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Optimum thickness of Mssbauer absorber

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Nuclear Science and Techniques 2000年第2期11卷 91-95页

作者： CHEN yi-Long yi Fan, zhang fu-Liang(Department of Physics of Wuhan University,Wuhan 430072) 武汉大学湖北武汉武汉大学湖北武汉 430072

If recoilless fraction fa is available, the optimum absorber thickness dopt can be calculated by maximizing the signal to noise ratio or Q factor. In this work,an approach presented is to get experimental Qexp as a function of the thickness,andthen fitting Qexp by its theoretical expression gives fa value. At last the dopt value is deduced from a maximum on the fitted *** such a way, thicknesses of six specimens with quadrupole or magnetic hyperfinc splitting were optimized.

关键词：穆斯堡尔光谱穆斯保尔效应信噪比最佳吸收厚度噪声光谱吸收

Cavitation vortex dynamics of unsteady sheet/cloud cavitating flows with shock wave using different vortex identification methods

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Journal of Hydrodynamics 2019年第3期31卷 475-494页

作者： Chang-chang Wang ying Liu Jie Chen fu-yi zhang Biao Huang Guo-yu Wang School of Mechanical Engineering Beijing Institute of Technology Beijing 100081 China

Cavitation is a complex multiphase flow phenomenon with an abrupt transient phase change between the liquid and the vapor, including multiscale vortical motions. The transient cavitation dynamics is closely associated with the evolution of the cavitation vortex structures. The present paper investigates the cavitation vortex dynamics using different vortex identification methods, including the vorticity method, the Q criterion method, the Omega method (Ω), the method and the Rortex method. The Q criterion is an eigenvalue-based criterion, and in the Ω method, the parameter is normalized, is independent of the threshold value and in most conditions Ω= 0.52 . The Rortex method is based on an eigenvector-based criterion. Numerical simulations are conducted using the implemented compressible cavitation solver in the open source software OpenFOAM for the sheet/cloud cavitating flows around a NACA66 (mod) hydrofoil fixed at a = 6°,= 1.25 and Re = 7.96 × 10^5 . The flow is characterized by the alternate interactions of the re-entrant flow and the collapse induced shock wave. Results include the vapor structures and the vortex dynamics in the unsteady sheet/cloud cavitating flows, with emphasis on the vortex structures in thecavitation region, the cavity interface, the cavity closure, the cavity wakes, and the foil wakes with the shedding cavity. The comparisons of the various methods, including that the vorticity method, the Q criterion method, the Ω method, the λ2 method and the Rortex method, show the performances of different methods in identifying the cavitation vortex structures. Generally, during the attached cavity growth stage, the Q criteria can well predict the vortex structures in the cavitation region and at the foil trailing edge in the pure liquid region, while with the Ω method and the Rortex method, the vortex structures outside the attached cavity and on the foil pressure side can also be predicted. The λ2 method can well predict the vortex structures in t

关键词： Cavitation vortex dynamics vortex identification sheet/cloud cavitating flow re-entrant jet shock wave OpenFOAM

A New Autoxidation-Michael Addition of a Glycoside Lactone Derivative

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有机化学 2003年第Z1期23卷 368-369页

作者： zhang fu-yi zhang Jian-Ye HUANG Li-Hua TAO Jing-Chao LIU Hong-Min Department of Chemistry Zhengzhou University Zhengzhou 450052 Department of Chemistry Zhengzhou University Zhengzhou 450052 Department of Chemistry Zhengzhou University Zhengzhou 450052 Department of Chemistry Zhengzhou University Zhengzhou 450052 Department of Chemistry Zhengzhou University Zhengzhou 450052

　　C-branched chain glycopyranosiduloses are very efficient chiral building blocks for synthesis of biologically active substances, containing carbocyclic ring systems. Synthesis of such type of structural units has ... 详细信息

关键词： active substances building blocks type of

Optimization of ultrasonic parameters for effective detachment of biofilm cells in an actual drinking water distribution system

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Journal of Zhejiang University-Science A(Applied Physics & Engineering) 2020年第3期21卷 167-178页

作者： Hong-xi PENG Yu SHAO yi-fu zhang Ruo-wei WANG David Z.ZHU Huan-yu CHEN Jing-qing LIU College of Civil Engineering and Architecture Zhejiang UniversityHangzhou 310058China College of Civil Engineering Hunan UniversityChangsha 410082China Civil and Environmental Engineering Department University of AlbertaAlberta T6G 2R3Canada Binhai Industrial Technology Research Institute of Zhejiang University Tianjin 300301China

