolysis, did not lead to significant HONO formation, with their contributions lower than NO + OH. HONO photolysis in the early morning initialized the daytime photochemistry at both the foot and the summit stations and also was a substantial radical source throughout the daytime, with contributions higher than or about one-quarter of O3 photolysis to OH initiation at the foot and the summit stations, respectively. Moreover, we found that OH dominated the atmospheric oxidizing capacity in the daytime, while NO3 appeared to be significant at night. Peaks of NO3 time series and diurnal variation reached 22 and 9 pptv, respectively. NO3 induced reactions contribute 18 % of nitrate formation potential (P(HNO3)) and 11 % of the isoprene (C5H8) oxidation throughout the whole day. At night, NO3 chemistry led to 51 % or 44 % of P(HNO3) or the C5H8 oxidation, respectively. NO3 chemistry may significantly affect night-time secondary organic and inorganic aerosol formation in this high-O3 region, implying that NO3 chemistry could significantly affect night-time secondary organic and inorganic aerosol formation in this high-O3 region. Considering the severe O3 pollution in the NCP and the very limited NO3 measurements, we suggest that besides direct measurements of HOx and primary HOx precursors (O3, HONO, alkenes, etc.), NO3 measurements should be conducted to understand the atmospheric oxidizing capacity and air pollution formation in this and similar regions.

Nitryl chloride (ClNO2), an important precursor of Cl atoms, significantly affects atmospheric oxidation capacity and O3 formation. However, sources of ClNO2 in inland China have not been fully elucidated. In this work, laboratory experiments were conducted to investigate heterogeneous reaction of N2O5 with eight saline mineral dust samples collected from different regions in China, and substantial formation of ClNO2 was observed. ClNO2 yields, φ(ClNO2), showed large variations (ranging from

Background: Autoimmune thrombocytopenia (ITP) and autoimmune hemolytic anemia (AIHA) can be observed in Waldenström Macroglobulinemia (WM). The cause of AIHA should be carefully distinguished during the disease management. Case Presentation: A 63-year-old female WM patient complicated with thrombocytopenia, who was admitted to our department with a complaint of abdominal pain. After first half of bortezomib/dexamethasone/rituximab (BRD) chemotherapy, her platelet level recovered, but subsequently decreased to extremely low level (around 1-2×109/L), and the patient suffered from platelet transfusion refractoriness. During the management of refractory thrombocytopenia, the patient developed severe hemolytic anemia, and further tests confirmed warm AIHA. FcγRIIα polymorphism test showed that the patient had FcγRIIα-131RH, which implied that the AIHA may not be WM-related. Given the effects of ibrutinib in controlling WM, ibrutinib single treatment was started, which quickly corrected the thrombocytopenia within five days, but not hemolysis. With a relatively safe platelet level, eltrombopag was stopped, and the hemolysis alleviated within three days after eltrombopag withdrawal. Conclusion: This is the first report on eltrombopag-induced AIHA, and we should always keep in mind of the drug induced hemolysis even in disorders with autoimmune background.

A field campaign was conducted from November to December 2017 at the campus of Peking University (PKU) to investigate the formation mechanism of the winter air pollution in Beijing with the measurement of hydroxyl and hydroperoxyl radical (OH and HO2) with the support from comprehensive observation of trace gases compounds. The extent of air pollution depends on meteorological conditions. The daily maximum OH radical concentrations are on average 2.0 × 106 cm−3 and 1.5 × 106 cm−3 during the clean and polluted episodes, respectively. The daily maximum HO2 radical concentrations are on average 0.4 × 108 cm−3 and 0.3 × 108 cm−3 during the clean and polluted episodes, respectively (diurnal averaged for one hour bin). A box model based on RACM2-LIM1 mechanism can reproduce the OH concentrations but underestimate the HO2 concentrations by 50% during the clean episode. The OH and HO2 concentrations are underestimated by 50% and 12 folds during the polluted episode, respectively. Strong dependence on nitric oxide (NO) concentration is found for both observed and modeled HO2 concentrations, with the modeled HO2 decreasing more rapidly than observed HO2, leading to severe HO2 underestimation at higher NO concentrations. The OH reactivity is calculated from measured and modeled species and inorganic compounds (carbon monoxide (CO), NO, and nitrogen dioxide (NO2)) make up 69%–76% of the calculated OH reactivity. The photochemical oxidation rate denoted by the OH loss rate increases by 3 times from the clean to polluted episodes, indicating the strong oxidation capacity in polluted conditions. The comparison between measurements at PKU site and a suburban site from one previous study shows that chemical conditions are similar in both urban and suburban areas. Hence, the strong oxidation capacity and its potential contribution to the pollution bursts are relatively homogeneous over the whole Beijing city and its surrounding areas.

