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Kinetic analysis of anaerobic phosphorus release during biological phosphorus removal process

DOU Junfeng, LIU Xiang, LUO Guyuan

《环境科学与工程前沿(英文)》 2007年 第1卷 第2期   页码 233-239 doi: 10.1007/s11783-007-0040-2

摘要: Enhanced biological phosphorus removal (EBPR) is a commonly used and sustainable method for phosphorus removal from wastewater. Poly-β-hydroxybutyrate (PHB), polyphosphate, and glycogen are three kinds of intracellular storage polymers in phosphorus accumulation organisms. The variation of these polymers under different conditions has an apparent influence on anaerobic phosphorus release, which is very important for controlling the performance of EBPR. To obtain the mechanism and kinetic character of anaerobic phosphorus release, a series of batch experiments were performed using the excessively aerated sludge from the aerobic unit of the biological phosphorus removal system in this study. The results showed that the volatile suspended solid (VSS) had an increasing trend, while the mixed liquid suspended sludge (MLSS) and ashes were reduced during the anaerobic phosphorus release process. The interruption of anaerobic HAc-uptake and phosphorus-release occurs when the glycogen in the phosphorus-accumulating-organisms is exhausted. Under the condition of lower initial HAc-COD, HAc became the limiting factor after some time for anaerobic HAc uptake. Under the condition of higher initial HAc-COD, HAc uptake was stopped because of the depletion of glycogen in the microorganisms. The mean ratio of ΔρP/Δρ, Δρ/ΔρPHB, ΔρP/ΔCOD, and ΔρPHB/ΔCOD was 0.48, 0.50, 0.44, and 0.92, respectively, which was nearly the same as the theoretical value. The calibrated kinetic parameters of the HAc-uptake and phosphorus-release model were evaluated as follows: Q was 164 mg/(g °h), Q was 69.9 mg/(g °h), K was 0.005, and KCOD was 3 mg/L. An apparently linear correlation was observed between the ratio of ΔρP/ΔCOD and pH of the solution, and the equation between them was obtained in this study.

关键词: interruption     process     ΔρP/Δρ     Enhanced biological     Poly-β-hydroxybutyrate    

Genomic and metabolomic analysis of with enhanced poly--glutamic acid production through atmospheric

《化学科学与工程前沿(英文)》 2022年 第16卷 第12期   页码 1751-1760 doi: 10.1007/s11705-022-2211-x

摘要: Poly-γ-glutamic acid is an extracellular polymeric substance with various applications owing to its valuable properties of biodegradability, flocculating activity, water solubility, and nontoxicity. However, the ability of natural strains to produce poly-γ-glutamic acid is low. Atmospheric and room temperature plasma was applied in this study to conduct mutation breeding of Bacillus licheniformis CGMCC 2876, and a mutant strain M32 with an 11% increase in poly-γ-glutamic acid was obtained. Genome resequencing analysis identified 7 nonsynonymous mutations of ppsC encoding lipopeptide synthetase associated with poly-γ-glutamic acid metabolic pathways. From molecular docking, more binding sites and higher binding energy were speculated between the mutated plipastatin synthase subunit C and glutamate, which might contribute to the higher poly-γ-glutamic acid production. Moreover, the metabolic mechanism analysis revealed that the upregulated amino acids of M32 provided substrates for glutamate and promoted the conversion between L- and D-glutamate acids. In addition, the glycolytic pathway is enhanced, leading to a better capacity for using glucose. The maximum poly-γ-glutamic acid yield of 14.08 g·L–1 was finally reached with 30 g·L–1 glutamate.

