Stimulating anaerobic digestion to degrade recalcitrant organic pollutants: Potential role of conductive materials-led direct interspecies electron transfer.

This review aims to provide a comprehensive understanding of the potential of CMs-dominated DIET in the degradation of recalcitrant organic pollutants in AD. The review covers the mechanisms and efficiencies of recalcitrant organic pollutant degradation by CMs-dominated DIET, the comparison of degradation pathways between DIET and chemical treatment, recent insights on DIET-enhanced degradation, and the evaluation of the potential and future development of CMs-dominated DIET. The review emphasizes the importance of coupled syntrophic microorganisms, electron flux, and physicochemical properties of CMs in enhancing the degradation performance of AD. Additionally, it highlights the advantages of DIET-led syntrophic metabolism over traditional oxidation technologies in terms of environmental friendliness and efficiency. Finally, the review acknowledges the potential risks associated with introducing CMs into AD systems and provides guidance for waste treatment and energy recovery.

Nitrogen removal of decentralized swine wastewater by pilot-scale source reduction - anaerobic baffled reactor - zoning constructed wetlands at low temperatures.

The study developed a cost-effective integrated technology to treat swine wastewater at the pilot-scale small pigsty. The swine wastewater, which was separated rinse water after flowing through the slatted floor and the innovatively constructed liquid-liquid separate collection device, was subsequently pumped into an anaerobic baffled reactor (ABR) and then through zoning constructed wetlands (CWs) comprised of CW1, CW2, and CW3. The liquid-liquid separate collection device effectively reduced COD, NH4-N, and TN by 57.82%, 52.39%, and 50.95%, respectively. The CW1 and CW2 enhanced TN removal and nitrification, respectively, through rapid adsorption-bioregeneration of zeolite. Moreover, rice straws were used as solid carbon sources in CW3 to successfully promote denitrification at 16.0 g/(m3·d). The integrated technology (slatted floor-liquid liquid separate collection-ABR-CWs) reduced COD, NH4-N, and TN by 98.17%, 87.22%, and 87.88%, respectively, at approximately 10 °C. Microbial analysis results confirmed that the CWs exhibited apparent functional zoning, with denitrifiers dominating in CW3, nitrifiers dominating in the zeolite layers of CW1 and CW2, and denitrifiers dominating in the brick slag layers of CWs. This cost-effective integrated technology demonstrated significant potential for treating swine wastewater at low temperatures.

Conductive materials as fantastic toolkits to stimulate direct interspecies electron transfer in anaerobic digestion: new insights into methanogenesis contribution, characterization technology, and downstream treatment.

Direct interspecies electron transfer (DIET) stimulated by conductive materials (CMs) enables intercellular metabolic coupling that can address the unfavorable thermodynamical dilemma inherent in anaerobic digestion (AD). Although the DIET mechanism and stimulation have been extensively summarized, the methanogenesis contribution, characterization techniques, and downstream processes of CMs-led DIET in AD are surprisingly under-reviewed. Therefore, this review aimed to address these gaps. First, the contribution of CMs-led DIET to methanogenesis was re-evaluated by comparing the effect of various factors, including volatile fatty acids, free ammonia, and functional enzymes. It was revealed that AD systems are usually intricate and cannot allow the methanogenesis stimulation to be singularly attributed to the establishment of DIET. Additionally, considerable attention has been attached to the characterization of DIET occurrence, involving species identification, gene expression, electrical properties, cellular features, and syntrophic metabolism, suggesting the significance of accurate characterization methods for identifying the syntrophic metabolism interactions. Moreover, the type of CMs has a significant impact on AD downstream processes involving biogas purity, sludge dewaterability, and biosolids management. Finally, the central bottleneck consists in building a mathematical model of DIET to explain the mechanism of DIET in a deeper level from kinetics and thermodynamics.

Development, dilemma and potential strategies for the application of nanocatalysts in wastewater catalytic ozonation: A review.