We describe an open-path cavity-enhanced absorption spectroscopy (OP-CEAS) technique for the ambient measurement of nitrate radicals (NO3) near 662 nm. Compared with the closed type of CEAS system with a sampling line, the OP-CEAS features high accuracy due to the lack of NO3 loss in the sampling line and cavity. On the basis of a 0.84 m long open-path cavity, the effective absorption length of ∼5 km is achieved by mirrors with a reflectivity of 0.99985 at 662 nm. The detection limit of OP-CEAS for the measurement of NO3 is 3.0 pptv (2σ) in 30 s, and the uncertainty is 11-15%. The instrument was successfully applied in a field measurement under low particulate matter (PM) loading conditions. As the sensitivity would be decreased due to strong PM extinction under heavy PM pollution conditions, we highlight the feasibility of this OP-CEAS configuration for field application in clean and moderate PM condition, such as forested regions affected by anthropogenic emissions. This technique is also appropriate for the field detection of other reactive trace gases in future studies.

Nighttime chemistry plays an important role in NOx and volatile organic compounds (VOCs) removal. A box model was used to study nighttime nitrate radical (NO3), O3 oxidation and nitrate products in Yangtze River Delta (YRD), China. The model input data were collected from five representative monitoring sites in YRD regions from 20 August to 11 September 2016. The production rate of NO3 was found very fast with the nocturnal average of 1–3 ppbv h−1 in different sites. Large directly NO3 loss frequency was determined from VOCs measurements, with the average of 0.01–0.03 s−1, which represented a lower limit due to the lack of monoterpene measurement. The model results show NO3 governs nocturnal oxidation of hydrocarbons (HCs) in YRD region (80%) and O3 contributes to 20% in average. The oxidation percentage attributable to NO3 increased against the NOx concentration, with 3.5–7.7 ppbv HCs removal by NO3 per night in average, suggesting that the production of organic nitrate by NO3 oxidation may be significant. As to products, the integrated inorganic nitrate production in the nighttime was considerable around 62% ± 20% of the whole day in urban sites, but the percentage was small in rural sites. More inorganic nitrate was produced with the increase of NOx, since the HCs oxidation by NO3 has already been saturated at night. This study highlights nocturnal fast oxidation by NO3 in YRD region, and the variability of oxidation is large in different NOx regime.

As nitrous acid (HONO) photolysis is an important source of hydroxyl radical (OH), apportionment of the ambient HONO sources is necessary to better understand atmospheric oxidation. Based on the data HONO-related species and various parameters measured during the one-month campaign at Wangdu (a rural site in North China plain) in summer 2014, a box model was adopted with input of current literature parametrizations for various HONO sources (nitrogen dioxide heterogeneous conversion, photoenhanced conversion, photolysis of adsorbed nitric acid and particulate nitrate, acid displacement, and soil emission) to reveal the relative importance of each source at the rural site. The simulation results reproduced the observed HONO production rates during noontime in general but with large uncertainty from both the production and destruction terms. NO2 photoenhanced conversion and photolysis of particulate nitrate were found to be the two major mechanisms with large potential of HONO formation but the associated uncertainty may reduce their importance to be nearly negligible. Soil nitrite was found to be an important HONO source during fertilization periods, accounted for (80 ± 6)% of simulation HONO during noontime. For some episodes of the biomass burning, only the NO2 heterogeneous conversion to HONO was promoted significantly. In summary, the study of the HONO budget is still far from closed, which would require a significant effort on both the accurate measurement of HONO and the determination of related kinetic parameters for its production pathways.

