A series of sustainable and reprocessible thermoplastic polyester elastomers P(BF-PBSS)s were synthesized using dimethyl-2,5-furandicarboxylate, 1,4-butanediol, and synthetic low-molecular-weight biobased polyester (PBSS).
Curcuminoids, namely curcumin and its analogs, are secondary metabolites that act as the primary active constituents of turmeric (Curcuma longa). The contents of these curcuminoids vary among species in the genus Curcuma. For this reason, we compared two wild strains and two cultivars to understand the differences in the synthesis of curcuminoids. Because the fluxes of metabolic reactions depend on the amounts of their substrate and the activity of the catalysts, we analyzed the metabolite concentrations and gene expression of related enzymes. We developed a method based on RNA sequencing (RNA-Seq) analysis that focuses on a specific set of genes to detect expression differences between species in detail. We developed a 'selection-first' method for RNA-Seq analysis in which short reads are mapped to selected enzymes in the target biosynthetic pathways in order to reduce the effect of mapping errors. Using this method, we found that the difference in the contents of curcuminoids among the species, as measured by gas chromatography-mass spectrometry, could be explained by the changes in the expression of genes encoding diketide-CoA synthase, and curcumin synthase at the branching point of the curcuminoid biosynthesis pathway.
The degradation of fluoroelastomers in hot HNO3 solution included the decrosslinking via hydrolysis of crosslinks and backbone cleavages by dehydrofluorination.
Perfluorooctanoic acid (PFOA) is an emerging persistent
organic
pollutant that is frequently detected throughout the drinking water
supply system. Here, we first found that PFOA could significantly
increase the formation of disinfection byproducts (DBPs) in unlined
iron pipes (UIPs) during the distribution process. The increased DBPs
were not due to the reaction of PFOA itself with free chlorine, but
the in situ formed Fe–PFOA complex played a key role. Notably,
PFOA could enhance iron release from UIPs and was greatly incorporated
into the iron particles to form Fe–PFOA complex. The •OH
generated by the Fe–PFOA heterogeneous reaction could break
large dissolved organic matter into small molecules that had higher
reactivity with chlorine. In addition, DBP precursors with more aromatic
structures were favorable for forming strong Fe−π interactions
with Fe–PFOA complex, resulting in more •OH for the
formation of aromatic DBPs. The cytotoxicity test showed that the
viability of cells exposed to DBPs from UIPs with 100 ng/L PFOA was
46.9%, while that without PFOA was 67.91%. Overall, this study provided
a new perspective on the risk of PFOA, with a focus not on PFOA itself
but on its potential to promote DBP-associated toxicity in iron-based
drinking water distribution pipes.
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