With the continuous development of nanomaterials in recent years, the application of nanocatalysts in catalytic ozone oxidation has attracted more and more researchers' attention due to their excellent catalytic properties. In this review, we systematically summarized the current research status of nanocatalysts mainly involving material categories, mechanisms and catalytic efficiency. Based on summary and analysis, we found most of the reported nanocatalysts were in the stage of laboratory research, which was caused by the nanocatalysts defects such as easy aggregation, difficult separation, and easy leakage. These defects might result in severe resource waste, economic loss and potentially adverse effects imposed on the ecosystem and human health. Aiming at solving these defects, we further analyzed the reasons and the existing reports, and revealed that coupling nano-catalyst and membrane, supported nanocatalysts and magnetic nanocatalysts had promising potential in solving these problems and promoting the actual application of nanocatalysts in wastewater treatment. Furthermore, the advantages, shortages and our perspectives of these methods are summarized and discussed.

Evaluation of pH regulation in carbohydrate-type municipal waste anaerobic co-fermentation: Roles of pH at acidic, neutral and alkaline conditions.

This study investigated and evaluated the roles of acidic (pH 4.0), neutral (pH 7.0) and alkaline (pH 10.0) in anaerobic co-fermentation of sewage sludge and carbohydrate-type municipal waste. CO2, CH4 and H2 are produced in acidic, neutral and alkaline fermentation, respectively. The neutral co-fermentation contained the vast number of aqueous metabolites as total of 22.12 g/L, with the advantage of over 50 % biodegradable components in extracellular polymeric substance and over 80 % hydrolysis rate. Acidic and alkaline pH facilitated ammonia release, with the max concentration of 0.46 g/L and 0.44 g/L, respectively. Microbial analysis indicated that pH is the key parameter to impact microbial activity and drive microbial community transition. The high abundance of Lactobacillus, Bifidobacterium and Clostridium was associated with harvest of ethanol, lactic acid and acetate in acidic, neutral and alkaline fermentation. Meanwhile, the floc feature showed better dewaterability (zeta potential -8.48 mV) and poor nutrient convey (distribution spread index 1.03) in acidic fermentation. In summary, acidic and alkaline fermentation were prioritised for targeted spectrum. Neutral fermentation was prioritised for high production. This study presented an upgraded understanding of the pH role in fermentation performance, microbial structure and sludge behaviour, which benefits the development of fermentation processing unit.

Target and Enhance Ethanol and Butyrate Production from Anaerobic Fermentation via the pH and Organic Loading Rate Combined Strategy.

The large capacity production and low utilization rate increase the difficulty of fruit and vegetable wastes (FVW) treatment. Efficient and targeted recovery strategies can solve these problems. This study investigated and proposed combined strategies via pH and organic loading rate (OLR) to target and enhance ethanol- and butyrate-dominant acidogenic production in the FVW mixed culture fermentation. Under pH 4.0, OLR 18 gCOD/(L∙d), and mesophilic (35 °C), ethanol-dominant fermentation was formed. The long-term operation (168 days) showed that the highest ethanol yield was 0.33 g/gCOD which was greater than that in other studies. Also, the hydrolysis rate of ethanol-type fermentation reached 74.5%. Besides, butyrate-type fermentation was stable at yield 0.39 g/gCOD following conditions: pH 6.0, OLR 28 gCOD/(L∙d), and 35 °C, of which hydrolysis and acidogenic rate were 78.0% and 62.0%, respectively. The high relative abundance of Lactobacillus, Olsenella, and Bifidobacterium played positive role in achieving ethanol, butyrate, and lactate production among various metabolic pathways. The results revealed the pH value together with OLR was the valid parameter to affect product formation and composition during FVW fermentation.

Effect of carbon source conditions on response of nitrifying sludge to 3,5-dichlorophenol.

