Real Refractive Indices and Formation Yields of Secondary Organic Aerosol Generated from Photooxidation of Limonene and α-Pinene: The Effect of the HC/NO_<i>x</i> Ratio

The refractive index is an important property affecting aerosol optical properties, which in turn help determine the aerosol direct effect and satellite retrieval results. Here, we investigate the real refractive indices (<i>m</i>_r) of secondary organic aerosols (SOA) generated from the photooxidation of limonene and α-pinene with different HC/NO_<i>x</i> ratios. Refractive indices were obtained from polar nephelometer data using parallel and perpendicular polarized 532 nm light combined with measured size distributions, and retrievals were performed using a genetic algorithm and Mie–Lorenz scattering theory. The absolute error associated with the <i>m</i>_r retrieval is ±0.03, and reliable retrievals are possible for mass concentrations above 5–20 μg/m³ depending on particle size. The limonene SOA data suggest the most important factor controlling the refractive index is the HC/NO_<i>x</i> ratio; the refractive index is much less sensitive to the aerosol age or mass concentration. The refractive index ranges from about 1.34 to 1.56 for limonene and from 1.36 to 1.52 for α-pinene, and generally decreases as the HC/NO_<i>x</i> ratio increases. Especially for limonene, the particle diameter is also inversely related to the HC/NO_<i>x</i> ratio; the final size mode increases from 220 to 330 nm as the HC/NO_<i>x</i> ratio decreases from 33 to 6. In an effort to explore the ability of models from the literature to explain the observed refractive indices, a recent limonene oxidation mechanism was combined with SOA partitioning and a structure–property relationship for estimating refractive indices of condensing species. The resulting refractive indices fell in a much narrower range (1.475 ± 0.02) of <i>m</i>_r than observed experimentally. We hypothesize the experimentally observed high <i>m</i>_r values are due to oligomerization and the low values to water uptake, small soluble molecules such as glyoxal and other factors, each of which is not included in the oxidation mechanism. Aerosol formation yields were measured over the mass concentration range from 6 to ∼150 μg/m³, over which they increased steadily, and were higher for high HC/NO_<i>x</i> ratio experiments

Highly Selective Excited State Intramolecular Proton Transfer (ESIPT)-Based Superoxide Probing

Two novel fluorescent probe conjugates of 2-(benzothiazol-2-yl)-phenol (HBT) enable ratiometric and selective superoxide detection by an established <i>excited state intramolecular proton transfer</i> (ESIPT) mechanism giving a 60-fold intensity increase

Dependence of Real Refractive Indices on O:C, H:C and Mass Fragments of Secondary Organic Aerosol Generated from Ozonolysis and Photooxidation of Limonene and α-Pinene

<div><p>The refractive index is a fundamental property controlling aerosol optical properties. Secondary organic aerosols have variable refractive indices, presumably reflecting variations in their chemical composition. Here, we investigate the real refractive indices (m_r) and chemical composition of secondary organic aerosols (SOA) generated from the oxidation of α-pinene and limonene with ozone and NO_x/sunlight at different HC/NO_x ratios. Refractive indices were retrieved from polar nephelometer measurements using parallel and perpendicular polarized 532-nm light. Particle chemical composition was monitored with a high-resolution time-of-flight aerosol mass spectrometer (HR-Tof-AMS). For photochemically generated SOA, the values of refractive indices are consistent with prior results, and ranged from about 1.34 to 1.55 for limonene and from 1.44 to 1.47 for α-pinene, generally increasing as the particles grew. While AMS fragments are strongly correlated to the refractive index for each type of SOA, the relationships are in most cases quite different for different SOA types. Consistent with its wide range of refractive index, limonene SOA shows larger variations compared to α-pinene SOA for most parameters measured with the AMS, including H:C, O:C, f₄₃ (<i>m/z</i> 43/organic), f_C4H7⁺, and others. Refractive indices for α-pinene ozonolysis SOA also fell in narrow ranges; 1.43–1.45 and 1.46–1.53 for particles generated at 19–22 and 23–29°C, respectively, with corresponding small changes of f₄₃ and H:C ratio and other parameters. Overall, H:C ratio, m/z 43 and 55 (C₂H₃O⁺, C₄H₇⁺) were the best correlated with refractive index for all aerosol types investigated. The relationships between m_r and most fragments support the notion that increasing condensation of less oxygenated semivolatile species (with a possible role for a concomitant decrease in low refractive index water) is responsible for the increasing m_rs observed as the experiments progress. However, the possibility that oligomerization reactions play a role cannot be ruled out.</p> </div

