Impact of soil-atmosphere HONO exchange on concentrations of HONO and O3 in the North China Plain.

Nitrous acid (HONO) is an important precursor of the hydroxyl radical (OH) and plays a vital role in atmospheric photochemistry and nitrogen cycling. Soil emissions have been considered as a potential source of HONO. Lately, the HONO emission via soil-atmosphere exchange (ESA-exchange) from soil nitrite has been validated and quantified through chamber experiments, but has not been assessed in the real atmosphere. We coupled ESA-exchange and the other seven potential sources of HONO (i.e., traffic, indoor and soil bacterial emissions, heterogeneous reactions on ground and aerosol surfaces, nitrate photolysis, and acid displacement) into the Weather Research and Forecasting model with Chemistry (WRF-Chem), and found that diurnal variations of the soil emission flux at the Wangdu site were well simulated. During the non-fertilization period, ESA-exchange contributed ∼28 % and âˆ¼35 % of nighttime and daytime HONO, respectively, and enhanced the net ozone (O3) production rate by ∼8 % across the North China Plain (NCP). During the preintensive/intensive fertilization period, the maximum ESA-Exchange contributions attained ∼70 %/83 % of simulated HONO in the afternoon across the NCP, definitely asserting its dominance in HONO production. ESA-Exchange enhanced the OH production rate via HONO photolysis by ∼3.5/7.0 times, and exhibited an increase rate of ∼13 %/20 % in the net O3 production rate across the NCP. The total enhanced O3 due to the eight potential HONO sources ranged from ∼2 to 20 ppb, and ESA-exchange produced O3 enhancements of ∼1 to 6 ppb over the three periods. Remarkably, the average contribution of ESA-exchange to the total O3 enhancements remained ∼30 %. This study suggests that ESA-exchange should be included in three-dimensional chemical transport models and more field measurements of soil HONO emission fluxes and soil nitrite levels are urgently required.

Dominant physical and chemical processes impacting nitrate in Shandong of the North China Plain during winter haze events.

Nitrate has been a dominant component of PM2.5 since the stringent emission control measures implemented in China in 2013. Clarifying key physical and chemical processes influencing nitrate concentrations is crucial for eradicating heavy air pollution in China. In this study, we explored dominant processes impacting nitrate concentrations in Shandong of the North China Plain during three haze events from 9 to 25 December 2021, named cases P1 (94.46 (30.85) µg m-3 for PM2.5 (nitrate)), P2 (148.95 (50.12) µg m-3) and P3 (88.03 (29.21) µg m-3), by using the Weather Research and Forecasting/Chemistry model with an integrated process rate analysis scheme and updated heterogeneous hydrolysis of dinitrogen pentoxide on the wet aerosol surface (HET-N2O5) and additional nitrous acid (HONO) sources (AS-HONO). The results showed that nitrate increases in the three cases were attributed to aerosol chemistry, whereas nitrate decreases were due mainly to the vertical mixing process in cases P1 and P2 and to the advection process in case P3. HET-N2O5 (the reaction of OH + NO2) contributed 45 % (51 %) of the HNO3 production rate during the study period. AS-HONO produced a nitrate enhancement of 24 % in case P1, 12 % in case P2 and 19 % in case P3, and a HNO3 production rate enhancement of 0.79- 0.97 (0.18- 0.60) µg m-3 h-1 through the reaction of OH + NO2 (HET-N2O5) in the three cases. This study implies that using suitable parameterization schemes for heterogeneous reactions on aerosol and ground surfaces and nitrate photolysis is vital in simulations of HONO and nitrate, and the MOSAIC module for aerosol water simulations needs to be improved.

ASPP1/2 positive patients with invasive breast cancers have good prognosis.