Nutritional conditions of activated sludge had a significant influence on nitrification inhibition response. This study comprehensively investigated the inhibition of 3,5-dichlorophenol (3,5-DCP) on nitrification of activated sludge with different C/N ratios and carbon source types. The corresponding extracellular polymeric substances (EPS), microbial communities and functional genes were analysed. The results indicated that the addition of carbon source would reduce the nitrification activity and nitrification sensitivity to 3,5-DCP, and the order of the EC50 was sequenced as sodium acetate > methanol > glucose. The response mechanisms of activated sludge under diverse carbon source conditions to 3,5-DCP were summarised as follows. When the 3,5-DCP content was increased from 0.4 mg/L to 0.8 mg/L, the protein content increased from 73.2 ± 2.6 mg/g SS ∼122.4 ± 4 mg/g SS to 92.2 ± 11.2 mg/g SS ∼130.8 ± 9.6 mg/g SS in the tightly bound EPS (TB-EPS). The increase of protein content was attributed to cellular self-protection mechanisms. Furthermore, fluorescence characteristic analysis revealed that tyrosine and tryptophan in loosely bound EPS (LB-EPS) might account for higher EC50 in activated sludge fed with methanol and sodium acetate. In addition, the redundancy analyses (RDA) showed activated sludge with organics enriched the resistant species, such as Proteobacteria and Patescibacteria, while activated sludge without organics enriched the sensitive species, such as Ferruginibacter. Finally, the nitrification genes were found to be consistent with nitrification activity. Thus, the findings provide new insights into nitrification inhibition mechanism under different carbon source conditions.

Enhanced denitrification of dispersed swine wastewater using Ca(OH)2-pretreated rice straw as a solid carbon source.

In a pilot-scale packed bed reactor, the denitrification performance and microbial community structure of the dispersed swine wastewater treatment using calcium hydroxide (Ca(OH)2) pretreated rice straw as a carbon source were investigated. In a Ca(OH)2-pretreated rice straw supported denitrification system (Ca(OH)2-RS), the removal efficiency of NO3--N was 96.39% at an influent NO3--N load of 0.04 kg/(m3•d). Meanwhile, there was no obvious accumulation of NO2--N or chemical oxygen demand (COD) in the effluent of Ca(OH)2-RS. The contents of soluble microbial byproduct-like substances and tryptophan-like substances in the effluent of Ca(OH)2-RS were reduced by 46.2% and 43.4%, respectively, compared with the influent. Overall, the Ca(OH)2-pretreated rice straw system had a strong resistance to fluctuations in water quality conditions, such as influent NO3--N and COD concentrations. According to the microbial assay results, the Ca(OH)2 pretreatment enriched more denitrifying bacteria. Among them, Proteobacteria (42.33%) and Bacteroidetes (35.28%) were the dominant bacteria. Moreover, the main denitrifying functional bacteria, generanorank_f_Saprospiraceae (13.32%), norank_f_Porphyromonadaceae (4.22%), and Flavobacterium (3.25%), were enriched in Ca(OH)2-RS. This suggested that using Ca(OH)2-pretreated rice straw as a carbon source was a stable and efficient technology to enhance the denitrification performance of dispersed swine wastewater.

Mechanical forces on trophoblast motility and its potential role in spiral artery remodeling during pregnancy.

During the first trimester of pregnancy, cytotrophoblasts (CTBs) differentiate into extravillous trophoblasts (EVTs). EVTs migrate from villus to decidua, invade maternal spiral arteries (SAs) and more strikingly, they migrate against blood flow along the vessels and replace endothelial cells (ECs), completing SA remodeling. Studies have indicated that trophoblast cells are mechanosensitive. They assemble ECs, which can align in the direction of fluid flow. However, how they sense blood flow and transform mechanical stimulations into chemical signals remain largely unexplored. What factors trigger their motility? what are the potential and major factors that guide them to find their path and empower them to migrate against flow? To answer these intricate questions, this review provides some of the novel aspects and sheds new insights into clinical applications.

A thorough observation of an ozonation catalyst under long-term practical operation: Deactivation mechanism and regeneration.

Heterogeneous catalytic oxidation, as an efficient advanced treatment technology, has been gradually applied in industrial wastewater treatment. The fixed bed technique is one of the most popular catalytic ozonation methods. However, few studies have concentrated on the long-term operation effects on catalysts. In this study, we conducted long-term (~5 years) observations of the operation of the largest petrochemical wastewater treatment plant (treatment capacity 120,000 m3/d) with catalytic ozonation technology in China. A commercial catalyst, which uses Al2O3 pellets supporting copper oxide was applied in this plant. The results showed that the catalytic efficiency gradually decreased from 60.65% to 25.98% since 2018, and the ozone dosage to COD removal ratio (ozone/COD) also increased from 0.82 to 1.93 mg/mg as the running time continued. By means of the comparison and characterization of fresh catalyst and used catalyst, a "mucus layer" was formed by the adsorption of negatively charged extracellular polymeric substances on the positively charged catalyst surface and the interception of the catalyst layer. The mucus layer significantly reduced the catalytic efficiency by isolating ozone with catalytic active sites and releasing extra organic contaminants during the catalytic process resulting in 53.97% TOC increase in the batch test. Meanwhile, regeneration experiments revealed that the TOC removal efficiency was 4.76% and 43.48% in presence of washed catalysts and calcinated catalysts, respectively. Compared with the fresh catalyst, 73% of the catalytic activity was recovered for calcinated catalyst. Consequently, this study provides much practical information, showing positive effects on the promotion of catalytic ozonation application in actual wastewater treatment.

