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A weak but inert hindered urethane bond for high-performance dynamic polyurethane polymers

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Chinese Chemical Letters 2024年第5期35卷 238-243页

作者： Fangzhou Wang Wentong gao Chenghui Li State Key Laboratory of Coordination Chemistry School of Chemistry and Chemical EngineeringCollaborative Innovation Center of Advanced MicrostructuresNanjing UniversityNanjing 210023China School of Materials Science and Engineering Nanjing Institute of TechnologyNanjing 211167China

Covalent adaptable networks(CANs),which share the properties of both thermosets and thermoplastics at the same time,are desirable for many *** bulky substituents is a feasible way to design dynamic covalent bonds for constructing CANs,as evidenced by the successful implementation in CANs based on hindered urea bonds(HUBs).However,the dynamicity induced by introducing bulky substituents always come with low bond energy,resulting in low mechanical strength and poor stability of the ***,we designed a novel hindered urethane bond,which is weak in thermodynamic(K_(eq)=1701.23 L/mol at 25℃)and inert in kinetic at low temperature,but stable in thermodynamic(K_(eq)=1.54×10^(4) L/mol at 100℃)and active in kinetic at high temperature(k_(-1)=0.105 h^(-1) at 80℃ and 0.315 h^(-1) at 120℃).As a result,the polyurethane based on it exhibits high mechanical properties(with Youngs’modulus of 1011±29MPa and flexible modulus reached 1833±50MPa)and excellent reversibility(can be reprocessed at 60℃ under 100 kPa in 30 min and completely healed at 40℃ in 10 min).Moreover,unlike to many CANs based on hindered urea bonds,our dynamic polyurethanes are highly stable in humid environment or even water solutions due to the slow hydrolysis *** highperformance dynamic polyurethane polymers are attractive for many applications.

关键词： Covalent adaptable networks Urethane bond Kinetics Thermodynamics

From concept to commercialization:A review of tubular solid oxide fuel cell technology

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Journal of Energy Chemistry 2024年第10期97卷 79-109页

作者： Ruyan Chen Yuan gao Jiutao gao Huiyu Zhang Martin Motola Muhammad Bilal Hanif Cheng-Xin Li State Key Laboratory for Mechanical Behavior of Materials School of Materials Science and Engineering Xi'an Jiaotong University Department of Inorganic Chemistry Faculty of Natural Sciences Comenius University Bratislava

The reduced sealing difficulty of tubular solid oxide fuel cells(SOFCs) makes the stacking of tubular cell groups relatively easy,and the thermal stress constraints during stack operation are smaller,which helps the stack to operate stably for a long *** special design of tubular SOFC structures can completely solve the problem of high-temperature sealing,especially in the design of multiple single-cell series integrated into one tube,where each cell tube is equivalent to a small electric stack,with unique characteristics of high voltage and low current output,which can significantly reduce the ohmic polarization loss of tubular *** paper provides an overview of typical tubular SOFC structural designs both domestically and *** on the geometric structure of tubular SOFCs,they can be divided into bamboo tubes,bamboo flat tubes,single-section tubes,and single-section flat tube ***,this article provides an overview of commonly used materials and preparation methods for tubular SOFCs,including commonly used materials and preparation methods for support and functional layers,as well as a comparison of commonly used preparation methods for microtubule SOFCs,It introduced the three most important parts of building a fuel cell stack:manifold,current collector,and ceramic adhesive,and also provided a detailed introduction to the power generation systems of different tubular SOFCs,Finally,the development prospects of tubular SOFCs were discussed.

关键词： Geometric structure Preparation methods Stack Support material Tubular solid oxide fuel cell

On the global smooth solutions of 3D incompressible Hall-MHD equations

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Applied Mathematics(A Journal of Chinese Universities) 2024年第2期39卷 319-327页

作者： YUE gao-cheng SUN Wen-da School of Mathematics Nanjing University of Aeronautics and AstronauticsNanjing 211106China

The present paper is devoted to the well-posedness issue for the 3D incompressible Hall-MHD system obtained from kinetic models. Our analysis strongly relies on the use of the Fourier analysis. We establish the global existence of smooth solutions for a class of large initial data, this result implies the initial velocity and magnetic field can be arbitrarily large.

