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Simultaneous enhanced ammonia and nitrate removal from secondary effluent in constructed wetlands using a new manganese-containing substrate

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Frontiers of Environmental Science & Engineering 2024年第4期18卷 91-102页

作者： Zhihao Xian Jun Yan Jingyi Dai Hao Wu Xin zhang Wenbo Nie fucheng Guo Yi Chen Key Laboratory of the Three Gorges Reservoir Region’s Eco-Environment(Ministry of Education) Chongqing UniversityChongqing 400044China College of Environment and Ecology Chongqing UniversityChongqing 400044China

Constructed wetlands(CWs)are widely used to treat secondary effluent.However,simultaneously removing ammonia(NH_(4)^(+)-N)and nitrate(NO_(3)^(–)–N)is challenging because of insufficient oxygen and carbon sources.In this study,a novel composite material(MPCM)comprising MnO2 and polycaprolactone was developed as a substrate for CWs to enhance the synchronous removal of NH_(4)^(+)–N and NO_(3)^(–)–N.The CWs with a higher MPCM content(H-CW),lower MPCM content(LCW),and controlled CW(C-CW)exhibited average NH_(4)^(+)–N removal efficiencies of 75.69%,70.49%,and 52.40%,respectively.The 15N isotope tracking technique showed that NH_(4)^(+)–N removal was attributed to anaerobic ammonia oxidation mediated by MnO2 reduction(Mnammox),which accounted for 17.16%–27.24%of the NH_(4)^(+)–N removal in the composite material layers(0–20 cm)of the H-CW and L-CW.The richness of ammonia oxidizers in the upper layers(40–50 cm)of the HCW and L-CW further facilitated NH_(4)^(+)–N removal.Moreover,the average total nitrogen(TN)removal efficiencies of the H-CW and L-CW were 1.99 and 1.59 times that of C-CW,respectively,owing to enhanced denitrification by MPCM.Furthermore,N2O emissions were reduced by 81.31%and 70.83%in the H-CW and L-CW,respectively.This study provides an effective approach for improving nitrogen removal and reducing N2O emissions during the treatment of secondary effluent by CWs.

关键词： Constructed wetland Nitrogen removal Manganese redox Polycaprolactone Nitrous oxide

Two types of coumarins-specific enzymes complete the last missing steps in pyran- and furanocoumarins biosynthesis

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Acta Pharmaceutica Sinica B 2024年第2期14卷 869-880页

作者： Yucheng Zhao Yuedong He Liangliang Han Libo zhang Yuanzheng Xia fucheng Yin Xiaobing Wang Deqing Zhao Sheng Xu Fei Qiao Yibei Xiao Lingyi Kong Department of Resources Science of Traditional Chinese Medicines School of Traditional Chinese Pharmacyand State Key Laboratory of Natural MedicinesChina Pharmaceutical UniversityNanjing 210009China College of Bioscience and Biotechnology Hunan Agricultural UniversityChangsha 410128China Jiangsu Key Laboratory of Bioactive Natural Product Research and State Key Laboratory of Natural Medicines Department of Natural Medicinal ChemistryChina Pharmaceutical UniversityNanjing 210009China Key Laboratory of Crop Gene Resources and Germplasm Enhancement in Southern China Ministry of AgricultureTropical Crops Genetic Resources InstituteChinese Academy of Tropical Agricultural SciencesHaikou 517317China Institute of Botany Jiangsu Province and Chinese Academy of SciencesNanjing 210014China Department of Pharmacology School of Pharmacyand State Key Laboratory of Natural MedicinesChina Pharmaceutical UniversityNanjing 210009China

Pyran-and furanocoumarins are key representatives of tetrahydropyrans and tetrahydrofurans,respectively,exhibiting diverse physiological and medical bioactivities.However,the biosynthetic mechanisms for their core structures remain poorly understood.Here we combined multiomics analyses of biosynthetic enzymes in Peucedanum praeruptorum and in vitro functional verification and identified two types of key enzymes critical for pyran and furan ring biosynthesis in plants.These included three distinct P.praeruptorum prenyltransferases(PpPT1e3)responsible for the prenylation of the simple coumarin skeleton 7 into linear or angular precursors,and two novel CYP450 cyclases(PpDC and PpOC)crucial for the cyclization of the linear/angular precursors into either tetrahydropyran or tetrahydrofuran scaffolds.Biochemical analyses of cyclases indicated that acid/base-assisted epoxide ring opening contributed to the enzyme-catalyzed tetrahydropyran and tetrahydrofuran ring refactoring.The possible acid/base-assisted catalytic mechanisms of the identified cyclases were theoretically investigated and assessed using site-specific mutagenesis.We identified two possible acidic amino acids Glu303 in PpDC and Asp301 in PpOC as vital in the catalytic process.This study provides new enzymatic tools in the epoxide formation/epoxide-opening mediated cascade reaction and exemplifies how plants become chemically diverse in terms of enzyme function and catalytic process.

