Atmospheric brown carbon in China haze is dominated by secondary formation.

Brown carbon (BrC) is a class of light-absorbing organic aerosols (OA) and has significant influence on atmospheric radiative forcing. However, the current limited understanding of the physicochemical properties of BrC restricts the accurate evaluation of its environmental effects. Here the optical characteristics and chemical composition of BrC during wintertime in the Yangtze River Delta (YRD) region, China were measured by using high-resolution aerosol mass spectrometry (HR-AMS) and UV-vis spectrometry. Our results showed that BrC in PM2.5 during the campaign was dominated by water-soluble organics, which consist of less oxidized oxygenated OA (LO-OOA), more oxidized oxygenated OA (MO-OOA), fossil fuel OA (FFOA) and biomass burning OA (BBOA). MO-OOA and BBOA were the strongest light absorbing BrC at 365 nm (Abs365), followed by LO-OOA and FFOA with a mass absorption coefficient (MAC) being 0.74 ± 0.04, 0.73 ± 0.03, 0.48 ± 0.04 and 0.39 ± 0.06 m2 g-1 during the campaign, respectively. In the low relative humidity (RH < 80 %) haze periods Abs365 of LO-OOA contributed to 44 % of the total light absorption at 365 nm, followed by MO-OOA (31 %), FFOA (21 %) and BBOA (4 %). In contrast, in the high-RH (RH > 80 %) haze periods Abs365 was dominated by MO-OOA, which accounted for 62 % of the total Abs365, followed by LO-OOA (17 %), BBOA (13 %) and FFOA (8 %). Chemical composition analysis further showed that LO-OOA and MO-OOA are produced from gas-phase photooxidation of VOCs and aerosol aqueous reactions, respectively, in which ammonia significantly enhanced the formation and light absorption of BrC in the high RH haze period. On average, >75 % of the total Abs365nm in the YRD region during the haze events was contributed by LO-OOA and MO-OOA, suggesting that atmospheric BrC in China haze periods is predominantly formed by secondary reactions.

Treadmill exercise training inhibits morphine CPP by reversing morphine effects on GABA neurotransmission in D2-MSNs of the accumbens-pallidal pathway in male mice.

Relapse is a major challenge in the treatment of drug addiction, and exercise has been shown to decrease relapse to drug seeking in animal models. However, the neural circuitry mechanisms by which exercise inhibits morphine relapse remain unclear. In this study, we report that 4-week treadmill training prevented morphine conditioned place preference (CPP) expression during abstinence by acting through the nucleus accumbens (NAc)-ventral pallidum (VP) pathway. We found that neuronal excitability was reduced in D2-dopamine receptor-expressing medium spiny neurons (D2-MSNs) following repeated exposure to morphine and forced abstinence. Enhancing the excitability of NAc D2-MSNs via treadmill training decreased the expression of morphine CPP. We also found that the effects of treadmill training were mediated by decreasing enkephalin levels and that restoring opioid modulation of GABA neurotransmission in the VP, which increased neurotransmitter release from NAc D2-MSNs to VP, decreased morphine CPP. Our findings suggest the inhibitory effect of exercise on morphine CPP is mediated by reversing morphine-induced neuroadaptations in the NAc-to-VP pathway.

Demographic patterns of two related desert shrubs with overlapping distributions in response to past climate changes.

