Removal efficiency and enzymatic mechanism of dibutyl phthalate (DBP) by constructed wetlands

Four vertical-flow constructed wetland systems were set up in the field in order to study the removal efficiency and possible enzymatic mechanism of the constructed wetlands in treating sewage containing different concentrations of dibutyl phthalate (DBP). Under DBP spiked concentrations of 0.5, 1.0, and 2.0 mg/L, good DBP removal rates of 62.08, 82.17, and 84.17% were achieved, respectively. Meanwhile, certain removal effects of general water quality parameters were observed in all four constructed wetlands: with high average removal rates of nitrate nitrogen (NO3 (-)-N) and chemical oxygen demand (COD) of 91.10 similar to 93.89 and 82.83 similar to 89.17%, respectively, with moderate removal efficiencies of total nitrogen (TN), total phosphorus (TP), ammonia nitrogen (NH4 (+)-N) of 44.59 similar to 49.67, 30.58 similar to 37.18, and 28.52 similar to 37.45%, respectively. Compared to the control, an increase of enzyme activities of urease, phosphatase, dehydrogenase, and nitrate reductase was observed in the treatments with DBP addition. In the presence of 0.5 mg/L of DBP concentration, the urease, phosphatase, and dehydrogenase activities reached the highest levels, with an increase of 350.02, 36.57, and 417.88% compared with the control, respectively. It appeared that the low concentration of DBP might better stimulate the release of enzymes.</p

A ribose-functionalized NAD+ with unexpected high activity and selectivity for protein poly-ADP-ribosylation.

Nicotinamide adenine dinucleotide (NAD+)-dependent ADP-ribosylation plays important roles in physiology and pathophysiology. It has been challenging to study this key type of enzymatic post-translational modification in particular for protein poly-ADP-ribosylation (PARylation). Here we explore chemical and chemoenzymatic synthesis of NAD+ analogues with ribose functionalized by terminal alkyne and azido groups. Our results demonstrate that azido substitution at 3'-OH of nicotinamide riboside enables enzymatic synthesis of an NAD+ analogue with high efficiency and yields. Notably, the generated 3'-azido NAD+ exhibits unexpected high activity and specificity for protein PARylation catalyzed by human poly-ADP-ribose polymerase 1 (PARP1) and PARP2. And its derived poly-ADP-ribose polymers show increased resistance to human poly(ADP-ribose) glycohydrolase-mediated degradation. These unique properties lead to enhanced labeling of protein PARylation by 3'-azido NAD+ in the cellular contexts and facilitate direct visualization and labeling of mitochondrial protein PARylation. The 3'-azido NAD+ provides an important tool for studying cellular PARylation

Macrophyte identity shapes water column and sediment bacterial community

By assembling mesocosms and utilizing high-throughput sequencing, we aim to characterize the shifts of the bacterial community in freshwaters driven by two contrasting submerged macrophyte species, Ceratophyllum demersum L. and Vallisneria spiralis L. Although the microbe in both the water column and sediment were largely modulated by the macrophyte, the effect varied considerably depending on bacterial locations and macrophyte species. Actinobacteria was the most abundant taxa in the water column of all the three treatments, but its abundances were significantly higher in the two planted treatments. Moreover, Alphaproteobacteria showed high abundance only in the unplanted control. For bacterial taxa in the sediment, C. demersum significantly increased the relative abundance of Anaerolineae but reduced the relative abundance of Betaproteobacteria and Gammaproteobacteria, while V. spiralis increased the relative abundance of Deltaproteobacteria and Gammaproteobacteria. Additionally, in the C. demersum treatment, the water column bacterial community increased more dramatically in richness, alpha diversity, and the relative abundance of the dominant taxa than those in the V. spiralis treatment. Taken together, the findings from this study reveal that the two species of submerged macrophyte modified the bacterial community in waters, despite the obvious interspecific performance differences

Inhibition of 26S Protease Regulatory Subunit 7 (MSS1) Suppresses Neuroinflammation

