Involvement of circ_0029407 in Caerulein-Evoked Cytotoxicity in Human Pancreatic Cells via the miR-579-3p/TLR4/NF-κB Pathway.

Acute pancreatitis (AP) is the most prevalent gastrointestinal inflammatory disease. Circular RNAs (circRNAs) are implicated in the development of AP. Here, we identified the precise action of circ_0029407 in AP development. Human pancreatic epithelial cells (HPECs) were stimulated with caerulein. Cell viability, proliferation, and apoptosis were gauged by Cell Counting Kit-8 (CCK-8), 5-ethynyl-2'-deoxyuridine (EdU), and flow cytometry assays, respectively. Circ_0029407, microRNA (miR)-579-3p, and toll-like receptor 4 (TLR4) were quantified by a qRT-PCR or western blot assay. Dual-luciferase reporter and RNA pull-down assays were performed to evaluate the direct relationship between miR-579-3p and circ_0029407 or TLR4. Our results indicated that circ_0029407 was markedly overexpressed in AP serum samples and caerulein-stimulated HPECs. Reduction of circ_0029407 attenuated caerulein-imposed HPEC damage by promoting cell proliferation and repressing cell apoptosis and inflammation. Mechanistically, circ_0029407 contained a miR-579-3p binding site, and miR-579-3p downregulation reversed the effect of circ_0029407 reduction on caerulein-imposed HPEC damage. TLR4 was identified as a direct and functional target of miR-579-3p, and TLR4 overexpression reversed the impact of miR-579-3p upregulation on attenuating caerulein-imposed HPEC damage. Moreover, circ_0029407 regulated the TLR4/nuclear factor NF-kappaB (NF-κB) signaling by acting as a competing endogenous RNA (ceRNA) for miR-579-3p. Our study suggests that circ_0029407 regulates caerulein-imposed cell injury in human pancreatic cells at least in part via the TLR4/NF-κB signaling pathway by functioning as a ceRNA for miR-579-3p.

Assessing the Impact of PM2.5-Bound Arsenic on Cardiovascular Risk among Workers in a Non-ferrous Metal Smelting Area: Insights from Chemical Speciation and Bioavailability.

Inhalation of fine particulate matter PM2.5-bound arsenic (PM2.5-As) may cause significant cardiovascular damage, due to its high concentration, long transmission range, and good absorption efficiency in organisms. However, both the contribution and the effect of the arsenic exposure pathway, with PM2.5 as the medium, on cardiovascular system damage in nonferrous smelting sites remain to be studied. In this work, a one-year site sample collection and analysis work showed that the annual concentration of PM2.5-As reached 0.74 µg/m3, which was 120 times the national standard. The predominant species in the PM2.5 samples were As (V) and As (III). A panel study among workers revealed that PM2.5-As exposure dominantly contributed to human absorption of As. After exposure of mice to PM2.5-As for 8 weeks, the accumulation of As in the high exposure group reached equilibrium, and its bioavailability was 24.5%. A series of animal experiments revealed that PM2.5-As exposure induced cardiac injury and dysfunction at the environmental relevant concentration and speciation. By integrating environmental and animal exposure assessments, more accurate health risk assessment models exposed to PM2.5-As were established for metal smelting areas. Therefore, our research provides an important scientific basis for relevant departments to formulate industry supervision, prevention and control policies.

Comprehensive comparison of integrated fixed-film activated sludge (IFAS) and AAO activated sludge methods: Influence of different operational parameters.