Numerous studies have revealed that past geological events and climatic fluctuations had profoundly affected the genetic structure and demographic patterns of species. However, related species with overlapping ranges may have responded to such environmental changes in different ways. In this study, we compared the genetic structure and population dynamics of two typical desert shrubs with overlapping distributions in northern China, Nitraria tangutorum and Nitraria sphaerocarpa, based on chloroplast DNA (cpDNA) variations and species distribution models. We sequenced two cpDNA fragments (trnH-trnA and atpH-atpI) in 633 individuals sampled from 52 natural populations. Twenty-four chlorotypes, including eight rare chlorotypes, were identified, and a single dominant haplotype (H4) widely occurred in the entire geographical ranges of the two species. There were also a few distinctive chlorotypes fixed in different geographical regions. Population structure analyses suggested that the two species had significantly different levels of total genetic diversity and interpopulation differentiation, which was highly likely correlated with the special habitat preferences of the two species. A clear phylogeographic structure was identified to exist among populations of N. sphaerocarpa, but not exist for N. tangutorum. The neutral tests, together with the distribution of pairwise differences revealed that N. tangutorum experienced a sudden demographic expansion, and its expansion approximately occurred between 21 and 7 Kya before present, while a rapid range expansion was not identified for N. sphaerocarpa. The ecological niche modeling (ENM) analysis indicated that the potential ranges of two species apparently fluctuated during the past and present periods, with obvious contraction in the Last Glacial Maximum (LGM) and recolonization in the present, respectively, comparing to the Last Interglacial (LIG). These findings suggest that the two species extensively occurred in the Northwest of China before the Quaternary, and the current populations of them originated from a few separated glacial refugia following their habitat fragmentation in the Quarternary. Our results provide new insights on the impact of past geological and climatic fluctuations on the population dynamics of desert plants in northwestern China, and further enforce the hypothesis that there were several independent glacial refugia for these species during the Quaternary glaciations.

Characteristics and sources of oxygenated VOCs in Hong Kong: Implications for ozone formation.

To investigate the characteristics of oxygenated volatile organic compounds (OVOCs) and their potential contribution to ozone (O3) generation, we conducted 3-h high-resolution observations during the summertime of 2022 and the wintertime of 2021. This study focused on a total of 28 OVOCs in five different chemical classes, which were encompassed at two representative sites in Hong Kong, including a roadside and an urban area. During the summertime, the total concentrations of quantified OVOCs (∑OVOCs) were 45 ± 12 and 63 ± 20 µg m-3 at the roadside and urban sites, respectively, whereas the ∑OVOCs decreased by 31 ± 11 % and 38 ± 13 %, respectively, during the wintertime. Among the classes of OVOCs, carbonyls and alcohols were the two predominant at both sites, with relatively higher concentration levels of acetone, methanol, butanaldehyde, and acrolein. The sources of OVOCs have significant spatial and temporal characteristics. Spatially, OVOCs were predominately attributed to primary emission and background at the roadside site, whereas they were a combination of primary emission, secondary formation, and background at the urban site. Temporally, background sources dominated the summertime OVOCs, while the contribution of primary emissions increased for the wintertime OVOCs. The O3 formation potential (OFP) for the OVOCs was calculated. The OFPs were 67 ± 16 and 119 ± 31 µg m-3 at the roadside and urban sites during the summertime, whereas the winter OFPs declined 30 % at the roadside and 38 % at the urban site. The background sources of carbonyls and alcohols at the roadside and of carbonyls and acrylates in the urban area were the major contributors to the summer OFP. Controlling the OVOC sources from local non-combustion sources such as gasoline-fuel evaporation and volatile chemical-containing products could lead to a reduction of OVOCs in the background and subsequently mitigate the OFP. This is beneficial for local O3 reduction in Hong Kong and surrounding regions.

The Relationship Between Fear and Anxiety Among Chinese Uninfected Residents During the Pandemic: A Conditional Process Analysis.

Background: This study aimed to explore the relationship between residents' COVID-19 fear and anxiety, consider whether this relationship is mediated through obsessions and the moderating role of self-efficacy on this mediating pathway. Methods: This study used an online questionnaire to obtain and assess fear, obsession, anxiety and self-efficacy in 1589 Chinese COVID-19 uninfected residents. A conditional process model was used to examine the relationships between variables. Results: Higher levels of fear were positively associated with obsession and anxiety. In addition, obsession was positively associated with anxiety, while self-efficacy attenuated the effect of fear on obsession and further mitigated the indirect effect of fear on anxiety through obsession. Conclusion: During the COVID-19 outbreak, uninfected residents suffered varying degrees of psychological distress. COVID-19 fear may have an effect on anxiety in COVID survivors through obsession, and self-efficacy as a protective factor for individual mental health partially attenuates the effect of COVID-19 fear on obsession and the indirect effect of fear on anxiety.

