Unveil the mechanism of photosensitized fluoroquinolones enhancing chlortetracycline photodegradation under simulated sunlight: Batch experiments and DFT calculation.

Fluoroquinolones (FQs), as the most commonly used antibiotics, are ubiquitous in the aquatic environment. The FQs' self-sensitization process could generate reactive oxygen species (ROS), which could react with other coexisting organic pollutants, impacting their transformation behaviors. However, the FQs' influences and mechanisms on the photochemical transformation of coexisting antibiotics are not yet revealed. In this study, we found ofloxacin (OFL) and norfloxacin (NOR), the two common FQs, can obviously accelerate chlortetracycline (CTC) photodegradation. In the presence of OFL and NOR (i.e., 10 µM), CTC photodegradation rate constants increased by 181.1% and 82.9%, respectively. With the help of electron paramagnetic resonance (EPR) and quenching experiments, this enhancement was attributed to aromatic ketone structure in FQs, which absorbed photons to generate ROS (i.e., 3OFL*, 3NOR*,1O2, and •OH). Notably, 3OFL* or 3NOR* was dominantly contributed to the enhanced CTC photodegradation, with the contribution ratios of 79.9% and 77.3% in CTC indirect photodegradation, respectively. Compared to CTC direct photodegradation, some new photodegradation products were detected in FQs solution, suggesting that 3OFL* or 3NOR* may oxide CTC through electron transfer. Moreover, the higher triple-excited state energy of OFL and NOR over DFT calculation implied that energy transfer from 3OFL* or 3NOR* to CTC was also theoretically feasible. Therefore, the presence of FQs could significantly accelerate the photodegradation of coexisting antibiotics mainly via electron or energy transfer of 3FQs*. The present study provided a new insight for accurately evaluating environmental behaviors and risks when multiple antibiotics coexist.

Importance of Chain Length in Propagation Reaction on •OH Formation during Ozonation of Wastewater Effluent.

During the ozonation of wastewater, hydroxyl radicals (•OH) induced by the reactions of ozone (O3) with effluent organic matters (EfOMs) play an essential role in degrading ozone-refractory micropollutants. The •OH yield provides the absolute •OH formation during ozonation. However, the conventional "tert-Butanol (t-BuOH) assay" cannot accurately determine the •OH yield since the propagation reactions are inhibited, and there have been few studies on •OH production induced by EfOM fractions during ozonation. Alternatively, a "competitive method", which added trace amounts of the •OH probe compound to compete with the water matrix and took initiation reactions and propagation reactions into account, was used to determine the actual •OH yields (Φ) compared with that obtained by the "t-BuOH assay" (φ). The Φ were significantly higher than φ, indicating that the propagation reactions played important roles in •OH formation. The chain propagation reactions facilitation of EfOMs and fractions can be expressed by the chain length (n). The study found significant differences in Φ for EfOMs and fractions, precisely because they have different n. The actual •OH yield can be calculated by n and φ as Φ = φ (1 + n)/(nφ + 1), which can be used to accurately predict the removal of micropollutants during ozonation of wastewater.

Carbon-defect-driven persulfate activation for highly efficient degradation of extracellular DNA contaminant: Radical oxidation and electron transfer pathways.

Extracellular DNA (eDNA), as a dynamic repository for antibiotic-resistant genes (ARGs), is a rising threat to public health. This work used a ball-milling method to enhance defect structures of activated carbon, and carbon defects exhibited an excellent capacity in persulfate (PS) activation for model eDNA and real ARGs degradation. The eDNA removal by defect-rich carbon with PS was 2.3-fold higher than that by unmilled activated carbon. The quenching experiment, electrochemical analysis and thermodynamic calculation showed that carbon defects could not only enhance the generation of SO4•- and •OH, but formed an electron transfer bridge between eDNA and PS, leading to the non-radical oxidation of eDNA. According to molecular calculations, the nitrogenous bases of DNA were the easiest sites to be oxidized by electron transfer pathway. This research offers a new way using defective carbon materials as PS activator for eDNA pollutants, and an insight into the non-radical mechanism of eDNA degradation.

Tracing the Transformation and Allocation of the Newly Applied-P in Calcareous Soil Using an Enriched Oxygen Isotope Labeling Technique.

