检索结果-南通市图书馆

Chinese Journal of Chemical Engineering 2022年第1期35卷 449-456页

作者： Siyuan Gao Yuanke Guo chen Ma Ding Ma Kequan Chen Pingkai Ouyang Xin Wang State Key Laboratory of Materials-Oriented Chemical Engineering College of Biotechnology and Pharmaceutical EngineeringNanjing Tech UniversityNanjing 211816China

Here,a dopa decarboxylase(DDC)from Harmonia axyridis was heterogeneously expressed in Escherichia coli for the efficient biosynthesis of dopamine.For the production of recombinant DDC,the cultivation conditions including IPTG concentration,temperature and induction time were optimized and obtained an optimal specific enzyme activity of 51.72 U·mg^(-1) crude extracts.After the purification of DDC with a recovery yield of 68.79%,its activity was further characterized.The Vmax,Km,Kcat,and Kcat/Km of DDC for d ihyd roxy pheny la la nine(dopa)were 0.02 mmol·ml^(-1)·s^(-1),2.328 mmol·ml^(-1),10435.90 s^(-1) and4482.77 ml,mmol respectively.The highest DDC activity was observed at the condition of pH 7.5 and 45℃.With the purified DDC,the feasibility to produce dopamine from L-dopa was evaluated.The optimal yield was determined at the following bioconversion conditions:pH of 7,0,the reaction temperature of 40℃,0.4 mmol·L^(-1) of PLP and 4 g·L^(-1) of L-dopa,Subsequently,a fed-batch process for the production of dopamine was developed and the effect of oxygen was evaluated.The titer,yield and productivity of dopamine reached up to 21.99 g·L^(-1)80.88%and 14.66 g·L^(-1)·h^(-1) at 90 min under anaerobic condition.

关键词： Dopa decarboxylase Dopamine Enzyme catalysis Fed-batch bioconversion

Engineering the native methylotrophs for the bioconversion of methanol to value-added chemicals:current status and future perspectives

在线全文

学校读者我要写书评

暂无评论

Green Chemical Engineering 2023年第2期4卷 199-211页

作者： Jing Wang Ruirui Qin Yuanke Guo chen Ma Xin Wang Kequan Chen Pingkai Ouyang State Key Laboratory of Materials-Oriented Chemical Engineering College of Biotechnology and Pharmaceutical EngineeringNanjing Tech UniversityNanjing211816China

Methanol is becoming an attractive fermentation feedstock for large-scale bioproduction of chemicals,due to its natural abundance and mature production technology.Native methylotrophs,which can utilize methanol as the only source of carbon and energy,are ideal hosts for methanol bioconversion due to their high methanol utili-zation rate and have been extensively employed in the production of value-added chemicals from methanol.Here,we review the natural methanol utilization pathways in native methylotrophs,describing the available synthetic biology tools developed for engineering native methylotrophs,and discuss the strategies for improving their methanol utilization efficiency.Finally,the representative examples of engineering the native methylotrophs to produce value-added products from methanol are summarized.Furthermore,we also discuss the major challenges and possible solutions for the application of native methylotrophs in methanol-based biomanufacturing.

关键词： Native methylotrophs Methanol Biomanufacturing Value-added chemicals

Are shared electric scooters energy efficient?

在线全文

学校读者我要写书评

暂无评论

Communications in Transportation Research 2021年第1期1卷 182-192页

作者： Yuxuan Wang Jiaming Wu Kequan Chen Pan Liu Jiangsu Key Laboratory of Urban ITS School of TransportationSoutheast UniversitySi Pai Lou#2Nanjing210096China Department of Architecture and Civil Engineering Chalmers University of TechnologyGothenburgSE41296Sweden

Shared electric scooters(e-scooter)are booming across the world and widely regarded as a sustainable mobility service.An increasing number of studies have investigated the e-scooter trip patterns,safety risks,and environmental impacts,but few considered the energy efficiency of e-scooters.In this research,we collected the operational data of e-scooters from a major provider in Gothenburg to shed light on the energy efficiency performance of e-scooters in real cases.We first develop a multiple logarithmic regression model to examine the energy consumption of single trips and influencing factors.With the regression model,a Monte Carlo simulation framework is proposed to estimate the fleet energy consumption in various scenarios,taking into account both trip-related energy usage and energy loss in idle status.The results indicate that 40%of e-scooter battery energy was wasted in idle status in the current practice,mainly due to the relatively low usage rate(0.83)of e-scooters.If the average usage rate drops below 0.5,the wasted energy could reach up to 53%.In the end,we present a field example to showcase how to optimally integrate public transport with e-scooters from the perspective of energy efficiency.We hope the findings of this study could help understand and resolve the current and future challenges regarding the ever-growing e-scooter services.