Combining decellularized adipose tissue with decellularized adventitia extravascular matrix or small intestinal submucosa matrix for the construction of vascularized tissue-engineered adipose.

Adipose tissue is an endocrine organ. It serves many important functions, such as energy storage, hormones secretion, and providing insulation, cushioning and aesthetics to the body etc. Adipose tissue engineering offers a promising treatment for soft tissue defects. Early adipose tissue production and long-term survival are closely associated with angiogenesis. Decellularized matrix has a natural ECM (extracellular matrix) component, good biocompatibility, and low immunogenicity. Therefore, in this study, the injectable composite hydrogels were developed to construct vascularized tissue-engineered adipose by using the pro-angiogenic effects of aortic adventitia extravascular matrix (Adv) or small intestinal submucosa (SIS), and the pro-adipogenic effects of decellularized adipose tissue (DAT). The composite hydrogels were cross-linked by genipin. The adipogenic and angiogenic abilities of composite hydrogels were investigated in vitro, and in a rat dorsal subcutaneous implant model. The results showed that DAT and SIS or Adv 1:1 composite hydrogel promoted the migration and tube formation of endothelial cells. Furthermore, DAT and SIS or Adv 1:1 composite hydrogel enhanced adipogenic differentiation of adipose-derived mesenchymal stem cells (ASCs) through activation of PPARγ and C/EBPα. The in vivo studies further demonstrated that DAT with SIS or Adv in a 1:1 ratio also significantly promoted adipogenesis and angiogenesis. In addition, DAT with SIS or Adv in a 1:1 ratio hydrogel recruited macrophage population with enhanced M2-type macrophage polarization, suggesting a positive effect of inflammatory response on angiogenesis. In conclusion, these data suggest that the composite hydrogels of DAT with SIS or Adv in 1:1 ratio have apparent pro-adiogenic and angiogenic abilities, thus providing a promising cell-free tissue engineering biomaterial with broad clinical applications. STATEMENT OF SIGNIFICANCE: Decellularized adipose tissue (DAT) has emerged as an important biomaterial in adipose tissue regeneration. Early adipose tissue production and long-term survival is tightly related to the angiogenesis. The revascularization of the DAT is a key issue that needs to be solved in adipose regeneration. In this study, the injectable composite hydrogels were developed by using DAT with Adv (aortic adventitia extravascular matrix) or SIS (small intestinal submucosa) in different ratio. We demonstrated that the combination of DAT with SIS or Adv in 1:1 ratio effectively improved the proliferation of adipose stem cells and endothelial cells, and promoted greater adipose regeneration and tissue vascularization as compared to the DAT scaffold. This study provides the potential biomaterial for clinical soft tissue regeneration.

The different cell-specific mechanisms of voluntary exercise and forced exercise in the nucleus accumbens.

Physical inactivity is a global epidemic. People who take the initiative to exercise will feel pleasure during the exercise process and stick with it for a long time, while people who passively ask for exercise will feel pain and cannot stick with it. However, the neural mechanisms underlying voluntary and forced exercise remain unclear. Here, we report that voluntary running increased the frequency and amplitude of miniature excitatory postsynaptic currents (mEPSC) but decreased membrane excitability in D1R-MSNs, whereas D2R-MSNs did not change in mEPSC and membrane excitability. Forced running increased the frequency of mEPSC and membrane excitability in D2R-MSNs, but D1R-MSNs did not change, which may be the mechanism by which forced exercise has a non-rewarding effect. These findings provide new insights into how voluntary and forced exercise mediate reward and non-reward effects.

Secondary Formation of Atmospheric Brown Carbon in China Haze: Implication for an Enhancing Role of Ammonia.

