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Tribological application and mechanism of epicuticular wax

Friction 2019年第1期7卷 44-58页

作者： xuwen ZHONG Yanqiu XIA Xin feng School of Energy Power and Mechanical Engineering North China Electric Power University

The plant cuticle is a complex mixture of omnipresent, commonly monofunctional, fatty acid derivatives and taxon-specific, generally bifunctional, specialty compounds. This study explored expanded applications for these substances. Four types of plant cuticles were distilled from leaves and the resulting lipid mixtures were analyzed using gas chromatography-mass spectrometry. These were then used as additives for a synthetic ester lubricant. A reciprocating friction and wear testing machine was utilized to investigate the resulting tribological properties. The worn surfaces of the lower discs were observed and analyzed using optical microscopy and time-of-flight secondary ion mass spectrometry. The results reveal that cuticular waxes can modify the friction properties of the base oil. Furthermore, cuticular waxes demonstrate better performance when compared to the commercially available additive molybdenum dithiocarbamates. A protective adsorption film was identified as the reason for the improved friction reduction and anti-wear properties of the lubricant on the friction pair. This study provides a reference for the study of new types of non-sulfur, phosphorus, and other active element additives and demonstrates considerable potential for the economical utilization of plant leaf waxes.

关键词： epicuticular wax tribological application GC-MS TOF-SIMS adsorption

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低产老化虾池的生态养殖的探讨

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湛江海洋大学学报 1999年第2期19卷 9-13页

作者：胡贤德苏强华冯伍湛江海洋大学科研处湛江524088 徐闻县迈陈对虾养殖塘

针对目前大批低产老化虾池的改造和可持续生产的问题，设计了一个自然生态养虾新模式。利用长期不能清淤的低产老化虾池和已造成生态失衡的虾池，实行疏放苗，精管理，综合利用、立体开发，混养、轮养。试验结果表明，养殖周期为８０... 详细信息

针对目前大批低产老化虾池的改造和可持续生产的问题，设计了一个自然生态养虾新模式。利用长期不能清淤的低产老化虾池和已造成生态失衡的虾池，实行疏放苗，精管理，综合利用、立体开发，混养、轮养。试验结果表明，养殖周期为８０～９０ｄ，对虾成活率６０．５％～７６％，体长达１０．１～１３．２ｃｍ，平均体重１７．２～１９．２ｇ／尾，饵料系数０．７７～０．８０，平均产量６４５～７８０ｋｇ／ｈｍ２，鲻鱼产量４２０～４６５ｋｇ／ｈｍ２。整个养殖过程虾池的各种水质理化因子基本符合要求。

关键词：斑节对虾低产老化虾池生态养殖

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Free-standing polydopamine films generated in the presence of different metallic ions: the comparison of reaction process and film properties

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RSC ADVANCES 2018年第33期8卷 18347-18354页

作者： Han, xuwen Tang, feng Jin, Zhaoxia Renmin Univ China Dept Chem Beijing 100872 Peoples R China

Polydopamine is widely used in surface modification, nanofiltration, photonic devices and drug delivery. The formation mechanism and properties of polydopamine are modified by the experimental conditions. Herein we demonstrated a comparison study of free-standing polydopamine films generated at the air-solution interface and their corresponding nanoparticles in solutions, in the presence of various metallic cations, Na+, Ca2+, Mg2+ and Co2+. Adding metallic ions influenced the intermediates in dopamine polymerization, and in turn the morphology and properties of the produced free-standing polydopamine films. Moreover, we observed that the polymerization process accompanying the stratification determines the formation of free-standing films at the air-solution interface: the fast polymerization of dopamine in a Co2+ environment leads to a rugged film surface and porous film body, whereas the comparatively slow polymerization of dopamine under conditions of other metallic ions results in a smooth and solid film. In addition, the water contact angles of the upper and lower surface of the polydopamine films were different. This investigation enriches our knowledge of dopamine polymerization in different environments, which is particularly useful for further application of free-standing polydopamine films.