It is important to obtain a considerable quantity of DNA from oligotrophic environments such as a drinking water distribution system(DWDS)to study microbial communities by molecular biotechnology,and DNA yield is always one of the biggest problems when performing metagenomic sequencing on drinking water *** obtain as many microbes as possible,ultrasound has been widely used in cell detachment,but studies on the optimal ultrasonic parameters for biofilm in DWDS have rarely been *** effects of three ultrasonic parameters,including power,duration,and the number of ultrasound treatments(USTs)on the selected monoculture bacteria(Pelomonas sp.)biofilm were studied *** the optimal values of each ultrasonic parameter were initially *** on these values,three levels of each ultrasonic parameter were selected,and then an orthogonal experiment was conducted to further study drinking water biofilm,and finally the optimal ultrasonic parameters for the effective separation of biofilm cells in DWDS were *** results showed that the optimal ultrasonic power,duration,and the number of USTs are 13 W,1 min,and 15,respectively.A 20-min interval is needed between two *** present optimal UST,which does not lose DNA quality,can increase the amount of extractable DNA by at least 4.78 times compared to samples without *** study provides a pretreatment methodology for extracting more and reliable DNA from biofilm in DWDS,and can better solve the problem of DNA collection in oligotrophic environments.

关键词： Biofilm Drinking water distribution system(DWDS) DNA yield DNA quality Ultrasound treatment(UST)

Preparation of silver nanoparticles through the reduction of straw-extracted lignin and its antibacterial hydrogel

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International Journal of Minerals,Metallurgy and Materials 2025年第2期32卷 504-514页

作者： Lou zhang Shuo Li fu Tang Jingkai zhang Yuetong Kang Hean zhang Lidong Li State Key Laboratory for Advanced Metals and Materials School of Materials Science and EngineeringUniversity of Science and Technology BeijingBeijing 100083China

Silver nanoparticles(Ag NPs)have attracted attention in the field of biomaterials due to their excellent antibacterial ***,the reducing and stabilizing agents used for the chemical reduction of Ag NPs are usually toxic and may cause water *** this work,Ag NPs(31.2 nm in diameter)were prepared using the extract of straw,an agricultural waste,as the reducing and stabilizing *** analysis revealed that the straw extract contained lignin,the structure of which possesses phenolic hydroxyl and methoxy groups that facilitate the reduction of silver salts into Ag *** surfaces of Ag NPs were negatively charged due to the encapsulation of a thin layer of lignin molecules that prevented their *** the prepared Ag NPs were added to the precursor solution of acrylamide,free radical polymerization was triggered without the need for extra heating or light irradiation,resulting in the rapid formation of an Ag NP-polyacrylamide composite *** inhibition zone test proved that the composite hydrogel possessed excellent antibacterial ability due to the presence of Ag *** prepared hydrogel may have potential applications in the fabrication of biomedical materials,such as antibacterial dressings.

关键词： silver nanoparticles hydrogel straw extraction antibacterial

基于均值-方差模型的P2P债权投资策略与风险度量问题研究

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管理评论 2017年第7期29卷 19-28页

作者：傅毅张寄洲周翠上海师范大学商学院上海200234 上海师范大学数理学院上海200234

2015年1月31日,全国首个P2P跨平台债权转让系统"投之家"的二级市场上线,这迅速使得P2P债权投资成为了业界与学术界的热门话题。本文考虑投资者同时持有风险资产和P2P债权,将投资者日常的现金流假设为泊松过程,应用随机控制方法建立了P2... 详细信息

2015年1月31日,全国首个P2P跨平台债权转让系统"投之家"的二级市场上线,这迅速使得P2P债权投资成为了业界与学术界的热门话题。本文考虑投资者同时持有风险资产和P2P债权,将投资者日常的现金流假设为泊松过程,应用随机控制方法建立了P2P债权投资的均值-方差模型,运用动态规划原理得到了模型对应的HJB方程,并解得HJB方程的最优投资策略和风险度量显式解。最后本文通过数值模拟分析了不同参数对模型结果的影响。

关键词：投资策略 P2P债权均值-方差模型互联网金融

Identifying the dynamic behaviors in complete reconstruction of Co-based complex precatalysts during electrocatalytic oxygen evolution

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Journal of Energy Chemistry 2025年第1期100卷 226-233页

作者： Jingfang zhang Danyang Wu Linke Cai Youluan Lu Fanpeng Cheng Lijuan Shi Qun yi Yao Liu yi Huang Key Laboratory of Green Chemical Engineering Process of Ministry of Education Engineering Research Center of Phosphorus Resources Development and Utilization of Ministry of Education Hubei Key Laboratory of Novel Reactor and Green Chemical Technology School of Chemical Engineering & Pharmacy Wuhan Institute of Technology Key Laboratory of Pesticide & Chemical Biology of Ministry of Education Engineering Research Center of Photoenergy Utilization for Pollution Control and Carbon Reduction of Ministry of Education College of Chemistry Central China Normal University College of Materials Science and Engineering Fuzhou University