关键词: ARTP mutagenesis     Bacillus licheniformis     poly-γ-glutamic acid     metabolomics    

Surface Polysaccharide Are Protective Against a Wide Range of Microbial Pathogens Producing β-1–6-Linked Poly-N-Acetylglucosamine

Xi Lu,Guoqing Li,Jing Pang,Xinyi Yang,Colette Cywes-Bentley,Xuefu You,Gerald B. Pier,

《工程(英文)》 doi: 10.1016/j.eng.2023.09.012

摘要: The β-1–6-linked poly-N-acetylglucosamine (PNAG) polymer is a conserved surface polysaccharide produced by many bacteria, fungi, and protozoan (and even filarial) parasites. This wide-ranging expression makes PNAG an attractive target for vaccine development, as it potentially encompasses a broad range of microorganisms. Significant progress has been made in discovering important properties of the biology of PNAG expression in recent years. The molecular characterization and regulation of operons for the production of PNAG biosynthetic proteins and enzymes have been studied in many bacteria. In addition, the physiological function of PNAG has been further elucidated. PNAG-based vaccines and PNAG-targeting antibodies have shown great efficacy in preclinical research. Furthermore, clinical tests for both vaccines and antibodies have been carried out in humans and economically important animals, and the results are promising. Although it is not destined to be a smooth road, we are optimistic about new vaccines and immunotherapeutics targeting PNAG becoming validated and eventually licensed for clinical use against multiple infectious agents.

关键词: Poly-     N     -acetylglucosamine     Conjugate vaccine     Monoclonal antibody    

Mutagenesis and selective breeding of a high producing

Tian WANG, Shiru JIA, Zhilei TAN, Yujie DAI, Shuai SONG, Guoliang WANG

《化学科学与工程前沿(英文)》 2012年 第6卷 第2期   页码 179-183 doi: 10.1007/s11705-012-1273-6

摘要: -Poly- -lysine ( -PL) is an -lysine linear homopolymer, which is produced by bacteria belonging to the family and by ergot fungi. However, the production of -PL by the wild bacteria strain is very low, which limits its utilization. In most bacteria including the genus, -lysine is a precursor of -PL and is biosynthesized by the -aspartate pathway. Aspartokinase (Ask) is the first key enzyme in this pathway and is subject to complex regulation such as the feedback inhibition by the end product amino acids. In addition, phosphoenolpyruvate carboxykinase is feedback-regulated by -aspartate. To reduce these feedback inhibitions and to improve -PL productivity, resistant mutants were produced using sulfaguanidine (SG) + glycine+ -lysine+ -3-hydroxynorvaline (AHV) as selective markers. Using the interaction between -PL and the charged dye in the solid culture medium, hundreds of colonies were simultaneously screened in a quick and effective manner. Finally, one -PL-producing strain, L9, was selected. The productivity of this strain during flask fermentation was 0.77 g/L, which was 15% higher than that of the original strain. Moreover, its fermentation performance and genetic characteristics were very stable.

关键词: ?-poly-L-lysine     plasma     AHV     Streptomyces diastatochromogenes     fermentation    

Ultrafast-laser-treated poly(3,4-ethylenedioxythiophene): poly(styrenesulfonate) electrodes with enhanced

《化学科学与工程前沿(英文)》 2023年 第17卷 第2期   页码 206-216 doi: 10.1007/s11705-022-2203-x

摘要: Poly(3,4-ethylenedioxythiophene):poly(styrenesulfonate) (PEDOT:PSS) is an important organic electrode for solution-processed low-cost electronic devices. However, it requires doping and post-solvent treatment to improve its conductivity, and the chemicals used for such treatments may affect the device fabrication process. In this study, we developed a novel route for exploiting ultrafast lasers (femtosecond and picosecond laser) to simultaneously enhance the conductivity and transparency of PEDOT:PSS films and fabricate patterned solution-processed electrodes for electronic devices. The conductivity of the PEDOT:PSS film was improved by three orders of magnitude (from 3.1 to 1024 S·cm–1), and high transparency of up to 88.5% (average visible transmittance, AVT) was achieved. Raman and depth-profiling X-ray photoelectron spectroscopy revealed that the oxidation level of PEDOT was enhanced, thereby increasing the carrier concentration. The surface PSS content also decreased, which is beneficial to the carrier mobility, resulting in significantly enhanced electrical conductivity. Further, we fabricated semitransparent perovskite solar cells using the as-made PEDOT:PSS as the transparent top electrodes, and a power conversion efficiency of 7.39% was achieved with 22.63% AVT. Thus, the proposed route for synthesizing conductive and transparent electrodes is promising for vacuum and doping-free electronics.