Although the expression of ASPP family members in multiple tumors has been studied, especially in various cell lines of breast cancer (BC), but the expressions pattern of ASPP family members in invasive BC tissues are not clear. We studied the expression and expression pattern of ASPPs family member in BCs, the relationship between ASPP family members and clinic-pathologic features of BCs was also analyzed. The results showed that the expression of ASPP1, ASPP2 and iASPP was observed on AE1/AE3+ tumor cells, and not on infiltrated lymphocytes and capillaries. The relationship between ASPP1 expression and pTNM stage has statistical difference (p＜0.01). The relationship between expression of ASPP2 and SBR grade has statistical difference (p＜0.05). The relationship between expression of iASPP and clinic-pathologic feature of patients has no statistical difference (p＞0.05). The patients with positive expression of ASPP1 and the patients with negative expression of ASPP1 have statistical difference in 3-year survival rate and 5-year survival rate (χ2 = 4.49, P = 0.03; χ2 = 3.79, P = 0.048). Overall, our work demonstrated that the expression of ASPP1/2 contributes to predict the prognosis of patients with BC.

Divergent summertime surface O3 pollution formation mechanisms in two typical Chinese cities in the Beijing-Tianjin-Hebei region and Fenwei Plain.

Recently, severe summertime ozone (O3) pollution has swept across most areas of China, especially the Beijing-Tianjin-Hebei (BTH) region and Fenwei Plain. By focusing on Beijing and Yuncheng, which are two typical cities in the BTH region and the Fenwei Plain, we intended to reveal the neglected fact that they had disparate emission features and atmospheric movements but suffered from similar high-O3 pollution levels. Field observations indicated that Yuncheng had lower volatile organic compound (VOC) and NOx concentrations but higher background O3 levels. The model simulation verified that both photochemical reactions and net O3 generation were stronger in Beijing. Ultimately, faster net O3 generation rates (8.4 ppbv/h) plus lower background O3 values in Beijing and lower net O3 generation rates (6.2 ppbv/h) plus higher background O3 values in Yuncheng caused both regions to reach similar O3 peak values in July 2020. However, different O3 control measures were appropriate for the two cities according to the different simulated O3-VOCs-NOx responses. Additionally, as surface O3 levels are greatly affected by the ongoing O3 production/depletion process that occurs in three dimensions, exploring the effects of spatially distributed O3 on surface O3 should be high on the agenda in the future.

Long-term winter observation of nitrous acid in the urban area of Beijing.

The particulate matter (PM) pollution has been significantly improved by carrying out various valid emission control strategies since 2013 in China. Meanwhile the variation trend of nitrous acid (HONO) is worthy to investigate due to its vital role in the atmospheric oxidation process. In this study, field observation in the winter is conducted to investigate the concentration of HONO in an urban area of Beijing. In the winter of 2019, the mean HONO concentration is 1.38 ppbV during the whole winter. Photo-enhanced NO2 heterogeneous reactions on the ground and aerosol surfaces were found as the possible daytime sources of HONO. Compared to O3, photolysis of HONO dominates the primary OH sources during the winter time. To understand the HONO pollution patterns by years variation, multi-year data is summarized and finds that primary pollutants including CO and NO decreased, but secondary pollutants i.e., HONO (mostly generated via secondary process) increased. Our study highlights the requirement to mitigate secondary pollution by control HONO concentration.

A comprehensive investigation on volatile organic compounds (VOCs) in 2018 in Beijing, China: Characteristics, sources and behaviours in response to O3 formation.

Observations of volatile organic compounds (VOCs) are a prerequisite for evaluating the effectiveness of government efforts targeting VOC pollution. Here, based on the one-year online VOC measurement in 2018 in Beijing, systematic analyses and model simulation were conducted to illuminate VOC characteristics, emission sources, regional hotspots and behaviours in response to O3 formation. The observed mean VOC concentration in 2018 was 29.12 ± 17.64 ppbv declined distinctly compared to that in 2015 and 2016. Vehicle exhaust (39.95%), natural gas/liquefied petroleum gas (22.04%) and industrial sources (20.64%) were the main contributors to VOCs in Beijing. Regional transport, mainly from the south-south-east (SSE) and south-south-west (SSW), quantitatively contributed 36.65%-55.06% to VOCs based on our developed method. O3 sensitivity tended to be in the transition regime in summer identified by ground-based and satellite observations. Strong solar radiation along with high temperature and low humidity aggravated O3 pollution that was further intensified by regional transport from southern polluted regions. The model simulation determined that turning off CH3CHO related reactions brought about the most predominantly short-term and long-run O3 reduction, indicating that control policies in VOC species should be tailored, instead of one-size-fits-all. Overall, region-collaborated and active VOC-species-focused strategies on VOC controls are imperative.