Optical characteristics and molecular compositions of brown carbon (BrC) were investigated during winter 2019 at a rural site of China with a focus on nitro-aromatic compounds (NACs) and imidazoles (IMs). The abundance of gaseous nitrophenols relative to CO during the campaign maximized at noontime, being similar to O3, while the particulate NACs during the haze periods strongly correlated with toluene and NO2, suggesting that NACs in the region are largely formed from the gas-phase photooxidation. Strong correlations of particulate IMs in the dry haze periods with the mass ratio of EC/PM2.5 and the concentration of levoglucosan were observed, indicating that IMs during the dry events are largely derived from biomass burning emissions. However, an increase in IMs with the increasing aerosol liquid water content and pH was observed in the humid haze events, along with much lower abundances of levoglucosan and K+ relative to PM2.5, suggesting that IMs were mostly formed from aqueous reactions in the humid haze periods. These IMs exponentially increased with an increasing NH3 owing to an aqueous reaction of carbonyls with free ammonia. Our findings for the first time revealed an enhancing effect of ammonia on BrC formation in China, especially in humid haze periods.

Ammonia in urban atmosphere can be substantially reduced by vehicle emission control: A case study in Shanghai, China.

To investigate the impact of emission controls on ammonia (NH3) pollution in urban atmosphere, observation on NH3 (1 hr interval) was performed in Shanghai before, during and after the 2019 China International Import Expo (CIIE) event, along with measurements on inorganic ions, organic tracers and stable nitrogen isotope compositions of ammonium in PM2.5. NH3 during the CIIE period was 6.5±1.0 µg/m3, which is 41% and 32% lower than that before and after the event, respectively. Such a decrease was largely ascribed to the emission controls in nonagricultural sources, of which contribution for measured NH3 in control phase abated by ∼20% compared to that during uncontrol period. Molecular compositions of PAHs and hopanes further suggested a dominant role of the reduced vehicle emissions in the urban NH3 abatement during the CIIE period. Our results revealed that vehicle exhaust emission control is an effective way to mitigate NH3 pollution and improve air quality in Chinese urban areas.

Investigation into the differences and relationships between gasSOA and aqSOA in winter haze pollution on Chongming Island, Shanghai, based on VOCs observation.

To investigate the formation of secondary organic aerosol (SOA) under current atmospheric conditions, we conducted a field observation of SOA precursors in the downwind region of the Yangtze River Delta (YRD) in winter 2019 using a variety of offline and online instruments. During the entire observation period, the averaged fine particulate SOA was 7.9 ± 2.3 µg m-3, with precursor concentrations of 31 ± 11 ppbv for the measured volatile organic compounds (VOCs) and 16 ± 12 ppbv for NOx. Compared to those on the clean days, SOA on the haze days increased by a factor of 1.6, while the VOC and NOx increased by a factor of 1.3 and 2.0, respectively. Aerosol liquid water content (ALWC) and oxygenated VOCs (OVOCs, including acetaldehyde, formic acid, acetone, acetic acid, methyl ethyl ketone, and methylglyoxal) relationships suggested that the gasSOA and aqSOA occurred simultaneously on Chongming Island in winter. The gasSOA was primarily formed by the oxidation of aromatics and NOx at low RH (RH < 80%) conditions. In contrast, the aqSOA was formed under higher RH (RH > 80%) conditions via a combination of daytime photochemical aqueous phase processes of water-soluble OVOCs and nocturnal dark aqueous phase processes of primary emissions from biomass. The inversed higher mass ratio of NACs to (benzene + toluene) and nitrogen oxidation ratio (NOR) in the daytime during the gasSOA-dominated haze periods indicated that gasSOA could be transformed to aqSOA at high NOx levels. Our results also suggested the importance of NOx and VOC reduction measures in directly mitigating gasSOA and indirectly mitigating aqSOA during winter haze pollution.

Increasing role of phenolic oxidative branch in daytime oxidation process of aromatics in Chinese haze period.