关键词: PEDOT:PSS     ultrafast laser     transparent electrode     ST-PSCs     patterning    

Hydrophilic modification of poly(aryl sulfone) membrane materials toward highly-efficient environmental

《化学科学与工程前沿(英文)》 2022年 第16卷 第5期   页码 614-633 doi: 10.1007/s11705-021-2115-1

摘要: Poly(aryl sulfone) as a typical membrane material has been widely used due to excellent mechanical, chemical and thermal stability. However, the inherent hydrophobicity of poly(aryl sulfone) based membranes bears with the fouling issue during applications, which makes the membrane tending to adsorb contaminants on the surface so as to result in decreased separation performance and lifetime. In this critical review, we give a comprehensive overview on characterizations of hydrophilic membrane and diverse hydrophilic modification approaches of poly(aryl sulfone) membranes, predominantly including bulky, blending and surface modification technology. The discussions on the different modification methods have been provided in-depth. Besides, focusing on modification methods and performance of modified membranes, the related mechanisms for the performance enhancement are discussed too. At last, the perspectives are provided to guide the future directions to develop novel technology to manipulate the hydrophilicity of poly(aryl sulfone) membranes toward diverse practical and multi-functional applications.

关键词: poly(aryl sulfone)     membrane separations     modification     hydrophilicity     water treatment    

Preparation and characterization of poly (vinylidene fluoride)/TiO

Weiying LI, Xiuli SUN, Chen WEN, Hui LU, Zhiwei WANG

《环境科学与工程前沿(英文)》 2013年 第7卷 第4期   页码 492-502 doi: 10.1007/s11783-012-0407-x

摘要: Poly(vinylidene fluoride) (PVDF)/titanium dioxide (TiO ) hybrid membranes were prepared using nano-TiO as the modifier, and characterized by Transmission Electron Microscope (TEM), Fourier transform infrared spectroscopy (FT-IR), scanning electron microscope (SEM), atomic force microscope (AFM), X-ray diffraction (XRD) and X-ray photoelectron spectroscopy (XPS). The characterization results demonstrated that nano-sized TiO particles dispersed homogeneously within the PVDF matrix, contributing to more hydroxyls and smoother surfaces. Moreover, permeate flux, retention factor, porosity, contact angle and anti-fouling tests were carried out to evaluate the effect of TiO concentration on the performance of PVDF membranes. Among all the prepared membranes, PVDF/TiO membrane containing 10 vol.% TiO exhibited the best hydrophilicity with an average pure water flux up to 237 L·m ·h , higher than that of unmodified PVDF membranes (155 L·m ·h ). Besides, the bovine serum albumin rejection of the hybrid membrane was improved evidently from 52.3% to 70.6%, and the contact angle was significantly lowered from 83° to 60°, while the average pore size and its distribution became smaller and narrower.

关键词: poly(vinylidene fluoride) (PVDF) membrane     nano-TiO2     anti-fouling performance     water treatment    

Effect of polyethylene glycol on the crystallization, rheology and foamability of poly(lactic acid) containing

《化学科学与工程前沿(英文)》 2023年 第17卷 第12期   页码 2074-2087 doi: 10.1007/s11705-023-2342-8

摘要: In this study, the rheological properties, crystallization and foaming behavior of poly(lactic acid) with polyamide 6 nanofibrils were examined with polyethylene glycol as a compatibilizer. Polyamide 6 particles were deformed into nanofibrils during drawing. For the 10% polyamide 6 case, polyethylene glycol addition reduced the polyamide 6 fibril diameter from 365.53 to 254.63 nm, owing to the smaller polyamide 6 particle size and enhanced interface adhesion. Rheological experiments revealed that the viscosity and storage modulus of the composites were increased, which was associated with the three-dimensional entangled network of polyamide 6 nanofibrils. The presence of higher aspect ratio polyamide 6 nanofibrils substantially enhanced the melt strength of the composites. The isothermal crystallization kinetics results suggested that the polyamide 6 nanofibrils and polyethylene glycol had a synergistic effect on accelerating poly(lactic acid) crystallization. With the polyethylene glycol, the crystallization half-time reduced from 103.6 to 62.2 s. Batch foaming results indicated that owing to higher cell nucleation efficiency, the existence of polyamide 6 nanofibrils led to a higher cell density and lower expansion ratio. Furthermore, the poly(lactic acid)/polyamide 6 foams exhibited a higher cell density and expansion ratio than that of the foams without polyethylene glycol.

