Publications by authors named "Qiaoying Wang"

17 Publications

  • Page 1 of 1

Superhigh co-adsorption of tetracycline and copper by the ultrathin g-CN modified graphene oxide hydrogels.

J Hazard Mater 2021 Sep 29;424(Pt B):127362. Epub 2021 Sep 29.

Guangzhou Key Laboratory Environmental Catalysis and Pollution Control, Guangdong Key Laboratory of Environmental Catalysis and Health Risk Control, School of Environmental Science and Engineering, Institute of Environmental Health and Pollution Control, Guangdong University of Technology, Guangzhou 510006, China.

Development of economic and efficient absorbent for the simultaneous removal of antibiotics and heavy metals is needed. In this study, a three-dimensional porous ultrathin g-CN (UCN) /graphene oxide (GO) hydrogel (UCN-GH) was prepared by co-assembling of UCN and GO nanosheets via the facile hydrothermal reaction. Characterizations indicated that the addition of UCN significantly decreased the reduction of CO and O-CO related groups of GO during the hydrothermal reaction and introduced amine groups on UCN-GH. The UCN-GH exhibited excellent ability on the co-removal of Cu(II) (q = 2.0-2.5 mmol g) and tetracycline (TC) (q = 1.2-3.0 mmol g) from water. The adsorption capacities were increased as UCN mass ratio increasing. The mutual effects between Cu(II) and TC were examined through adsorption kinetics and isotherm models. Characterizations and computational chemistry analysis indicated that Cu(II) is apt to coordinate with the amine groups on UCN than with oxygen groups on GO, which accounts for the enhanced adsorption ability of UCN-GH. In the binary system, Cu(II) acts as a bridge between TC and UCN-GH enhanced the removal of TC. The effects of pH and regular salt ions on the removal of Cu(II)/TC were examined. Moreover, the prepared UCN-GH also showed comparable co-adsorption capacities in practical water/wastewater.
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http://dx.doi.org/10.1016/j.jhazmat.2021.127362DOI Listing
September 2021

Effects of microplastics accumulation on performance of membrane bioreactor for wastewater treatment.

Chemosphere 2021 Aug 21;287(Pt 1):131968. Epub 2021 Aug 21.

State Key Laboratory of Pollution Control and Resource Reuse, College of Environmental Science and Engineering, Tongji University, Shanghai, 200092, China; Shanghai Institute of Pollution Control and Ecological Security, Shanghai, 200092, China.

The effective interception of membrane leads to the accumulation of microplastics (MPs) in membrane bioreactor (MBR) process for long-term operation. However, the influence of MPs accumulation on the performance of MBR hasn't been well understood. In this study, the accumulation of polypropylene microplastics (PP-MPs) in two MBRs run for 3 yr with or without discharging sludge was simulated by operating the lab-scale MBRs for 84 days. The variations of pollutant removal, membrane fouling, composition of soluble microbial product (SMP) and extracellular polymeric substance (EPS), and microbial community of MBRs were systematically investigated. The results show that the removal efficiency of COD and NH-N was not depressed by PP-MPs accumulation. However, the presence of PP-MPs in the range of 0.14-0.30 g/L could inhibit the growth of microorganisms, enhance the secretion of SMP and EPS, and reduce the microbial richness and diversity. In the contrary, the high concentration of PP-MPs (2.34-5.00 g/L) exhibited the opposite effects and mitigated membrane fouling, suggesting the important role of MPs concentration. It was also found that the exposure to high concentration of PP-MPs enhanced relative abundance of Clostridia, and inhibited the growth of Proteobacteria. The findings of this study provide a foresight to understand the effects of MPs accumulation on the performance of MBRs.
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http://dx.doi.org/10.1016/j.chemosphere.2021.131968DOI Listing
August 2021

Evaluation of nutrient removal performance and resource recovery potential of anaerobic/anoxic/aerobic membrane bioreactor with limited aeration.

Bioresour Technol 2021 Nov 8;340:125728. Epub 2021 Aug 8.

Tongji University, Shanghai Institute of Pollution Control and Ecological Security, State Key Laboratory of Pollution Control and Resource Reuse, School of Environmental Science and Engineering, Shanghai 200092, China.