Coupling of membrane-based bubbleless micro-aeration for 2,4-dinitrophenol degradation in a hydrolysis acidification reactor.

Micro-aeration hydrolysis acidification (HA) is an effective method to enhance the removal of toxic and refractory organic matter, but the difficulty in stable dosing control of trace oxygen limits its wide application. Membrane-based bubbleless aeration has been proved as an ideal aeration method because of its higher oxygen transfer rate, more uniform mass transfer, and lower cost than HA. However, the available information on its application in HA is limited. In this study, membrane-based bubbleless micro-aeration coupled with hydrolysis acidification (MBL-MHA) was exploited to investigate the performance of 2,4-dinitrophenol (2,4-DNP) degradation via comparing it with bubble micro-aeration HA (MHA) and anaerobic HA. The results indicated that the performances in MBL-MHA and MHA were higher than those in HA during the experiment. 2,4-DNP degradation rates under redox microenvironments caused by counter-diffusion in MBL-MHA (84.43∼97.28%) were higher than those caused by co-diffusion in MHA (82.41∼94.71%) under micro-aeration of 0.5-5.0 mL air/min. The 2,4-DNP degradation pathways in MBL-MHA were nitroreduction, deamination, aromatic ring cleavage, and fermentation, while those in MHA were hydroxylation, aromatic ring cleavage, and fermentation. Reduction/oxidation-related, interspecific electron transfer-related species, and fermentative species in MBL-MHA were more abundant than that in MHA. Ultimately, more reducing/oxidizing forces formed by more redox proteins/enzymes from these rich species could enhance 2,4-DNP degradation in MBL-MHA.

Inhibition of biological acidification and mechanism of crotonaldehyde removal with glucose cometabolism.

Biological acidification is an effective method in the treatment or pretreatment of industrial wastewater. Crotonaldehyde is a typical characteristic organic pollutant in petrochemical wastewater, but its effect on biological acidification is unclear. To investigate the inhibitory characteristic of crotonaldehyde on biological acidification and the mechanism of crotonaldehyde removal, variations in volatile fatty acid (VFA) yields, enzyme activities, biodegradation products, and microbial community structures were investigated by batch experiments in the presence of crotonaldehyde. The results showed that crotonaldehyde caused a 50% effect concentration (EC50) on the specific acidogenic activity (SAA) of 204.17 mg/L before 24 h, and then, the inhibitory effect was removed after 48 h as the dosage of crotonaldehyde was less than 1000 mg/L. Accordingly, crotonaldehyde was completely reduced to crotonyl alcohol by nicotinamide adenine dinucleotide (NADH) or oxidized to (E)-crotonic acid by aldehyde dehydrogenase (DHO) after 48 h. Next, 1-buanol and n-butyric acid were further metabolites, while the n-hexanoic acid detected with high-concentration crotonaldehyde might be due to the ORB pathway with 1-buanol as an electron donor. The dominant bacterial communities were Clostridium_sensu_stricto_1, Clostridium_sensu_stricto_11, Clostridium_sensu_stricto_12, which were related to the biodegradation process of crotonaldehyde. The findings of this research could provide a theoretical underpinning for developing the biological technologies to pretreat crotonaldehyde wastewater.

Inhibitory effect of individual and mixtures of nitrophenols on anaerobic toxicity assay of anaerobic systems: Metabolism and evaluation modeling.