To understand the photooxidation mechanisms of aromatic compounds in the NOx-rich atmosphere, gaseous aromatics and their oxidization products (i.e., methyl glyoxal (MGLY), and nitrated phenols (NPs) including nitrophenols (NPhs) and methylnitrophenols (MNPs)) were measured with a 1-h time resolution on Chongming Island, a downwind region of the Yangtze River Delta (YRD) metropolitans of China in winter 2019 by using a proton-transfer-reaction mass spectrometer (PTR-MS). During the entire observation period, concentrations of the measured VOCs were 9.6 ± 7.1 ppbv for aromatics, 118 ± 59 pptv for MGLY, 36 ± 10 pptv for NPhs, and 9.3 ± 2.8 pptv for MNPs, respectively. Secondary NPs (SNPs) accounted for only 19-24 % of the total nitrated phenols during the clean and transition periods but increased to 44 % of the total on the hazy days. Moreover, the daytime mixing ratios of SNPs increased along with an increasing NO2 concentration during the clean and transition periods, but in the haze period the daytime SNPs first increased along with the increasing NO2 levels and then increased much more sharply when NO2 was >25 ppbv. Such highly proportional and sharply increased daytime SNPs in the haze period indicated an enhanced phenolic oxidation under the high NOx conditions. In addition, the lack of correlations between aromatics and MGLY, increased MGLYaro (MGLY produced by aromatics), and sharply increased ΔSNPs / Δ(benzene + toluene) further suggested that such an increasing role of the phenolic oxidative branch in the daytime oxidation process of aromatics during the YRD haze period was caused by the strong atmospheric oxidation capacity and the high level of NOx.

Adipose-derived stem cells with miR-150-5p inhibition laden in hydroxyapatite/tricalcium phosphate ceramic powders promote osteogenesis via regulating Notch3 and activating FAK/ERK and RhoA.

Adipose-derived mesenchymal stem cells (ADSCs) are multipotent stromal cells and play huge role in forming and repairing bone tissues. Emerging evidence shows that MicroRNAs (miRNAs) are involved in ADSCs differentiation. Here, we explored the role of miR-150-5p and its related mechanisms in ADSCs osteogenesis. Real-time PCR was used to determine miR-150-5p expression during ADSCs osteogenesis. miR-150-5p inhibitors, miR-150-5p ADV or short hairpin RNA (shRNA) of Notch3 were transfected to ADSCs for analyzing the effects on osteogenesis. The mixture of hydroxyapatite/tricalcium phosphate (HA/TCP) ceramic powders and transfected ADSCs was implanted into BALB/C nude mice. Micro-CT and histological methods were performed to evaluate the new bone formation. Compared with negative control (NC) and miR-150-5p overexpression, inhibition of miR-150-5p increased ADSCs osteogenesis by regulating Notch3. MiR-150-5p overexpression decreased the expression of pFAK, pERK1/2, and RhoA, while these were up-regulated when miR-150-5p was inhibited, or notch3 was silenced. Furthermore, miR-150-5p inhibition partially reversed the suppression effect of notch3 knockdown on osteogenesis in vitro and in vivo. This study demonstrated the critical function of miR-150-5p during osteogenesis. The combination of ADSCs with miR-150-5p inhibition and HA/TCP might be a promising strategy for bone damage repair. STATEMENT OF SIGNIFICANCE: Osteoporosis is a common chronic metabolic bone disease in humans. Bone tissue engineering based on mesenchymal stem cells, biomaterials, and growth factors, provides a promising way to treat osteoporosis and bone defects. ADSCs commonly differentiate into adipose cells, they can also differentiate into osteogenic cell lineages. Nucleic acids and protein have usually been considered as regulators of ADSCs osteogenic differentiation. In the current study, we demonstrated the combination of ADSCs with miR-150-5p inhibition and hydroxyapatite/tricalcium phosphate ceramic powders enhanced bone regeneration. Furthermore, miR-150-5p/Notch3 axis regulating osteogenesis via the FAK/ERK1/2 and RhoA pathway was assessed. The current study showed the application of ADSCs in bone regeneration might be a promising strategy for osteoporosis and bone damage repairing.