关键词： E-scooters Shared mobility Sustainable transportation Monte Carlo simulation

The influence of the NCO/OH ratio and the 1,6-hexanediol/ dimethylol propionic acid molar ratio on the properties of waterborne polyurethane dispersions based on 1,5-pentamethylene diisocyanate

在线全文

维普期刊数据库

学校读者我要写书评

暂无评论

Frontiers of Chemical Science and Engineering 2019年第1期13卷 80-89页

作者： Jiao Feng Qiuhao Lu Weimin Tan Kequan Chen Pingkai Ouyang State Key Laboratory of Materials-Oriented Chemical Engineering College of Biotechnology and Pharmaceutical Engineering Nanjing Tech University Nanjing 211816 China National Engineering Research Center for Coatings CNOOC Changzhou Paint and Coatings Industry Research Institute Co. Ltd. Changzhou 213016 China

1,5-Pentamethylene diisocyanate, a novel aliphatic diisocyanate formed from bio-based 1,5-pentamethylenediamine, has been used as a hard segmented material to synthesize polyurethane. In this study, several waterborne polyurethane (WPU) dispersions have been successfully prepared by a prepolymer process from 1,5-pentamethylene diisocyanate poly(polyether) with different NCO/OH ratios and 1,6-hexanediol (HDO)/dimethylol propionic acid (DMPA) molar ratios. The Fourier transfonn infrared (FTIR) spectra, thermogravimetric analysis, differential scanning calorimetry, X-ray diffiraction, and a mechanical tensile test were used to investigate the structures, thermal stability, phase separation, crystallinity, mechanical properties, and adhesive performance of the WPU dispersions. The FTIR results indicate that the degree of hydrogen bonding and the numbers of urea groups increase as the NCO/OH ratio and HDO/DMPA molar ratio increase. Furthermore, the phase separation increases and the thermal stability decreases as the NCO/OH ratio increases or the HDO/DMPA molar ratio decreases. Finally, WPU3.0-2.4 (NCO/OH = 3, HDO/DMPA = 2.4) exhibits a maximum tensile strength and shear strength, pointing to its possible use as an adhesive. These results could provide a very valuable reference for industrial applications of WPU.

关键词： 1,5-pentamethylene diisocyanate polyurethane water based

The production of enantiopure D-lysine from L-lysine by a two-strain coupled system

在线全文

维普期刊数据库

学校读者我要写书评

暂无评论

Chinese Journal of Chemical Engineering 2020年第11期28卷 2832-2836页

作者： Sheng Xu Xiaolu Lu Xin Wang Zhen Gao Kequan Chen Pingkai Ouyang State Key Laboratory of Materials-Oriented Chemical Engineering College of Biotechnology and Pharmaceutical EngineeringNanjing Tech UniversityNanjing 211816China

The microbial production of D-lysine to replace chemical approach has gained great interest with the rising concerns over the environment.Here,we employed recombinant E.coli strain BL21-LYR with lysine racemase and strain BL-22A-RB-YB with L-lysine monooxygenase and 5-aminovaleramide amidohydrolase to establish a two-strain coupling whole-cell bioconversion system for D-lysine production from L-lysine.To improve the optical purity of D-lysine,the optimal reaction condition for resolution of DL-lysine after the racemization was investigated.The specificity of BL-22A-RB-YB for L^-lysine and the effects of reaction condition on bioconversion efficiency of whole-cell were accordingly determined.Under the optimal condition,a maximum 53.5 g·L^-1 D-lysine and 48.2 g·L^-15-AVA were obtained with yield of 47.4%and 42.3%,respectively,by the microbial racemization and asymmetric degradation process.The final D-lysine enantiomeric excess was over 99%.Meanwhile,a valuable compound 5-aminovaleric acid was synthesized with the production of D-lysine,indicating the economic feasibility of the two-strain coupling system.

