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To understand diurnal variations in PM2.5 composition and aerosol extract absorption, PM2.5 samples were collected at intervals of 2 hr from 8:00 to 20:00 and 6 hr from 20:00 to 8:00 (the next day) in northern Nanjing, China, during the winter and summer of 2019–2020 and analyzed for bulk components, organic tracers, and light absorption of water and methanol extracts—a proxy measure of brown carbon (BrC). Diurnal patterns of measured species reflected the influences of primary emissions and atmospheric processes. Light absorption coefficients of water (Abs365,w) and methanol extracts (Abs365,m) at 365 nm shared a similar diurnal profile peaking at 18:00–20:00, generally following changes in biomass burning tracers. However, Abs365,w, Abs365,m, and their normalizations to organic aerosols increased at 14:00–16:00, earlier than that of levoglucosan in the late afternoon, which was attributed to secondarily formed BrC. The methanol extracts showed a less drastic decrease in light absorption at night than the water extracts and elevated absorption efficiency during 2:00–8:00. This is due to the fact that the water‐insoluble OC has a longer lifetime and stronger light absorption than the water‐soluble OC. According to the source apportionment results solved by positive matrix factorization (PMF), biomass burning and secondary formation were the major BrC sources in northern Nanjing, with an average total relative contribution of about 90%. Compared to previous studies, diurnal source cycles were added to the PMF simulations in this work by using time‐resolved speciation data, which avoided misclassification of BrC sources. Plain Language Summary: Light‐absorbing organic carbon (OC), also known as "brown carbon", plays an important role in influencing the Earth's radiative balance. Filter samples of particulate matter with an aerodynamic diameter of less than 2.5 μm (PM2.5) were collected at a resolution of 2 hr from 8:00 to 20:00 and a resolution of 6 hr from 20:00 to 8:00 (the next day) in northern Nanjing, China, during the winter and summer of 2019 and 2020. To understand the diurnal variations of BrC and its sources, each sample was analyzed for bulk components (OC, elemental carbon, and water‐soluble ions), organic molecular markers, and light absorption by BrC, and a receptor model was used to identify potential BrC sources based on PM2.5 composition data. We found that diurnal variations of BrC generally followed changes in concentrations of levoglucosan‐a tracer of biomass burning; the increase in BrC absorption in the early afternoon was caused by secondary formation of BrC chromophores; biomass burning and secondary formation were the main sources of BrC. Time‐resolved measurements of PM2.5 components were rarely used to investigate the diurnal variations of BrC and its sources, which is very important for modeling the climate impact of BrC. Key Points: Diurnal variations in PM2.5 bulk components and organic tracers reflect diurnal cycles of sourcesLight absorption of water and methanol extracts of PM2.5 exhibited a similar diurnal profile that followed changes in levoglucosanShort‐term and high time‐resolved data of organic tracers should be used for source apportionment to avoid misclassification [ABSTRACT FROM AUTHOR]

By developing a nontarget tandem mass spectrometry experiment workflow, we identified the most probable structures of 100 brown carbon (BrC) chromophores in five types of atmospherically relevant samples including ambient aerosols, biomass burning aerosols, road tunnel aerosols, toluene secondary organic aerosol and rainwater. These chromophores were classified into nine groups, that is, 31 nitrophenols, 12 benzoic acids, 11 oxygenated polycyclic aromatic hydrocarbons, 10 phenols, 10 aryl amides/amines, 9 phenylpropene derivatives, 9 coumarins and flavonoids, 5 pyridines, and 3 nitrobenzoic acids. Among them, aryl amides/amine chromophores, which were mostly found in rainwater, were reported for the first time. The identified chromophores accounted for 20.9%–83.5% of total light absorption over 300–400 nm wavelength or total ion intensity in the 5 types of samples. We identified the characteristic chromophore groups in each sample type and identical chromophores among different sample types, especially between the source samples and ambient aerosols. Gas‐particle distribution and diurnal variation of 13 BrC compounds in the atmosphere were measured by an online high‐resolution chemical ionization mass spectrometer equipped with a Filter Inlet for Gases and Aerosols. It was found that gas‐particle distribution of BrC compounds was dictated by their functional group, oxygen and carbon atom numbers. The BrC compounds containing nitro‐group had higher nighttime concentrations, while those without nitro‐group had higher daytime concentrations. Plain Language Summary: Brown carbon chromophores absorb near‐ultraviolet and visible light and thus influence atmospheric radiation and atmospheric chemistry. By developing a nontarget tandem mass spectrometry experiment workflow, we identified the most probable structures of a large diversity of brown carbon (BrC) chromophores in atmospherically relevant samples like ambient aerosols, biomass burning aerosols, road tunnel aerosols, secondary organic aerosol and rainwater. The similarity and difference of BrC chromophores in these samples were investigated, with a focus on exploring the source of the chromophores in ambient aerosols. For the first time, an online high‐resolution chemical ionization mass spectrometer was applied to measure gas‐particle distribution and diurnal variation of BrC chromophores in the atmosphere. Key Points: We developed a nontarget tandem mass spectrometry experiment workflow to identify the most probable structures of brown carbon (BrC) chromophoresWe identified 100 BrC chromophores in five types of atmospheric samples, among which 33 chromophores was reported for the first timeFilter Inlet for Gases and Aerosols‐chemical ionization mass spectrometer was applied to measure gas‐particle distribution and diurnal variation of BrC chromophores in the atmosphere [ABSTRACT FROM AUTHOR]