This study proposes a novel strategy to obtain high-efficiency synchronous removal of nitrogen and phosphorus from wastewater by the limited-aeration anaerobic/anoxic/aerobic membrane bioreactor (AAO-MBR) and evaluates its resource recovery potential. Effects of membrane flux on pollutants removal and membrane fouling were investigated, and the optimal flux of 30 L/(m·h) was obtained with efficient nitrogen and phosphorus removal of 81.5 ± 6.1% and 96.7 ± 2.1%. Compared with traditional and chemical-aided AAO-MBRs, limited-aeration AAO-MBR also alleviated membrane fouling by enlarging sludge flocs, improved sludge activities, and enriched the functional bacteria and genes. The sludge denitrification activity and phosphorus uptake activity of the limited-aeration AAO-MBR were 1.7 and 4.2 times as those of the traditional AAO-MBR. Low-temperature sludge pyrolysis results showed that sludge from limited-aeration AAO-MBR had higher nutrient storage and release capacity. This study proved the efficient nutrient removal capacity and high resource recovery potential of the limited-aeration AAO-MBR process.
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http://dx.doi.org/10.1016/j.biortech.2021.125728DOI Listing
November 2021

Efficacy of a novel electrochemical membrane-aerated biofilm reactor for removal of antibiotics from micro-polluted surface water and suppression of antibiotic resistance genes.

Bioresour Technol 2021 Oct 10;338:125527. Epub 2021 Jul 10.

State Key Laboratory of Pollution Control and Resource Reuse, Advanced Membrane Technology Center of Tongji University, Shanghai Institute of Pollution Control and Ecological Security, College of Environmental Science and Engineering, Tongji University, Shanghai 200092, PR China. Electronic address:

An electrochemical membrane-aerated biofilm reactor (EMABR) was developed for removing sulfamethoxazole (SMX) and trimethoprim (TMP) from contaminated water. The exertion of electric field greatly enhanced the degradation of SMX and TMP in the EMABR (~60%) compared to membrane-aerated biofilm reactor (MABR, < 10%), due to the synergistic effects of the electro-oxidation (the generation of reactive oxygen species) and biological degradation. Microbial community analyses demonstrated that the EMABR enriched the genus of Xanthobacter, which was potentially capable of degrading aromatic intermediates. Moreover, the EMABR had a lower relative abundance of antibiotic resistance genes (ARGs) (0.23) compared to the MABR (0.56), suggesting the suppression of ARGs in the EMABR. Further, the SMX and TMP degradation pathways were proposed based on the detection of key intermediate products. This study demonstrated the potential of EMABR as an effective technology for removing antibiotics from micro-polluted surface water and suppressing the development of ARGs.
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http://dx.doi.org/10.1016/j.biortech.2021.125527DOI Listing
October 2021

Dissecting FGF Signalling to Target Cellular Crosstalk in Pancreatic Cancer.

Cells 2021 04 8;10(4). Epub 2021 Apr 8.

Centre for Tumour Biology, Barts Cancer Institute, Queen Mary University of London, Charterhouse Square, London EC1M 6BQ, UK.

Pancreatic ductal adenocarcinoma (PDAC) has a poor prognosis with a 5 year survival rate of less than 8%, and is predicted to become the second leading cause of cancer-related death by 2030. Alongside late detection, which impacts upon surgical treatment, PDAC tumours are challenging to treat due to their desmoplastic stroma and hypovascular nature, which limits the effectiveness of chemotherapy and radiotherapy. Pancreatic stellate cells (PSCs), which form a key part of this stroma, become activated in response to tumour development, entering into cross-talk with cancer cells to induce tumour cell proliferation and invasion, leading to metastatic spread. We and others have shown that Fibroblast Growth Factor Receptor (FGFR) signalling can play a critical role in the interactions between PDAC cells and the tumour microenvironment, but it is clear that the FGFR signalling pathway is not acting in isolation. Here we describe our current understanding of the mechanisms by which FGFR signalling contributes to PDAC progression, focusing on its interaction with other pathways in signalling networks and discussing the therapeutic approaches that are being developed to try and improve prognosis for this terrible disease.
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http://dx.doi.org/10.3390/cells10040847DOI Listing
http://www.ncbi.nlm.nih.gov/pmc/articles/PMC8068358PMC
April 2021

Effects of graphene derivatives on polyvinylidene fluoride membrane modification evaluated with XDLVO theory and quartz crystal microbalance with dissipation.