Due to limited land availability in municipal wastewater treatment plants, integrated fixed-film activated sludge (IFAS) technology offers significant advantages in improving nitrogen removal performance and treatment capacity. In this study, two systems, IFAS and Anaerobic-Anoxic-Oxic Activated sludge process (AAO), were compared by adjusting parameters such as hydraulic retention time (HRT), nitrifying solution recycle ratio, sludge recycle ratio, and dissolved oxygen (DO). The objective was to investigate pollutant removal capacity and differences in microbial community composition between the two systems. The study showed that, at an HRT of 12 h, the IFAS system exhibited an average increase of 5.76%, 8.85%, and 12.79% in COD, NH4+-N, and TN removal efficiency respectively, compared to the AAO system at an HRT of 16 h. The TP concentration in the IFAS system reached 0.82 mg/L without the use of additives. The IFAS system demonstrated superior effluent results under lower operating conditions of HRT, nitrification solution recycle ratio, and DO. The 16S rDNA analysis revealed higher abundance of denitrification-related associated flora, including Proteobacteria, Bacteroidetes, and Planctomycetota, in the IFAS system compared to the AAO system. Similarities were observed between microorganisms attached to the media and activated sludge in the anaerobic, anoxic, and oxic tanks. q-PCR analysis indicated that the incorporation of filler material in the IFAS system resulted in similar abundance of nitrifying bacteria genes on the biofilm as in the oxic tank. Additionally, denitrifying genes showed higher levels due to aeration scouring and the presence of alternating aerobic-anaerobic environments on the biofilm surface, enhancing nitrogen removal efficiency.

Effect of liver cancer on the accumulation and hepatobiliary transport of per- and polyfluoroalkyl substances.

In this study, we examined the distribution of per- and polyfluoroalkyl substances (PFASs) in liver and bile tissues from the patients with liver cancer (n = 202) and healthy controls (n = 30), and calculated the hepatobiliary transport efficiency (TB-L) of PFASs. Among 21 PFASs, 13 PFASs were frequently detected in the liver (median: 8.80-16.3 ng/g) and bile (median: 11.03-14.26 ng/mL) samples. PFAS concentrations in liver were positively correlated with age, with higher levels of PFASs in the older. Variance analysis showed that gender and BMI (Body Mass Index) have an important impact on the distribution of PFASs. A U-shaped trend in TB-L of PFASs with the increasing of carbon chain length was found for the first time, and the TB-L of most PFASs in the control was higher than that of those in cases (p < 0.05), suggesting that hepatic injury would affect their transport. PFASs were positively associated with liver injury biomarkers, including γ-glutamyl transferase (GGT), alanine aminotransferase (ALT), and total bilirubin (TB) levels (p < 0.05). This is the first study on examining the hepatobiliary transport characteristics of PFASs, which may help understand the connection between PFAS accumulation and liver cancer risk.

Co-precipitation of Cd with struvite during phosphorus recovery.

During the struvite recovery process, Cd, a hazardous metal commonly found in waste streams, can be sequestered by struvite. This study investigated the influence of Cd2+ on the precipitation of struvite. Quantitative X-ray diffraction (QXRD) results showed that the purity of struvite decreased from 99.1% to 73.6% as Cd concentration increased from 1 to 500 µM. Scanning electron microscopy (SEM) revealed a roughened surface of struvite, and X-ray photoelectron spectroscopy (XPS) analysis indicated that the peak area ratio of Cd-OH increased from 19.4% to 51.3%, while the area ratio of Cd-PO4 decreased from 86.6% to 48.7% as Cd concentrations increased from 10 to 500 µM. The findings suggested that Cd2+ disrupted the crystal growth of struvite, and mainly combined with -OH and -PO4 to form amorphous Cd-bearing compounds co-precipitated with struvite. Additionally, Mg-containing amorphous phases were formed by incorporating Mg2+ with -OH and -PO4 during struvite formation.

Characteristics and mechanism of phosphate removal by lanthanum modified bentonite in the presence of dissolved organic matter.