In this study, collocated filter samples of particulate matter with aerodynamic diameter less than 2.5 μm (PM2.5) from northern Nanjing were extracted using water and methanol, followed by analysis of light absorption. A backup quartz filter was used to correct sampling artifacts caused by adsorption of gaseous organics. The collocated precision of light‐absorbing properties of water‐soluble organic carbon (WSOC) and methanol‐extractable organic carbon (MEOC) were parameterized using correlation coefficient (r), coefficient of divergence (COD), and average relative percent difference (ARPD, %). In general, the light absorption of WSOC and MEOC showed good agreement (r > 0.80, COD < 0.20) between collocated samples. Performing artifact correction is necessary and will increase the heterogeneity between collocated measurements. The duplicate‐derived ARPD values of MEOC absorption were more than 60% higher than those of WSOC absorption. Then, it would be inappropriate to assume a uniform uncertainty fraction (e.g., ∼10%) for WSOC and MEOC absorption in future studies on their climate effects and source apportionment. To apportion artifact‐corrected absorption of aerosol extracts to specific emission sources or formation pathways, positive matrix factorization was performed by using concentration data of selected bulk species and organic molecular markers. Among the nine identified factor/sources, the biomass burning factor had the highest average contributions to the absorption of both WSOC (31.6%) and MEOC (48.0%), followed by dust resuspension and coal combustion factors. Unlike combustion‐related primary emissions, the factors containing influences from atmospheric processing (e.g., secondary nitrate) contributed more fractions of WSOC absorption than MEOC absorption. Key Points: Collocated measurements provide an approach to estimate uncertainties in light‐absorbing properties of solvent‐extractable organic carbonIgnoring the adsorption of gaseous organics onto filter medium will lead to significant overestimation of brown carbon absorptionAerosol sources influenced by aging processes contributed more fractions of aqueous extracts absorption than methanol extracts absorption [ABSTRACT FROM AUTHOR]

This study seeks to understand the ambient levels, gas/particle partitioning, and sources of nonpolar organic molecular makers (OMMs) at a suburban site in Nanjing, China. Particle‐ and gas‐phase OMMs were collected using a medium volume sampler equipped with two quartz filters in series and a polyurethane foam (PUF)/XAD‐4/PUF (PXP) adsorbent sandwich. More than 100 pairs of filter and PXP samples were collected diurnally from September 2018 to September 2019. The concentration profiles of total n‐alkanes and polycyclic aromatic hydrocarbons were peaking at n‐C12–n‐C17 homologs (9.98 ± 5.43–38.4 ± 17.7 ng m−3) and naphthalene (92.5 ± 56.7 ng m−3), respectively, followed by decreasing concentrations with further increases in molecular weight. Three artifact correction methods with different pre‐assumptions on relative contributions of evaporation loss to backup filter measurements were used to separate particle‐ and gas‐phase OMMs. The resulting particle‐phase fractions showed significant differences for OMMs with vapor pressure <10−9 atm at 298.15 K. Absorptive gas/particle partitioning coefficients of OMMs were empirically calculated based on measurements and theoretically predicted for comparison. The results obtained under the three artifact correction methods suggested growing importance of evaporation loss with decreased vapor pressure. Positive matrix factorization (PMF) was performed for source apportionment using total (PMFtotal) and particle‐phase (PMFparticle) OMMs data, respectively. Besides eliminating the influence of gas/particle partitioning, the involvements of more volatile species and gaseous OMMs data improved the identification of specific emission sources, supporting the usage of total OMMs data over a wide vapor pressure range for PMF source apportionment. Key Points: The particulate fractions of organic molecular markers attained their minima in summer, when the total concentrations increasedEvaporation loss might be the main sampling artifact of particulate organics when the vapor pressure is lower than 10−10 atmTotal concentrations of organic molecular markers over a wide vapor pressure range should be used for positive matrix factorization analysis [ABSTRACT FROM AUTHOR]

Acetaminophen (APAP) is a widely applied drug for the alleviation of pain and fever, which is also a dose‐depedent toxin. APAP‐induced acute liver injury has become one of the primary causes of liver failure which is an increasingly serious threat to human health. Neutrophils are the major immune cells in human serving as the first barrier against the invasion of pathogen. It has been reported that neutrophils patriciate in the occurrence and development of APAP‐induced liver injury. However, evolving evidences suggest that neutrophils also contribute to tissue repair and actively orchestrate resolution of inflammation. Here, we addressed the complex roles in APAP‐induced liver injury on the basis of brief introduction of neutrophil's activation, recruitment and migration. [ABSTRACT FROM AUTHOR]