High crop yield losses induced by potential HONO sources - A modelling study in the North China Plain.

Nitrous acid (HONO) is a major source of hydroxyl radicals in the troposphere through its photolysis, and can significantly influence ozone (O3) levels, thereby causing considerable crop yield losses. Previous studies have assessed relative crop yield losses by using exposure-response equations with observed or simulated O3, however, the contribution of enhanced O3 due to potential HONO sources to the crop yield losses has never been quantified. In this study, for the first time, we evaluated the crop yield losses caused by potential HONO sources in the North China Plain (NCP), which is one of the major grain-producing areas in China suffering from heavy O3 pollution, by using the Weather Research and Forecasting/Chemistry (WRF-Chem) model during the wheat and maize growing seasons of 2016. HONO simulations were significantly improved after including six potential HONO sources in the WRF-Chem model. The potential HONO sources produced a daily maximum 8-h O3 enhancement of 8.1/8.2 ppb during the wheat/maize growing seasons, respectively, and led to ~11.4%/3.3% relative yield losses for wheat/maize, respectively, corresponding to approximately US$3.78/0.66 billion losses, respectively, in NCP in 2016. The above results suggest that potential HONO sources play a significant role in O3 formation and could induce high crop yield losses globally.

Biocompatible and biodegradable scaffold based on polytrimethylene carbonate-tricalcium phosphate microspheres for tissue engineering.

Biocompatible polymers and drug delivery vehicles have been driving development in bone regeneration. However, most bone scaffolds show poor degradation and proliferation. In this study, a composite microsphere scaffold was prepared using vancomycin hydrochloride(VH)-loaded polytrimethylene carbonate(PTMC) microsphere (PTMC-VH). Adopting a thermal technique, a three-dimensional oleic acid-modified tricalcium phosphate (PTMC-OA-TCP)/PTMC-VH microsphere scaffold was prepared. It had a porosity of 41-47 % and pore size of 129-154 µm. The highest drug loading and release efficiency were obtained with the scaffold produced using 2.4 % polymer concentration and 0.5 %polyvinyl alcohol. The scaffold with PTMC-VH microsphereshad enhancedmechanical properties, water absorption capacity, and degradation. In addition, the PTMC-OA-TCP scaffold had comparable performance with bone cement control in terms of bone regeneration in vivo. In summary, the prepared bioactive scaffolds, which had favorable mechanical properties and facilitated osteogenesis, could be a promising alternative for bone cement in bone tissue engineering.

Cable-car measurements of vertical aerosol profiles impacted by mountain-valley breezes in Lushan Mountain, East China.

In-situ field observations of vertical aerosol profiles for one month in complex terrain (Lushan Mountain, China) were carried out using a cable car, which resolved detailed vertical distributions of mountain aerosols with low-cost operation. Cable-car observations were conducted during the early morning and late afternoon, when mountain and valley winds dominated, respectively. The diurnal aerosol variations at the top and foot of Lushan Mountain were analyzed based on environmental and meteorological stations. The observations indicated that the mountain-valley breezes notably impacted the mountain-area aerosol distribution under weak weather conditions. More uniform aerosol profiles for the afternoon than the morning, with their decreasing rates of PM2.5 (particles with diameters less than 2.5 µm) were 1.64 and 2.28 µg m-3/100 m, respectively. The PM2.5/PM10 ratio at the mountain top increased from 0.69 to 0.81, and that at the mountain base decreased from 0.75 to 0.70 from morning to afternoon. The PM2.5 concentration decreased in and around Lushan Mountain from daytime to nighttime, with the impacted diameter of the 300-m topography line being smaller than ~5 km, while the concentration increased in Jiujiang City. The relative decreasing rate of PM2.5 was higher at the mountain top site (~20%) than at the base site (~2%) from daytime to nighttime. Moreover, uniform aerosol profiles could have been caused by regional transport through a relatively strong low-level synoptic flow (~5 m s-1) and the mountain's dynamic lifting effect.

HONO Budget and Its Role in Nitrate Formation in the Rural North China Plain.