Gas-to-Aerosol Phase Partitioning of Atmospheric Water-Soluble Organic Compounds at a Rural Site in China: An Enhancing Effect of NH3 on SOA Formation.

Partitioning gaseous water-soluble organic compounds (WSOC) to the aerosol phase is a major formation pathway of atmospheric secondary organic aerosols (SOA). However, the fundamental mechanism of the WSOC-partitioning process remains elusive. By simultaneous measurements of both gas-phase WSOC (WSOCg) and aerosol-phase WSOC (WSOCp) and formic and acetic acids at a rural site in the Yangtze River Delta (YRD) region of China during winter 2019, we showed that WSOCg during the campaign dominantly partitioned to the organic phase in the dry period (relative humidity (RH) < 80%) but to aerosol liquid water (ALW) in the humid period (RH > 80%), suggesting two distinct SOA formation processes in the region. In the dry period, temperature was the driving factor for the uptake of WSOCg. In contrast, in the humid period, the factors controlling WSOCg absorption were ALW content and pH, both of which were significantly elevated by NH3 through the formation of NH4NO3 and neutralization with organic acids. Additionally, we found that the relative abundances of WSOCp and NH4NO3 showed a strong linear correlation throughout China with a spatial distribution consistent with that of NH3, further indicating a key role of NH3 in WSOCp formation at a national scale. Since WSOCp constitutes the major part of SOA, such a promoting effect of NH3 on SOA production by elevating ALW formation and WSOCg partitioning suggests that emission control of NH3 is necessary for mitigating haze pollution, especially SOA, in China.

Emerging Potential of Exosomes on Adipogenic Differentiation of Mesenchymal Stem Cells.

The mesenchymal stem cells have multidirectional differentiation potential and can differentiate into adipocytes, osteoblasts, cartilage tissue, muscle cells and so on. The adipogenic differentiation of mesenchymal stem cells is of great significance for the construction of tissue-engineered fat and the treatment of soft tissue defects. Exosomes are nanoscale vesicles secreted by cells and widely exist in body fluids. They are mainly involved in cell communication processes and transferring cargo contents to recipient cells. In addition, exosomes can also promote tissue and organ regeneration. Recent studies have shown that various exosomes can influence the adipogenic differentiation of stem cells. In this review, the effects of exosomes on stem cell differentiation, especially on adipogenic differentiation, will be discussed, and the mechanisms and conclusions will be drawn. The main purpose of studying the role of these exosomes is to understand more comprehensively the influencing factors existing in the process of stem cell differentiation into adipocytes and provide a new idea in adipose tissue engineering research.

[Pollution Characteristics and Sources of Wintertime Atmospheric Brown Carbon at a Background Site of the Yangtze River Delta Region in China].

To investigate the pollution characteristics and sources of atmospheric brown carbon (BrC) in Chongming Island, a background site of the Yangtze River Delta (YRD) region in China, PM2.5 samples collected from December 2018 to January 2019 were analyzed to determine their chemical compositions and optical properties. The results showed that the light absorption coefficient (Abs365,M) of BrC extracted by methanol at 365 nm was (5.39±3.33) M-1·m-1, which was 1.3 times of the water extracted BrC. Both increased significantly with the increase of pH values, suggesting that less acidic conditions can enhance the light absorption ability of BrC. In winter, both Abs365 and MAE365 (mass absorption efficiency) were higher in the nighttime than in the daytime. A strong linear correlation observed between Abs365 and levoglucosan (R2=0.72) indicated that many light absorbing substances in Chongming Island were derived from biomass burning emissions. During the campaign, nitro-aromatic compounds (NACs) and PAHs accounted for (1.5±1.1) ng·m-3 and (8.3±4.7) ng·m-3, respectively, contributing to 0.1% and 0.067% of the absorption of the total BrC at 365 nm, respectively. Positive matrix factorization (PMF) analysis further showed that biomass and fossil fuel combustions were the main sources of BrC in Chongming Island in winter, accounting for 56% of the total BrC, followed by secondary formation, accounting for 24% of the total BrC, with road dust contributing only 6%.