Hepatitis B virus (HBV) infection is a major public health problem. The high levels of HBV DNA and HBsAg are positively associated with the development of secondary liver diseases, including hepatocellular carcinoma (HCC). Current treatment with nucleos(t)ide analogues mainly reduces viral DNA, but has minimal, if any, inhibitory effect on the viral antigen. Although IFN reduces both HBV DNA and HBsAg, the serious associated side effects limit its use in clinic. Thus, there is an urgent demanding for novel anti‐HBV therapy. In our study, viral parameters were determined in the supernatant of HepG2.2.15 cells, HBV‐expressing Huh7 and HepG2 cells which transfected with HBV plasmids and in the serum of HBV mouse models with hydrodynamic injection of pAAV‐HBV1.2 plasmid. RT‐qPCR and Southern blot were performed to detect 35kb mRNA and cccDNA. RT‐qPCR, Luciferase assay and Western blot were used to determine anti‐HBV effects of MLN4924 and the underlying mechanisms. We found that treatment with MLN4924, the first‐in‐class neddylation inhibitor currently in several phase II clinical trials for anti‐cancer application, effectively suppressed production of HBV DNA, HBsAg, 3.5kb HBV RNA as well as cccDNA. Mechanistically, MLN4924 blocks cullin neddylation and activates ERK to suppress the expression of several transcription factors required for HBV replication, including HNF1α, C/EBPα and HNF4α, leading to an effective blockage in the production of cccDNA and HBV antigen. Our study revealed that neddylation inhibitor MLN4924 has impressive anti‐HBV activity by inhibiting HBV replication, thus providing sound rationale for future MLN4924 clinical trial as a novel anti‐HBV therapy. [ABSTRACT FROM AUTHOR]

Ammonia control has received increasing attention as a measure to decrease particulate concentrations. Modeling analysis of observation data from central China over the period of September 2015 to August 2016 shows clear asymmetric responses of particulate pH and mass to ammonia emissions. With a change of ±80% of NHx (NH3 + NH4+), the corresponding ΔpH are +0.5 and −3.0, respectively, and the corresponding particulate NH4+ changes are +2.62% and −61.8%, respectively. This asymmetry implies that there is a Critical Total Ammonia Concentration, above which particulate pH and mass are insensitive to ammonia control. Analysis of the observation data suggests that the Critical Total Ammonia Concentration is −25%. The estimated cost for an NHx reduction of 25% is $140 – 320 million for Hubei province, which is the initial cost barrier before ammonia control can effectively affect particulate pH and mass in central China. This cost barrier will increase as NOx and SO2 emissions decrease. Key Points: Only after NHx reduction exceeds 25% can ammonia control effectively reduce the inorganic aerosol massMore NHx reduction will be required to reach the critical point of effective ammonia control as NOx and SO2 emissions decreaseA large enough NHx reduction (60%–80%) renders concurrent reduction of NOx emissions ineffective and even the effect of SO2 emission control is reduced [ABSTRACT FROM AUTHOR]

Background: In previous studies, a TiO2 coating was prepared on Ti surface through micro‐arc oxidation (MAO) by using calcium acetate as electrolyte, and the effects of the coating on cell attachment were testified. The main elemental compositions of the MAO coatings can be Ca, P, Ti and O. The Ca and P can promote the adhesion and differentiation of osteoblast. Dandelion polysaccharide is one kind of the active constituent of Taraxacum mongolicum, a Chinese medicinal herb, widespreading in nature. Aim/Hypothesis:This study aimed to investigate the effects of the MAO coating on mesenchymal stem cells while loading with dandelion polysaccharide. Material and Methods: (i) The schistose‐shaped Ti (_I_n_i_ = 15) were supplied. MAO treatment was performed on the machined implants by a MAO equipment. Furthermore, the MAO coating has been loading with 2.0 mg/L dandelion polysaccharide solution. A pure Ti and MAO coating that has been served as control (_I_n_i_ = 15, pure Ti surface = 5, MAO coating surface = 5, MAO coating loading with dandelion polysaccharide). (ii) Scanning electron microscopy was used to observe the Ti surface morphology. The elemental concentrations of the surfaces were quantified by energy dispersive X‐ray spectrometer. The phase composition was analyzed by X‐ray diffraction (iii) BMSCs were seeded on the surface of different groups and cultured. Then CCK‐8 kit was used to detect the adhesion and proliferation at selected time points. (iv) SPSS 20.0 software was used for statistical analysis. Results: (i) The coating with regular microstructure (diameter 1.0–6.0 mm) was prepared by micro‐arc oxidation on titanium substrates. (Fig.1) (ii) At 2 and 4 hours, the number of BMSCs of MAO group and MAO load group are more than Ti group and the difference was statistically significant, but there was no significant difference between the two groups. (Fig.2) (iii) At 3 days, the number of BMSCs of MAO load group are more than Ti group and MAO group, and the difference was statistically significant, while at 5 days and 7 days, there was no significant difference between MAO group and MAO load group. (Fig.3) Conclusions and Clinical Implications:Micro arc oxidation method was used to successfully product a coating rich in calcium and phosphorus elements and loaded with dandelion polysaccharide. (ii) The experiment in vitro showed that dandelion polysaccharide may promote proliferation of BMSCs on the surface of MAO coatings while cannot promote the adhesion.