Transition metal-based nanomaterials have emerged as promising electrocatalysts for oxygen evolution reaction（OER）. Considerable research efforts have shown that self-reconstruction occurs on these nanomaterials under operating conditions of OER process. However, most of them undergo incomplete reconstruction with limited thickness of reconstruction layer, leading to low component utilization and arduous exploration of real catalytic mechanism. Herein, we identify the dynamic behaviors in complete reconstruction of Co-based complexes during OER. The hollow phytic acid（PA） cross-linked CoFe-based complex nanoboxes with porous nanowalls are designed because of their good electrolyte penetration and mass transport ability, in favor of the fast and complete reconstruction. A series of experiment characterizations demonstrate that the reconstruction process includes the fast substitution of PA by OH-to form Co（Fe）(OH)xand subsequent potential-driven oxidation to Co（Fe）OOH. The obtained CoFeOOH delivers a low overpotential of 290 mV at a current density of 10 mA cm-2and a long-term *** experiment results together with theory calculations reveal that the Fe incorporation can result in the electron rearrangement of reconstructed CoFeOOH and optimization of their electronic structure,accounting for the enhanced OER activity. The work provides new insights into complete reconstruction of metal-based complexes during OER and offers guidelines for rational design of high-performance electrocatalysts.

关键词： Complete reconstruction Co-based complex Precatalysts Oxygen evolution reaction

A New Autoxidation-Michael Addition of a Glycoside Lactone Derivative

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A New Autoxidation-Michael Addition of a Glycoside Lactone D...

供水系统中冲刷对金属管道内壁生物膜脱落的影响作用（英文）

第三届全国有机化学学术会议

作者： zhang,fu-yi, zhang, Jian-Ye HUANG, Li-Hua TAO, Jing-Chao LIU, Hong-Min (Department of Chemistry, Zhengzhou University, Zhengzhou 450052)

＜正＞ C-branched chain glycopyranosiduloses are very efficient chiral building blocks for synthesis of biologically ac-tive substances,containing carbocyclic ring *** of such type of structural units has accordinglygained imporance in recent *** the stereoselective addition of a nucleophile to a glycosidulose is anefficient way for synthesis of C-branched chain sugar,previous studies on their syntheses were focused on the use offully protected sugrs,because partially protected and unprotected glycosiduloses are very difficult to synthesize se-

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Journal of Zhejiang University-Science A(Applied Physics & Engineering) 2017年第4期18卷 313-328页

作者： Jing-qing LIU Zhi-feng LUO Ke LIU yi-fu zhang Hong-xi PENG Bao-lan HU Hong-xing REN Xiao-yan ZHOU Shang-de QIU Xiao-fang HE Ping YE Hamid BASTANI Li-ping LOU College of Civil Engineering and Architecture Zhejiang University Hangzhou 310058 China College of Civil Engineering and Architecture Zhejiang University of Technology Hangzhou 310014 China College of Environmental and Resource Sciences Zhejiang University Hangzhou 310058 China Shaoxing Water Environmental Science Institute Co. Ltd. Shaoxing 312000 China Jiayuan Water Supply and Sewerage Company Jiaxing 314000 China

目的:在市政供水管网系统中,由冲刷引起的管道内壁生物膜脱落可能造成饮用水二次污染。本文旨在通过研究冲刷前后生物膜理化特性和微生物种群结构的变化,探讨不同金属管材管道和不同冲刷流速对生物膜脱落的影响,从而为管道生物安全的风... 详细信息

目的:在市政供水管网系统中,由冲刷引起的管道内壁生物膜脱落可能造成饮用水二次污染。本文旨在通过研究冲刷前后生物膜理化特性和微生物种群结构的变化,探讨不同金属管材管道和不同冲刷流速对生物膜脱落的影响,从而为管道生物安全的风险评估提供科学依据。创新点:不同菌属的细菌对水力冲刷的敏感程度不同;各菌属对水力变化的敏感程度既与菌属本身的性质有关,也与其附着生长的管材有关。方法:1.采用R2A培养基平板计数、16S rD NA检测、荧光定量聚合酶链式反应及454焦磷酸测序技术。2.通过理化指标检测与测序相结合的方式进行分析,并以丰度图和热度图的形式呈现结果。结论:1.球墨铸铁管内壁生物膜的抗水力剪切能力较强,能够抵抗低剪切冲刷,在高剪切力冲刷后才会明显脱落,而灰口铸铁管和不锈钢复合管内壁生物膜的抗水力剪切能力较弱,低剪切力冲刷工况便会导致生物膜的明显脱落。2.生物膜对冲刷的抵抗作用在其群落的属水平和纲水平上有显著变化,这与群落本身和管材特性均有关联。

关键词：供水管网系统生物膜冲刷金属管道