Important contribution of N2O5 hydrolysis to the daytime nitrate in Xi'an, China during haze periods: Isotopic analysis and WRF-Chem model simulation.

Nitrate, as one of the major components of tropospheric aerosols, plays a crucial role in winter haze formation. While, the formation mechanism of the high production of nitrate in Chinese megacities is still not fully understood. To quantify the contributions of major formation pathways to nitrate, airborne particles in Xi'an, inland China during the winter of 2017 were measured and analyzed for the water-soluble ions and stable nitrogen/oxygen isotope compositions of nitrate in PM2.5, followed by a WRF-Chem model simulation. The oxygen isotopic results indicated that N2O5 hydrolysis was an important formation pathway for the daytime nitrate in the haze episodes. The model simulation further revealed that N2O5 hydrolysis contribution increased from 8.2% to 20.5% of the total nitrate over 14:00-16:00 p.m., clearly showing that N2O5 formation followed by a heterogeneous hydrolysis to nitrate can effectively proceed in daytime under the abundantly co-existing O3, NO2 and NH3 conditions.

Spatial and Temporal Distributions and Sources of Anthropogenic NMVOCs in the Atmosphere of China: A Review.

As the key precursors of O3, anthropogenic non-methane volatile organic compounds (NMVOCs) have been studied intensively. This paper performed a meta-analysis on the spatial and temporal variations of NMVOCs, their roles in photochemical reactions, and their sources in China, based on published research. The results showed that both non-methane hydrocarbons (NMHCs) and oxygenated VOCs (OVOCs) in China have higher mixing ratios in the eastern developed cities compared to those in the central and western areas. Alkanes are the most abundant NMHCs species in all reported sites while formaldehyde is the most abundant among the OVOCs. OVOCs have the highest mixing ratios in summer and the lowest in winter, which is opposite to NMHCs. Among all NMVOCs, the top eight species account for 50%-70% of the total ozone formation potential (OFP) with different compositions and contributions in different areas. In devolved regions, OFP-NMHCs are the highest in winter while OFP-OVOCs are the highest in summer. Based on positive matrix factorization (PMF) analysis, vehicle exhaust, industrial emissions, and solvent usage in China are the main sources for NMHCs. However, the emission trend analysis showed that solvent usage and industrial emissions will exceed vehicle exhaust and become the two major sources of NMVOCs in near future. Based on the meta-analysis conducted in this work, we believe that the spatio-temporal variations and oxidation mechanisms of atmospheric OVOCs, as well as generating a higher spatial resolution of emission inventories of NMVOCs represent an area for future studies on NMVOCs in China.

Rapid sulfate formation from synergetic oxidation of SO2 by O3 and NO2 under ammonia-rich conditions: Implications for the explosive growth of atmospheric PM2.5 during haze events in China.

Extremely high levels of atmospheric sulfate aerosols have still frequently occurred in China especially in winter haze periods and often been underestimated by models due to some missing formation mechanisms. Here we investigated the heterogeneous reaction dynamics of SO2 oxidation by the abundantly co-existing O3 and NO2 in the urban atmosphere of China by using a laboratory smog chamber simulation technique. Our results showed that with an increase of NH3 concentrations from 0.05 ppm to 1.5 ppm, SO2 oxidation by O3 can be greatly promoted and lead to an exponential increase of diameter growth factor (GF) of particles in the chamber from 1.29 to 1.98 for NaCl seeds and from 1.20 to 1.60 for (NH4)2SO4 seeds, along with an increasing uptake coefficient (γ) of SO2 from 4.47 × 10-5 to 1.52 × 10-4 on NaCl seeds and from 2.32 × 10-5 to 5.74 × 10-5 on (NH4)2SO4 seeds, respectively. The heterogeneous production of sulfate from oxidation of SO2 under NH3-rich conditions by O3 and NO2 mixture in the chamber was 2.0-3.5 times the sum of sulfate from SO2 oxidations by O3 and NO2, suggesting a strongly synergetic effect of the mixed oxidants on the heterogeneous oxidation of SO2, which can cause rapid formation of (NH4)2SO4 and NH4NO3 and is responsible for the explosive growth of PM2.5 in the winter haze period of China. Our chamber results further showed that such synergetic process is only efficient under NH3-rich conditions, clearly indicating that the combined controls on O3, NOx and NH3 are necessary for further mitigating the PM2.5 pollution in China.