Lanthanum modified bentonite (LMB) is a widely used adsorbent for removing inorganic phosphorus from polluted water to prevent eutrophication. However, its efficiency can be affected by various environmental factors, including dissolved organic matter (DOM), which is still unclear. In this study, we systematically explored the influence of model DOMs, including HA, bovine serum albumin (BSA), and sodium alginate (SA), on phosphate adsorption by LMB, as well as to elucidate the underlying adsorption mechanisms. Our results showed that only HA had a significant effect on phosphate adsorption by LMB, causing inhibition. When three DOMs were mixed with phosphate in different proportions and DOM was mainly HA, the performance of phosphate adsorption on LMB became worse, while BSA can slightly offset this impact. The kinetics of HA and phosphate adsorption on LMB followed the pseudo-second-order kinetic model, and isotherms fitted the Langmuir model, with a maximum adsorption capacity of 5.7 mg g-1 for P and 12 mg g-1 for HA. However, when HA and phosphate were mixed based on their Qm, a C/P molar ratio of 5.35, LMB preferentially adsorbed phosphate. HA invasion was also disadvantageous for phosphate removal by LMB, in which P adsorption was less efficient at low-concentrations. However, during co-adsorption the adsorption capacity for HA was higher. With a secondary addition of higher levels of P, both pollutants were adsorbed more effectively. In the natural water experiment, phosphate concentration decreased with increasing shaking time, while the UV254 value showed a downward trend, indicating that LMB also adsorbed HA. Characterization results showed that La and phosphate formed LaPO4 precipitation, forming La-O-P inner-sphere complexes as the main mechanism of phosphate removal by LMB. La and HA formed La-HA complexes, with O-CO bonds from HA competing for lanthanum with phosphate. Despite HA obstructing pores from adsorbent, LMB still maintained a good binding ability with phosphate. It may form La-P-HA ternary complexes during adsorption to keep HA adsorption amount.

Contribution and Effects of PM2.5-Bound Lead to the Cardiovascular Risk of Workers in a Non-Ferrous Metal Smelting Area Considering Chemical Speciation and Bioavailability.

Lead is known to have toxic effects on the cardiovascular system. Owing to its high concentration, transmission range, and absorption efficiency in organisms, inhalation of fine particulate matter (PM2.5)-bound lead (PM2.5-Pb) may cause significant cardiovascular damage. However, the contribution and adverse effects of PM2.5-Pb on workers and residents in non-ferrous metal smelting areas are not fully understood. In this work, the concentration and chemical speciation of PM2.5-Pb were analyzed to determine its pollution characteristics at a typical non-ferrous metal smelting site. A panel study conducted among factory workers revealed that PM2.5-Pb exposure makes an important contribution to the human absorption of Pb. Although the chemical speciation of PM2.5-Pb suggested poor water solubility, a high bioavailability was observed in mice (tissue average value: 50.1%, range: 31.1-71.1%) subjected to inhalation exposure for 8 weeks. Based on the bioavailability data, the relationship between PM2.5-Pb exposure and cardiovascular damage was evaluated in animal simulation experiments. Finally, a damage threshold and cardiovascular-specific risk assessment model were established for the non-ferrous metal smelting area. Our project not only accurately estimates the risk of PM2.5-bound heavy metals on the cardiovascular system but also offers a scientific basis for future prevention and therapy of PM2.5-Pb-related diseases.

Quantitative, morphological, and structural analysis of Ni incorporated with struvite during precipitation.

Struvite precipitation is a promising strategy for the simultaneous recovery of nitrogen and phosphorus from waste streams. However, waste streams typically contain high amounts of metal contaminants, including Ni, which can be easily sequestered by struvite, but the behavior of Ni during struvite precipitation remains unclear. Thus, this study investigates the influence of Ni concentrations on struvite precipitation. The quantitative X-ray diffraction (QXRD) results revealed that the purity of struvite decreased from 96.6 to 41.1% with the Ni concentrations increased from 0.1-100 mg·L-1. At lower Ni concentrations of 0.1-1 mg·L-1, scanning electron microscopy (SEM) showed a roughened surface of struvite crystal, and this was combined with X-ray absorption near edge structure (XANES) data that indicated a stack of Ni-OH and Ni-PO4 on struvite surface. At Ni concentrations of 10-25 mg·L-1, Ni primarily crystalized as Ni-struvite (NiNH4PO4·6H2O), as detected by QXRD. At higher Ni concentrations of 25-100 mg·L-1, the co-precipitation of amorphous Ni phosphate(s) (e.g., Ni3(PO4)2) and Ni hydroxide (e.g., Ni(OH)2) was identified by XANES. Specifically, the X-ray photoelectron spectroscopy (XPS) analysis detected the formation of amorphous Mg hydroxide(s) and phosphate(s) at Ni of 25-100 mg·L-1. The overall results revealed that Ni formed Ni-OH and Ni-PO4 on struvite surface at 0.1-1 mg·L-1, whereas Ni precipitated as separated phases (e.g. Ni-struvite, Ni hydroxide and phosphate) at 10-100 mg·L-1. The existence of Ni disturbed the crystal growth of struvite and promoted the formation of Ni-struvite, amorphous products during struvite formation.