Nitrate (NO3) radical is an important oxidant in the atmosphere as it regulates the NOx budget and impacts secondary pollutant formation. Here, a long-term observational dataset of NO3-related species at an urban site in Beijing was used to investigate changes in the NO3 budget and their atmospheric impacts during 2013–2019, in this period the Clean Air Actions Plan was carried out in China. We found that (1) changes in NO3 precursors (NO2 and O3) led to a significant increase in NO3 formation in the surface layer in winter but a decrease in summer; (2) a reduction in NOx promoted thermal equilibrium, favoring the formation of NO3 rather than dinitrogen pentoxide (N2O5). The simultaneous decrease in PM2.5, during these years, further weakened the N2O5 heterogeneous uptake; (3) a box model simulation revealed that both the reactions of NO3 with volatile organic compounds (VOC) and N2O5 uptake were weakened in summer, implying that the policy actions implemented help to moderate secondary aerosol formation caused by NO3 and N2O5 chemistry in summer; and (4) during winter, both NO3 + VOC and N2O5 uptake were enhanced. Specifically, for the N2O5 uptake, the rapid increase in NO3 production, or to some extent, NO3 oxidation capacity, far outweighed the negative shift effect, leading to a net enhancement of N2O5 uptake in winter, which indicates that the action policy implemented led to an adverse effect on particulate nitrate formation via N2O5 uptake in winter. This may explain the persistent winter particulate nitrate pollution in recent years. Our results highlight the systematic changes in the NO3 budget between 2013 and 2019 in Beijing, which subsequently affect secondary aerosol formation in different seasons.

Nitrated phenols (NPs) are important atmospheric pollutants that affect air quality, radiation, and health. The recent development of the time-of-flight chemical ionization mass spectrometer (ToF-CIMS) allows quantitative online measurements of NPs for a better understanding of their sources and environmental impacts. Herein, we deployed nitrate ions as reagent ions in the ToF-CIMS and quantified six classes of gaseous NPs in Beijing. The concentrations of NPs are in the range of 1 to 520 ng m-3. Nitrophenol (NPh) has the greatest mean concentration. Dinitrophenol (DNP) shows the greatest haze-to-clean concentration ratio, which may be associated with aqueous production. The high concentrations and distinct diurnal profiles of NPs indicate a strong secondary formation to overweigh losses, driven by high emissions of precursors, strong oxidative capacity, and high NOx levels. The budget analysis on the basis of our measurements and box-model calculations suggest a minor role of the photolysis of NPs (

Objective Observational epidemiologic studies have reported a relationship between selenium status and risk for autoimmune diseases. However, the associations are susceptible to confounding or reverse causality. Thus, the aim of this study was to investigate the potential causal associations of selenium concentrations with the risk for common autoimmune diseases using a two-sample Mendelian randomization (MR) design. Methods A meta-analysis of genome-wide association studies (GWASs) of selenium among 9639 individuals of European ancestry was used to identify genetic instruments. Summary statistics of systemic lupus erythematosus, rheumatoid arthritis, and inflammatory bowel disease were obtained from publicly available GWASs, respectively. We conducted MR study using the inverse-variance weighted method, supplemented with weighted median and likelihood-based methods as sensitivity analysis. Cochran Q test and MR-Egger regression were used to detect heterogeneity and potential directional pleiotropy. MR-Pleiotropy RESidual Sum and Outlier test was used to identify outlier single-nucleotide polymorphisms. Results Genetically predicted high selenium level was associated with a decreased risk for SLE (odds ratio, 0.85; 95% confidence interval, 0.77–0.93; P = 0.001) per natural log-transformed selenium concentrations, with similar results in sensitivity analyses. No evidence of heterogeneity, pleiotropy, or outlier single-nucleotide polymorphisms were detected (all P > 0.05). However, genetically determined selenium concentrations may be not associated with risk for rheumatoid arthritis or inflammatory bowel disease in the primary analysis and subsequent sensitivity analyses. Conclusions The present study suggested a protective role of selenium on the risk for systemic lupus erythematosus. Further studies are warranted to elucidate the underlying mechanisms.