关键词： Tetrahydropyrans Tetrahydrofurans Baldwin rules Coumarins CYP450cyclase

Anisotropy of wrought magnesium alloys: A focused overview

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Journal of Magnesium and Alloys 2022年第6期10卷 1476-1510页

作者： Baodong Shi Chong Yang Yan Peng fucheng zhang Fusheng Pan National Engineering Research Center for Equipment and Technology of Cold Rolled Strip School of Mechanical EngineeringYanshan UniversityHebei-West-Str.438Qinhuangdao 066004PR China State Key Laboratory of Metastable Materials Science and Technology Yanshan UniversityQinhuangdao 066004PR China National Engineering Research Center for Magnesium Alloys(CCMg) Chongqing UniversityChongqing 400044PR China

In this paper, the relationship between anisotropic mechanical properties and the corresponding microstructure evolution of wrought magnesium alloys is critically reviewed. Experimental observations of the strong anisotropy(including the strength differential effect) induced by texture and twinning are discussed under different loading conditions(i.e., monotonic, cyclic and multiaxial loading). An accurate constitutive model is essential to describe the mechanical responses and to predict the forming performance considering engineering applications. Therefore, macroscale constitutive modeling of the anisotropy of magnesium alloys with directional distortional hardening are comprehensively reviewed with different approaches. To clarify the origin of the anisotropic behavior, physics-based mesoscale modeling of the anisotropy is also compared in detail.

关键词： Wrought Mg alloys Mechanical anisotropy Deformation mechanism Constitutive modeling

Roles of pre-formed martensite in below-Ms bainite formation,microstructure,strain partitioning and impact absorption energies of low-carbon bainitic steel

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Journal of Materials Science & Technology 2022年第1期96卷 69-84页

作者： Lihe Qian Zhi Li Tongliang Wang Dongdong Li fucheng zhang Jiangying Meng State Key Laboratory of Metastable Materials Science and Technology Yanshan UniversityQinhuangdao 066004China National Engineering Research Center for Equipment and Technology of Cold Strip Rolling Yanshan UniversityQinhuangdao 066004China Library of Yanshan University Yanshan UniversityQinhuangdao 066004China

The roles of pre-formed martensite(PM)in below-Ms bainite formation,microstructure,crystallography,strain partitioning and mechanical properties of a low-carbon bainitic steel were investigated using electron-backscattered diffraction,transmission electron microscopy,micro digital image correlation technique and mechanical tests.It is demonstrated that the pre-formation of martensite eliminates the incubation time for bainite transformation at various austempering temperatures below Ms,indicative of its acceleration effect at the early stage of transformation.This effect is mainly attributed to the surfaces or tips of the PM acting as the nuclei of subsequently-formed bainite,with initial bainite tending to form around the PM.However,the finishing time for below-Ms bainite transformation,especially at even lower temperatures,is retarded,owing to the dividing effect of PM on parent austenite grains,the decreasing effect of lowered isothermal temperature on the diffusion rate of carbon atoms and the strengthening effect of lowered isothermal temperature on supercooled austenite.PM and its adjacent bainitic laths have nearly the same crystallographic orientation and belong to the same block.The pre-formation of martensite largely refines the bainitic blocks/laths and retained austenite.The specimens with PM show relatively uniform strain partitioning among various phases,contrasting with the specimens without PM,for which strains are highly concentrated in the bainite region nearby fresh martensite/austenite(M/A)blocks or between adjacent M/A blocks.The impact absorption energies of the specimens with PM,when austempered at 30-60℃ below Ms,are more than twice higher than those of the specimens without PM,at no expense of tensile properties.

