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Quinones and humus are ubiquitous in the biosphere and play an important role in the anaerobic biodegradation and biotransformation of organic acids, poisonous compounds as well as inorganic compounds. The impact of humic model compound, anthraquinone-2, 6-disulfonate (AQDS) on anaerobic phenol and p-cresol degradation were studied. Four methanogenic AQDS-free phenol and p-cresol enrichments and two phenol-AQDS enrichments were obtained using two sludges with potential biodegradability of phenol and cresol isomers as inoculum. 16S rRNA gene-cloning analysis combined with fluorescence in situ hybridization revealed that syntrophic aromatic compound degrading bacterium Syntrophorhabdus aromaticivorans was dominant in four AQDS-free enrichments, whereas phenol degrading Cryptanaerobacter phenolicus was dominant in two phenol-AQDS enrichments. Neither co-culture of S. aromaticivorans with Methanospirillum hungatei nor two phenol-AQDS enrichments could metabolize phenol using AQDS as the terminal electron acceptor. Further degradation experiments suggested that C. phenolicus related microbes in two phenol-AQDS enrichments were responsible for the conversion of phenol to benzoate, and benzoate was further degraded by benzoate degraders of Syntrophus aciditrophicus or Sporotomaculum syntrophicum to acetate.

Shield tunnels are widely used in underground transportation. The shield tail brush is an important component of the shield machine, but also can exert an adverse influence on the segment as it can induce considerable and uneven pressure thereon. Therefore, it is necessary to consider the tail brush pressure in calculations on the segment. However, there are few studies on the calculation method of this pressure. As a consequence, this study carried out laboratory tests on the tail brush, and revealed the two-stage nature of its pressure-compression curve, which can be fitted well by a line together with a polynomial function. In addition, formulas describing the tail brush pressure distribution along the circumference were derived by theoretical analysis. Furthermore, by summarizing the distribution law, simplified formulas for the tail brush pressure acting upon the segment along the circumference and lengthwise due to vertical shield posture adjustment were established. The results can be used in calculations on the segment to improve the segment design and provide guidance for shield tunnel construction.

Nicotinamide adenine dinucleotide phosphate (NADPH) dehydrogenase is an oxidoreductase involved in many physiological processes and metabolic pathways. However, its role in filamentous fungal physiology is still unclear. In the present study, three canonical NADPH dehydrogenase genes (Panph1, Panph2, and Panph3) in the fungus Podospora anserina were deleted, and multiple mutants were constructed. Results show a significantly increased number of fruiting bodies in the NADPH dehydrogenase mutant, with the nphΔΔΔ triple mutant exhibiting higher sensitivity to oxidative stress, suggesting an active‐site protein misfolding. Specifically, the antioxidant genes Nox and CAT in the WT were significantly down‐regulated, confirming NADPH availability; however, in the NADPH mutant, these genes were significantly upregulated (p ≤ 0.001) as a response to nullify the constraint imposed by NADPH deletion and alleviate oxidative stress. Furthermore, an increase in substrate‐level phosphorylation compensated for a significant decrease in oxidative phosphorylation due to NADPH gene deletion. The NADPH/NADP+ ratio, a driving force for the intracellular redox potential, showed a significant increase in the nphΔΔΔ triple mutant. Meanwhile, the NADPH mutant inhibited the β‐oxidative pathway, decreasing fatty acid degradation, but promoted fatty acid biosynthesis, reflecting the role of NADPH in the metabolic programming of cellular respiration and energy utilization processes in fungi. Our study provides genetic evidence for the role of the NADPH dehydrogenase gene in oxidative defence and energy metabolism in P. anserina. NADPH dehydrogenase gene deletion significantly triggered NADPH/NADP+ increase in mutant strains. NADPH gene deletion promoted Fatty acid biosynthesis and repressed β‐oxidation. NADPH gene deletion decreased oxidative phosphorylation and increased substrate‐level phosphorylation. Mutants exhibited hypersensitivity to oxidative stress, but promoted more fruiting body differentiations.

Background High-temperature requirement protease A2 (HtrA2/Omi) is a mitochondrial chaperone that is highly conserved from bacteria to humans. It plays an important role in mitochondrial homeostasis and apoptosis. In this study, we investigated the role of HtrA2 in mouse oocyte maturation. Methods The role of HtrA2 in mouse oocyte maturation was investigated by employing knockdown (KD) or overexpression (OE) of HtrA2 in young or old germinal vesicle (GV) oocytes. We employed immunoblotting, immunostaining, fluorescent intensity quantification to test the HtrA2 knockdown on the GV oocyte maturation progression, spindle assembly checkpoint, mitochondrial distribution, spindle organization, chromosome alignment, actin polymerization, DNA damage and chromosome numbers and acetylated tubulin levels. Results We observed a significant reduction in HtrA2 protein levels in aging germinal vesicle (GV) oocytes. Young oocytes with low levels of HtrA2 due to siRNA knockdown were unable to complete meiosis and were partially blocked at metaphase I (MI). They also displayed significantly more BubR1 on kinetochores, indicating that the spindle assembly checkpoint was triggered at MI. Extrusion of the first polar body (Pb1) was significantly less frequent and oocytes with large polar bodies were observed when HtrA2 was depleted. In addition, HtrA2 knockdown induced meiotic spindle/chromosome disorganization, leading to aneuploidy at metaphase II (MII), possibly due to the elevated level of acetylated tubulin. Importantly, overexpression of HtrA2 partially rescued spindle/chromosome disorganization and reduced the rate of aneuploidy in aging GV oocytes. Conclusions Collectively, our data suggest that HtrA2 is a key regulator of oocyte maturation, and its deficiency with age appears to contribute to reproduction failure in females.