关键词： _D-Lysine Microbial resolution Two-strain coupling system

Combination of ARTP mutagenesis and color-mediated highthroughput screening to enhance 1-naphthol yield from microbial oxidation of naphthalene in aqueous system

在线全文

学校读者我要写书评

暂无评论

Frontiers of Chemical Science and Engineering 2020年第5期14卷 793-801页

作者： chenggang Qiu Alei Zhang Sha Tao Kang Li Kequan Chen Pingkai Ouyang College of Biotechnology and Pharmaceutical Engineering Nanjing Tech UniversityNanjing 211800China State Key Laboratory of Materials-Oriented Chemical Engineering Nanjing Tech UniversityNanjing 211800China

Strain QCG of the aerobic bacteria Bacillus cereus is capable of producing l-naphthol from naphtha-lene,this strain was first isolated and characterized in this study.Strain QCG was mutagenized to enhance l-naphthol production,using atmospheric and room temperature plasma(ARTP)technology.Then,a microbial clone screening system was used to accelerate the operation.Meanwhile,a novel color-mediated high-throughput screening using 4-aminoantipyrine was performed to screen mutants.The optimal mutant strain QCG4 produced 19.58土0.34 mg·L-1-naphthol from naphthalene that was 47.32%higher than that of the original strain(13.29+0.28 mg·L-1).In addition,the optimal conditions for l-naphthol production via whole-cell catalysis of strain QCG4 were determined to be an OD600 of40,150 mg.L I naphthalene,and 7.5%dimethyl formamide as a co-solvent at pH 7.5 and 26℃ for 3 h,resulting in 41.18士0.12 mg·L-l-naphthol,i.e.,the mutant strain produces a 2.1-fold higher yield compared to the original strain.

关键词： Bacillus cereus QCG naphthalene 1-naphthol ARTP mutagenesis high-throughput screening 4-aminoan-tipyrine

Mass Transfer, Gas Holdup, and Kinetic Models of Batch and Continuous Fermentation in a Novel Rectangular Dynamic Membrane Airlift Bioreactor

在线全文

维普期刊数据库

学校读者我要写书评

暂无评论

Engineering 2022年第6期8卷 153-163页

作者： Ganlu Li Kequan Chen Yanpeng Wei Jinlei Zeng Yue Yang Feng He Hui Li Pingkai Ouyang College of Biotechnology and Pharmaceutical Engineering Nanjing Tech UniversityNanjing 211816China Jiangsu Jicui Industrial Biotechnology Research Institute Co. Ltd.Nanjing 211800China

Compared with conventional cylinder airlift bioreactors(CCABs)that produce coarse bubbles,a novel rectangular dynamic membrane airlift bioreactor(RDMAB)developed in our lab produces fine bubbles to enhance the volumetric oxygen mass transfer coefficient(k_(L)a)and gas holdup,as well as improve the bioprocess in a bioreactor.In this study,we compared mass transfer,gas holdup,and batch and con-tinuous fermentation for RNA production in CCAB and RDMAB.In addition,unstructured kinetic models for microbial growth,substrate utilization,and RNA formation were established.In batch fermentation,biomass,RNA yield,and substrate utilization in the RDMAB were higher than those in the CCAB,which indicates that dynamic membrane aeration produced a high k_(L)a by fine bubbles;a higher k_(L)a is more bene-ficial to aerobic fermentation.The starting time of continuous fermentation in the RDMAB was 20 h ear-lier than that in the CCAB,which greatly improved the biological process.During continuous fermentation,maintaining the same dissolved oxygen level and a constant dilution rate,the biomass accumulation and RNA concentration in the RDMAB were 9.71% and 11.15% higher than those in the CCAB,respectively.Finally,the dilution rate of RDMAB was 16.7% higher than that of CCAB during con-tinuous fermentation while maintaining the same air aeration.In summary,RDMAB is more suitable for continuous fermentation processes.Developing new aeration and structural geometry in airlift bioreac-tors to enhance k_(L)a and gas holdup is becoming increasingly important to improve bioprocesses in a bioreactor.

关键词： Airlift bioreactor Dynamic membrane Kinetic model Batch fermentation Continuous fermentation

Green catalytic engineering:A powerful tool for sustainable development in chemical industry

在线全文

学校读者我要写书评

暂无评论

Frontiers of Chemical Science and Engineering 2018年第4期12卷 835-837页

作者： Kequan Chen Dangguo cheng Chong Peng Dan Wang Jintao Zhang State Key Laboratory of Materials-Oriented Chemical Engineering College of Biotechnology and Pharmaceutical Engineering Nanjhag Tech UniversityNanjing 211816China Zhejiang Provincial Key Laboratory of Advanced Chemical Engineering Manufacture Technology College of Chemical and Biological EngineeringZhejiang UniversityHangzhou 310027China Dalian Research Institute of Petroleum and Petrochemicals SINOPECDalian 116045China State Key Laboratory of Organic-Inorganic Composites College of Chemical EngineeringBeijing University of Chemical Technology Beijing 100029China Key Laboratory for Colloid and Interface Chemistry (Ministry of Education) School of Chemistry and Chemical Engineering Shandong UniversityJinan 250100China

