Reduced Aerosol Uptake of Hydroperoxyl Radical May Increase the Sensitivity of Ozone Production to Volatile Organic Compounds

A multiphase chemical kinetic box model (PKU-MARK) was constructed to numerically drive the hydroperoxyl radical (HO2) uptake coefficients (γHO2) using observation data from a comprehensive summer field campaign in rural China. The associated multiphase chemistry mechanism of HO2 uptake was investigated. The chemical and physical features of aerosol particles were explicitly considered in the simulations. The importance of transition metals in HO2 heterogeneous processes was confirmed by a heterogeneous flux investigation. Heterogeneous processes were proposed to have impacts on the ozone sensitivity regime, which can be separated into either “nitrogen oxides (NOx) limited” (peroxyl radical self-reaction dominates the chain termination step) or “volatile organic compounds (VOCs) limited” (the OH + NO2 reaction dominates). In this study, while the HO2 heterogeneous process could not change the ozone sensitivity regime classification in a single day, it could decrease net ozone production rates to 6 ppbV h–1, particularly in the morning of the “VOCs limited” period. The impacts of aerosols on ozone production sensitivity were further analyzed to demonstrate the potential tensions between particle and ozone control strategies in high-aerosol loading areas. Effective reduction of VOCs while applying the particle control strategy may be a viable solution that requires further investigation

Characteristics of Particulate Carbon Emissions from Real-World Chinese Coal Combustion

Particulate matter emissions from a series of different Chinese coal combustion systems were collected and analyzed for elemental and organic carbon (EC, OC), and molecular markers. Emissions from both industrial boilers and residential stoves were investigated. The coal used in this study included anthracite, bituminite, and brown coal, as well as commonly used coal briquettes produced in China for residential coal combustion. Results show significant differences in the contribution of carbonaceous species to particulate mass emissions. Industrial boilers had much higher burn out of carbon yielding particulate matter emissions with much lower levels of OC, EC, and speciated organic compounds, while residential stoves had significantly higher emissions of carbonaceous particulate matter with emission rates of approximately 100 times higher than that of industrial boilers. Quantified organic compounds emitted from industrial boilers were dominated by oxygenated compounds, of which 46−68% were organic acids, whereas the dominate species quantified in the emissions from residential stoves were PAHs (38%) and n-alkanes (20%). An important observation was the fact that emission factors of PAHs and the distribution of hopanoids were different among the emissions from industrial and residential coal combustion even using the same coal for combustion. Although particulate matter emissions from industrial and residential combustion were different in many regards, picene was detected in all samples with detectable OC mass concentrations, which supports the use of this organic tracer for OC from all types of coal combustion. 17α(H),21β(H)-29-norhopane was the predominant hopanoid in coal combustion emissions, which is different from mobile source emissions and may be used to distinguish emissions from these different fossil fuel sources

Observation-Based Estimations of Relative Ozone Impacts by Using Volatile Organic Compounds Reactivities

The incremental reactivity and measured volatile organic compound (VOC) concentrations have been widely used to estimate ozone impacts of VOC emissions. However, these studies usually use the maximum incremental reactivity (MIR) that deviated from the real airshed conditions and ignore the consumption of VOCs due to photochemical reactions between emissions and measurement. This study proposed that ozone impacts should be derived by multiplying incremental reactivities based on real airshed conditions (R-IR) by ambient VOC concentrations corrected by kinetic reactivity. This method reflected the ambient photo-oxidation condition and the chemical decay of VOCs in the period between their emissions and measurement. This study derived the R-IR scales and estimated the ozone impact of 79 VOCs in the summer in the megacity Shanghai and small city Taian in eastern China. It was found that alkenes and aromatics had the highest ozone impacts in the megacity Shanghai and small city Taian, respectively. The R-IR values in those two Chinese cities showed significant consistency with U.S. MIR, indicating that ozone in eastern China could be generally VOC limited

Observation-Based Estimations of Relative Ozone Impacts by Using Volatile Organic Compounds Reactivities

The incremental reactivity and measured volatile organic compound (VOC) concentrations have been widely used to estimate ozone impacts of VOC emissions. However, these studies usually use the maximum incremental reactivity (MIR) that deviated from the real airshed conditions and ignore the consumption of VOCs due to photochemical reactions between emissions and measurement. This study proposed that ozone impacts should be derived by multiplying incremental reactivities based on real airshed conditions (R-IR) by ambient VOC concentrations corrected by kinetic reactivity. This method reflected the ambient photo-oxidation condition and the chemical decay of VOCs in the period between their emissions and measurement. This study derived the R-IR scales and estimated the ozone impact of 79 VOCs in the summer in the megacity Shanghai and small city Taian in eastern China. It was found that alkenes and aromatics had the highest ozone impacts in the megacity Shanghai and small city Taian, respectively. The R-IR values in those two Chinese cities showed significant consistency with U.S. MIR, indicating that ozone in eastern China could be generally VOC limited