We present a comprehensive field campaign conducted in Beijing, September 2016, to elucidate the photochemical smog pollution, i.e. Ozone (O3). The observed daily maximum hydroxyl radical (OH) and hydroperoxy radical (HO2) concentrations were up to 1 × 107 cm-3 and 6 × 108 cm-3, respectively, indicating the active photochemistry in autumn Beijing. Photolysis of nitrous acid (HONO) and O3 contributed 1-2 ppbv h-1 to OH primary production during daytime. OH termination were dominated by the reaction with nitric oxide (NO) and nitrogen dioxide (NO2), which were in general larger than primary production rates, indicating other primary radical sources maybe important. The measurement of radicals facilitates the direct determination of local ozone production rate P (Ox) (Ox = O3 + NO2). The integrated P(Ox) reached 75 ppbv in afternoon (for 4 h) when planetary boundary layer was well developed. At the same time period, the observed total oxidant concentrations Ox, increased significantly by 70 ppbv. In addition, the Ox measurement showed compact increase in 12 stations both temporally and spatially in Beijing, indicating that active photochemical production happened homogenously throughout the city. The back-trajectory analysis showed that Beijing was isolated from the other cities during the episode, which further proved that the fast ozone pollution was contributed by local photochemical production rather than regional advection.

BACKGROUND: Smoking cessation is important in patients with tuberculosis because it can reduce the high rates of treatment failure and mortality. We aimed to assess the effectiveness and safety of cystine as a smoking cessation aid in patients with tuberculosis in Bangladesh and Pakistan.; METHODS: We did a randomised, double-blind, placebo-controlled, trial at 32 health centres in Bangladesh and Pakistan. Eligible patients were adults (aged >18 years in Bangladesh; aged >15 years in Pakistan) with pulmonary tuberculosis diagnosed in the previous 4 weeks, who smoked tobacco on a daily basis and were willing to stop smoking. Patients were randomly assigned (1:1) to receive behavioural support plus either oral cytisine (9 mg on day 0, which was gradually reduced to 1·5 mg by day 25) or placebo for 25 days. Randomisation was done using pregenerated block randomisation lists, stratified by trial sites. Investigators, clinicians, and patients were masked to treatment allocation. The primary outcome was continuous abstinence at 6 months, defined as self-report (of not having used more than five cigarettes, bidis, a water pipe, or smokeless tobacco products since the quit date), confirmed biochemically by a breath carbon monoxide reading of less than 10 parts per million. Primary and safety analysis were done in the intention-to-treat population. This trial is registered with the International Standard Randomised Clinical Trial Registry, ISRCTN43811467, and enrolment is complete.; FINDINGS: Between June 6, 2017, and April 30, 2018, 2472 patients (1527 patients from Bangladesh; 945 patients from Pakistan) were enrolled and randomly assigned to receive cytisine (n=1239) or placebo (n=1233). At 6 months, 401 (32·4%) participants in the cytisine group and 366 (29·7%) participants in the placebo group had achieved continuous abstinence (risk difference 2·68%, 95% CI -0·96 to 6·33; relative risk 1·09, 95% CI 0·97 to 1·23, p=0·114). 53 (4·3%) of 1239 participants in the cytisine group and 46 (3·7%) of 1233 participants in the placebo group reported serious adverse events (94 events in the cytisine group and 90 events in the placebo group), which included 91 deaths (49 in the cytisine group and 42 in the placebo group). None of the adverse events were attributed to the study medication.; INTERPRETATION: Our findings do not support the addition of cytisine to brief behavioural support for the treatment of tobacco dependence in patients with tuberculosis.; FUNDING: European Union Horizon 2020 and Health Data Research UK.; TRANSLATIONS: For the Bengali and Urdu translations of the abstract see Supplementary Materials section. Copyright © 2020 The Author(s). Published by Elsevier Ltd. This is an Open Access article under the CC BY 4.0 license. Published by Elsevier Ltd.. All rights reserved.