The single and combined inhibitory effects of different nitrophenols on the anaerobic toxicity assay (ATA) of anaerobic sludge and the variations in the content of extracellular polymeric substances (EPS) were investigated. The results indicated that 2,4-dinitrophenol (2,4-DNP) demonstrated the highest inhibitory effect, followed by 4-nitrophenol (4-NP) and 2-nitrophenol (2-NP), and the combined effects of binary and ternary nitrophenols induced additive toxicity. Furthermore, 2,4-DNP, the dominant toxic nitrophenol, at various concentrations and toxicant ratios, was the major contributor to the combined inhibitory effects of the nitrophenol mixtures. Abundant EPS could be secreted by the anaerobic sludge under the inhibitory effects of toxic 2-NP, 4-NP, and 2,4-DNP at concentrations from 0 to 200 mg/L to resist the adverse effects of the external environment. The protein contents of both loosely bound EPS (LB-EPS) and tightly bound EPS (TB-EPS) exhibited a better linear positive correlation relationship (R2 > 0.92) with the inhibitory rates of 2-NP, 4-NP, and 2,4-DNP, indicating that the proteins generated in the EPS of anaerobic sludge could be a stress response. Therefore, increasing the concentration of the toxic nitrophenols could enhance the stress response and increase protein production. Parallel factor (PARAFAC) analysis for TB-EPS and LB-EPS further confirmed that the major proteins were tyrosine, tryptophan, and aromatic proteins. Moreover, with an increase in the concentrations of 2-NP, 4-NP, and 2,4-DNP from 0 to 200 mg/L, microbial cell lysis and death in anaerobic sludge could be increasingly severe. Thus, this study provides new insights into the inhibitory effects of nitrophenol mixtures, which are frequently found in pharmaceutical and petrochemical effluents, on anaerobic sludge.

Iron foam coupled hydrolysis acidification for trichloroacetaldehyde treatment: Strengthening characteristics and mechanism.

This research studied transformative characteristics and enhanced mechanism of trichloroacetaldehyde (TCAL), one of chlorinated acetaldehydes (CAAs), by coupled-type iron foam enhanced hydrolysis acidification (HA) reactor. Main results were given that better dechlorination and aldehyde removal were achieved at this process than coupled-type iron foam enhanced HA, alone iron foam and HA reactor. The reasons were due to better strengthening effects of iron foam and HA, iron foam reduced TCAL toxicity to microbes caused an improvement of microbial activity, therefore, volatile fatty acids (VFAs) content and acetate acid (Ac) ratio were increased compared with HA. Moreover, it promoted the enrichment of Actinobacteriota and Firmicutes, and more extracellular polymeric substance (EPS) and enzymes enhanced dechlorination and aldehyde removal. Certainly, microbes reduced iron foam passivation and facilitated its oxidation further improved the strengthening effect.

Corrigendum: Total Flavonoids of Rhizoma Drynariae Promotes Differentiation of Osteoblasts and Growth of Bone Graft in Induced Membrane Partly by Activating Wnt/ß-Catenin Signaling Pathway.

[This corrects the article DOI: 10.3389/fphar.2021.675470.].

RNA Demethylase FTO Mediated RNA m6A Modification Is Involved in Maintaining Maternal-Fetal Interface in Spontaneous Abortion.

The N6-methyladenosine (m6A) RNA modification regulates the expression of genes associated with various biological and pathological processes, including spontaneous abortion (SA). The aim of this study was to determine the role of the m6A demethylase fat mass and obesity (FTO)- associated protein in SA. The FTO,IGF2BP1 and IGF2BP2 mRNA levels were significantly lower in the chorionic villi obtained from spontaneously aborted pregnancies compared to that of normal pregnancies, while the expression levels of METTL3 and WTAP were significantly elevated. However, ALKBH5, YTHDF2, and IGF2BP3 were elevated with no statistical significance between groups. In addition, MDA was elevated and SOD levels were decreased in the villi tissues of the SA group compared to the normal group, which was indicative of placental oxidative stress in the former. Furthermore, the expression of FTO and HLA-G were significantly decreased in the trophoblasts of the SA patients compared to that of normal pregnant women, while that of m6A was markedly higher in the former. In addition, the HLA-G and VEGFR mRNA levels were downregulated in the SA versus the control group, and that of MMP2, MMP7, MMP9 and VEGFA were upregulated. Finally, The RIP assay showed significantly decreased levels of FTO-bound HLA-G, VEGFR and MMP9 RNA in SA patients (P < 0.05), which corresponded to an increase in transcripts enriched with the m6A antibody (P < 0.05). However, compared with normal pregnant women, the levels of HLA-G, VEGFA, VEGFR, and MMP2 mRNA bound by YTHDF2 were significantly decreased in SA patients. Compared to the normal pregnant women, both FTO- and m6A-bound MMP7 were significantly increased in SA patients (P < 0.05), but YTHDF2 almost unbound to MMP7 mRNA. In summary, the downregulation of FTO in the chorionic villi disrupts immune tolerance and angiogenesis at the maternal-fetal interface, resulting in aberrant methylation and oxidative stress that eventually leads to SA.