Nitrous acid (HONO) is a major precursor of tropospheric hydroxyl radical (OH) that accelerates the formation of secondary pollutants. The HONO sources, however, are not well understood, especially in polluted areas. Based on a comprehensive winter field campaign conducted at a rural site of the North China Plain, a box model (MCM v3.3.1) was used to simulate the daytime HONO budget and nitrate formation. We found that HONO photolysis acted as the dominant source for primary OH with a contribution of more than 92%. The observed daytime HONO could be well explained by the known sources in the model. The heterogeneous conversion of NO2 on ground surfaces and the homogeneous reaction of NO with OH were the dominant HONO sources with contributions of more than 36 and 34% to daytime HONO, respectively. The contribution from the photolysis of particle nitrate and the reactions of NO2 on aerosol surfaces was found to be negligible in clean periods (2%) and slightly higher during polluted periods (8%). The relatively high OH levels due to fast HONO photolysis at the rural site remarkably accelerated gas-phase reactions, resulting in the fast formation of nitrate as well as other secondary pollutants in the daytime.

Effect of potential HONO sources on peroxyacetyl nitrate (PAN) formation in eastern China in winter.

As an important secondary photochemical pollutant, peroxyacetyl nitrate (PAN) has been studied over decades, yet its simulations usually underestimate the corresponding observations, especially in polluted areas. Recent observations in north China found unusually high concentrations of PAN during wintertime heavy haze events, but the current model still cannot reproduce the observations, and researchers speculated that nitrous acid (HONO) played a key role in PAN formation. For the first time we systematically assessed the impact of potential HONO sources on PAN formation mechanisms in eastern China using the Weather Research and Forecasting/Chemistry (WRF-Chem) model in February of 2017. The results showed that the potential HONO sources significantly improved the PAN simulations, remarkably accelerated the ROx (sum of hydroxyl, hydroperoxyl, and organic peroxy radicals) cycles, and resulted in 80%-150% enhancements of PAN near the ground in the coastal areas of eastern China and 10%-50% enhancements in the areas around 35-40°N within 3 km during a heavy haze period. The direct precursors of PAN were aldehyde and methylglyoxal, and the primary precursors of PAN were alkenes with C > 3, xylenes, propene and toluene. The above results suggest that the potential HONO sources should be considered in regional and global chemical transport models when conducting PAN studies.

Porphyromonas gingivalis Promotes the Proliferation and Migration of Esophageal Squamous Cell Carcinoma through the miR-194/GRHL3/PTEN/Akt Axis.

Recent studies have revealed that Porphyromonas gingivalis is closely related to the occurrence and progression of esophageal squamous cell carcinoma (ESCC). However, the underlying mechanism of P. gingivalis in ESCC has not been well elucidated. To explore the mechanism of P. gingivalis infection in ESCC, cellular proliferation, invasion, and migration models of KYSE-30 and KYSE-150 cells infected by P. gingivalis at a multiplicity of infection (MOI) of 10 were established. The results showed that P. gingivalis infection could drastically increase the proliferation, invasion, and migration ability of ESCC. Furthermore, the results of high-throughput sequencing showed that miR-194 was considerably upregulated in infected cells compared with control cells, which was further verified by qRT-PCR. The inhibition or overexpression of miR-194 had a significant effect on KYSE-30 and KYSE-150 cell migration and invasion. Additionally, the levels of GRHL3 and PTEN were decreased in P. gingivalis-infected esophageal cancer cells compared with uninfected esophageal cancer cells. Furthermore, dual-luciferase experiments confirmed that GRHL3 is a direct target of miR-194. In addition, the GRHL3-related pathway was investigated, and the levels of GRHL3 and PTEN were downregulated while the level of p-Akt was upregulated after P. gingivalis infection. Taken together, these findings indicated that P. gingivalis might promote ESCC proliferation and migration via the miR-194/GRHL3/PTEN/Akt signaling axis.

Enhanced Suppression of Disulfide Cross-Linking Micelles Nanocarriers Loaded miR-145 Delivering System via Down-Regulation of MYC and FSCN1 in Colon Cancer Cells.