Water Environ Res 2021 Mar 23;93(3):360-369. Epub 2020 Oct 23.

State Key Laboratory of Pollution Control and Resource Reuse, Shanghai Institute of Pollution Control and Ecological Security, School of Environmental Science and Engineering, Tongji University, Shanghai, China.

In this study, the different graphene derivatives, graphene oxide (GO), carboxylic acid-modified graphene (G-COOH), and amine-modified graphene (G-NH ), were used to prepare polyvinylidene fluoride (PVDF) composite membranes. The membrane modification performance was evaluated using the extended Derjaguin-Landau-Verwey-Overbeek theory and quartz crystal microbalance dissipation monitoring. The results show that the addition of low-dose GO and G-NH can improve membrane surface porosity and permeability. The hydrophilicity and electron donor monopolarity of PVDF/GO composite membranes were enhanced by adding more than 0.024 wt% GO, thus improving its antifouling ability. In addition, the enhancement of hydrophilicity, free energy of cohesion, and antifouling ability of composite membrane modified with G-COOH and G-NH was more significant compared with that of GO with the same dosage, which implies the important role of functional group in additives. This study provides new insights for the blending modification of PVDF membranes by systematically comparing the addition of graphene derivatives with different functional groups. PRACTITIONER POINTS: The comprehensive comparison of membrane modification with different graphene derivatives was investigated. The enhancement of hydrophilicity and antifouling ability of membranes modified with G-COOH and G-NH was more significant than that of GO. The free energy of cohesion of nanocomposite membrane was affected by the functional group of additives. G-NH composite membrane had the best comprehensive performance with great hydrophilicity, permeability, and antifouling performance.
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http://dx.doi.org/10.1002/wer.1418DOI Listing
March 2021

Impact of COD/N on anammox granular sludge with different biological carriers.

Sci Total Environ 2020 Aug 12;728:138557. Epub 2020 Apr 12.

College of Environmental Science and Engineering, Tongji University, Shanghai 200092, China.

The purpose of this study is to investigate the effect of COD/N interference on mature anammox granular sludge formed by different biological carriers. Three anammox granular sludge rectors were established with no biological carriers (R1), GAC (R2) and PVA-gel bead (R3), respectively. As the COD/N ratio increased to 1:2, the activity of anaerobic ammonia oxidizing bacteria in R1 and R2 was significantly inhibited. However, the nitrogen removal effect of R3 did not decrease dramatically, and the nitrogen removal rate in this phase was 1.54 ± 0.05 kg N/m·d. As the COD/N ratio increased to 1:1.5, the removal of NH-N in all reactors gradually decreased. The order of COD resistance of the three reactors in this study was R3 > R2 > R1. It was found that Candidatus Brocadia might be sensitive to the presence of organic matter. The abundance of heterotrophic denitrifying bacteria increased gradually in each reactor under increased influent COD/N ratios.
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http://dx.doi.org/10.1016/j.scitotenv.2020.138557DOI Listing
August 2020

Coupling ammonia nitrogen adsorption and regeneration unit with a high-load anoxic/aerobic process to achieve rapid and efficient pollutants removal for wastewater treatment.

Water Res 2020 Mar 9;170:115280. Epub 2019 Nov 9.