MOESM1 of A mitochondrial division inhibitor, Mdivi-1, inhibits mitochondrial fragmentation and attenuates kainic acid-induced hippocampal cell death

Additional file 1: Figure S1. A crystal violet-stained brain section (A) and the number of NeuN-positive cells in the CA3 region of CTL, KA, KA+M, and M mice (B). Figure S2. Morphological properties of mitochondria in the CA3 regions of CTL, KA, KA+M, and M mice; mitochondrial area and perimeter (A) and mitochondrial number/field and percentage of deformed mitochondria (B). Figure S3. Immunoflourescence images showing the GABA receptor ι-1 and p-Drp1 in the CA3 regions (A) and the percentage of p-Drp1 and GABA-positive cells (B). Figure S4. Mdivi-1 effects on mitochondrial OPA1, Mfn2, and CypD expression in the hippocampus 24h after KA injection.  Figure S5. Iba-1 expression levels (A) and the number of activated microglial cells (B) in the CA3 regions of CTL, KA, KA+M, and M mice

Highly Fluorescent and Specific Molecular Probing of (Homo)Cysteine or Superoxide: Biothiol Detection Confirmed in Living Neuronal Cells

Chemodosimetric action in detection of cysteine and homocysteine (310- and 290-fold) and superoxide inputs (336-fold increase) gives significant fluorescence intensity increases. Detection limits of 2.13 × 10^–5 M, 1.37 × 10^–5 M, and 2.71 × 10^–5 M, respectively, are biorelevant and are consistent with “OR” logic gating, demonstrated in intracellular biothiol detection in neuronal cells by way of novel fluorescein derivatization. As per our knowledge, this is the first example of a novel fluorescent probe based on the nucleophilic substitution reaction of biothiols and superoxide through ester cleavage

La Croix du Nord : supplément régional à la Croix de Paris ["puis" grand journal quotidien du Nord de la France]

22 décembre 19091909/12/22 (A21,N6990).Appartient à l’ensemble documentaire : NordPdeC

MOESM6 of High-fat diet-induced obesity exacerbates kainic acid-induced hippocampal cell death

Additional file 6: Table S2. List of primary antibodies

MOESM2 of High-fat diet-induced obesity exacerbates kainic acid-induced hippocampal cell death

Additional file 2: Table S1. Effects of a HFD on serum metabolic parameters

Significant Reductions in Secondary Aerosols after the Three-Year Action Plan in Beijing Summer

Air quality in China has continuously improved during the Three-Year Action Plan (2018–2020); however, the changes in aerosol composition, properties, and sources in Beijing summer remain poorly understood. Here, we conducted real-time measurements of aerosol composition in five summers from 2018 to 2022 along with WRF-Community Multiscale Air Quality simulations to characterize the changes in aerosol chemistry and the roles of meteorology and emission reductions. Largely different from winter, secondary inorganic aerosol and photochemical-related secondary organic aerosol (SOA) showed significant decreases by 55–67% in summer, and the most decreases occurred in 2021. Comparatively, the decreases in the primary aerosol species and gaseous precursors were comparably small. While decreased atmospheric oxidation capacity as indicated by ozone changes played an important role in changing SOA composition, the large decrease in aerosol liquid water and small increase in particle acidity were critical for nitrate changes by decreasing gas-particle partitioning substantially (∼28%). Analysis of meteorological influences demonstrated clear and similar transitions in aerosol composition and formation mechanisms at a relative humidity of 50–60% in five summers. Model simulations revealed that emission controls played the decisive role in reducing sulfate, primary OA, and anthropogenic SOA during the Three-Year Action Plan, while meteorology affected more nitrate and biogenic SOA