Sunlight-induced degradation of COVID-19 antivirals arbidol in natural aquatic environments: Mechanisms, pathways and toxicity.

Insights into COVID-19 antivirals' environmental fate and ecological risk are urgently required due to their increasing concentrations in aquatic environments, which have rarely been studied. Herein, we first investigated the photochemical transformation and the resulting alterations in toxicity of arbidol, an antiviral drug with relatively higher toxicity. The photolysis of arbidol was rapid with a rate constant of 0.106 min-1 due to its superior ultraviolet light absorption, in which the direct photolysis was predominated with a contribution of 91.5%. Despite its substantial photolysis, only 14.45% of arbidol was mineralized after 100 min, implying that arbidol and its products might have a long-term impact on aquatic environment. It was inferred that arbidol was photolyzed mainly via the loss of thiophenol, bromine, and alkylamine, based on twelve photolytic products identified. Notably, the experimental results demonstrated that the photolysis process increased the acute toxicity of arbidol, and the toxicity prediction indicated that the ecotoxicity of two photolytic products was very high with LC50 values below 0.1 mg/L. Due to the co-effect of multiple constituents, the photolytic rate observed in wastewater treatment plant effluent and in river water was comparable to that in ultra-pure water, while it was slightly enhanced in lake water. The presence of dissolved organic matter suppressed arbidol photolysis, while NO3- exhibited a promotion effect. These results would be of great significance to assess the fate and risk of COVID-19 antivirals in natural aquatic environments.

Toxic mechanisms of the antiviral drug arbidol on microalgae in algal bloom water at transcriptomic level.

Increasing antivirals in surface water caused by their excessive consumption pose serious threats to aquatic organisms. Our recent research found that the input of antiviral drug arbidol to algal bloom water can induce acute toxicity to the growth and metabolism of Microcystis aeruginosa, resulting in growth inhibition, as well as decrease in chlorophyll and ATP contents. However, the toxic mechanisms involved remained obscure, which were further investigated through transcriptomic analysis in this study. The results indicated that 885-1248 genes in algae were differentially expressed after exposure to 0.01-10.0 mg/L of arbidol, with the majority being down-regulated. Analysis of commonly down-regulated genes found that the cellular response to oxidative stress and damaged DNA bonding were affected, implying that the stress defense system and DNA repair function of algae might be damaged. The down-regulation of genes in porphyrin metabolism, photosynthesis, carbon fixation, glycolysis, tricarboxylic acid cycle, and oxidative phosphorylation might inhibit chlorophyll synthesis, photosynthesis, and ATP supply, thereby hindering the growth and metabolism of algae. Moreover, the down-regulation of genes related to nucleotide metabolism and DNA replication might influence the reproduction of algae. These findings provided effective strategies to elucidate toxic mechanisms of contaminants on algae in algal bloom water.

The environmental risks of antiviral drug arbidol in eutrophic lake: Interactions with Microcystis aeruginosa.

The environmental risks resulting from the increasing antivirals in water are largely unknown, especially in eutrophic lakes, where the complex interactions between algae and drugs would alter hazards. Herein, the environmental risks of the antiviral drug arbidol towards the growth and metabolism of Microcystis aeruginosa were comprehensively investigated, as well as its biotransformation mechanism by algae. The results indicated that arbidol was toxic to Microcystis aeruginosa within 48 h, which decreased the cell density, chlorophyll-a, and ATP content. The activation of oxidative stress increased the levels of reactive oxygen species, which caused lipid peroxidation and membrane damage. Additionally, the synthesis and release of microcystins were promoted by arbidol. Fortunately, arbidol can be effectively removed by Microcystis aeruginosa mainly through biodegradation (50.5% at 48 h for 1.0 mg/L arbidol), whereas the roles of bioadsorption and bioaccumulation were limited. The biodegradation of arbidol was dominated by algal intracellular P450 enzymes via loss of thiophenol and oxidation, and a higher arbidol concentration facilitated the degradation rate. Interestingly, the toxicity of arbidol was reduced after algal biodegradation, and most of the degradation products exhibited lower toxicity than arbidol. This study revealed the environmental risks and transformation behavior of arbidol in algal bloom waters.