Different phosphorus (P) fertilizations significantly impact the transformation of the applied-P in soils. However, knowledge about how different P fertilization regimes influence the allocation of the amended-P in soil remains incomplete. Herein, we carried out a pot experiment to explore the fate of applied-P in calcareous soil using an oxygen isotope labeling technique (18O-P18O43-). Treatments included check (CK), single, and repeated applications. The phosphorus mass balance result showed that more than 48.5% of the applied-P was held in labile and moderately labile fractions with the repeated treatment, while approximately 27.4% of the added-P was recovered in nonlabile forms in the single application treatment. The isotopic tracer (18O-P18O43-) result demonstrated that the δ18OP values of NaHCO3-P and NaOH-P in the repeated P application were significantly higher than those in the single P application. Ultimately, better agronomic performances of the crops and higher PUE were achieved in the repeated treatment. Our findings highlighted that repeated P fertilization can improve P availability by reducing P fixation. These results pronounced that the enriched oxygen isotope technique can be considered an effective approach for tracing applied-P in soils.

A review: Application of allelochemicals in water ecological restoration--algal inhibition.

Problems caused by harmful algal blooms have attracted worldwide attention due to their severe harm to aquatic ecosystems, prompting researchers to study applicable measures to inhibit the growth of algae. Allelochemicals, as secondary metabolites secreted by plants, have excellent biocompatibility, biodegradability, obvious algal inhibiting effect and little ecological harm, and have promising application prospect in the field of water ecological restoration. This review summarized the research progress of allelochemicals, including (i) definition, development, and classification, (ii) influencing factors and mechanism of algal inhibition, (iii) the preparation methods of algal inhibitors based on allelochemicals. The future research directions of allelochemicals sustained-released microspheres (SRMs) were also prospected. In the future, it is urgent to explore more efficient allelochemicals, to study the regulation mechanism of allelochemicals in natural water bodies, and to improve the preparation method of allelopathic algal suppressant. This paper proposed a feasible direction for the development of allelochemicals SRMs which exhibited certain guiding significance for their application in water ecological restoration.

Weighted gene co-expression network analysis reveals specific modules and biomarkers in Parkinson's disease.

BACKGROUND: Parkinson's disease (PD) ranks as the second most frequently occurring neurodegenerative disease. The precise pathogenic mechanism of this disease remains unknown. The aim of the present study was to identify the biomarkers in PD and classify the primary differentially expressed genes (DEGs). METHODS: The present study searched for and downloaded mRNA expression data from the Gene Expression Omnibus database to identify differences in mRNA expression in the substantia nigra (SN) and blood of patients with PD and healthy controls. In addition, in order to investigate the biological functions of the classified dysregulated genes, the present study utilized Gene Set Enrichment Analysis (GSEA), Gene Ontology (GO), reverse transcription-quantitative PCR (RT-qPCR), gene co-expression network analysis and the Kyoto Encyclopedia of Genes and Genomes (KEGG) pathway analysis. A receiver operating characteristic (ROC) curve was applied to assay TMEM243 as a diagnostic marker. RESULTS: Between PD and controls in GSE20292, the present study identified 1862 DEGs. Using the weighted gene co-expression network analysis, the present study identified 15 modules in PD. The module preservation analysis revealed that the tan, blue and green-yellow modules were the most stable. KEGG pathway analysis revealed that five DEGs in the black module were significantly enriched in the ubiquitin-mediated proteolysis pathway, nucleotide excision repair pathway, mismatch repair pathway. The present study selected 303 genes with high connectivity in blue, green-yellow and tan modules as hub genes, where 58 were differentially expressed in both the GSE20292 and GSE54536 datasets. In the SN and blood, 11 genes exhibited the same trend of expression. Furthermore, in the blood samples of patients with PD, the results displayed a significant upregulation of TMEM243. The expression levels of CCR4, CAMK1D, ACTR1B and SPSB3 increased, while both the levels of INA and PSMD4 decreased. These findings are consistent with the bioinformatics analysis results but are not statistically significant. TMEM243 can be considered as a diagnostic biomarker (area under the curve = 0.694; sensitivity, 80 %; specificity, 56 %; P < 0.018). CONCLUSION: TMEM243 was distinctly upregulated in the blood samples of patients with PD, as validated via RT-qPCR, and was highly sensitive, revealing its potential as a biomarker for the future diagnosis of PD.