The mainstream silver recovery has problems such as resource waste, weak silver selectivity, and complicated operation. Here, self-propelled magnetic enhanced capture hydrogel (magnetic NbFeB/MXene/GO, MNMGH) was prepared by self-crosslinking encapsulation method. MNMGH achieved high selectivity (Kd = 23.31 mL/g) in the acidic range, and exhibited ultrahigh silver recovery capacity (1604.8 mg/g), which greatly improved by 66% with the assistance of in-situ magnetic field. The recovered silver crystals could be directly physically exfoliated, without acid/base additions. The selective sieving effect of adsorption, MNMGH preferentially adsorbed Ag(I), and then selectively reduced to Ag(0), realizing dual-selective recovery. The in-situ magnetic field enhanced selective adsorption by enhancing mass transfer, reactivity of oxygen-containing functional groups. Furthermore, density function theory simulations demonstrated that the in-situ magnetic field could lower the silver reduction reaction energy barrier to enhance the selective reduction. Three-drive synergy system (reduction drive, adsorption drive and magnetic drive) achieved ultrahigh silver recovery performance. This study pioneered an in-situ magnetic field assisted enhancement strategy for dual-selective (adsorption/reduction) recovery of precious metal silver, which provided new idea for low-carbon recovery of noble metal from industrial waste liquids. Here, self-propelled magnetic enhanced capture hydrogel was prepared, which achieved high selectivity (Kd = 23.31 mL/g) in the acidic range, and exhibited ultrahigh silver recovery capacity (1604.8 mg/g). The recovered silver crystals could be directly physically exfoliated, without acid/base additions. [Display omitted] •In-situ magnetic enhanced capture MNMGH exhibited ultra-high silver capacity.•The in-site magnetic field enhanced dual-selectivity for recovery silver.•Three-drive system exhibited stable selective recovery performance over a wide pH range.•Physical stripping of coral dendritic gold, green recovery of high-purity silver.

BackgroundThe discard of used adsorbents may pose a great threat to human health and ecological environment. This work herein reported a facile and feasible method, with aims of (i) reusing the calcined layered double hydroxide (CLDH) adsorbent after azo dye adsorption, and (ii) being further used as a photocatalyst to enhance the degradation of typical pharmaceuticals. Calcination under inner gas flow has been utilized to carbonize adsorbed azo dye and a kind of novel carbonaceous CLDH composite material (CM-CLDH) was synthesized. This fabricated material was used as a catalyst for Ibuprofen removal in water samples under simulated sunlight irradiation.ResultsAccording to our experimental results, combination of carbonaceous material with CLDH showed an enhanced photocatalytic performance compared to original CLDH materials. More than 90% of Ibuprofen could be removed in less than 180 min. Introduction of carbon material narrowed catalyst’s band gap and turned its conduct band potential to a more negative state, which brought considerable light absorption and higher oxidation ability of photo-induced electrons. Furthermore, photoluminescent spectra and transient photocurrent examination confirmed that carbon material suppressed recombination of photo-induced electrons and holes through faster electron transportation. Under experimental conditions, the removal efficiency of Ibuprofen by CM-CLDH composite kept above 90% during five cycles.ConclusionCalcination under inner gas flow can transform organic pollutant-adsorbed CLDH to CM-CLDH composite with higher photocatalytic performance. A feasible way to reuse spent LDH adsorbents was proposed, which is a benefit to reduce second pollution of spent adsorbents in environment.