Shanghai Institute of Pollution Control and Ecological Security, Shanghai, 200092, China; State Key Laboratory of Pollution Control and Resource Reuse, College of Environmental Science and Engineering, Tongji University, Shanghai, 200092, China. Electronic address:

In this study, an ammonium nitrogen (NH-N) adsorption and regeneration (AAR) was constructed by a zeolite-packed column and NaClO-NaCl regeneration unit, and coupled with an anoxic/aerobic (AO) system to achieve efficient removal of carbon, nitrogen and phosphorus under short hydraulic retention time (HRT) and sludge retention time (SRT). Compared to conventional anaerobic/anoxic/aerobic (AAO) process, the proposed AO-AAR process achieved more efficient and stable nitrogen removal with greatly shorter HRT (5.6 h) and SRT (8 d) at 10.4 °C, with NH-N and total nitrogen in the effluent below 1.5 and 8.0 mg/L, respectively. The AO-AAR also obtained efficient phosphorus removal (<0.5 mg/L) by dosing aluminum in aerobic tank. High load and short SRT deteriorated sludge settleability and dewaterability, but enhanced methane production by improving sludge biodegradability. Dosing aluminum made the AO operating module more stable with improved settleability and dewaterability, and further enhanced methane production. Short HRT and SRT also resulted in the thriving of filamentous bacteria (Thiothrix) and heterotrophic nitrifiers (Acinetobacter, Pseudomonas and Rhodobacter) in the AO module, which helped in enhancing denitrification potential and nitrification efficiency under low temperature. Long-term operation showed that exchange capacity and physicochemical properties of zeolite were unchanged under NaClO-NaCl regeneration by introducing the tail gas from aerobic tank into the used regenerant to remove Ca and Mg exchanged from effluent of the AO module. Techno-economic analysis showed that the AO-AAR process is attractive and sustainable for municipal wastewater treatment by significantly improving nitrogen removal, greatly reducing land occupancy, enhancing methane production and achieving efficient reduction of carbon dioxide emission.
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http://dx.doi.org/10.1016/j.watres.2019.115280DOI Listing
March 2020

Molecular Mechanisms of the Action of Myricetin in Cancer.

Mini Rev Med Chem 2020 ;20(2):123-133

Department of Pharmacy, Nanchong Center Hospital, The Second Clinical Medical College, North Sichuan Medical College (University), Nanchong, 637000, Sichuan, China.

Natural compounds, such as paclitaxel and camptothecin, have great effects on the treatment of tumors. Such natural chemicals often achieve anti-tumor effects through a variety of mechanisms. Therefore, it is of great significance to conduct further studies on the anticancer mechanism of natural anticancer agents to lay a solid foundation for the development of new drugs. Myricetin, originally isolated from Myrica nagi, is a natural pigment of flavonoids that can inhibit the growth of cancer cells (such as liver cancer, rectal cancer, skin cancer and lung cancer, etc.). It can regulate many intracellular activities (such as anti-inflammatory and blood lipids regulation) and can even be bacteriostatic. The purpose of this paper is to outline the molecular pathways of the anticancer effects of myricetin, including the effect on cancer cell death, proliferation, angiogenesis, metastasis and cell signaling pathway.
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http://dx.doi.org/10.2174/1389557519666191018112756DOI Listing
October 2020

Removal mechanisms of aqueous Cr(VI) using apple wood biochar: a spectroscopic study.

J Hazard Mater 2020 02 1;384:121371. Epub 2019 Oct 1.

State Key Laboratory of Pollution Control and Resource Reuse, Shanghai Institute of Pollution Control and Ecological Security, College of Environmental Science and Engineering, Tongji University, Shanghai, 200092, PR China. Electronic address:

Highly toxic Cr(VI) poses huge threats to human health and ecosystem. This study utilized biochar obtained from apple wood which is favorable for the formation of high C content biochar for removing Cr(VI) from aqueous media. Cr(VI) removal was highly pH-dependent with the highest Cr(VI) removal efficiency (99.9%) at pH 2.0. Fourier-transform infrared spectroscopy (FTIR) results showed that the functionalities CO and CO on biochar were likely involved in Cr(VI) treatment. Results of X-ray photoelectron spectroscopy (XPS) analysis and X-ray absorption near-edge structure (XANES) spectra indicated that the majority of Cr exhibited as the reduced Cr(III) on the biochar. Confocal micro X-ray fluorescence (μ-XRF) maps confirmed the heterogeneous distribution of Cr on biochar. The electrostatic attraction, Cr(VI) reduction, Cr(III) complexation, and ion exchange likely accounted for the principal processes of Cr(VI) removal from water. These results showed that biochar can be an effective reactive medium for remediation of Cr(VI) in an aqueous solution. This study firstly integrated the Cr(VI) removal data with XANES and confocal μ-XRF mapping to obtain a deeper understanding of Cr speciation and distribution on biochar, which was critical for identifying the key role of functional groups and Cr(VI) removal mechanisms using apple wood biochar.
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http://dx.doi.org/10.1016/j.jhazmat.2019.121371DOI Listing
February 2020