Robustness optimization for rapid prototyping of functional artifacts based on visualized computing digital twins.

This study presents a robustness optimization method for rapid prototyping (RP) of functional artifacts based on visualized computing digital twins (VCDT). A generalized multiobjective robustness optimization model for RP of scheme design prototype was first built, where thermal, structural, and multidisciplinary knowledge could be integrated for visualization. To implement visualized computing, the membership function of fuzzy decision-making was optimized using a genetic algorithm. Transient thermodynamic, structural statics, and flow field analyses were conducted, especially for glass fiber composite materials, which have the characteristics of high strength, corrosion resistance, temperature resistance, dimensional stability, and electrical insulation. An electrothermal experiment was performed by measuring the temperature and changes in temperature during RP. Infrared thermographs were obtained using thermal field measurements to determine the temperature distribution. A numerical analysis of a lightweight ribbed ergonomic artifact is presented to illustrate the VCDT. Moreover, manufacturability was verified based on a thermal-solid coupled finite element analysis. The physical experiment and practice proved that the proposed VCDT provided a robust design paradigm for a layered RP between the steady balance of electrothermal regulation and manufacturing efficacy under hybrid uncertainties.

Photoaging mechanisms of microplastics mediated by dissolved organic matter in an iron-rich aquatic environment.

As emerging pollutants, microplastics (MPs) have aroused worldwide concern due to their ubiquitous distribution, environmental persistence, and potential ecological risks. However, the ageing mechanisms, environmental behaviours and risks of photoaged MPs mediated by environmental factors remain obscure. Herein, systems containing a light source, humic acid (HA) and Fe were established to investigate the natural photoaging process of MPs including polyvinyl chloride (PVC) and polyethylene terephthalate (PET). The dehydrochlorination reaction of PVC-MP was inhibited by HA and Fe, which resulted from the coeffect of photon competition, excited state quenching, radical deactivation or transformation, and defect structure destruction. In contrast, the enhanced fluorescence effect suggested that the photooxidation reactions of PET-MP were promoted by HA and Fe. Therefore, the presence of HA and Fe in the environment inhibited the photoreduction of MPs while favoring the photooxidative process. Additionally, the adsorption capacity for 17α-ethinylestradiol and the cytotoxicity of MPs were increased after ageing in the hv + HA and hv + HA + Fe systems, which was attributed to the changes in morphology, elements and functional groups. This study provided new insight into the ageing behaviours of MPs in the natural environment with widespread dissolved organic matter and Fe.

Cytotoxicity and pro-inflammatory effect of polystyrene nano-plastic and micro-plastic on RAW264.7 cells.

Numerous studies have shown that exposure to micro- or nano-plastics led to the cell viability and function of macrophages in the intestine tissue might be one possible mechanism. This study investigated the cytotoxicity and pro-inflammatory effect of 80 nm polystyrene-nano-plastic (PS-NP) and 3 µm PS-micro-plastic (PS-MP) on mouse macrophages RAW264.7 cells. Our results showed that exposure to PS-NP or PS-MP induced apoptosis of cells at 5 or 10 µg/mL, respectively. Besides, PS-NP enhanced the secretion of inflammatory cytokines (Tumor necrosis factor-α, Interleukin-6 and Interleukin-10) with the lowest effective concentration (LOEC) of 1, 0.01, and 0.01 µg/mL, respectively. PS-MP enhanced secretion of TNF-α and IL-10 with the LOEC of 1 and 0.01 µg/mL, respectively. We further studied the possible mechanisms of the effects of PS-NP or PS-MP on RAW264.7 cells. We found they might cause cytotoxicity and inflammatory effects by producing reactive oxygen species and nitric oxide in the cells. Accordingly, our results demonstrated that PS-NP and PS-MP had cytotoxicity and pro-inflammatory effect on macrophages, which might further lead to intestinal inflammation. Moreover, we revealed that the PS-NP had more potent adverse impacts on macrophages than PS-MP.