关键词: poly(lactic acid)     foaming     microfibrillation     rheological property     crystallization    

Design and analysis of dual fuel methanol-power poly-generation

Minghua WANG , Zheng LI , Weidou NI ,

《能源前沿(英文)》 2009年 第3卷 第3期   页码 341-347 doi: 10.1007/s11708-009-0023-z

摘要: A dual fuel head poly-generation flowsheet was designed based on coal gas and coke oven gas. To help clearly understand the system performance, a 1.2×10−3.2×10kg methanol and 274―496MW power poly-generation system was simulated by using the commercially available software ASPEN Plus and GT Pro. The technology scheme, the operating parameters, and the efficiency of the system were also analyzed and evaluated, which will be used for building industrial devices.

关键词: dual fuel     methanol-power poly-generation     CO2 and CH4 reforming     splitting ratio    

Nano-hydroxyapatite formation via co-precipitation with chitosan-g-poly(

Yang YU, Hong ZHANG, Hong SUN, Dandan XING, Fanglian YAO

《化学科学与工程前沿(英文)》 2013年 第7卷 第4期   页码 388-400 doi: 10.1007/s11705-013-1355-0

摘要: With the excellent biocompatibility and osteoconductivity, nano-hydroxyapatite (nHA) has shown significant prospect in the biomedical applications. Controlling the size, crystallinity and surface properties of nHA crystals is a critical challenge in the design of HA based biomaterials. With the graft copolymer of chitosan and poly( -isopropylacrylamide) in coil and globule states as a template respectively, a novel composite from chitosan-g-poly( -isopropylacrylamide) and nano-hydroxyapatite (CS-g-PNIPAM/nHA) was prepared via co-precipitation. Zeta potential analysis, thermogravimetric analysis and X-ray diffraction were used to identify the formation mechanism of the CS-g-PNIPAM/nHA composite and its morphology was observed by transmission electron microscopy. The results suggested that the physical aggregation states of the template polymer could induce or control the size, crystallinity and morphology of HA crystals in the CS-g-PNIPAM/nHA composite. The CS-g-PNIPAM/nHA composite was then introduced to chitosan-gelatin (CS-Gel) polyelectronic complex and the cytocompatibility of the resulting CS-Gel/composite hybrid film was evaluated. This hybrid film was proved to be favorable for the proliferation of MC 3T3-E1 cells. Therefore, the CS-g-PNIPAM/nHA composite is a potential biomaterial in bone tissue engineering.

关键词: chitosan     poly(N-isopropylacrylamide)     hydroxyapatite     coil     globule     bone tissue engineering    

Molecular diffusion in ternary poly(vinyl alcohol) solutions

《化学科学与工程前沿(英文)》 2022年 第16卷 第6期   页码 1003-1016 doi: 10.1007/s11705-021-2121-3

摘要: The diffusion kinetics of a molecular probe—rhodamine B—in ternary aqueous solutions containing poly(vinyl alcohol), glycerol, and surfactants was investigated using fluorescence correlation spectroscopy and dynamic light scattering. We show that the diffusion characteristics of rhodamine B in such complex systems is determined by a synergistic effect of molecular crowding and intermolecular interactions between chemical species. The presence of glycerol has no noticeable impact on rhodamine B diffusion at low concentration, but significantly slows down the diffusion of rhodamine B above 3.9% (w/v) due to a dominating steric inhibition effect. Furthermore, introducing surfactants (cationic/nonionic/anionic) to the system results in a decreased diffusion coefficient of the molecular probe. In solutions containing nonionic surfactant, this can be explained by an increased crowding effect. For ternary poly(vinyl alcohol) solutions containing cationic or anionic surfactant, surfactant–polymer and surfactant–rhodamine B interactions alongside the crowding effect of the molecules slow down the overall diffusivity of rhodamine B. The results advance our insight of molecular migration in a broad range of industrial complex formulations that incorporate multiple compounds, and highlight the importance of selecting the appropriate additives and surfactants in formulated products.