As a critical precursors of ozone (O3) and secondary organic aerosols, volatile organic compounds (VOCs) play a vital role in air quality, human health, and climate change. In this study, a campaign of comprehensive field observations and VOC grid sampling was conducted in Xi’an, China from June 20 to July 20, 2019 to identify the spatiotemporal concentration levels, sources, and secondary transformation potential of VOCs. During the observation period, the average VOC concentrations at the Chanba (CB), Di Huan Suo (DHS), Qinling (QL), and gridded sampling sites were 27.8 ± 8.9, 33.8 ± 10.5, 15.5 ± 5.8, and 29.1 ± 8.4 ppb, respectively. Vehicle exhaust was the primary source of VOC emissions in Xi’an, and the contributions of vehicle exhaust to VOCs at the CB, DHS, and QL sites were 41.3 %, 30.6 %, and 23.6–41.4 %, respectively. While industrial emissions were the second-largest source of VOCs in urban areas, contributions from ageing sources were high in rural areas. High potential source contribution function values primarily appeared in eastern and southern Xi’an near the sampling site, which indicates that Xi'an exhibits a strong local VOC source. Moreover, alkenes, aromatics, and oxygenated VOCs played a dominant role in secondary transformation, which is a major concern in reducing O3 pollution in Xi’an.

Intense pulsed light (IPL) is capable of entirely replacing thermal annealing (curing and contact formation) within back end processing of silicon heterojunction solar cells. In order to demonstrate this, full-size silicon heterojunction (SHJ) cells with IPL-processed screen-printed metal contacts are evaluated. Such cells reach conversion efficiencies of up to 23.0%. On average, IPL-annealed SHJ cells outperform their thermally treated pendants by 0.3-0.4% abs , in particular because of higher open-circuit voltages and fill factors. Moreover, IPL offers high throughput and low footprint. This results in a cost of ownership reduction potential of 6% rel compared to state-of-the-art thermal annealing.

A comprehensive field campaign was carried out in summer 2019 in Chengdu, which obtained the first complete radical dataset of Chengyu Urban Agglomeration. Observed daily concentration maxima of radicals by the laser-induced-fluorescence (LIF) technique were in the range of (2-10)×106 cm-3 for OH and (4-15)×108 cm-3 for HO2. During daytime, OH reactivities were generally high (5-32 s-1). The missing reactivity was not be observed within uncertainty, and inorganics, observed VOCs and the calculated oxidation products contributed about one-third in total reactivity, respectively.The chemical box model RACM 2 was used to interpret the observed radical concentrations. The model over-predicted OH and HO2 at noon during the O3 polluted episode. Constraining the model by the observed HO2 concentration, the overestimation of OH can be explained almost by the overestimation of HO2. Besides, as in the previous field campaigns (e.g. Pennsylvania, Mexico City, New York and so on), the underestimation of the net conversion of OH into HO2 enlarged with the increasing NO concentration, indicating the conversion of HO2 into OH still need to be studied based on the discussion above. Different schemes to improve the agreement between observed and modelled HO2 were explored in this work. The sensitivity tests indicated observed and modelled HO2 can be agreed well by reducing the HO2 yield in the reaction of OH and HCHO a half.The oxidation rate of primary pollutants dominated by OH radicals was significantly higher than that in winter Beijing, which contributes significantly to secondary pollution, especially O3. Besides, the atmospheric self-cleaning ability and recycling efficiency both peaked for about 600 pptv of NO, indicating small amounts of NO can help to maintain the atmospheric oxidation. The campaign emphasizes the important role of HO2 yield in the reaction channels of OH and VOCs especially, and the need for further laboratory experiments of the HO2 yield measurement in order to understand radical chemistry in VOC-rich air.

Heterogeneous uptake of dinitrogen pentoxide ( N2O5 ) and production of nitryl chloride ( ClNO2 ) are important nocturnal atmospheric processes that have significant implications for the production of secondary pollutants. However, the understanding of N2O5 uptake processes and ClNO2 production remains limited, especially in China. This study presents a field investigation of the N2O5 heterogeneous uptake coefficient ( γ ( N2O5 )) and ClNO2 production yield ( ϕ ) in a polluted area of northern China during the summer of 2014. The N2O5 uptake coefficient and ClNO2 yield were estimated by using the simultaneously measured ClNO2 and total nitrate in 10 selected cases, which have concurrent increases in the ClNO2 and nitrate concentrations and relatively stable environmental conditions. The determined γ ( N2O5 ) and ϕ values varied greatly, with an average of 0.022 for γ ( N2O5 ) ( ±0.012 , standard deviation) and 0.34 for ϕ ( ±0.28 , standard deviation). The variations in γ ( N2O5 ) could not be fully explained by the previously derived parameterizations of N2O5 uptake that consider nitrate, chloride, and the organic coating. Heterogeneous uptake of N2O5 was found to have a strong positive dependence on the relative humidity and aerosol water content. This result suggests that the heterogeneous uptake of N2O5 in Wangdu is governed mainly by the amount of water in the aerosol, and is strongly water limited, which is different from most of the field observations in the US and Europe. The ClNO2 yield estimated from the parameterization was also overestimated comparing to that derived from the observation. The observation-derived ϕ showed a decreasing trend with an increasing ratio of acetonitrile to carbon monoxide, an indicator of biomass burning emissions, which suggests a possible suppressive effect on the production yield of ClNO2 in the plumes influenced by biomass burning in this region. The findings of this study illustrate the need to improve our understanding and to parameterize the key factors for γ ( N2O5 ) and ϕ to accurately assess photochemical and haze pollution.