The photolytic behavior of COVID-19 antivirals ribavirin in natural waters and the increased environmental risk.

Increasing drug residues in aquatic environments have been caused by the abuse of antivirals since the global spread of the COVID-19 epidemic, whereas research on the photolytic mechanism, pathways and toxicity of these drugs is limited. The concentration of COVID-19 antivirals ribavirin in rivers has been reported to increase after the epidemic. Its photolytic behavior and environmental risk in actual waters such as wastewater treatment plant (WWTP) effluent, river water and lake water were first investigated in this study. Direct photolysis of ribavirin in these media was limited, but indirect photolysis was promoted in WWTP effluent and lake water by dissolved organic matter and NO3-. Identification of photolytic intermediates suggested that ribavirin was photolyzed mainly via C-N bond cleavage, splitting of the furan ring and oxidation of the hydroxyl group. Notably, the acute toxicity was increased after ribavirin photolysis owing to the higher toxicity of most of the products. Additionally, the overall toxicity was greater when ARB photolysis in WWTP effluent and lake water. These findings emphasize the necessity to concern about the toxicity of ribavirin transformation in natural waters, as well as to limit its usage and discharge.

The disinfectant residues promote the leaching of water contaminants from plastic pipe particles.

Disinfection treatment is an indispensable water purification process, but it can leave trace concentrations of disinfectant in the purified water. Disinfectants oxidation can age plastic pipes and release hazardous microplastics and chemicals into drinking water. Lengths of commercially-available unplasticized polyvinyl chloride and polypropylene random copolymer water pipe were ground into particles and exposed to micro-molar concentrations of ClO2, NaClO, trichloroisocyanuric acid, or O3 for up to 75 days. The disinfectants aged the plastic and changed its surface morphology and functional groups. Meanwhile, disinfectants could significantly promote the release of organic matter from plastic pipes into the water. ClO2 generated the highest concentrations of organic matter in the leachates from both plastics. Plasticizers, antioxidants and low molecular weight organic matter were detected in all of the leachates. Leachate samples inhibited the proliferation of CT26 mouse colon cancer and induced oxidative stress in the cells. Even trace concentrations of residual disinfectant can constitute a drinking water risk.

[Enhanced reductive decoloration of methylene blue by polyacrylic acid modified zero-valent iron nanoparticles].

Nano zerovalent iron ( NZVI) technology has attracted tremendous amount of interests for degrading a number of environmental contaminants found both in surface water and underground water. However, these nanoscale particles are prone to aggregate, which may result in the decrease of its reactivity in liquid phase. Iron nanoparticles (Fe NPs) modified with polyacrylic acid (PAA) has enhanced the dispersion of NZVI and reduced its agglomeration. For the first time, PAA modified NPs (PAA-Fe NPs) were used for degradation of methylene blue in water phase. The PAA-Fe NPs prepared were characterized in terms of TEM, SEM, XRD and specific surface area. The results indicated that, the surface area of PAA-Fe NPs was increased, compared with unmodified pristine zero-valent iron NPs, and PAA-Fe NPs were smoother with smaller particle size. With addition of 0.1 g x L(-1) of PAA, the decolorization efficiency of methylene blue by PAA-Fe NPs was 98.84% in 60 min, which was 27.32% higher than that of pristine Fe NPs. Decolorization efficiencies were also affected by initial pH value, initial concentration of methylene blue, dosage of PAA-Fe NPs, and degradation temperature. Kinetic analyses based on the experimental data illustrated that the decolorization reaction of methylene blue fitted well to the pseudo first-order kinetics model.