Diflovidazin damages the hematopoietic stem cells to zebrafish embryos via the TLR4/ NF-κB/ p53 pathway.

Exposure to environmental contaminants frequently induces the occurrence of blood diseases, but the underlying molecular mechanisms are scarcely known. The toxicity of Diflovidazin (DFD), a widely used mite-remover, to the blood system of non-target organisms requires urgent elucidation. To investigate the deleterious effects of DFD (2, 2.5, and 3 mg/L) on the development and survive of hematopoietic stem cells (HSCs), the zebrafish model was used in this study. DFD exposure reduced the number of HSCs and their subtypes, including macrophages, neutrophils, thymus T-cells, erythrocytes, and platelets. The significant changes in the abnormal apoptosis and differentiation of HSCs were the major reasons for the reduction in blood cells. Using small-molecule antagonists and p53 morpholino revealed that the NF-κB/p53 pathway was responsible for the apoptosis of HSCs upon DFD exposure. The restoration results attributed to the TLR4 inhibitor and molecular docking showed that the TLR4 protein, which was upstream of NF-κB signaling, played a vital role in DFD toxicology. This study elucidates the role and molecular mechanism of DFD in damaging zebrafish HSCs. It provides a theoretical basis for the occurrence of various blood diseases in zebrafish and other organisms.

Can ultrafiltration singly treat the iron- and manganese-containing groundwater?

The presence of Fe2+ and Mn2+ would cause severe ultrafiltration (UF) membrane fouling and limited its extensive application in treating the groundwater. A pilot-scale gravity-driven membrane (GDM) process which coupled the dual roles of biocake layer and UF membrane was introduced to treat the groundwater under high Mn2+concentrations and low temperature conditions. The results indicated that flux stabilization was observed during long-term GDM filtration with average stabilized fluxes of 3.6-5.7 L m-2 h-1. GDM process conferred efficient removals of Fe2+ and Mn2+ with both average removals > 95%. Pre-adding manganese oxides (MnOx) could effectively shorten the ripening period of manganese removal from 50 to 30 days, and simultaneously contribute to the Mn2+ removal and flux improvements. The presence of Mn2+ facilitated the formation of heterogeneous structures of biocake layer to primarily determine the flux stabilization of GDM, while the influence of extracellular polymeric substances (EPS) concentrations was nearly negligible. Besides, the Mn2+ removal was primarily attributed to the biocake layer other than UF membrane itself, and the chemically auto-catalytic oxidation by MnOx particles played the pivotal role. Therefore, these findings provide relevance for establishing new strategies in treating the iron-and manganese-containing groundwater.

Bio-cake layer based ultrafiltration in treating iron-and manganese-containing groundwater: Fast ripening and shock loading.

Groundwater was a desired alternative for decentralized water supply. However, the presence of iron, manganese and ammonia significantly limited its extensive adoptions. In this study, an innovative gravity-driven membrane (GDM) process has been developed to address such problems. The results indicated that GDM process can efficiently diminish the concentrations of iron, manganese and ammonia, with average removal efficiencies of 97%, 95% and 70%, respectively, since the bio-cake layer on the membrane surface can serve as a dynamic barrier for the foulants rejection. In GDM filtration, the manganese removal was mainly attributed to the synergistic effects between the chemically auto-catalytic oxidation by manganese oxides (MnOx) and biological activity by manganese-oxidizing bacteria (MnOB). Pre-addition of MnOx particles into GDM system could significantly enhance the manganese removal and shorten its ripening time by approximately 50%. During long-term filtration, the fluxes of GDM remained stabilized (4-5 L m-2 h-1), and MnOx particles pre-additions could improve the stable fluxes by 23%-37%. The flux stabilization of GDM process was mainly determined by the heterogeneous structures of bio-cake layer, and the generated iron and manganese oxides would improve its heterogeneities. Furthermore, MnOx assisted GDM process conferred robust capacities in resisting the shock loading of manganese and ammonia in the feed water, and the highest concentrations of manganese and ammonia were suggested to be less than 2.96 mg/L and 0.9 mg/L, respectively. Therefore, these findings are full of relevance to develop new strategies to treat the iron- and manganese-containing groundwater and promote the extensive application of UF technology for decentralized water supply.

Application of heat-activated peroxydisulfate pre-oxidation for degrading contaminants and mitigating ultrafiltration membrane fouling in the natural surface water treatment.

Membrane fouling is posing a critical obstacle limiting the widespread application of ultrafiltration (UF). Among the numerous membrane foulants, natural organic matter (NOM) is one of the most problematic since it exists ubiquitously in natural waters and can cause severe membrane fouling. This study investigated the removal of NOM in surface water and the mitigation of membrane fouling using heat-activated peroxydisulfate (PDS) as a pretreatment for UF process. The results demonstrated that the NOM was efficiently removed, with ultraviolet absorbance (UV254) and dissolved organic carbon (DOC) decreasing by approximately 71% and 52%, respectively, at a PDS dose of 0.8 mM within 60 min (80 °C). The chromatograms of high performance size exclusion chromatography (HPSEC) indicated that some high molecular weight humic substances with a peak at approximately 10 kDa were oxidized to low molecular weight organic matters distributed in the range of < 100 Da during the pretreatment process. Moreover, three-dimensional fluorescence parallel factor analysis (PARAFAC) indicated that humic-like substances were much more easily degraded by heat-activated PDS pretreatment than protein-like substances. These results indicated that some unsaturated NOM fractions were first degraded and then mineralized to carbon dioxide during pretreatment. Meanwhile, the destroyed structure of humic substances might hinder its binding with high valence cations to reduce the possibility of high valence cations deposited on the membrane surface, thereby reducing membrane fouling. Therefore, membrane fouling could be significantly mitigated due to the shifts of NOM concentration and structure by heat-activated PDS pretreatment in the surface water treatment.