Design and Synthesis of Novel Arctigenin Analogues for the Amelioration of Metabolic Disorders

Analogues of the natural product (−)-arctigenin, an activator of adenosine monophosphate activated protein kinase, were prepared in order to evaluate their effects on 2-deoxyglucose uptake in L6 myotubes and possible use in ameliorating metabolic disorders. Racemic arctigenin <b>2a</b> was found to display a similar uptake enhancement as does (−)-arctigenin. As a result, the SAR study was conducted utilizing racemic compounds. The structure–activity relationship study led to the discovery of key substitution patterns on the lactone motif that govern 2-deoxyglucose uptake activities. The results show that replacement of the <i>para</i>-hydroxyl group of the C-2 benzyl moiety of arctigenin by Cl has a pronounced effect on uptake activity. Specifically, analogue <b>2p</b>, which contains the <i>p</i>-Cl substituent, stimulates glucose uptake and fatty acid oxidation in L6 myotubes

Aerosol Liquid Water Driven by Anthropogenic Inorganic Salts: Implying Its Key Role in Haze Formation over the North China Plain

This study reveals aerosol liquid water content (ALWC) in PM_2.5 ranged from 2% up to 74%, and the associated secondary inorganic fraction rose from 24% to 55%, while ambient relative humidity (RH) increased from 15% to 83% in the atmosphere over Beijing. Unexpectedly, the secondary inorganic fraction in PM_2.5 increased with an increase in the ambient RH, which is a meteorological parameter independent of anthropogenic activities, indicating the presence of a feedback mechanism driven by Henry’s law and thermodynamic equilibrium. During haze episodes, simultaneously elevated RH levels and anthropogenic secondary inorganic mass concentrations resulted in an abundant ALWC. The condensed water could act as an efficient medium for multiphase reactions, thereby facilitating the transformation of reactive gaseous pollutants into particles and accelerating the formation of heavy haze. ALWC was well correlated with the mass concentrations of both nitrate and sulfate, indicating both nitrate and sulfate salts play key roles in determining ALWC. Coincident with a significant reduction in SO₂ emissions throughout China, nitrates will become a dominant anthropogenic inorganic salt driving ALWC. Thus, the abundance of ALWC and its effects on the aerosol chemistry and climate should be reconsidered

Novel Class of Colony-Stimulating Factor 1 Receptor Kinase Inhibitors Based on an <i>o</i>‑Aminopyridyl Alkynyl Scaffold as Potential Treatment for Inflammatory Disorders

Colony-stimulating factor 1 receptor (CSF-1R) is involved in inflammatory disorders as well as in many types of cancer. Based on high-throughput screening and docking results, we performed a detailed structure–activity-relationship study, leading to the discovery of a new series of compounds with nanomolar IC50 values against CSF-1R without the inhibition of fibroblast growth factor receptors. One of the most promising hits, compound 29, potently inhibited CSF-1R kinase with an IC50 value of 0.7 nM, while it showed no inhibition to the same family member FMS-like tyrosine kinase 3. Compound 29 displayed excellent anti-inflammatory effects against RAW264.7 macrophages indicated by significant inhibition against the activation of the CSF-1R pathway with low cytotoxicity. In addition, compound 29 exhibited strong in vivo anti-inflammatory efficacy alongside favorable drug characteristics. This novel compound 29 may serve as a new drug candidate with promising applications in inflammatory disorders

Optimization and Synthesis of Pyridazinone Derivatives as Novel Inhibitors of Hepatitis B Virus by Inducing Genome-free Capsid Formation

The capsid of hepatitis B virus (HBV) plays a vital role in virus DNA replication. Targeting nucleocapsid function has been demonstrated as an effective approach for anti-HBV drug development. A high-throughput screening and mechanism study revealed the hit compound <b>4a</b> as an HBV assembly effector (AEf), which could inhibit HBV replication by inducing the formation of HBV DNA-free capsids. The subsequent SAR study and drug-like optimization resulted in the discovery of the lead candidate <b>4r</b>, with potent antiviral activity (IC₅₀ = 0.087 ± 0.002 μM), low cytotoxicity (CC₅₀ = 90.6 ± 2.06 μM), sensitivity to nucleoside analogue-resistant HBV mutants, and synergistic effect with nucleoside analogues in HepG2.2.15 cells