Acute exposure to N-Ethylpentylone induces developmental toxicity and dopaminergic receptor-regulated aberrances in zebrafish larvae.

N-Ethylpentylone (NEP) is one of the most recent novel stimulants, and there is limited understanding of its toxicity. Here we employed zebrafish model for analyzing the effects of NEP on early embryos and cardiovascular and nervous systems at late developmental stages. We first observed multi-malformations in early embryos and larvae after NEP administration, together with significant deregulations of brain and heart development-associated genes (neurog1, her6, elavl3, nkx2.5, nppa, nppb, tnnt2a) at transcriptional level. Low-dosed NEP treatment induced an anxiety-like phenotype in zebrafish larvae, while higher doses of NEP exerted an inhibitory effect on locomotion and heart rate. Besides, the expression of th (tyrosine hydroxylase) and th2 (tyrosine hydroxylase 2), identifying dopamine (DA) release, were significantly increased during one-hour free swimming after effective low-dosed NEP administration, along with the upregulation of gene fosab and fosb related to stress and anxiety response. D1R antagonist SCH23390 and D2R antagonist sulpiride partially alleviated the aberrances of locomotion and heart rate, indicating dopaminergic receptors were involved in the bidirectional dosage-dependent pattern of NEP-induced performance. Meanwhile, sulpiride offset the upregulated expression of th, th2 and fosab in the group of 1.5 µM NEP, which highlighted the significant role of D2R in NEP-induced locomotive effects. This study systematically described the developmental, neuronal and cardiac toxicity of NEP in zebrafish, and identified the dopaminergic receptors as one of the downstream effectors of NEP administration.

Determination of Ethyl Glucuronide and Ethyl Sulfate in Human Whole Blood and Vitreous Humor by LC-MS-MS and Applications to the Interpretation of Postmortem Ethanol Findings.

Identifying the source of ethanol in a decedent remained a complicated problem for forensic toxicologists because of postmortem ethanol formation. As ethanol's non-oxidative metabolites, ethyl glucuronide (EtG) and ethyl sulfate (EtS) have the potential to distinguish between antemortem ethanol consumption and postmortem ethanol formation, due to their high sensitivity and selectivity. In the current study, a simple and quick liquid chromatography tandem mass spectrometry (LC-MS/MS) method was developed for the determination of EtG and EtS in human whole blood and vitreous humor (VH). A total of 20 µL of the sample was precipitated by methanol, and the analytes were detected by LC-MS/MS in a run of 6 min. This method achieved high sensitivity (limits of detection: 2 ng/mL for both EtG and EtS), with linearity in the range of 5-10,000 ng/mL in both whole blood and VH. Deviations in accuracy, inter- and intra-day precision were all lower than 15% at three quality control levels. Subsequently, this method was applied to 62 real forensic cases. Only blood samples were available in 52 cases. Paired blood and VH samples were present in 10 cases. The concentrations of EtG and EtS in blood were in the range of 0-22,264.8 ng/mL and 0-2,126.0 ng/mL, respectively. In one case with both blood and VH, the blood ethanol concentration was 1.22 mg/mL, with EtG and EtS both below limits of quantification (5 ng/mL) in VH, and no EtG and EtS found in whole blood. The results suggested that EtG and EtS were useful markers for the interpretation of ethanol resource in postmortem blood and VH.