Recently, researchers have focused on immunosuppression induced by rifampicin. Our previous investigation found that rifampicin was neuroprotective by inhibiting the production of pro-inflammatory mediators, thereby suppressing microglial activation. In this study, using 2-dimensional gel electrophoresis (2-DE) and mass spectrometry (MS), we discovered that 26S protease regulatory subunit 7 (MSS1) was decreased in rifampicin-treated microglia. Western blot analysis verified the downregulation of MSS1 expression by rifampicin. As it is indicated that the modulation of the ubiquitin-26S proteasome system (UPS) with proteasome inhibitors is efficacious for the treatment of neuro-inflammatory disorders, we next hypothesized that silencing MSS1 gene expression might inhibit microglial inflammation. Using RNA interference (RNAi), we showed significant reduction of IkBα degradation and NF-kB activation. The production of lipopolysaccharides-induced pro-inflammatory mediators such as inducible nitric oxide synthase (iNOS), nitric oxide, cyclooxygenase-2, and prostaglandin E2 were also reduced by MSS1 gene knockdown. Taken together, our findings suggested that rifampicin inhibited microglial inflammation by suppressing MSS1 protein production. Silencing MSS1 gene expression decreased neuroinflammation. We concluded that MSS1 inhibition, in addition to anti-inflammatory rifampicin, might represent a novel mechanism for the treatment of neuroinflammatory disorders

Fatigue Performance and Fatigue Life Prediction for RV-20E Reducers Based on the Crankshaft Heat Treatment Strengthening Process

Fatigue performance of RV-20E reducers is investigated experimentally herein; load and life curves of RV-20E with different crankshaft heat treatment strengthening processes are obtained. The optimum surface microstructure and optimum surface hardness of the crankshaft for improving the fatigue life of the RV-20E reducer are analyzed, and the failure mode and failure mechanism of the crankshaft of the RV-20E reducer are discussed. Based on the S-N theory and the Miner theory, and combined with the force analysis of RV-20E, the life parameter of RV-20E reducers based on the crankshaft needle roller bearing assembly is derived, and the test data is compared and analyzed. The analysis and comparison show that the life parameter can effectively correlate the fatigue life of RV-20E reducers and can be used to predict the fatigue life of RV-20E reducers

General trends in freshwater ecological restoration practice in China over the past two decades: the driving factors and the evaluation of restoration outcome

Background Although freshwater ecological restoration (FER) has undergone an immense development over the past two decades in China either in the number of projects or in the spatial scale of implementations, a dearth of clear and comprehensive trends in this field is still a particular concern. We conducted a literature survey through searching the database of Web of Science between 1997 and 2017 to investigate the driving force behind FER practice and to summarize the restoration outcomes. Results A total of 2047 publications were hit and 198 of them were finally retained after manual screening. The number of studies in this field has been steadily increasing in recent years and their provincial distribution is positively correlated with GDP growth and the investment to pollution control and environmental protection, suggesting that economic development is a key driving factor of FER practice. Among the remaining articles, nearly half (46.5%) focus on lake ecosystems, and 34.8% and 32.8% of the studies indicate that land reclamation and eutrophication are the predominant causes of freshwater ecosystem degradation. The overarching target of the restoration is biodiversity increase (31.4%), followed by water quality improvement (24.7%) and ecosystem services (23.9%). Revegetation is a dominant restoration approach (40.9%). Reference sites for assessment of restoration projects are normally control locations without intervention (60%), or the status of the targeted sites before the interventions. For the restoration outcome evaluation, 86% of the studies present positive outcomes in terms of water quality improvement, and 79% have improvement in biological features. The most frequently monitored organisms are macrophytes (31%), followed by benthos as indicators of ecological condition. Conclusions Economic growth, water pollution and investment into environmental protection are the main driving factors of FER practice in China. The effort of restoration and evaluation over the past two decades has not been limited to improving hydrological function and water quality, but also pay increasingly more attention to biological processes and ecological integrity, and further the ecosystem services in recent years. However, the lack of long-term monitoring and socioeconomic attributes considered in restoration success assessments are still particular issues that need to be addressed in the future FER researches and projects