Circulating microRNAs from serum exosomes as potential biomarkers in patients with spontaneous abortion.

BACKGROUND: Spontaneous abortion (SA) is a common complication in early pregnancy. Nevertheless, SA's etiology is complex, and the underlying molecular mechanisms of the pathogenesis behind SA remains unclear. The present study aims to find the feasibility of using serum exosomal miRNAs as novel biomarkers for SA. METHODS: In our study, we isolated the serum exosomes from the peripheral blood of the subjects. Then transmission electron microscopy (TEM), WB, and in vitro exosome tracing experiments were used. Comprehensive exosomal miRNA sequencing was performed to profile the differentially expressed miRNAs between the SA and normal pregnancy groups. Furthermore, genes targeted by miRNAs were further predicted and verified by TargetScan, miRDB, miRTarBase, miRWalk and HMDD V3.2. Kyoto Encyclopedia of Genes and Genomes (KEGG) pathway analysis and pathway category were performed by the DIANA-miRPath v3.0 online tool. We then validated the expression levels of selected miRNAs by qRT-PCR. ROC analysis was performed to explore the clinical utility of the two miRNA as biomarkers for SA. RESULTS: TEM, NTA measurements and WB analysis showed the successful isolation of exosomes. Exosome labeling by PKH26 proved that exosomes could be efficiently taken up by primary decidual cells. Sequencing data found that with a total of 2,588, there were 189 significantly expressed exosomal miRNAs between the two groups. The most significantly expressed miRNA (miR-371a-5p, miR-206, miR-147b, miR-6859-5p, miR-410-3p, miR-1270 and miR-524-5p) were selected for further analysis. Through KEGG pathway analysis and pathway category, nine risk pathways were revealed. Among them, the Wnt signaling pathway, the Hippo signaling pathway, and the FoxO signaling pathway were pinpointed as major high-risk pathways. As a single marker, miR-371a-5p and miR-206 had a specificity of 83.3% and 70.8% at the sensitivity of 62.5% and 66.7%, respectively. The combined two markers achieved a specificity of 75% at the sensitivity of 79.2%. CONCLUSIONS: Our results suggest that the circulating miRNAs from exosomes are altered in patients with SA. Findings of this exploratory study may provide potential biomarkers for SA.

Total Flavonoids of Rhizoma Drynariae Promotes Differentiation of Osteoblasts and Growth of Bone Graft in Induced Membrane Partly by Activating Wnt/ß-Catenin Signaling Pathway.