Nitryl chloride (ClNO2) accumulation at night acts as a significant reservoir for active chlorine and impacts the following day's photochemistry when the chlorine atom is liberated at sunrise. Here, we report simultaneous measurements of N2O5 and a suite of inorganic halogens including ClNO2 and reactions of chloride with volatile organic compounds (Cl–VOCs) in the gas and particle phases utilising the Filter Inlet for Gas and AEROsols time-of-flight chemical ionisation mass spectrometer (FIGAERO-ToF-CIMS) during an intensive measurement campaign 40 km northwest of Beijing in May and June 2016. A maximum mixing ratio of 2900 ppt of ClNO2 was observed with a mean campaign nighttime mixing ratio of 487 ppt, appearing to have an anthropogenic source supported by correlation with SO2, CO and benzene, which often persisted at high levels after sunrise until midday. This was attributed to such high mixing ratios persisting after numerous e-folding times of the photolytic lifetime enabling the chlorine atom production to reach 2.3 × 105 molecules cm−3 from ClNO2 alone, peaking at 09:30 LT and up to 8.4 × 105 molecules cm−3 when including the supporting inorganic halogen measurements.Cl–VOCs were observed in the particle and gas phases for the first time at high time resolution and illustrate how the iodide ToF-CIMS can detect unique markers of chlorine atom chemistry in ambient air from both biogenic and anthropogenic sources. Their presence and abundance can be explained via time series of their measured and steady-state calculated precursors, enabling the assessment of competing OH and chlorine atom oxidation via measurements of products from both of these mechanisms and their relative contribution to secondary organic aerosol (SOA) formation.

We present the in-situ measurements in Chengdu, a major city in south west of China, in September 2016. The concentrations of ozone and its precursor were measured at four sites. Although the campaign was conducted in early autumn, up to 100 ppbv (parts per billion by volume) daily maximum ozone was often observed at all sites. The observed ozone concentrations showed good agreement at all sites, which implied that ozone pollution is a regional issue in Chengdu. To better understand the ozone formation in Chengdu, an observation based model is used in this study to calculate the ROx radical concentrations (ROx = OH + HO2 + RO2) and ozone production rate (P(O3)). The model predicts OH daily maximum is in the range of 4–8 × 106 molecules cm−3, and HO2 and RO2 are in the range of 3–6 × 108 molecules cm−3. The modelled radical concentrations show a distinct difference between ozone pollution and attainment period. The relative incremental reactivity (RIR) results demonstrate that anthropogenic VOCs reduction is the most efficient way to mitigate ozone pollution at all sites, of which alkenes dominate >50% of the ozone production. Empirical kinetic modelling approach shows that three out of four sites are under the VOC-limited regime, while Pengzhou is in a transition regime due to the local petrochemical industry. The ozone budget analysis showed that the local ozone production driven by the photochemical process is important to the accumulation of ozone concentrations.