关键词： Polymerization

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数字化视角下应急测绘管理服务平台的研究与设计

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测绘与空间地理信息 2025年第3期48卷 41-43页

作者：马旭文万术海唐伟王沛冯思园浙江省测绘科学技术研究院浙江杭州311100

为了高效应对重大突发事件和维护人民生命财产安全情景下的数字化管理的深度应用,通过相关文献资料的研究,并结合浙江省应急测绘管理工作的实际需求,提出一种面向突发事件全闭环管理的应急测绘管理服务平台的设计方案。系统阐述了平台... 详细信息

为了高效应对重大突发事件和维护人民生命财产安全情景下的数字化管理的深度应用,通过相关文献资料的研究,并结合浙江省应急测绘管理工作的实际需求,提出一种面向突发事件全闭环管理的应急测绘管理服务平台的设计方案。系统阐述了平台的业务流程、总体框架、功能模块和关键技术。该平台有效提升了应急测绘灾前、灾中、灾后的管理水平和工作效率,实现了事前防范准备、事发监测预警、事中处置救援、事后应急复盘的全流程管理。

关键词：数字化应急测绘管理闭环平台

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A comprehensive analysis of the microbial diversity in natural and engineered ecosystems based on high-throughput sequencing of 16S rRNA gene

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INTERNATIONAL BIODETERIORATION & BIODEGRADATION 2019年 140卷 160-168页

作者： Xia, Yu He, xuwen feng, Zeshen Zhang, Qing Yang, Hongying China Univ Min & Technol Beijing Sch Chem & Environm Engn Beijing 100083 Peoples R China Northeastern Univ Sch Met Shenyang 110819 Liaoning Peoples R China

Understanding microbial diversity across different ecosystems is important for discerning the mechanisms shaping the microbial community assembly. However, knowledge on differentiations of microbial diversity in various habitats especially engineered systems remains very limited. A comprehensive comparison of microbial diversity across natural and engineered environments, namely heavy metal polluted farm soil, forest, wastewater treatment plants (WWTPs), anaerobic digesters (ADs) and the Caspian Sea sediments, was made base on a collection of 115 samples from seven published 16S rRNA gene datasets generated by high-throughput sequencing. In each sample, 16,590 and 19,771 qualified sequences were detected, and they were classified into 615 to 3,162 operational taxonomic units (OTUs). The microbial communities in the engineered systems especially the AD showed relatively low alpha taxonomic and phylogenetic diversity. A total of 49 genera were present in more than 80% of the samples, accounting for 6.0% in population number and 25.6% in relative abundance (RA). The average abundance-weighted rRNA operon copy number of the communities from ADs and a food wastewater treatment plant (FW) was higher than that of others, suggesting that high loading rate of pollutants in ADs and FW resulted in relatively high abundance of r-strategists. Among 104 typical human bacterial pathogens (HBPs), 2 to 25 HBPs were detected in each sample, accounting for 0.05%-21.34% in RA. Mycobacterium phlei was widely present in 111 samples with an average RA of 0.12%. The number and RA of all the HBPs in each sample did not show an obvious ecosystem type related pattern. Results of detrended correspondence analysis (DCA) and cluster analysis showed that the microbial communities clustered based on habitat types. The communities of WWTPs and soil were very similar, falling into one cluster. For any two communities from the datasets, 75.6% of their beta nearest taxon index (beta NTI) values were h

关键词： Microbial community Natural environments Engineered systems Diversity Environmental conditions High-throughput sequencing

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Adsorption of PAHs on the Sediments from the Yellow River Delta as a Function of Particle Size and Salinity

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SOIL & SEDIMENT CONTAMINATION 2015年第2期24卷 103-115页

作者： Wang, Jianbing Wang, Can Huang, Qiuying Ding, feng He, xuwen China Univ Min & Technol Sch Chem & Environm Engn Beijing 100083 Peoples R China Henan Polytech Inst Dept Chem Engn Nanyang Peoples R China Minist Environm Protect Appraisal Ctr Environm & Engn Beijing Peoples R China

