Covalent-organic frameworks (COFs) as porous crystalline materials show promising potential applications. However,d eveloping facile strategies for the construction of COFs directly from amorphous covalent organic polymers (COPs) is still agreat challenge.T othis end, we report anovel approach for easy preparation of COFs from amorphous COPs through the linkage replacement under different types of reactions.F our COFs with high crystallinity and porosity were constructed via the linkage substitution of polyimide-linked COPs to imine-linked COFs as well as imine-linked COPs to polyimide-linked COFs.T he realization of the linkage substitution would significantly expand the researchs cope of COFs.
The field of covalent organic frameworks (COFs) has been developed significantly in the past decade on account of their important characteristics and vast application potential. On the other hand, the discovery of novel synthetic methodology is still ac hallenging task to further promote the preparation of COFs.H erein, an interesting protocol for the conversion of amorphous nonporous covalent organic polymers (COPs) to COFs was established, affording four COFs with high crystallinity and porosity.S pecifically,i mine-linked amorphous COP-1 was successfully converted to COF-1-4 by replacing one type of linker with other organic building blocks. The realization of this conversion provides afacile method for constructing COFs from COPs.
Two two-dimensional covalent organic frameworks (COFs, TJNU-203 and TJNU-204) with high crystallinity and large specific surface areas are rationally fabricated from a three-connected distorted building block and linear linkers. The...
Dimethyl selenide (DMSe) is one of the major volatile
organoselenium
compounds released from aquatic and terrestrial environments through
microbial transformation and plant metabolism. The detailed processes
of DMSe leading to secondary organic aerosol (SOA) formation and the
pulmonary health effects induced by inhalation of DMSe-derived SOA
remain largely unknown. In this study, we characterized the chemical
composition and formation yields of SOA produced from the oxidation
of DMSe with OH radicals and O3 in controlled chamber experiments.
Further, we profiled the transcriptome-wide gene expression changes
in human airway epithelial cells (BEAS-2B) after exposure to DMSe-derived
SOA. Our analyses indicated a significantly higher SOA yield resulting
from the OH-initiated oxidation of DMSe. The oxidative potential of
DMSe-derived SOA, as measured by the dithiothreitol (DTT) assay, suggested
the presence of oxidizing moieties in DMSe-derived SOA at levels higher
than typical ambient aerosols. Utilizing RNA sequencing (RNA-Seq)
techniques, gene expression profiling followed by pathway enrichment
analysis revealed several major biological pathways perturbed by DMSe-derived
SOA, including elevated genotoxicity, DNA damage, and p53-mediated
stress responses, as well as downregulated cholesterol biosynthesis,
glycolysis, and interleukin IL-4/IL-13 signaling. This study highlights
the significance of DMSe-derived SOA as a stressor in human airway
epithelial cells.
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