The degradation mechanisms of perfluorooctanoic acid (PFOA) and perfluorooctane sulfonic acid (PFOS) by different chemical methods: A critical review.

Per- and polyfluoroalkyl substances (PFASs) are a class of artificial compounds comprised of a perfluoroalkyl main chain and a terminal functional group. With them being applied in a wide range of applications, PFASs have drawn increasing regulatory attention and research interests on their reductions and treatments due to their harmful effects on environment and human beings. Among numerous studies, chemical treatments (e.g., photochemical, electrochemical, and thermal technologies) have been proved to be important methods to degradation PFASs. However, the pathways and mechanisms for the degradation of PFASs through these chemical methods still have not been well documented. This article therefore provides a comprehensive review on the degradation mechanisms of two important PFASs (perfluorooctanoic acid (PFOA) and perfluorooctane sulfonic acid (PFOS)) with photochemical, electrochemical and thermal methods. Different decomposition mechanisms of PFOA and PFOS are reviewed and discussed. Overall, the degradation pathways of PFASs are associated closely with their head groups and chain lengths, and H/F exchange and chain shortening were found to be predominant degradation mechanisms. The clear study on the degradation mechanisms of PFOA and PFOS should be very useful for the complete degradation or mineralization of PFASs in the future.

Occurrence and abundance of poly- and perfluoroalkyl substances (PFASs) on microplastics (MPs) in Pearl River Estuary (PRE) region: Spatial and temporal variations.

Although the occurrence and distribution of various chemicals on microplastics (MPs) has been widely studied, little was known about the concentrations of poly- and perfluoroalkyl substances (PFASs) on MPs. In this study, MPs from eight rivers draining into Pearl River Estuary (PRE) region were collected and analyzed. Higher concentrations of PFASs on MPs (105-9.07 × 103 ng g-1) were found in the drain outlets receiving wastewater from most urbanized cities with large population densities. On the other hand, lower concentrations of PFASs on MPs (10.3-227.8 ng g-1) were found in the drain outlets receiving wastewater mostly from agricultural and forested areas. Specially, 8:2 disubstituted polyfluoroalkyl phosphates (8:2 diPAP) was detected with the highest frequency, in 92.5% of the samples. Furthermore, a positive Spearman correlation was found between 6:2 disubstituted polyfluoroalkyl phosphates (6:2 diPAP) and perfluorotetradecanoic acid (PFTeDA) (rs = 0.621, p = 0.012), indicating they might share similar sources. PFASs on MPs were found to vary significantly with different seasons. Higher concentrations of PFASs on MPs were found in dry seasons, while lower concentrations were observed in wet seasons. The results of this study should be important for the understanding of PFAS occurrence and distribution on MPs and the partitioning mechanism of PFASs on MPs in estuary systems.

Co-precipitation of Cu and Zn in precipitation of struvite.