关键词: fluorescence correlation spectroscopy     poly(vinyl alcohol)     anomalous diffusion     crowding effects     dynamic light scattering     binding effects     rhodamine B    

Controlled drug release of 5-amino salicylic acid by poly(2-hydroxyethylmethacrylate) grafted agar

G. Usha RANI,Kartick Prasad DEY,Srijita BHARTI,Sumit MISHRA

《化学科学与工程前沿(英文)》 2014年 第8卷 第4期   页码 465-470 doi: 10.1007/s11705-014-1452-8

摘要: The utilization of poly (2-hydroxyethylmethacrylate) grafted agar (Ag-g-P(HEMA)) as a matrix for the controlled release of 5-aminosalicylic acid was investigated. Grafted copolymers of 2-hydroxyethylmethacrylate (HEMA) monomers on agar were synthesized by microwave assisted method. drug release studies were performed at pH values of 2 and 7 in order to investigate the possibility of pH triggered release for colon targeted drug delivery. Further, the percent grafting . (the time taken for release of 50% of the enclosed drug) value was studied and the results indicate that it may be possible to develop a programmable drug release matrix based on grafted polysaccharide. Ag-g-P(HEMA) appears to be a useful matrix for controlled release.

关键词: agar     controlled drug release     5-Amino salicylic acid     poly(2-hydroxyethylmethacrylate) grafted agar    

Solvent-resistant porous membranes using poly(ether−ether ketone): preparation and application

《化学科学与工程前沿(英文)》 2023年 第17卷 第10期   页码 1536-1559 doi: 10.1007/s11705-022-2221-8

摘要: Poly(ether−ether ketone) (PEEK) is a linear aromatic macromolecule, which can form semi-crystalline aggregative status, allowing PEEK materials to have strong environment tolerance and excellent physicochemical properties. PEEK materials have become a promising alternative to fabricate particular membranes used in extreme conditions. In the past few decades, many researches and evolutions have emerged in membrane fabrication with PEEK materials and its applications for treating organic solvents and their mixtures; however, there are little systematic and comprehensive literature to summarize fabrication approaches, compile applications, and elaborate PEEK property-structure relationship. In this review, the main approaches to fabricate PEEK-based membranes are illustrated concretely, including conventional thermal-induced and non-solvent-induced phase separation, and novel chemical-induced crystallization; the representative applications in ultrafiltration, nanofiltration and membrane contactor containing organic solvents are demonstrated systematically. Meanwhile, the mechanism to tune PEEK solubility in solvents, which can be achieved by altering monomers in synthesis processes or changing membrane preparation routes, is deeply analyzed. Moreover, the existing problems and the future prospects are also discussed. This review provides positive guidance for designing and fabricating membranes using PEEK and its derivative materials for task-specific applications in harsh conditions.

关键词: PEEK     phase inversion     solvent-resistant membrane     nanofiltration     membrane contactor    

crystal morphology and melting behavior of isothermally crystallized composites of short carbon fiber and poly

Mingtao RUN, Hongzan SONG, Yanping HAO

《化学科学与工程前沿(英文)》 2009年 第3卷 第3期   页码 255-264 doi: 10.1007/s11705-009-0008-9

摘要: The spherulites of the short carbon fiber(SCF)/poly (trimethylene terephthalate) (PTT) composites formed in limited space at designed temperatures, and their melting behaviors were studied by the polarized optical microscopy, atomic force microscopy (AFM), and scanning electron microscopy (SEM), respectively. The results suggest that SCF content, isothermal crystallization temperatures, and the film thicknesses influence the crystal morphology of the composites. The dimension of the spherulites is decreased with increasing SCF content, but whether banded or nonbanded spherulites will form in the composites is not dependent on SCF content. However, the crystal morphology of the composites depends strongly on the temperature. When the isothermal crystallization temperatures increase from 180°C to 230°C, the crystal morphology of SCF/PTT composites continuously changes in the following order: nonbanded → banded → nonbanded spherulites. Discontinuous circle lines form in the film when the film thickness increases from 30 to 60 μm. Basing on the SEM observation, it is found that these circle lines are cracks formed due to the constriction difference of the different parts of the spherulites. These cracks are formed when the film is cooled from the isothermal crystallization temperature to the room temperature at a slow cooling rate; while they will disappear gradually at different temperatures in the heating process. The crack will appear/disappear first around the center of the spherulite when the film was cooled/heated. The nontwisted or slightly twisted lamellas will reorganize to form highly twisted lamellas inducing apparent banded texture of the spherulites.