The capability for contact formation on indium tin oxide layers of different low-temperature screen printing silver pastes after thermal curing and photonic sintering is evaluated in detail. The 80-nm-thick indium tin oxide layers used in this study are sputtered at three different oxygen gas flows and, consequently, differ by their electrical and optical properties. All pastes are analyzed by means of simultaneous thermogravimetry-differential scanning calorimetry. After printing and contact formation processing, the lateral resistivity of the metal contacts and their contact resistivity to the indium tin oxide layers are determined. Furthermore, the microstructure of the metal electrodes is investigated to gain a deeper understanding of the underlying contact formation mechanisms. Besides low-temperature curing at T curing, low = 180–220 °C, as conventionally applied to silicon heterojunction solar cells, photonic sintering and thermal curing at medium temperatures T curing, mid = 250–350 °C are utilized. The higher curing temperatures in the range of T curing, mid enhance the sintering and densification processes of the different pastes, and thereby, lateral resistivities of 2.4–3.5 μΩ⋅cm and contact resistivities of 1.0–2.5 mΩ⋅cm2 are achieved. The results indicate a promising industry-relevant non-firing-through metallization approach for, e.g., poly-silicon-based structures like tunnel oxide passivating contacts, which allow comparatively high temperatures for contact formation processing. With thermal curing at T curing, low and photonic sintering, both compatible with temperature-sensitive silicon heterojunction solar cells, lateral finger resistivities of 6.5–9.4 μΩ⋅cm and contact resistivities of 1.2–2.5 mΩ⋅cm2 are achieved. Thereby, photonic sintering has the potential of a significantly reduced process time from several minutes down to 1–4 ms.

The first wintertime in situ measurements of hydroxyl (OH), hydroperoxy ( HO2 ) and organic peroxy ( RO2 ) radicals ( ROx = OH + HO 2 + RO 2 ) in combination with observations of total reactivity of OH radicals, kOH in Beijing are presented. The field campaign “Beijing winter finE particle STudy – Oxidation, Nucleation and light Extinctions” (BEST-ONE) was conducted at the suburban site Huairou near Beijing from January to March 2016. It aimed to understand oxidative capacity during wintertime and to elucidate the secondary pollutants' formation mechanism in the North China Plain (NCP). OH radical concentrations at noontime ranged from 2.4 × 10 6 cm - 3 in severely polluted air ( k OH ∼ 27 s - 1 ) to 3.6 × 10 6 cm - 3 in relatively clean air ( k OH ∼ 5 s - 1 ) . These values are nearly 2-fold larger than OH concentrations observed in previous winter campaigns in Birmingham, Tokyo, and New York City. During this campaign, the total primary production rate of ROx radicals was dominated by the photolysis of nitrous acid accounting for 46 % of the identified primary production pathways for ROx radicals. Other important radical sources were alkene ozonolysis (28 %) and photolysis of oxygenated organic compounds (24 %). A box model was used to simulate the OH, HO2 and RO2 concentrations based on the observations of their long-lived precursors. The model was capable of reproducing the observed diurnal variation of the OH and peroxy radicals during clean days with a factor of 1.5. However, it largely underestimated HO2 and RO2 concentrations by factors up to 5 during pollution episodes. The HO2 and RO2 observed-to-modeled ratios increased with increasing NO concentrations, indicating a deficit in our understanding of the gas-phase chemistry in the high NOx regime. The OH concentrations observed in the presence of large OH reactivities indicate that atmospheric trace gas oxidation by photochemical processes can be highly effective even during wintertime, thereby facilitating the vigorous formation of secondary pollutants.

In the troposphere, ozone is a harmful gas compound to both human health and vegetation. Ozone is produced from the reaction of NOx ( NO + NO2) and VOCs (volatile organic compounds) with light. Due to the highly nonlinear relationships between ozone and its precursors, proper ozone mitigation relies on the knowledge of chemical mechanisms. In this study, an observation-based method is used to simulate ozone formation and elucidate its controlling factors for a rural site on the North China Plain. The instantaneous ozone production rate is calculated utilizing a box model using the dataset obtained from the Wangdu campaign. First, the model was operated in a time-dependent mode to calculate the ozone production rate at each time stamp. The calculated ozone formation rate showed a diurnal average maximum value of 17 ppbv/h (1-h diurnal averaged). The contribution of individual peroxy radicals to ozone production was analyzed. In addition, the functional dependence of calculated P(O3) reveals that ozone production was in a NOx-limited regime during the campaign. Furthermore, the missing peroxy radical source will further extend NOx-limited conditions to earlier in the day, making NOx limitation dominate more of a day than the current chemical model predicts. Finally, a multiple scenarios mode, also known as EKMA (empirical kinetic modeling approach), was used to simulate the response of P(O3) to the imaginary change in precursor concentrations. We found that ozone production was in the NOx-limited region. However, the use of NO2 measured by the molybdenum converter and/or the absence of a peroxy radical source in the current chemical model could over-emphasize the VOC-limited effect on ozone production.