Influence of Solution Chemistry and Soft Protein Coronas on the Interactions of Silver Nanoparticles with Model Biological Membranes.

Environ Sci Technol 2016 Mar 17;50(5):2301-9. Epub 2016 Feb 17.

Department of Geography and Environmental Engineering, Johns Hopkins University , Baltimore, Maryland 21218-2686, United States.

The influence of solution chemistry and soft protein coronas on the interactions between citrate-coated silver nanoparticles (AgNPs) and model biological membranes was investigated by assembling supported lipid bilayers (SLBs) composed of zwitterionic 1,2-dioleoyl-sn-glycero-3-phosphocholine (DOPC) on silica crystal sensors in a quartz crystal microbalance with dissipation monitoring (QCM-D). Our results show that the deposition rates of AgNPs on unmodified silica surfaces increased with increasing electrolyte concentrations under neutral pH conditions. Similar trends were observed when AgNPs were deposited on SLBs, hence indicating that the deposition of AgNPs on model cell membranes was controlled by electrostatic interactions. In the presence of human serum albumin (HSA) proteins at both pH 7 and pH 2, the colloidal stability of AgNPs was considerably enhanced due to the formation of HSA soft coronas surrounding the nanoparticles. At pH 7, the deposition of AgNPs on SLBs was suppressed in the presence of HSA due to steric repulsion between HSA-modified AgNPs and SLBs. In contrast, pronounced deposition of HSA-modified AgNPs on SLBs was observed at pH 2. This observation was attributed to the reduction of electrostatic repulsion as well as conformation changes of adsorbed HSA under low pH conditions, resulting in the decrease of steric repulsion between AgNPs and SLBs.
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http://dx.doi.org/10.1021/acs.est.5b04694DOI Listing
March 2016

High quality, patient centred and coordinated care for Alstrom syndrome: a model of care for an ultra-rare disease.

Orphanet J Rare Dis 2015 Nov 24;10:149. Epub 2015 Nov 24.

Department of Endocrinology, University Hospital of Birmingham, London, UK.

Background: Patients with rare and ultra-rare diseases make heavy demands on the resources of both health and social services, but these resources are often used inefficiently due to delays in diagnosis, poor and fragmented care. We analysed the national service for an ultra-rare disease, Alstrom syndrome, and compared the outcome and cost of the service to the standard care.

Methods: Between the 9th and 26th of March 2014 we undertook a cross-sectional study of the UK Alstrom syndrome patients and their carers. We developed a semi-structured questionnaire to assess our rare patient need, quality of care and costs incurred to patients and their careers. In the UK all Alstrom syndrome patients are seen in two centres, based in Birmingham, and we systematically evaluated the national service and compared the quality and cost of care with patients' previous standard of care.

Results: One quarter of genetically confirmed Alstrom syndrome UK patients were enrolled in this study. Patients that have access to a highly specialised clinical service reported that their care is well organised, personalised, holistic, and that they have a say in their care. All patients reported high level of satisfaction in their care. Patient treatment compliance and clinic attendance was better in multidisciplinary clinic than the usual standard of NHS care. Following a variable costing approach based on personnel and consumables' cost, our valuation of the clinics was just under £700/patient/annum compared to the standard care of £960/patient/annum. Real savings, however, came in terms of patients' quality of life. Furthermore there was found to have been a significant reduction in frequency of clinic visits and ordering of investigations since the establishment of the national service.