Total flavonoids of Rhizoma drynariae (TFRD), a Chinese medicine, is widely used in the treatment of fracture, bone defect, osteoporosis and other orthopedic diseases, and has achieved good effects. Purpose of this trial was to explore efficacy of TFRD on bone graft's mineralization and osteoblasts' differentiation in Masquelet induced membrane technique in rats. Forty male Sprague-Dawley rats were randomly divided into high dose group (H-TFRD), middle dose group (M-TFRD), low dose group (L-TFRD) and control group (control). The critical size bone defect model of rats was established with 10 rats in each group. Polymethyl methacrylate (PMMA) spacer was implanted into the defect of right femur in rats. After the formation of the induced membrane, autogenous bone was implanted into the induced membrane. After 12 weeks of bone graft, bone tissues in the area of bone graft were examined by X-ray, Micro-CT, hematoxylin-eosin (HE) and Masson trichrome staining to evaluate the growth of the bone graft. The ß-catenin, c-myc, COL1A1, BMP-2 and OPN in bone graft were quantitatively analyzed by Western blot and Immunohistostaining. Osteoblasts were cultured in the medium containing TFRD. Cell Counting Kit-8 (CCK-8) method, Alkaline phosphatase (ALP) and Alizarin Red S (ARS) staining, Western blot, RT-PCR and other methods were used to detect the effects of TFRD on the proliferation of osteoblasts and the regulation of Wnt/ß-catenin signaling pathway. In vivo experiments showed that the growth and mineralization of bone graft in TFRD group was better. Moreover, the expression of Wnt/ß-catenin and osteogenesis-related proteins in bone tissue of TFRD group was more than that in other groups. In vitro experiments indicated that osteoblasts proliferated faster, activity of ALP was higher, number of mineralized nodules and proteins related to osteogenesis were more in TFRD group. But blocking Wnt/ß-catenin signaling pathway could limit these effects. Therefore, TFRD could promote mineralization of bone graft and differentiation of osteoblasts in a dose-dependent manner during growing period of the bone graft of induced membrane technique, which is partly related to the activation of Wnt/ß-catenin signaling pathway.

Additional polypyrrole as conductive medium in artificial electrochemically active biofilm (EAB) to increase the sensitivity of EAB based biosensor in water quality early-warning.

Researchers believe that adding conductive mediums in electrochemically active biofilms (EABs) would improve the sensitivity of EAB-based biosensor for real-time water quality early-warning through facilitating the extracellular electron transfer (EET), which has been hardly evidenced mostly because naturally formed EABs employed in previous biosensor studies were recognized distinct and incapable of delivering comparable electrical signals. By preparing artificial EABs where Shewanella oneidensis MR-1 was encapsulated in sodium alginate (SA), this study solved how polypyrrole (PPy) as conductive medium would affect the sensitivity of EAB-based biosensor, as well as mass transfer of toxicant during this process. Different mass ratios (0.125:1, 0.25:1 and 1:1) of PPy over SA were tested, and the sensitivity promoted by 20%, 15% and 6%, respectively. Results indicated that a small amount of PPy addition (PPy: SA = 0.125: 1 in mass ratio) was more effective to increase the biosensor's sensitivity compared to larger amount of PPy employed in EAB. This was when improved conductivity introduced by PPy would dominate in affecting the sensitivity over contrarily weakened mass transfer in the meantime.

Single and joint inhibitory effect of nitrophenols on activated sludge.

In this study, single and joint inhibitory effects of nitrophenols on activated sludge and variations on the content of extracellular polymeric substances (EPS) were investigated. Results indicate that the nitrophenols adversely affected the organic and NH3-N removal of activated sludge and the adverse effect of nitrophenols on autotrophic bacteria was higher than that on heterotrophic bacteria. Further, 2,4-dinitrophenol (2,4-DNP) demonstrated the highest inhibitory effect, followed by 4-nitrophenol (4-NP) and 2-nitrophenol (2-NP), and the combined effects of binary and ternary nitrophenols induced additive toxicity. At various concentrations and toxicant ratios, 2,4-DNP, as the dominant toxic nitrophenol, was the major contributor to the joint inhibition effects of the mixed nitrophenols. At lower concentrations of 2-NP (below 100 mg/L), 4-NP (below 50 mg/L), and 2,4-DNP (below 10 mg/L), large amounts of both tightly bound EPS (TB-EPS) and loosely bound EPS (LB-EPS) were secreted for the normal physiological activities of the microbiological cells. After further stimulation with higher concentrations of 2-NP (above 100 mg/L), 4-NP (above 50 mg/L), and 2,4-DNP (above 10 mg/L), the inhibitory effect of nitrophenols on bacterial metabolism evidently increased. However, the EPS production sharply reduced, particularly with respect to protein production. Parallel factor analysis for TB-EPS and LB-EPS further confirmed that the major proteins were tyrosine, tryptophan, and aromatic proteins. Thus, this study provides new insights into the inhibitory effects of mixed nitrophenols, which are frequently found in pharmaceutical and petrochemical effluents.