Struvite recovered from wastewater can be used as a slow-release fertilizer. Nevertheless, hazardous metals easily precipitated with struvite would increase the ecological risk for its agricultural use. In this study, the influence of individual and coexistence of Cu and Zn on the precipitation of struvite was investigated. The loading of Cu and/or Zn in precipitates increased with the increase of initial metal concentrations (0.1-100 mg/L). Quantitative X-ray diffraction (QXRD) analysis revealed that the increase of Cu and/or Zn level in reaction solution disturbed crystal growth of struvite and promoted the formation of amorphous phase(s). Scanning electron microscopy (SEM) revealed the pit formation on struvite crystal surfaces, combined with X-ray photoelectron spectroscopy (XPS) data, the results indicated a surface interaction for the formation of Cu-OH and Cu-NH3 on struvite surface at Cu of 0.1-10 mg/L. With the increase of Cu to 25-100 mg/L, the precipitation of amorphous Cu phosphate(s) was confirmed by XPS and QXRD. At Zn of 0.1-10 mg/L, the enrichment of Zn-PO4 and Zn-OH on struvite surface was observed, whereas, the precipitation of amorphous Zn hydroxide(s) was confirmed at Zn of 25-100 mg/L. At Cu and Zn co-existed solution, the decrease of Cu-PO4 and increase of Zn-PO4 suggested the competitive binding of PO4 between Cu and Zn. In addition, the formation of amorphous Mg hydroxide(s) and phosphate(s) was detected regardless of the addition of Cu in solutions. The overall results revealed that the existence of Cu and Zn during struvite formation can greatly affect its content by formation of different metal-containing products.

Sorption behavior of 6:2 chlorinated polyfluorinated ether sulfonate (F-53B) on four kinds of nano-materials.

6:2 chlorinated polyfluorinated ether sulfonate (with the trade name F-53B, a substitute for PFOS) is one type of Per- and polyfluoroalkyl substances (PFASs), which is widely used as a chromium mist inhibitor in China. It has been found in environment commonly. In this study, the sorption behavior of F-53B on four kinds of nano-materials: alumina nanopowder (ANP), alumina nanowires (ANW), hydrophilic bentonite nanoclay (HBNC) and surface modified nanoclay (SMNC) were investigated. The kinetics results indicated that the sorption of F-53B on four nano-materials reached equilibrium within 2 h and the sorption process were fitted better by the pseudo-second-order kinetic model than the pseudo-first-order kinetic model. The thermodynamic study showed that the sorption of F-53B on nano-materials were exothermic and spontaneous. As the increase of temperature, the maximum sorption capacity of ANP, ANW, HBNC, SMNC increased, and reached 868.75, 91.35, 5.15, 2465.09 µg/g at 25 °C, respectively. The surface modified nanoclay (SMNC) was better than the others for removing F-53B from aquatic environment. To investigate the effects of pH and ion strength, the particle size and zeta potential of sorbents at different pH and ion strength were measured by Dynamic Light Scattering (DLS), and concluded that the sorption mechanism of F-53B on two kinds of nanoalumina mainly included electrostatic attraction and agglomeration effects, while hydrophobic interaction played an important role on the sorption of F-53B on nanoclay. This study revealed the sorption behavior and mechanism of F-53B on four kinds of nano-materials, and the results provided theoretical support for removing F-53B from electroplating wastewater with nano-materials.

[Analysis of clinical characteristics of patients with chronic critical illness after sepsis].