Colorectal carcinoma is a complex disease accounting for adenoma tumors and an aggressive phenotype, and the third leading cause of cancer death. In the past decades, miRNAs have been associated with molecular pathways of cancer and other diseases. The dysregulated miRNAs play an inhibitory or promoting role in tumorigenesis. Therefore, restoration of tumor-suppressed microRNAs (miRNA) may offer novel therapeutic approaches for cancer treatment. Nevertheless, the poor bioavailability of miRNA due to their rapid enzymatic degradation is a critical barrier in cancer gene therapy. To overcome this dilemma, we designed disulfide cross-linking micelles (DCM) nanocarrier for delivery of miR-145 to colon cancer cells and investigated its therapeutic efficacy in vitro and in vivo. Results indicated that the presence of DCM nanocarrier loaded with miR-145 enhanced selective delivery of miR-145 and facilitated cellular uptake, significantly up-regulating miR-145 expression in HCT-116 cell lines. Consequently, the cell proliferation was inhibited by arresting cell cycle at the G1 phase. Further, apoptosis of HCT-116 cells treated with miR-145 complex nanoparticles may be via downregulation of oncogenes MYC and FSCN1, predicting regulatory targets for miR-145. These results pave the way for further investigations into the potential of miR-145 complex nanocarrier for cancer gene therapy.

Characterization and sources of volatile organic compounds (VOCs) and their related changes during ozone pollution days in 2016 in Beijing, China.

Concentrations of 99 volatile organic compounds (VOCs) were continuously measured online at an urban site in Beijing, China, in January, April, July, and October 2016. Characterization and sources of VOCs and their related changes during days with heavy ozone (O3) pollution were analysed. The total observed concentration of VOCs (TVOCs) was 44.0 ± 28.9 ppbv. The VOC pollution level has decreased in Beijing but remains higher than in other Chinese cities. Alkanes comprised the highest proportion among seven major sampled VOC groups. The concentrations and sources of ambient VOCs showed obvious temporal variations. Six emission sources were identified by the positive matrix factorization (PMF), including biomass burning, coal combustion, gasoline vehicles, diesel vehicles, solvent usage, and biogenic + secondary emissions. The combustion source was the key control factor for VOC reduction in Beijing. From the potential source contribution function (PSCF) and concentration-weighted trajectory (CWT) model, Beijing, Tianjin, Hebei, Shanxi, Inner Mongolia, Shandong, and Henan were identified as major potential source regions of ambient VOCs. O3 formation was sensitive to VOCs in Beijing according to the VOC/NOx ratio (ppbC/ppbv, 8:1 threshold). High- and low-O3 days in July were identified, and high O3 levels were due to both enhanced VOC emission levels and meteorological conditions favourable to the production of O3. These findings provide evidence that the fuel combustion and regional transport have a great impact on concentrations and sources of VOCs in urban Beijing.

Aerosol optical properties under different pollution levels in the Pearl River Delta (PRD) region of China.

To clarify the aerosol hygroscopic growth and optical properties of the Pearl River Delta (PRD) region, integrated observations were conducted in Heshan City of Guangdong Province from October 19 to November 17, 2014. The concentrations and chemical compositions of PM2.5, aerosol optical properties and meteorological parameters were measured. The mean value of PM2.5 increased from less than 35 (excellent) to 35-75 µg/m3 (good) and then to greater than 75 µg/m3 (pollution), corresponding to mean PM2.5 values of 24.9, 51.2, and 93.3 µg/m3, respectively. The aerosol scattering hygroscopic growth factor (f(RH = 80%)) values were 2.0, 2.12, and 2.18 for the excellent, good, and pollution levels, respectively. The atmospheric extinction coefficient (σext) and the absorption coefficient of aerosols (σap) increased, and the single scattering albedo (SSA) decreased from the excellent to the pollution levels. For different air mass sources, under excellent and good levels, the land air mass from northern Heshan had lower f(RH) and σsp values. In addition, the mixed aerosol from the sea and coastal cities had lower f(RH) and showed that the local sources of coastal cities have higher scattering characteristics in pollution periods.

Investigating the characteristics and source analyses of PM2.5 seasonal variations in Chengdu, Southwest China.