关键词： Bainite Martensite Impact toughness Transformation kinetics Strain partitioning

Roles of Al in enhancing the thermal stability of reverted austenite and mechanical properties of a medium-Mn TRIP steel containing 2.7 Mn

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Journal of Materials Science & Technology 2023年第36期167卷 119-136页

作者： Wenlu Yu Lihe Qian Xu Peng Tongliang Wang Kaifang Li Chaozhang Wei Zhaoxiang Chen fucheng zhang Jiangying Meng State Key Laboratory of Metastable Materials Science and Technology Yanshan UniversityQinhuangdao 066004China National Engineering Research Center for Equipment and Technology of Cold Strip Rolling Yanshan UniversityQinhuangdao 066004China School of Mechanical Engineering Yanshan UniversityQinhuangdao 066004China

Often,the addition of more than 4 wt.%Mn to medium-Mn steels is necessary to enhance the thermal stability of intercritical austenite for achieving sufficient amounts of retained austenite(RA)at room tem-perature.In this paper,a medium-Mn steel with Mn content as low as 2.7 wt.%was designed via alloying with a small amount of Al,and the microstructure and mechanical properties of the steel,subjected to intercritical annealing(IA)at 745°C for different times followed by oil quenching,were investigated.Results show that the volume fraction of RA increases first and then decreases with IA time,with the maximum of 0.36 obtained at IA time of 50 min.It is demonstrated that Al addition slows down the in-terface migration and growth kinetics of reverted austenite via retarding C diffusion in ferrite during IA,which,hence,decreases the amount and size of the reverted austenite and partitions more C and Mn into it.This suggests that Al plays a favorable role in enhancing the thermal stability of reverted austenite and increasing the amount of austenite retained at room temperature.Due to the presence of large amounts of RA and the strong transformation-induced plasticity effect generated during plastic deformation,the steel exhibits persistent high strain hardening and superior mechanical properties,comparable to those of reported medium-Mn steels containing higher Mn content.The present result offers a new insight into the role of Al in adjusting microstructure-property relationships and opens a promising way for designing low-cost,high performance medium-Mn steels with low Mn content for industrial applications.

关键词： Medium-Mn steel Transformation-induced plasticity Transformation kinetics Austenite thermal stability Mechanical properties

Development of and Perspective on High-Performance Nanostructured Bainitic Bearing Steel

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Engineering 2019年第2期5卷 319-328页

作者： fucheng zhang Zhinan Yang State Key Laboratory of Metastable Materials Science and Technology Yanshan University Qinhuangdao 066004 China National Engineering Research Center For Equipment and Technology of Cold Strip Rolling Yanshan University Qinhuangdao 066004 China

Bearings are the most important component of nearly all mechanical equipment, as they guarantee the steady running of the equipment, which is especially important for high-end equipment such as highspeed trains and shield tunneling machines. Requirements regarding the quality of bearings are increasing with the rapid development in technology. A country’s bearings manufacturing level directly reflects the level of that country’s steel metallurgy and machinery manufacturing. The performance of the bearing steel is the critical factor that determines the quality of a bearing. The development of new bearing steel with higher performance is the ambition of material researchers and the expectation of the manufacturing industry. Many famous bearing manufacturing enterprises are competing to develop the new generation of bearing steel. Nanostructured bainitic bearing steel (NBBS), which is a newly developed bearing steel, not only possesses high strength and toughness, but also exhibits excellent wear resistance and rolling contact fatigue (RCF) resistance. In recent years, relevant achievements in NBBS in China have led to significant progress in this field. NBBS was first used in China to manufacture large bearings for wind turbines and heavy-duty bearings, with excellent performance. As a result, NBBS and its corresponding heat-treatment process have been included in the national and industry standards for the first time. The bearing industry considers the exploitation of NBBS to be epoch-making, and has termed this kind of bearing as the second generation of bainitic bearing. In this paper, the development of NBBS is reviewed in detail, including its advantages and disadvantages. Further research directions for NBBS are also proposed.

关键词： Nanostructured bainitic bearing steel Bearing steel Nanostructured bainite Development

Two new ornithurine birds from the Early Cretaceous of western Liaoning,China

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Chinese Science Bulletin 2001年第15期46卷 1258-1264页

作者： Zhonghe Zhou fucheng zhang Chinese Acad Sci Inst Vertebrate Paleontol & Paleoanthropol Beijing 100044 Peoples R China