Particulate nitrate ( p NO 3 - ) is an important component of secondary aerosols in urban areas. Therefore, it is critical to explore its formation mechanism to assist with the planning of haze abatement strategies. Here we report vertical measurements of NOx and O3 by in situ instruments on a movable carriage on a tower during a winter heavy-haze episode (18 to 20 December 2016) in urban Beijing, China. Based on the box model simulation at different heights, we found that p NO 3 - formation via N2O5 heterogeneous uptake was negligible at ground level due to N2O5 concentrations of near zero controlled by high NO emissions and NO concentration. In contrast, the contribution from N2O5 uptake was large at high altitudes (e.g., > 150 m), which was supported by the lower total oxidant ( NO2 + O3 ) level at high altitudes than at ground level. Modeling results show the specific case that the nighttime integrated production of p NO 3 - for the high-altitude air mass above urban Beijing was estimated to be 50 µ g m −3 and enhanced the surface-layer p NO 3 - the next morning by 28 µ g m −3 through vertical mixing. Sensitivity tests suggested that the nocturnal NOx loss by NO3 – N2O5 chemistry was maximized once the N2O5 uptake coefficient was over 2 × 10 −3 on polluted days with Sa at 3000 µ m 2 cm −3 in wintertime. The case study provided a chance to highlight the fact that p NO 3 - formation via N2O5 heterogeneous hydrolysis may be an important source of particulate nitrate in the urban airshed during wintertime.

A time-of-flight chemical ionization mass spectrometer (CIMS) utilizing the Filter Inlet for Gas and Aerosol (FIGAERO) was deployed at a regional site 40 km north-west of Beijing and successfully identified and measured 17 sulfur-containing organics (SCOs are organo/nitrooxy organosulfates and sulfonates) with biogenic and anthropogenic precursors. The SCOs were quantified using laboratory-synthesized standards of lactic acid sulfate and nitrophenol organosulfate (NP OS). The variation in field observations was confirmed by comparison to offline measurement techniques (orbitrap and high-performance liquid chromatography, HPLC) using daily averages. The mean total (of the 17 identified by CIMS) SCO particle mass concentration was 210 ± 110 ng m−3 and had a maximum of 540 ng m−3, although it contributed to only 2 ± 1 % of the organic aerosol (OA). The CIMS identified a persistent gas-phase presence of SCOs in the ambient air, which was further supported by separate vapour-pressure measurements of NP OS by a Knudsen Effusion Mass Spectrometer (KEMS). An increase in relative humidity (RH) promoted partitioning of SCO to the particle phase, whereas higher temperatures favoured higher gas-phase concentrations.Biogenic emissions contributed to only 19 % of total SCOs measured in this study. Here, C10H16NSO7, a monoterpene-derived SCO, represented the highest fraction (10 %) followed by an isoprene-derived SCO. The anthropogenic SCOs with polycyclic aromatic hydrocarbon (PAH) and aromatic precursors dominated the SCO mass loading (51 %) with C11H11SO7, derived from methyl naphthalene oxidation, contributing to 40 ng m−3 and 0.3 % of the OA mass. Anthropogenic-related SCOs correlated well with benzene, although their abundance depended highly on the photochemical age of the air mass, tracked using the ratio between pinonic acid and its oxidation product, acting as a qualitative photochemical clock. In addition to typical anthropogenic and biogenic precursors the biomass-burning precursor nitrophenol (NP) provided a significant level of NP OS. It must be noted that the contribution analysis here is only representative of the detected SCOs. There are likely to be many more SCOs present which the CIMS has not identified.Gas- and particle-phase measurements of glycolic acid suggest that partitioning towards the particle phase promotes glycolic acid sulfate production, contrary to the current formation mechanism suggested in the literature. Furthermore, the HSO4 ⋅ H2SO4− cluster measured by the CIMS was utilized as a qualitative marker for acidity and indicates that the production of total SCOs is efficient in highly acidic aerosols with high SO42− and organic content. This dependency becomes more complex when observing individual SCOs due to variability of specific VOC precursors.