In 2015, comprehensive observations were carried out in Chengdu, Sichuan Province, China, to elucidate the seasonal variation characteristics of the concentrations, chemical compositions, and the sources of PM2.5 pollution. The meteorological parameters, gaseous pollutants and chemical compositions of PM2.5 were measured. The annual average concentration of PM2.5 in Chengdu was 67.44 ±â€¯48.78 µg/m3. The highest seasonal PM2.5 mass concentration occurred in winter with an average of 103.04 ±â€¯66.76 µg/m3, followed by spring, autumn, and summer, and the wind speed had an important impact on the diffusion of PM2.5. The seasonal variation characteristics of chemical components in PM2.5 were analysed. The contribution and chemical conversion ability of secondary aerosols increased with increasing of PM2.5 concentration. Source appointment of positive matrix factorization (PMF) shows that the main sources of PM2.5 were secondary aerosols, coal combustion, biomass burning, vehicle emissions, dust and industrial sources, which have more obvious seasonal differences than other sources, and secondary aerosols and coal combustion were the major sources. Conditional probability function (CPF) analysis showed that the local sources of high PM2.5 concentrations were mainly from the eastern and southeastern areas of Chengdu. Potential source contribution function (PSCF), concentration weighted trajectory (CWT) and backward trajectory cluster analyses indicated that the southern, southeast and eastern parts of the Sichuan Basin were the most likely potential sources of PM2.5, and the unique geographical and topographical factors in Chengdu play important roles in the transport and diffusion of pollutants in this region.

Insights into the phenomenon of an explosive growth and sharp decline in haze: A case study in Beijing.

A severe haze episode occurred in winter in the North China Plain (NCP), and the phenomenon of an explosive growth and sharp decline in PM2.5 (particulate matter with an aerodynamic diameter equal to or less than 2.5 µm) concentration was observed. To study the systematic causes for this phenomenon, comprehensive observations were conducted in Beijing from November 26 to December 2, 2015; during this period, meteorological parameters, LIDAR data, and the chemical compositions of aerosols were determined. The haze episode was characterized by rapidly varying PM2.5 concentration, and the highest PM2.5 concentration reached 667 µg/m3. During the haze episode, the NCP was dominated by a weak high-pressure system and continuously low PBL (planetary boundary layer) heights, which are unfavorable conditions for the diffusion of pollutants. The large increases in the concentrations of SNA (SO42-, NO3- and NH4+) during the haze implied that the formation of SNA was the largest contribution. Water vapor also played a vital role in the formation of haze by promoting the chemical transformation of secondary pollutants, which led to higher PM2.5 concentrations. The spatial distributions of PM2.5 in Beijing at different times and the backward trajectories of the air masses also indicated that pollutants from surrounding provinces in particular, contributed to the higher PM2.5 concentration.

Seasonal effects of additional HONO sources and the heterogeneous reactions of N2O5 on nitrate in the North China Plain.

We coupled the heterogeneous hydrolysis of N2O5 into the newly updated Weather Research and Forecasting model with Chemistry (WRF-Chem) to reveal the relative importance of the hydrolysis of N2O5 and additional nitrous acid (HONO) sources for the formation of nitrate during high PM2.5 events in the North China Plain (NCP) in four seasons. The results showed that additional HONO sources produced the largest nitrate concentrations in winter and negligible nitrates in summer, leading to a 10% enhancement of a PM2.5 peak in southern Beijing and a 15% enhancement in southeastern Hebei in winter. In contrast, the hydrolysis of N2O5 produced high nitrate in summer and low nitrate in winter, with the largest contribution of nearly 20% for a PM2.5 peak in southeastern Hebei in summer. During PM2.5 explosive growth events, the additional HONO sources played a key role in nitrate increases in southern Beijing and southwestern Hebei in winter, whereas the hydrolysis of N2O5 contributed the most to a rapid increase in nitrate in other seasons. HONO photolysis produced more hydroxyl radicals, which were >1.5 µg m-3 h-1 in the early explosive stage and led to a rapid nitrate increase at the southwestern Hebei sites in winter, while the heterogeneous reaction of N2O5 contributed greatly to a significant increase in nitrate in summer. The above results suggest that the additional HONO sources and the heterogeneous hydrolysis of N2O5 contributed the most to nitrate formation in NCP in winter and summer, respectively.