In a seawater environment, the particle size of sediment and salinity play an important role in the adsorption behaviors of polycyclic aromatic hydrocarbons (PAHs) on sediment. In this study, batch adsorption experiments were carried out with the sediments from the Yellow River Delta (YRD) to explore the effect of particle size and salinity on the adsorption behaviors of phenanthrene (Phe), fluoranthene (Fla), and pyrene (Pyr). Adsorption isotherms of PAHs on different-sized sediments can be described by a Freundlich model with the correlation coefficients ranging from 0.96 to 0.99. The adsorption capacity of PAHs was in reverse proportion to the particle size of the sediments and in direct proportion to salinity. The sediments with smaller particle size possessed higher content of aromatic and fat components, which had strong adsorption capacity toward PAHs. Salinity influenced the adsorption behaviors of PAHs by changing the solubility of PAHs and the physicochemical properties of the sediments. The salting-out constants of Phe, Fla, and Pyr were in the range of 0.292 to 0.296, 0.230 to 0.289, and 0.293 to 0.307 l/mol, respectively. These research findings are of importance to an assessment of the fate and transport of PAHs in seawater-sediment systems.

关键词： fate and transport fluoranthene pyrene Phenanthrene

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Recent advances in the synthesis of biodegradable polyesters by sustainable polymerization: lipase-catalyzed polymerization

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RSC ADVANCES 2020年第59期10卷 36230-36240页

作者： Liu, Ying Song, Lijie feng, Na Jiang, Wei Jin, Yongri Li, xuwen Jilin Univ Coll Chem 2699 Qianjin Rd Changchun 130012 Jilin Peoples R China Jilin Prov Acad Tradit Chinese Med Clin Hosp 1 Changchun 130021 Peoples R China Zhengzhou Univ Acad Med Sci Dept Mol Pathol Applicat Ctr Precis MedAffiliated Hosp 2 Zhengzhou 450052 Henan Peoples R China

Over the past three decades, enzymatic polymerization has dramatically developed and gradually broadened as a creative methodology in the construction of polymeric materials with tailor-made structures and properties. Compared with transition metal catalyst polymerizations, enzymatic polymerization is more attractive in the biomedicine field due to the metal-free residue, good biocompatibility, and few by-products. Meanwhile, enzymatic polymerization has far more activity towards macrolides. In this review, the synthesis of lipase-catalyzed polymer materials is systematically summarized, focusing on the synthesis of the complex and well-defined polymers. The enzymatic polyester synthesis was then discussed concerning the different reaction types, including ring-opening polymerization, polycondensation, a combination of ring-opening polymerization with polycondensation, and chemoenzymatic polymerization. Besides, exploration of novel biocatalysts and reaction media was also described, with particular emphasis on the enzymes obtainedviaimmobilization or protein engineering strategies, green solvents, and reactors. Finally, recent developments in catalytic kinetics and mechanistic studies through the use of spectroscopy, mathematics, and computer techniques have been introduced. Besides, we addressed the remaining central issues in enzymatic polymerization and discussed current studies aimed at providing answers.

关键词： Ring opening polymerization

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Zeolite biofilm aeration filter plays a pre-nitritation role in autotrophic nitrogen removal from iron oxide red wastewater

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JOURNAL OF CHEMICAL TECHNOLOGY AND BIOTECHNOLOGY 2020年第12期95卷 3261-3269页

作者： feng, Xinghui Wang, Xiaojun Wang, Ruixin Zheng, xuwen Zhong, Zhong Chen, Xiaozhen South China Univ Technol Sch Environm & Energy Guangzhou Peoples R China Minist Educ Key Lab Pollut Control & Ecosyst Restorat Ind Clu Guangzhou Peoples R China Hua An Biotech Co Ltd Foshan Peoples R China