Conclusions: Our study has shown that organised, multidisciplinary "one stop" clinics are patient centred and individually tailored to the patient need with a better outcome and comparable cost compared with the current standard of care for rare disease. Our proposed care model can be adapted to several other rare and ultra-rare diseases.
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http://dx.doi.org/10.1186/s13023-015-0366-yDOI Listing
http://www.ncbi.nlm.nih.gov/pmc/articles/PMC4657378PMC
November 2015

Novel synthesis strategy for composite hydrogel of collagen/hydroxyapatite-microsphere originating from conversion of CaCO3 templates.

Nanotechnology 2015 Mar 26;26(11):115605. Epub 2015 Feb 26.

National Engineering Research Centre for Biomaterials, Sichuan University, Chengdu 610064, People's Republic of China.

Inspired by coralline-derived hydroxyapatite, we designed a methodological route to synthesize carbonated-hydroxyapatite microspheres from the conversion of CaCO3 spherulite templates within a collagen matrix under mild conditions and thus constructed the composite hydrogel of collagen/hydroxyapatite-microspheres. Fourier transform infrared spectroscopy (FTIR) and x-ray diffraction (XRD) were employed to confirm the successful generation of the carbonated hydroxyapatite phase originating from CaCO3, and the ratios of calcium to phosphate were tracked over time. Variations in the weight portion of the components in the hybrid gels before and after the phase transformation of the CaCO3 templates were identified via thermogravimetric analysis (TGA). Scanning electron microscopy (SEM) shows these composite hydrogels have a unique multiscale microstructure consisting of a collagen nanofibril network and hydroxyapatite microspheres. The relationship between the hydroxyapatite nanocrystals and the collagen fibrils was revealed by transmission electron microscopy (TEM) in detail, and the selected area electron diffraction (SAED) pattern further confirmed the results of the XRD analyses which show the typical low crystallinity of the generated hydroxyapatite. This smart synthesis strategy achieved the simultaneous construction of microscale hydroxyapatite particles and collagen fibrillar hydrogel, and appears to provide a novel route to explore an advanced functional hydrogel materials with promising potentials for applications in bone tissue engineering and reconstruction medicine.
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http://dx.doi.org/10.1088/0957-4484/26/11/115605DOI Listing
March 2015

Start-up of an anaerobic dynamic membrane digester for waste activated sludge digestion: temporal variations in microbial communities.

PLoS One 2014 2;9(4):e93710. Epub 2014 Apr 2.

State Key Laboratory of Pollution Control and Resource Reuse, School of Environmental Science and Engineering, Tongji University, Shanghai, PR China.

An anaerobic dynamic membrane digester (ADMD) was developed to digest waste sludge, and pyrosequencing was used to analyze the variations of the bacterial and archaeal communities during the start-up. Results showed that bacterial community richness decreased and then increased over time, while bacterial diversity remained almost the same during the start-up. Proteobacteria and Bacteroidetes were the major phyla. At the class level, Betaproteobacteria was the most abundant at the end of start-up, followed by Sphingobacteria. In the archaeal community, richness and diversity peaked at the end of the start-up stage. Principle component and cluster analyses demonstrated that archaeal consortia experienced a distinct shift and became stable after day 38. Methanomicrobiales and Methanosarcinales were the two predominant orders. Further investigations indicated that Methanolinea and Methanosaeta were responsible for methane production in the ADMD system. Hydrogenotrophic pathways might prevail over acetoclastic means for methanogenesis during the start-up, supported by specific methanogenic activity tests.
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http://journals.plos.org/plosone/article?id=10.1371/journal.pone.0093710PLOS
http://www.ncbi.nlm.nih.gov/pmc/articles/PMC3973557PMC
January 2015

An anaerobic dynamic membrane bioreactor (AnDMBR) for landfill leachate treatment: performance and microbial community identification.

Bioresour Technol 2014 Jun 13;161:29-39. Epub 2014 Mar 13.

State Key Laboratory of Pollution Control and Resource Reuse, School of Environmental Science and Engineering, Tongji University, 1239 Siping Road, Shanghai 200092, PR China.