Catalysts play critical roles in modern chemical industry and more than 85% of all chemical processes involve the use of catalysts. The sustainable development of chemical industry calls for green catalytic engineering, which refers to the engineering design and development of environment- friendly, high-efficiency and cost-effective catalysts and catalytic processes for the Industrial manufacture of useful products and energy. It may be difficult to predict the future, but we are glad to identify the current trends that are likely to become ever more important, which is green catalytic engineering. To emphasize the latest advances in the exciting field, to explore efficient strategies for the future development, and to address challenges in chemical industry, we presents a Mini-Special Issue in Frontiers of Chemical Science and Engineering that highlights two featured research articles and three reviews on green catalytic engineering.

关键词：

Efficient production of cyclic adenosine monophosphate from adenosine triphosphate by the N-terminal half of adenylate cyclase from Escherichia coli

在线全文

维普期刊数据库

学校读者我要写书评

暂无评论

Chinese Journal of Chemical Engineering 2020年第8期28卷 2167-2172页

作者： chen Ma Jing Wang Xuelin Wang Dandan Mai Yuqi Jin Kequan Chen Xin Wang Pingkai Ouyang State Key Laboratory of Materials-Oriented Chemical Engineering College of Biotechnology and Pharmaceutical EngineeringNanjing Tech UniversityNanjing 211816China

In this study,we aimed at developing an efficient biocatalytic process for bio-production of cyclic adenosine monophosphate(c AMP)from adenosine triphosphate(ATP).First,adenylate cyclase from Escherichia coli MG1655(EAC)and Bordetella Pertussis(BAC)were expressed in E.coli BL21(DE3)and comparatively analyzed for their activities.As a result,EAC from E.coli MG1655 exhibited a higher activity.However,amount of EAC were obtained in an insoluble form.Therefore,we expressed the first 446 amino acids of EAC(EAC446)to avoid the inclusion body.The effects of induction temperature,incubation time,and incubation p H were further evaluated to improve the expression of EAC446.Subsequently,the reaction process for the production of c AMP with ATP as a starting material was investigated.As none of c AMP was detected in the whole-cell based biocatalytic process,the reaction catalyzed by the crude enzyme was determined for c AMP production.What's more,the reaction temperature,reaction p H,metal ion additives and substrate concentration was optimized,and the maximum c AMP production of 18.45 g·L^-1was achieved with a yield of 95.4%after bioconversion of 6 h.

关键词： Adenylate cyclase Cyclic adenosine monophosphate(cAMP) Adenosine triphosphate(ATP) Bioconversion

The production of biobased diamines from renewable carbon sources: Current advances and perspectives

在线全文

学校读者我要写书评

暂无评论

Chinese Journal of Chemical Engineering 2021年第2期34卷 4-13页

作者： Xin Wang Siyuan Gao Jing Wang Sheng Xu Hui Li Kequan Chen Pingkai Ouyang State Key Laboratory of Materials-Oriented Chemical Engineering College of Biotechnology and Pharmaceutical EngineeringNanjing Tech UniversityNanjing 211816JiangsuChina Zhejiang Zhongshan Chemical Industry Group Co.Ltd Huzhou 313100Chin

Bio-based diamines are considered to be a promising alternative to traditional fossil-fuel-based diamines,the important platform chemical for the synthesis of polymer materials.In this review,the current status of the art of the synthesis of aliphatic and aromatic diamines from renewable biomass are considered.In the case of aliphatic diamines,we describe strategies for biologically producing diamines with different carbon numbers including 1,3-diaminopropane,1,4-butanediamine,1,5-pentanediamine,1,6-diaminohexane,1,8-diaminooctane,1,10-diaminodecane,and 1,12-diaminododecane.In addition,aromatic diamines produced from various kinds of renewable biomass,including lignin,cashew nut shell,and terpenoids,are reviewed here.Furthermore,the application of typical diamines in synthesis of polyurethane and polyamide are also reviewed.

关键词： Aliphatic diamines Aromatic diamines Polyamide Polyurethane