This study focused on the start-up and operating characteristics of the endogenous partial denitrification (EPD) process with different carbon sources. Two sequencing batch reactors (SBRs) with sodium acetate (SBR1#) and glucose (SBR2#) as carbon sources were operated under anaerobic/oxic (A/O) and anaerobic/anoxic/oxic (A/A/O) modes successively for 240 d. The results showed that COD removal efficiency reached 85% and effluent COD concentrations were below 35 mg/L in both SBRs. The difference was that faster absorption and transformation of sodium acetate was achieved compared to glucose (COD removal rate (CRR) was 7.54 > 2.22 mgCOD/(L·min) in SBR1# compared to SBR2#). EPD could be started up with sodium acetate and glucose as carbon sources, respectively, and desirable high nitrite accumulations were both obtained at influent NO3−−N (NO3−-Ninf) increased from 20 to 40 mg/L with nitrate-to-nitrite transformation ratio (NTR) and specific NO3−-N deduction rate (rNa) of 88.4~90% and 2.41~2.38 mgN/(gVSS·h), respectively. However, at NO3−-N of 50~60 mg/L, both the NTR and rNa in SBR1# were higher compared to SBR2# (86.5% > 83.9% and 1.58 > 1.20 mgN/(gVSS·h), respectively). Hereafter, when NO3−-N was increased by 70~90 mg/L, lower NTR and rNa were observed in SBR1# than in SBR2# (72% and 78%, 1.16 and 1.32 mgN/(gVSS·h), respectively). Additionally, similar internal carbon transformations were observed to drive EPD for NO2−−N accumulation, especially for higher and faster carbon transformation with sodium acetate as carbon source compared to glucose. However, precise control of anoxic time as the peak point of nitrite (TNi,max) was still the key to achieve high NO2−−N accumulation.

A novel composite adsorbent, hydroxyapatite/ manganese dioxide （HAp/MnO2）, has been developed for the purpose of removing lead ions from aqueous solutions. The combination of HAp with MnO2 is meant to increase its adsorption capacity. Various factors that may affect the adsorption efficiency, including solution pH, coexistent substances such as humic acid and competing cations （Ca2＋, Mg2＋）, initial solute concentration, and the duration of the reaction, have been investigated. Using this composite adsorbent, solution pH and coexistent calcium or magnesium cations were found to have no significant influence on the removal of lead ions under the experi- mental conditions. The adsorption equilibrium was described well by the Langmuir isotherm model, and the calculated maximum adsorption capacity was 769 mg. gl. The sorption processes obeyed the pseudo-second-order kinetics model. The experimental results indicate that HAp/MnO2 composite may be an effective adsorbent for the removal of lead ions from aqueous solutions.

A series of calcium-containing layered double hydroxides (LDHs) and calcined product (CLDH) were synthesized using a comparative simple synthesis method (without using organic solvents and with a shortened reaction time) and applied in the adsorption of arsenic in water. The adsorption performance of arsenate on these LDHs and CLDH were studied using batch tests. The effects of various factors during the adsorption process, such as pH of the solution, dosage of materials, coexisting ions, contact time, and initial arsenate concentration, were evaluated. The maximum adsorption capacity of arsenate on three materials (CaFe-CLDH, CaFe-Cl-LDH, CaFe-NO3-LDH) were 156.0 mg·g−1, 150.5 mg·g−1, and 148.0 mg·g−1, respectively. When the concentration of CaFe-CLDH was 0.5 g·L−1, the concentration of arsenate was reduced from 5000 μg·L−1 to 10 μg·L−1 after adsorption. Moreover, when the CaFe-NO3-LDH or CaFe-Cl-LDH dosage was 1.0 g·L−1, a similar decontamination result could be achieved. The synthesized CaFe-CLDH was used to treat actual contaminated water samples from a river in a mining area north of Lengshuijiang City in Hunan Province, China. After treating using CaFe-CLDH, the residual arsenic concentration of actual water samples can fully meet the requirements for arsenic in the drinking water standards of the World Health Organization and China. This indicates that synthetic CaFe-CLDH has the potential to serve as an effective adsorbent for the removal of arsenic contamination.

Domestic water purification devices (point-of-use) are important choices for people to deal with sudden drinking water contamination. Especially for sudden heavy metal and arsenic contamination, home water purification units can play a key role as a secondary line of defense. Most of the arsenic removal studies are limited to meeting the requirements of local water quality standards and few studies have been conducted on arsenic removal from household water purifiers. In this paper, the distribution characteristics of arsenic in water at the end of the pipeline network in the Shanghai water supply area have been investigated. Three types of household water purifiers, mainly with membrane separation technology, were selected to treat the simulated arsenic contamination in tap water sources. The effects of pH and inorganic salts on arsenic removal were studied in comparison to the results of coexisting ion concentrations in tap water. The results showed that the total arsenic concentrations in different tap water samples range from 0.479–1.195 µg L−1, which is lower than the limit value for arsenic concentration set by China’s drinking water standard GB 5749–2006 (10 µg L−1) and by the World Health Organization (10 µg L−1). It is found that reverse osmosis and nanofiltration water purifiers were more effective in removing As(V), with removal rate above 97.7%, and less effective in removing As(III), the rate ranging from 40.1 to 56.3%. Preliminary validation was provided for the safety of household water purifiers in securing universal and sudden drinking water contamination. Domestic water purifiers are effective in reducing the risk of arsenic exposure in drinking water.