OBJECTIVE: To investigate the clinical characteristics of patients who develop chronic critical illness (CCI) after sepsis. METHODS: The survival patients with sepsis admitted to the department of critical medicine of Baoan Central Hospital of Shenzhen for the first time from April 2019 to October 2020 were enrolled. According to clinical outcomes, patients were divided into CCI group [intensive care unit (ICU) stay ≥ 14 days, with persistent organ dysfunction] and rapid recovery (RAP) group. The baseline characteristic on admission and clinical outcomes of patients in the two groups were collected and compared. Blood samples were collected to measure serum interleukins (IL-6, IL-10) levels and peripheral blood lymphocyte count (LYM) count were obtained from all patients after admission. The differences of above indexes on the 1st, 7th and 14th day in ICU between the two groups were compared, the 180 day cumulative survival rate of the two groups was observed. RESULTS: (1) Twenty-two septic patients developed CCI and 28 patients with RAP were included. There were no significant differences in gender and infection site between the two groups. The age, acute physiology and chronic health evaluation II (APACHE II), sequential organ failure assessment (SOFA), proportion of septic shock, mechanical ventilation time, length of ICU stay, total length of hospital stay and proportion of secondary infection of CCI patients were higher than those in RAP group [age (years old): 61.0±13.8 vs. 50.3±13.9, proportion of patients aged ≥ 65 years old: 54.5% (12/22) vs. 25.0% (7/28), APACHE II score: 20.5±4.4 vs. 14.4±4.3, SOFA score: 10 (7, 12) vs. 5 (3, 8), septic shock ratio: 40.9% (9/22) vs. 17.9% (5/28), time of mechanical ventilation (days): 18.5 (12.0, 28.0) vs. 5.0 (3.0, 7.0), length of ICU stay (days): 26 (18, 46) vs. 8 (6, 12), total length of hospital stay (days): 31 (26, 51) vs. 14 (12, 17), secondary infection ratio: 72.7% (16/22) vs. 7.1% (2/28), all P < 0.05]. (2) The IL-6 levels of CCI group were higher than that of RAP group at all time points (ng/L: 176.86±103.54 vs. 113.32±71.34 on the 1st day, 84.72±46.06 vs. 54.98±26.61 on the 7th day, 44.28±20.20 vs. 17.76±4.70 on the 14th day, all P < 0.05). On the 1st and 7th day of admission, there were no significant differences in IL-10 and LYM levels between the two groups. On the 14th day of admission, IL-10 levels in CCI group were higher than that in RAP group (ng/L: 15.09±3.61 vs. 8.92±1.98, P < 0.05), while LYM was relatively lower [×109/L: 0.62 (0.43, 1.02) vs. 1.17 (0.93, 1.71), P < 0.05]. (3) The Log-Rank test results of Kaplan-Meier survival curve showed that the 180-day cumulative survival rate of CCI group was significantly lower than that of RAP group (63.6% vs. 96.4%, Log-Rank: χ2 = 9.024, P = 0.007). CONCLUSIONS: Septic patients with advanced age, high APAHCE II score and high SOFA score are prone to secondary CCI, resulting in long hospital stay, high secondary infection rate and poor prognosis. The occurrence of CCI may be related to the continuous expression of proinflammatory mediators and subsequent immunosuppression.

The incorporation of Pb2+ during struvite precipitation: Quantitative, morphological and structural analysis.

Struvite precipitated from wastewaters is an important fertilizer. However, struvite derived from wastewater usually contains toxic Pb, which can bring contamination to soil and even plants. Thus, understanding the incorporation mechanisms of Pb2+ during struvite precipitation is critical to its safe application. Here the influence of Pb concentration on struvite precipitation was assessed. When the initial Pb concentrations were at the range of 0.1-1 mg/L, the formation of pitting and roughening on struvite crystal surfaces was observed by scanning electron microscopy (SEM), indicating a surface interaction between Pb and struvite. Combined with X-ray photoelectron spectra (XPS), the results confirmed that the formed Pb-enriched layer with Pb-OH and Pb-PO4 bonds was absorbed on struvite surface during precipitation. When Pb concentrations were increased to 10-100 mg/L, the precipitation of dominating Pb phase, crystalline Pb10(PO4)6(OH)2, was confirmed by X-ray diffraction (XRD). Combined with XPS, the amorphous Pb hydroxide/phosphate and Mg phosphate were also detected in struvite solids. Our findings revealed that at low concentrations (0.1-1 mg/L), Pb can affect the mineral surface by surface absorption, whereas Pb precipitated as separated phase(s) (e.g. Pb10(PO4)6(OH)2, Pb hydroxide and/or phosphate) at high Pb concentrations (10-100 mg/L). Thus, the initial Pb2+ concentrations in wastewater will dictate final struvite contents and Pb-bearing phases in recovered solids.