关键词: poly(trimethylene terephthalate)     short carbon fiber     banded spherulites     crack    

Microwave assisted synthesis of poly(2-hydroxyethylmethacrylate) grafted agar (Ag-g-P(HEMA)) and its

Gautam SEN, G. Usha RANI, Sumit MISHRA

《化学科学与工程前沿(英文)》 2013年 第7卷 第3期   页码 312-321 doi: 10.1007/s11705-013-1344-3

摘要: Poly(2-hydroxyethylmethacrylate) chains were grafted onto the backbone of agar using a microwave assisted method involving a combination of microwave irradiation and ceric ammonium nitrate to initiate the grafting reaction. The synthesized graft copolymers were characterized by intrinsic viscosity measurements, Fourier transform infrared spectroscopy, elemental analysis (C, H, N, O and S) and scanning electron microscopy. Ag-g-P(HEMA)-2 showed a much higher flocculation efficacy than agar. The optimized dosage of flocculation for Ag-g-P(HEMA)-2 in the wastewater was found to be 0.75 ppm. Compared to agar, Ag-g-P(HEMA)-2 was found to considerably reduce the pollutant load in the wastewater.

关键词: agar     flocculant     microwave assisted synthesis     jar test protocol     poly(HEMA) grafted agar     wastewater treatment    

标题 作者 时间 类型 操作

Kinetic analysis of anaerobic phosphorus release during biological phosphorus removal process

DOU Junfeng, LIU Xiang, LUO Guyuan

期刊论文

Genomic and metabolomic analysis of with enhanced poly--glutamic acid production through atmospheric

期刊论文

Surface Polysaccharide Are Protective Against a Wide Range of Microbial Pathogens Producing β-1–6-Linked Poly-N-Acetylglucosamine

Xi Lu,Guoqing Li,Jing Pang,Xinyi Yang,Colette Cywes-Bentley,Xuefu You,Gerald B. Pier,

期刊论文

Mutagenesis and selective breeding of a high producing

Tian WANG, Shiru JIA, Zhilei TAN, Yujie DAI, Shuai SONG, Guoliang WANG

期刊论文

Ultrafast-laser-treated poly(3,4-ethylenedioxythiophene): poly(styrenesulfonate) electrodes with enhanced

期刊论文

Hydrophilic modification of poly(aryl sulfone) membrane materials toward highly-efficient environmental

期刊论文

Preparation and characterization of poly (vinylidene fluoride)/TiO

Weiying LI, Xiuli SUN, Chen WEN, Hui LU, Zhiwei WANG

期刊论文

Effect of polyethylene glycol on the crystallization, rheology and foamability of poly(lactic acid) containing

期刊论文

Design and analysis of dual fuel methanol-power poly-generation

Minghua WANG , Zheng LI , Weidou NI ,

期刊论文

Nano-hydroxyapatite formation via co-precipitation with chitosan-g-poly(

Yang YU, Hong ZHANG, Hong SUN, Dandan XING, Fanglian YAO

期刊论文

Molecular diffusion in ternary poly(vinyl alcohol) solutions

期刊论文

Controlled drug release of 5-amino salicylic acid by poly(2-hydroxyethylmethacrylate) grafted agar

G. Usha RANI,Kartick Prasad DEY,Srijita BHARTI,Sumit MISHRA

期刊论文

Solvent-resistant porous membranes using poly(ether−ether ketone): preparation and application

期刊论文

crystal morphology and melting behavior of isothermally crystallized composites of short carbon fiber and poly

Mingtao RUN, Hongzan SONG, Yanping HAO

期刊论文

Microwave assisted synthesis of poly(2-hydroxyethylmethacrylate) grafted agar (Ag-g-P(HEMA)) and its

Gautam SEN, G. Usha RANI, Sumit MISHRA

期刊论文