Multiphase Chemistry in the Atmosphere.

Earth's atmosphere comprises a complex mix of gas and condensed phases, where condensed phases facilitate multiphase chemical reactions that would not occur in the gas phase alone. These reactions drive dynamic physical and chemical processes across various spatial and temporal scales, playing a crucial role in the cycling of atmospheric trace constituents. Multiphase chemistry significantly influences geochemical cycles, human health, and climate.

Reducing Soil-Emitted Nitrous Acid as a Feasible Strategy for Tackling Ozone Pollution.

Severe ozone (O) pollution has been a major air quality issue and affects environmental sustainability in China. Conventional mitigation strategies focusing on reducing volatile organic compounds and nitrogen oxides (NO) remain complex and challenging. Here, through field flux measurements and laboratory simulations, we observe substantial nitrous acid (HONO) emissions () enhanced by nitrogen fertilizer application at an agricultural site.

Direct Formation of Electronic Excited NO Contributes to the High Yield of HONO during Photosensitized Renoxification.

Photosensitized renoxification of HNO is found to produce HONO in an unexpectedly high yield, which has been considered an important source for atmospheric HONO. Conventionally, the production of HONO is ascribed to the secondary photolysis of the primarily formed NO. In this study, by using humic acid (HA) as a model environmental photosensitizer, we provide evidence of the direct formation of NO in its electronic excited state (NO*) as a key intermediate during the photosensitizing renoxification of HNO.

Key Role of Equilibrium HONO Concentration over Soil in Quantifying Soil-Atmosphere HONO Fluxes.

Nitrous acid (HONO) is an important component of the global nitrogen cycle and can regulate the atmospheric oxidative capacity. Soil is an important source of HONO. [HONO]*, the equilibrium gas-phase concentration over the aqueous solution of nitrous acid in the soil, has been suggested as a key parameter for quantifying soil fluxes of HONO.

Photoinduced Uptake and Oxidation of SO on Beijing Urban PM.

Sulfate, as a major component of aerosol particles, greatly contributes to haze formation and affects global climate change. Although formation pathways of sulfate aerosols from the conversion of SO have been extensively studied, the discrepancy between field observations and model simulations suggests that there are still unknown sulfate sources. Herein, we report for the first time a photoinduced SO uptake and oxidation pathway in Beijing urban PM aerosols.

Enhanced Photochemical Volatile Organic Compounds Release from Fatty Acids by Surface-Enriched Fe(III).

Both Fe(III) and fatty acids are ubiquitous and important species in environmental waters. Because they are amphipathic, many fatty acids are surface active and prone to enrichment at the air-water interface. Here, we report that by using nonanoic acid (NA) as a model fatty acid, coexisting Fe(III), even at concentrations as low as 1 μM, markedly enhanced the photochemical release of NA-derived volatile organic compounds (VOCs) such as octanal and octane into the air.

Development of Bisindole-Substituted Aminopyrazoles as Novel GSK-3β Inhibitors with Suppressive Effects against Microglial Inflammation and Oxidative Neurotoxicity.

Development of glycogen synthase kinase-3β (GSK-3β) inactivation-centric agents with polypharmacological profiles is increasingly recognized as a promising therapeutic strategy against the multifactorial etiopathology of Alzheimer's disease (AD). In this respect, a series of disubstituted aminopyrazole derivatives were designed and synthesized as a new class of GSK-3β inhibitors. Most of these derivatives possess GSK-3β inhibitory activities with IC values in the micromolar ranges, among which bisindole-substituted aminopyrazole derivative displayed moderate GSK-3β inhibition (IC = 1.

Photochemical aging of Beijing urban PM: Production of oxygenated volatile organic compounds.

PM has become the dominant atmospheric pollutant in many countries. Many components of PM are highly photoactive. However, the photochemical aging of PM remains poorly understood.

The Key Role of Sulfate in the Photochemical Renoxification on Real PM.

The active nitrogen species (HONO, NO, and NO) have important impacts on the atmospheric oxidative capacity and the transformation of many atmospheric species. In this study, a fast photochemical renoxification rate of adsorbed HNO/NO to active nitrogen species (HONO, NO, and NO) was detected on real urban PM, and sulfate was found to play a key role in this process. Different from the reported direct photolysis pathway, the photochemical reaction of HNO/NO on PM is dominated by a photosensitizing mechanism.

Development of Novel -hydroxypyridone Derivatives as Potential Anti-Ischemic Stroke Agents.

Our previous study had identified ciclopirox (CPX) as a promising lead compound for treatment of ischemic stroke. To find better neuroprotective agents, a series of -hydroxypyridone derivatives based on CPX were designed, synthesized, and evaluated in this study. Among these derivatives, compound exhibits significant neuroprotection against oxygen glucose deprivation and oxidative stress-induced injuries in neuronal cells.

Photochemical Aging of Soot in the Aqueous Phase: Release of Dissolved Black Carbon and the Formation of O.

The photochemical aging of soot in the aqueous phase could have an important influence on water environments such as fog water and wet aerosols in the atmosphere, as well as lakes and oceans. In this study, we systematically investigated the photochemistry of soot in the aqueous phase. Soot releases dissolved black carbon into the aqueous phase during photoreactions, which is attributed to the phototransformation of the nonpolar unsaturated C-H species in soot to polar carbonyl-containing species.

Nitrate-Enhanced Oxidation of SO on Mineral Dust: A Vital Role of a Proton.

Heterogeneous oxidation of SO on mineral dust is a significant source of sulfate in the atmosphere. Given that a large fraction of nitrate is deposited on the mineral aerosols, the determination of the effect of nitrate on the SO oxidation on mineral dust and its in-depth mechanism are much desired. In this work, we report nitrate-enhanced SO oxidation on authentic mineral dust.

Neuroprotective Effect of Natural Alkaloid Fangchinoline Against Oxidative Glutamate Toxicity: Involvement of Keap1-Nrf2 Axis Regulation.

Oxidative glutamate toxicity plays a vital role in the neurodegeneration diseases, including Alzheimer's diseases (AD). This study set out with the aim to investigate the beneficial effects of fangchinoline (FAN), a natural alkaloid, against glutamate-induced oxidative damage, and to clarify the underlying cellular and biochemical mechanisms. FAN prevented HT22 cells death from oxidative glutamate cytotoxicity in a dose-dependent manner, and significantly attenuated the overproduction of intracellular reactive oxygen species (ROS) and reversed the reduction of superoxide dismutase (SOD) activity induced by glutamate.

Role of elemental carbon in the photochemical aging of soot.

Soot, which consists of organic carbon (OC) and elemental carbon (EC), is a significant component of the total aerosol mass in the atmosphere. Photochemical oxidation is an important aging pathway for soot. It is commonly believed that OC is photoactive but EC, albeit its strong light absorption, is photochemically inert.

Photochemical Aging of Beijing Urban PM: HONO Production.

Photochemical aging represents an important transformation process of aerosol particles in the atmosphere, which greatly influences the physicochemical properties and the environmental impact of aerosols. In this work, we find that Beijing urban PM aerosol particles release substantial HONO, a significant precursor of •OH radicals, into the gas phase during the photochemical aging process. The generation of HONO exhibits a high correlation with the amount of nitrate in PM.