Transformation of hazardous lead into aluminosilicate ceramics: structure evolution and lead leaching.

This study investigated crystallization mechanisms for the formation of lead aluminosilicate by sintering lead stabilization with kaolin-based precursors. PbAl2Si2O8 was found to be the only stable lead aluminosilicate in low-PbO system and demonstrates its highly intrinsic resistance to acid attack in leaching test. A three-stage PbAl2Si2O8 formation mechanism was supported by the results of the changing temperature in the system. Amorphization of sintered products was observed in both PbO/kaolinite and PbO/mullite systems at 600-700°C. When the temperature was increased to 750-900°C, the crystallochemical formation of lead aluminosilicates (i.e., Pb4Al4Si3O16, Pb6Al6Si2O21, and PbAl2Si2O8) was observed. Pb4Al4Si3O16 and Pb6Al6Si2O21 were found to be the intermediate phases at 700-900°C. Finally, PbAl2Si2O8 was found to be the only crystallite phase to host Pb at above 950°C. A maximum of 80% and 96.7% Pb can be incorporated into PbAl2Si2O8 in PbO/kaolinite and PbO/mullite systems, respectively, but the final products exhibited different microstructures. To reduce environmental hazard of lead, this strategy demonstrated a preferred mechanism of immobilizing lead into PbAl2Si2O8 structure via kaolin-based precursors.

Enhanced removal of veterinary antibiotic from wastewater by photoelectroactive biofilm of purple anoxygenic phototroph through photosynthetic electron uptake.

Purple anoxygenic phototrophs have been recently attracted substantial attention for their growing potential in wastewater treatment and their diverse metabolic patterns can be regulated for process control and optimization. In this study, the photoheterotrophic metabolism of Rhodopseudomonas palustris (R. palustris) was modified by photosynthetic electron uptake using a poised electrode which was explored to enhance removal of veterinary antibiotic from aqueous medium. The results showed that R. palustris grown as biofilm on electrode surface had excellent photoelectroactive activity and the photosynthetic electron uptake from the photoelectroactive biofilm significantly enhanced antibiotic florfenicol (FLO) degradation. The specific degradation rate of FLO at the set electrode potential of 0 V was 2.59-fold higher than that without applied potential. Enhanced co-metabolic reductive dehalogenation by use of the photosynthetic electrons extracted from co-substrate was mainly responsible for FLO degradation which eliminated the antibacterial activity of FLO. The electrode potential controlled the processes of photosynthetic electron uptake and its resultant FLO degradation. The fastest degradation of FLO was achieved at 0 V because the electrode poised at this potential stroke a proper balance between the enhancing photosynthetic electron uptake by serving as electron acceptor and minimizing competition with FLO for the photosynthetic electron from co-substrate. The activity of photoelectroactive biofilm was not negatively affected by FLO at environmental relevant concentration, suggesting its great potential for removal of antibiotic contaminants in wastewater. R. palustris could serve as a reservoir for floR resistance gene but its abundance can be diminished by choosing appropriate electrode potential.

Size-fractionated particle-bound heavy metals and perfluoroalkyl substances in dust from different indoor air.

The indoor air quality issue and its potential health problems are attracting increasingly attentions. In this study, micro-orifice uniform deposit impactor (MOUDI) was used to sample suspended particles from four typical indoor environments, including residence, office, cyber classroom, and chemical analysis room. Size-dependent concentrations of perfluoroalkyl substances (PFASs) and heavy metals in suspended particles were analyzed. Then, the International Commission on Radiological Protection deposition model was employed to estimate deposition efficiencies and fluxes of size-fractioned PFASs and heavy metals in the human respiratory tract. Most of the contaminants deposited in head airways, where coarse particles (aerodynamic diameter or Dp > 1.8 µm) contributed the most. By contrast, in the alveolar region fine particles (Dp < 1.8 µm) were dominant. The chronic daily intake through inhalation of PFASs and heavy metals via airborne particles were 10.3-37.5 pg kg-1days-1 and 3.1-25.9 mg kg-1days-1, respectively. The estimated total hazardous quotient of PFASs and heavy metals were 4.4 × 10-5-1.7 × 10-3 and 9.9 × 10-3-1.05 × 10-1, which is far lower than the acceptable threshold of 1. However, the incremental lifetime cancer risk induced by As, Cd, Co, Cr, and Ni were estimated to be 1.11 × 10-5-1.41 × 10-4 in total, which exceeded the acceptable threshold of 10-6. These findings implicate that there were health risks, especially cancer risks caused by heavy metals associated with airborne particles in urban indoor environments.

