Seasonal variations and intercorrelations of polycyclic aromatic hydrocarbons, heavy metals and environmentally persistent free radicals in PM in Ulaanbaatar, Mongolia.

Simulated combustion experiments have identified polycyclic aromatic hydrocarbons (PAHs) and metal oxides as critical species in the formation of environmental persistent free radicals (EPFRs). However, little evidence exists regarding the interactions among PAHs, metals, and EPFRs in the real atmosphere. In this study, we collected PM samples in downtown Ulaanbaatar in four seasons from 2020 to 2021, and analyzed the seasonal variations of 16 PAHs, 14 heavy metals and EPFRs in PM.

Pollution characteristics and light-driven evolution of environmentally persistent free radicals in PM in two typical northern cities of China.

Environmentally persistent free radicals (EPFRs) in PM can pose significant health risks by generating reactive oxygen species (ROS). In this study, Beijing and Yuncheng were chosen as two representative northern cities of China that mainly relied on natural gas and coal respectively as the energy source for domestic heating in winter. The pollution characteristics and exposure risks of EPFRs in PM around the heating season of 2020 were investigated and compared between the two cities.

Gas-PM partitioning, health risks, and sources of atmospheric PAHs in a northern China city: Impact of domestic heating.

The diurnal variation, gas-particle partitioning, health risks, and sources of polycyclic aromatic hydrocarbons (PAHs) were investigated in a northern basin city of China in winter, 2020. The mean concentrations of particulate and gaseous PAHs were 87.90 ng m and 69.

Oxidative potential associated with water-soluble components of PM in Beijing: The important role of anthropogenic organic aerosols.

Oxidative stress is the mainstream toxicological mechanism for the adverse health outcomes of ambient aerosols. However, our understanding of the crucial redox-active species affecting the oxidative potential of water-soluble aerosols (OP) remains limited. In this study, the OP of PM in Beijing was measured using dithiothreitol (DTT) assay, including DTT consumption rate and ·OH formation rate.

Seasonal variation of dicarboxylic acids in PM in Beijing: Implications for the formation and aging processes of secondary organic aerosols.

Dicarboxylic acids are a group of highly oxidized components, which can provide insights into the formation mechanism and aging process of secondary organic aerosols (SOA). Based on the 12-h day and night PM samples collected in downtown Beijing in January, April, July and October of 2017, dicarboxylic acids and relevant components were measured to investigate their seasonal variation pattern and sources. High concentrations of the identified organic acids were observed, following the decreasing order of July > January > October > April.

A comprehensive comparison of residue-level methylation levels with the regression-based gene-level methylation estimations by ReGear.

Motivation: DNA methylation is a biological process impacting the gene functions without changing the underlying DNA sequence. The DNA methylation machinery usually attaches methyl groups to some specific cytosine residues, which modify the chromatin architectures. Such modifications in the promoter regions will inactivate some tumor-suppressor genes.

A catalyst-free four-component domino reaction for the synthesis of functionalized 3-acyl-1,5-benzodiazepines.

Various functional 3-acyl-1,5-benzodiazepines containing carboxyl, ester and acyl groups at the 2-position were synthesized via an efficient, sustainable and catalyst-free domino reaction. During the synthesis process, one new cycle and four new bonds (one C-C, two C-N and one C[double bond, length as m-dash]C) were constructed by the nucleophilic substitution, nucleophilic addition, dehydration and cyclization reaction by the H+ shift. Furthermore, a total of 26 examples were examined by reacting inexpensive starting materials of N,N-dimethylformamide dimethyl acetal, aromatic ketones, 1,2-phenylenediamine compounds and aldehyde derivatives.

Photocatalytic reduction of Cr (VI) on nano-sized red phosphorus under visible light irradiation.

Red phosphorus as a novel visible-light-responsive and metal-free photocatalyst has attracted extensive attention in the area of energy conversion and environmental remediation. Herein, nano-sized red phosphorus photocatalyst was synthesized via a hydrothermal and ultrasonic method and used for reduction of Cr (VI) for the first time. The as-prepared photocatalysts were characterized by XRD, UV-Vis-DRS, XPS, SEM, TEM and photoelectrochemical measurements.