We describe two new ornithurine birds from the Early Cretaceous Jiufotang Formation of western Liaoning, northeast China: Yanornis martini gen. et sp. nov. and Yixianornis grabaui gen. et sp. nov. They represent the best fossil record of ornithurine birds known from the Early Cretaceous. They are more advanced than the most primitive ornithurine Liaoningornis, and are more similar to the other two Chinese Early Cretaceous ornithurines Chaoyangia and Songlingornis. Compared with Confuciusornis, Liaoxiornls and Eoenantiornis from the same age, the two new birds show remarkable advanced characteristics and suggest the presence of powerful flight capability like modern birds. Compared with Yixianornis and Chaoyangia, Yanornis is larger, with a more elongated skull and relatively long wings. The new discoveries indicate that by the Early Cretaceous both enantiornithine and ornithurine birds had already radiated significantly. The flight structures of Yanornis and Yixianornis are hardly distinguishable from

关键词： Ornithurae origin radiation Jiufotang Formation Yanornis Yixianornis

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框架刚度计算方法对箱梁畸变效应分析的影响

东南大学学报（自然科学版） 2024年第2期54卷 423-431页

作者：魏彦红张元海周福成刘泽翔兰州交通大学土木工程学院兰州730070

研究了用位移法和力法计算的框架刚度对箱梁畸变效应分析结果的影响.首先分别用位移法和力法推导出了箱梁的抗畸变惯性矩解析式,然后建立了畸变控制微分方程,并给出箱梁同时承受偏心均布和集中荷载时该方程的初参数解.利用这2种解析法... 详细信息

研究了用位移法和力法计算的框架刚度对箱梁畸变效应分析结果的影响.首先分别用位移法和力法推导出了箱梁的抗畸变惯性矩解析式,然后建立了畸变控制微分方程,并给出箱梁同时承受偏心均布和集中荷载时该方程的初参数解.利用这2种解析法和有限元软件对悬臂梁模型和简支梁算例的畸变效应进行了研究.结果表明:2种解析法计算的矩形截面箱梁的畸变翘曲正应力、畸变横向正应力和畸变角一致,与实测值和有限元结果均吻合良好;2种解析法计算的梯形截面箱梁的畸变矩、畸变双力矩基本一致,与有限元结果均吻合良好,但二者计算的梯形截面箱梁的畸变角、单位宽度横向弯矩存在明显差异,其中力法计算的单位宽度横向弯矩更接近有限元结果;随着腹板倾斜度的增大,2种解析法计算的畸变框架刚度和畸变框架刚度之差均增大,而畸变翘曲刚度先减小再增大.

关键词：薄壁箱梁位移法力法框架刚度畸变效应

已知波形信号的时差频差估计方法研究与性能分析

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信号处理 2024年第2期40卷 292-300页

作者：刘严朱毅张源郭福成国防科技大学电子科学学院湖南长沙410073

借助深入分析和长期积累,非合作定位系统可以获得关于电视、广播、导航等电磁信号波形的丰富先验信息,对这些信息加以利用有望大幅提高对信号参数的估计精度。该文针对导航、通信等欺骗干扰源及非法用户的无源定位需求,在观测站与辐射... 详细信息

借助深入分析和长期积累,非合作定位系统可以获得关于电视、广播、导航等电磁信号波形的丰富先验信息,对这些信息加以利用有望大幅提高对信号参数的估计精度。该文针对导航、通信等欺骗干扰源及非法用户的无源定位需求,在观测站与辐射源之间存在相对运动的场景下,围绕已知波形信号开展时差频差估计问题研究。首先,通过引入已知的信号波形信息对观测站接收数据进行建模,直观呈现了观测数据与不同观测站信号相对于原始信号时延、频移的关系。随后,充分利用入射信号波形已知这一有利条件,通过估计两个观测站各自的时延和频移,并对不同观测站上的估计结果进行差分,提出了一种针对已知波形信号的双站时差、频差估计方法。在此基础上,该文分析了已知波形信号时频差估计精度的理论下界,揭示了时频差估计精度受观测站接收信号幅度等因素的影响情况,并进一步分析了双站时频差估计精度与单通道时延、频移估计精度之间的关系。最后,借助仿真实验验证了论文所提出的时频差估计方法在不同环境中的参数估计性能,以及信号波形先验信息的利用给时频差参数估计精度带来的提升情况。仿真结果表明,在所设定的信号环境中,该文所提出的方法对低信噪比的适应能力比基于互模糊函数的传统方法增强了15 dB左右;当该方法的参数估计性能达到收敛之后,其时差频差估计精度与CRLB非常吻合。

关键词：时差频差估计已知信号波形运动观测站互模糊函数克拉美-罗界(CRLB)