In this study, a pilot-scale anaerobic dynamic membrane bioreactor was operated for 142days for treating landfill leachate. Under stable operation, average COD removal efficiency of 62.2% was achieved when the reactor was fed with the raw leachate containing total ammonium concentration above 3000mg/L and COD above 13,000mg/L. The methane content in the biogas was in the range of 70-90%, and the average methane yield was 0.34L/g CODremoved at the organic loading rate of 4.87kg COD/(m(3)d). Pyrosequencing analyses indicated that during the operation the archaeal community was relatively stable while obvious changes took place in the bacterial community. Alkaliphilus, Petrimonas, Fastidiosipila and vadinBC27 were the abundant fermentation bacteria in bacterial communities. Moreover, phylum TM6 gradually became the most dominant bacterial community and reached the highest relative abundance of 32.9% as the operation elapsed. In archaeal communities, genus Methanosarcina was identified as the dominant methanogen.
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http://dx.doi.org/10.1016/j.biortech.2014.03.014DOI Listing
June 2014

Analysis of nitrification efficiency and microbial community in a membrane bioreactor fed with low COD/N-ratio wastewater.

PLoS One 2013 7;8(5):e63059. Epub 2013 May 7.

State Key Laboratory of Pollution Control and Resource Reuse, School of Environmental Science and Engineering, Tongji University, Shanghai, PR China.

In this study, an approach using influent COD/N ratio reduction was employed to improve process performance and nitrification efficiency in a membrane bioreactor (MBR). Besides sludge reduction, membrane fouling alleviation was observed during 330 d operation, which was attributed to the decreased production of soluble microbial products (SMP) and efficient carbon metabolism in the autotrophic nitrifying community. 454 high-throughput 16S rRNA gene pyrosequencing revealed that the diversity of microbial sequences was mainly determined by the feed characteristics, and that microbes could derive energy by switching to a more autotrophic metabolism to resist the environmental stress. The enrichment of nitrifiers in an MBR with a low COD/N-ratio demonstrated that this condition stimulated nitrification, and that the community distribution of ammonia oxidizing bacteria (AOB) and nitrite oxidizing bacteria (NOB) resulted in faster nitrite uptake rates. Further, ammonia oxidation was the rate-limiting step during the full nitrification.
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http://journals.plos.org/plosone/article?id=10.1371/journal.pone.0063059PLOS
http://www.ncbi.nlm.nih.gov/pmc/articles/PMC3646889PMC
December 2013

Gadolinium-labeled peptide dendrimers with controlled structures as potential magnetic resonance imaging contrast agents.

Biomaterials 2011 Nov 23;32(31):7951-60. Epub 2011 Jul 23.

National Engineering Research Center for Biomaterials, Sichuan University, Chengdu 610064, China.

Gadolinium (Gd(3+)) based dendrimers with precise and tunable nanoscopic sizes are excellent candidates as magnetic resonance imaging (MRI) contrast agents. Control of agents' sensitivity, biosafety and functionality is key to the successful applications. We report the synthesis of Gd(III)-based peptide dendrimers possessing highly controlled and precise structures, and their potential applications as MRI contrast agents. These agents have no obvious cytotoxicity as verified by in vitro studies. One of the dendrimer formulations with mPEG modification showed a 9-fold increase in T(1) relaxivity to 39.2 Gd(III) mM(-1) s(-1) comparing to Gd-DTPA. In vivo studies have shown that the mPEGylated Gd(III)-based dendrimer provided much higher signal intensity enhancement (SI) in mouse kidney, especially at 60 min post-injection, with 54.8% relatively enhanced SI. The accumulations of mPEGylated dendrimer in mouse liver and kidney were confirmed through measurement of gadolinium by inductively coupled plasma atomic emission spectroscopy (ICP-AES). Meanwhile, mPEGylated dendrimer showed much higher Gd(III) concentration in blood with 38 μg Gd(III)/g blood at 1 h post-injection comparing to other dendrimer formulations. These findings provide an attractive alternative strategy to the design of multifunctional gadolinium-based dendrimers with controlled structures, and open up possibilities of using the Gd(III)-based peptide dendrimers as MRI probes.
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http://dx.doi.org/10.1016/j.biomaterials.2011.07.006DOI Listing
November 2011
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