Seasonal variation of microbial community for the treatment of tail water in constructed wetland

Effects of seasons and hydraulic loading rates (HLR) on the treatment performance and the response of the microbial community of vertical flow constructed wetland treating tail water were investigated. The seasonal treatment performance was evaluated at four HLR of 125, 250, 375 and 500 mm/d, respectively. The microbial community was detected by MiSeq Illumina platform at HLR 125 and 375 mm/d. The wetland showed significantly higher chemical oxygen demand (COD) and total nitrogen (TN), total phosphorus (TP) at HLR 125 mm/d, compared with other HLR. Overall removal efficiency was 61.47%, 71.40% and 76.31% for COD, TN and TP, respectively, while no significant differences for COD, TN and TP removal were found at HLR of 250, 375 and 500 mm/d. The best removal efficiency for COD and TN was achieved in summer and autumn, while the best TP removal was achieved in winter. Nitrification bacteria (Nitrosomonas and Nitrospira) were significantly higher in HLR 125 mm/d, whereas sequences associated with denitrification had no significant difference at the two HLR. The results can partially explain the significantly higher NH4+-N removal in HLR 125 mm/d and relatively low nitrogen performance in winter

dibutylphthalateadsorptioncharacteristicsusingthreecommonsubstratesinaqueoussolutions

In recent years, the presence and adverse impacts of phthalic acid esters in aquatic environments have gained increasing attention. This work investigated the adsorption behavior of a typical phthalic acid ester, dibutyl phthalate (DBP), onto steel slag, gravel, and shell sand (substrates commonly used in constructed wetlands). The influence of dissolved organic matter (DOM) on DBP adsorption was investigated using humic acid as a proxy for DOM. The results demonstrated that the adsorption of DBP to three substrates reached equilibrium within 96 h, and the adsorption kinetics were well fitted by a pseudo-second-order model. The DBP adsorption isotherms were best fitted by the Langmuir adsorption model. The DBP adsorption capacity decreased in the order of steel slag>gravel>shell sand, with values of 656 mg/kg, 598 mg/kg, and 6.62 mg/kg at 25°C, respectively. DBP adsorbed to the surface of all substrates in a monolayer via an endothermic process. The DBP adsorption capacities of steel slag and gravel decreased as the DOM content increased. The DBP adsorption mechanisms to steel slag and gravel mainly involved the surface coordination of DBP with –OH or –COOH groups and electrostatic interactions. The results of this work suggest that steel slag and gravel may be ideal substrates for use in constructed wetlands to treat wastewater polluted with DBP

Dibutyl phthalate adsorption characteristics using three common substrates in aqueous solutions

In recent years, the presence and adverse impacts of phthalic acid esters in aquatic environments have gained increasing attention. This work investigated the adsorption behavior of a typical phthalic acid ester, dibutyl phthalate (DBP), onto steel slag, gravel, and shell sand (substrates commonly used in constructed wetlands). The influence of dissolved organic matter (DOM) on DBP adsorption was investigated using humic acid as a proxy for DOM. The results demonstrated that the adsorption of DBP to three substrates reached equilibrium within 96 h, and the adsorption kinetics were well fitted by a pseudo-second-order model. The DBP adsorption isotherms were best fitted by the Langmuir adsorption model. The DBP adsorption capacity decreased in the order of steel slag>gravel>shell sand, with values of 656 mg/kg, 598 mg/kg, and 6.62 mg/kg at 25 degrees C, respectively. DBP adsorbed to the surface of all substrates in a monolayer via an endothermic process. The DBP adsorption capacities of steel slag and gravel decreased as the DOM content increased. The DBP adsorption mechanisms to steel slag and gravel mainly involved the surface coordination of DBP with -OH or -COOH groups and electrostatic interactions. The results of this work suggest that steel slag and gravel may be ideal substrates for use in constructed wetlands to treat wastewater polluted with DBP. (C) Higher Education Press and Springer-Verlag GmbH Germany, part of Springer Nature 201