BACKGROUND The completely autotrophic nitrogen removal over nitrite (CANON) system has excellent performance in treating ammonium-rich wastewater and it depends on ammonia oxidizing bacteria (AOB) working together with anammox bacteria in a reactor. Higher ammonium nitrogen loading requires higher aeration to provide sufficient dissolved oxygen (DO) for nitritation, whereas high-strength aeration in theCANON will destroy the sludge structure and inhibit the activity of anammox bacteria. The present study uses a stable pre-nitritation system to reduce a part of nitritation and also decrease aeration intensity in the CANON. RESULTS Continuous aeration to maintain the DO concentration between 1.5 and 4.3 mg L(-1)in the CANON achieved a stable nitrogen removal rate (1.22 kg N m(-3)d(-1)) from iron oxide red wastewater with 400-1016 mg N L(-1)after 183 days of operation. Using a mixed alkalinity donor [sodium carbonate (Na2CO3) and bicarbonate (NaHCO3)] in the combined system can save approximate to 14.1-28.2% of the alkalinity cost compared with using NaHCO(3)only. CONCLUSIONS A zeolite biofilm aeration filter (ZBAF) used in a pre-nitritation process can tolerate high DO concentration of <= 6.5 mg L(-1)for nitritation and avoid all of the nitritation taking place in the CANON system. This can protect the sludge structure and anammox bacteria from high-strength aeration erosion. (c) 2020 Society of Chemical Industry

关键词： pre-nitritation zeolite dissolved oxygen control Anammox granular sludge

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Dynamic design method of digital twin process model driven by knowledge-evolution machining features

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INTERNATIONAL JOURNAL OF PRODUCTION RESEARCH 2022年第7期60卷 2312-2330页

作者： Liu, Jinfeng Zhao, Peng Jing, xuwen Cao, Xuwu Sheng, Sushan Zhou, Honggen Liu, Xiaojun feng, feng Jiangsu Univ Sci & Technol Sch Mech Engn Zhenjiang 212003 Jiangsu Peoples R China Southeast Univ Sch Mech Engn Nanjing Peoples R China Shaanxi Diesel Engine Heavy Ind Co Ltd Xingping Peoples R China

Machining plan is the core of guiding manufacturing production and is regarded as one of the keys to ensure the quality of product processing. Existing process design methods are inefficient to quickly handle the machining plan changed induced by the unpredictable events in real-time production. It inevitably causes time and economic losses for the enterprise. In order to express the evolutionary characteristics of product processing, the construction method of digital twin process model (DTPM) is proposed based on the knowledge-evolution machining features. Three key technologies include correlation structure of process knowledge, expression method of the evolution geometric features and the association mechanism between two are solved. On this basis, the construction framework of DTPM is illustrated. Then, the organisation and management mechanism of multi-source heterogeneous data is discussed in detail. At last, a case study of the complex machined part is researched, the results show that the processing time reduced by about 7% and the processing stability improved by 40%. Meanwhile, the implementation scheme, application process and effect of this case are described in detail to provide reference for enterprises.

关键词： Digital twin process knowledge machining features dynamic evolution

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Highly efficient synthesis of hydrogen-bonded aromatic tetramers as macrocyclic receptors for selective recognition of lithium ions

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ORGANIC CHEMISTRY FRONTIERS 2019年第15期6卷 2654-2661页

作者： Guo, xuwen Yang, Yizhou Peng, Zhiyong Cai, Yimin feng, Wen Yuan, Lihua Sichuan Univ Coll Chem Key Lab Radiat Phys & Technol Minist Educ Chengdu 610064 Sichuan Peoples R China

Persistently folded aromatic amide macrocycles comprising four monomeric units (biphenyl-cyclo[4]aramide) were synthesized with high efficiency via a one-step approach along with the larger cyclic oligomer, biphenyl-cyclo[8]aramide as a minor product. Such cyclic hydrogen-bonded aromatic tetramers feature four amide oxygens enclosing a cavity with small dimensions, enabling the selective complexation of alkali metal ions, particularly Li+, with high affinity. The cyclization efficiency and selectivity of smaller macrocycles was further improved using fragment coupling and Li+-based template approaches. In addition, the superior binding ability of biphenyl-cyclo[4]aramide towards Li+ over its acyclic analogues was observed, demonstrating a remarkable macrocyclic effect.

关键词： Amides

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