Effect of sintering temperature on mineral composition and heavy metals mobility in tailings bricks.

In this study, the mixing mechanism and phase transition process of different metals during the sintering of tailings bricks with four different metal oxides (CuO, PbO, ZnO, and CdO) at temperatures ranging from 700 to 1100 °C for 2 h were investigated. The properties of the sintered product was characterized and analyzed, and the results showed that the main crystalline phases are quartz, cristobalite, hematite, and mullite while the metal oxides are ascribed to copper ferrite spinel (CuFe2O4), gahnite (ZnAl2O4), zinc ferrite spinel (ZnFe2O4), lead feldspar (PbAl2Si2O8), and cadmium feldspar (CdAl2Si2O8). Further analysis indicates that the heavy metals were transited into spinel or silicate structures with favorable efficiency. This indicates a good heavy-metal fixation effect from the structural change after the sintering process. Finally, the leaching experiments of the sintered samples suggest that the metal leaching decreased to a low and stable value when the sintering temperature was higher than 950 °C, which meets the China standard (GB 5085.3-2007). The above results indicate that the sintering process facilitates the combination of Cu, Zn, Pb and Cd offering an effective and safe method for the application of materials that contain tailings.

Effect of solution chemistry and aggregation on adsorption of perfluorooctanesulphonate (PFOS) to nano-sized alumina.

The interaction of pollutants with nanomaterials has attracted attention due to the extensive application of nanomaterials. In this study, the adsorption behavior of PFOS on nano-alumina with different shapes was investigated. First, the adsorption isotherms and kinetics of PFOS on alumina nanoparticles (NPs) and nanowires (NWs) were measured to calculate thermodynamic parameters. The effects of solution chemistry (e.g., pH, ionic strength, and the presence of humic acid) on adsorption were further studied. The different aggregation behavior of alumina NPs and NWs were the critical factor for PFOS adsorption, as demonstrated through dynamic light scattering (DLS) experiments. This study is the first to investigate the aggregation effects on PFOS adsorption on nanomaterials and the results should be useful in identifying the important roles of shape and aggregation of nanomaterials on the fate of organic pollutants in the environment.

Thermogravimetric and mass-spectrometric analyses of combustion of spent potlining under N2/O2 and CO2/O2 atmospheres.

Thermal decomposition and gaseous evolution of the spent potlining (SPL) combustion were quantified using thermogravimetric and mass-spectrometric analyses in CO2/O2 and N2/O2 atmospheres using three heating rates (15, 20 and 25 °C/min). The thermal decomposition of SPL occurred mainly between 450 and 800 °C. Based on the four kinetic methods of Friedman, Starink, Kissinger-Akahira-Sunose and Flynn-Wall-Ozawa under the various conversion degrees (α) from 0.1 to 0.7, the lowest apparent activation energy was estimated at 149.81 kJ/mol in the 70% CO2/30% O2 atmosphere. The pre-exponential factor, and changes in entropy, enthalpy and free Gibbs energy were also estimated. The reaction model did not suggest a single reaction of the SPL combustion. With the α value of 0.25-0.7, the following function best described the reaction based on the Malek method: f(α) = 1/2α and G(α) = lnα2. The gases released during the combustion process included CO2, CO, NOx, HCN, and HF.