关键词： 3D Hall-MHD well-posedness Fourier analysis

Bayesian partial pooling to reduce uncertainty in overcoring rock stress estimation

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Journal of Rock Mechanics and Geotechnical Engineering 2024年第4期16卷 1192-1201页

作者： Yu Feng Ke gao Suzanne Lacasse Norwegian Geotechnical Institute OsloNorway Department of Earth and Space Sciences Southern University of Science and TechnologyShenzhenChina

The state of in situ stress is a crucial parameter in subsurface engineering,especially for critical projects like nuclear waste *** one of the two ISRM suggested methods,the overcoring(OC)method is widely used to estimate the full stress tensors in rocks by independent regression analysis of the data from each OC ***,such customary independent analysis of individual OC tests,known as no pooling,is liable to yield unreliable test-specific stress estimates due to various uncertainty sources involved in the OC *** address this problem,a practical and no-cost solution is considered by incorporating into OC data analysis additional information implied within adjacent OC tests,which are usually available in OC measurement ***,this paper presents a Bayesian partial pooling(hierarchical)model for combined analysis of adjacent OC *** performed five case studies using OC test data made at a nuclear waste repository research site of *** results demonstrate that partial pooling of adjacent OC tests indeed allows borrowing of information across adjacent tests,and yields improved stress tensor estimates with reduced uncertainties simultaneously for all individual tests than they are independently analysed as no pooling,particularly for those unreliable no pooling stress estimates.A further model comparison shows that the partial pooling model also gives better predictive performance,and thus confirms that the information borrowed across adjacent OC tests is relevant and effective.

关键词： Overcoring stress measurement Uncertainty reduction Partial pooling Bayesian hierarchical model Nuclear waste repository

Estimation and verification of green tide biomass based on UAV remote sensing

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Journal of Oceanology and Limnology 2024年第4期42卷 1216-1226页

作者： Xiaopeng JIANG Zhiqiang gao Zhicheng WANG CAS Key Laboratory of Coastal Environmental Processes and Ecological Remediation Yantai Institute of Coastal Zone ResearchChinese Academy of SciencesYantai 264003China Shandong Key Laboratory of Coastal Environmental Processes Yantai Institute of Coastal Zone ResearchChinese Academy of SciencesYantai 264003China University of Chinese Academy of Sciences Beijing 100049China

Since 2007,the Yellow Sea green tide has broken out every summer,causing great harm to the environment and *** satellite remote sensing(RS)has been used in biomass research,there are several shortcomings,such as mixed pixels,atmospheric interference,and difficult field *** biomass of green tide has been lacking a high-precision estimation *** this study,high-resolution unmanned aerial vehicle(UAV)RS was used to quantitatively map the biomass of green *** utilizing experimental data from previous studies,a robust relationship was established to link biomass to the red-green-blue floating algae index(RGB-FAI).Then,the lab-based model for green tide biomass from visible images taken by the UAV camera was developed and validated by field *** sults show that the accurate and cost-effective method is able to estimate the green tide biomass and its changes in given local waters of the near and far *** study provided an effective complement to the traditional satellite RS,as well as high-precision quantitative techniques for decision-making in disaster management.

关键词： green tide biomass estimation quantitative technique Yellow Sea unmanned aerial vehicle(UAV) remote sensing(RS)

Stability behavior of the Lanxi ancient flood control levee after reinforcement with upside-down hanging wells and grouting curtain

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Journal of Mountain Science 2024年第1期21卷 84-99页

作者： QIN Zipeng TIAN Yan gao Siyuan ZHOU Jianfen HE Xiaohui HE Weizhong gao Jingquan School of Water Conservancy and Environment Engineering Zhejiang University of Water Resources and Electric PowerHangzhou 310018China Department of Civil Engineering Imperial College LondonLondonSW71BFEngland Lanxi Water Affairs Bureau Lanxi 321102China Zhejiang Water Conservancy Engineering Consulting Co. LtdHangzhou 310051China

The stability of the ancient flood control levees is mainly influenced by water level fluctuations, groundwater concentration and rainfalls. This paper takes the Lanxi ancient levee as a research object to study the evolution laws of its seepage, displacement and stability before and after reinforcement with the upside-down hanging wells and grouting curtain through numerical simulation methods combined with experiments and observations. The study results indicate that the filled soil is less affected by water level fluctuations and groundwater concentration after reinforcement. A high groundwater level is detrimental to the levee's long-term stability, and the drainage issues need to be fully considered. The deformation of the reinforced levee is effectively controlled since the fill deformation is mainly borne by the upside-down hanging wells. The safety factors of the levee before reinforcement vary significantly with the water level. The minimum value of the safety factors is 0.886 during the water level decreasing period, indicating a very high risk of the instability. While it reached 1.478 after reinforcement, the stability of the ancient levee is improved by a large margin.

关键词： Stability analysis Multiple factors Antiseepage reinforcement Upside-down hanging well Grouting curtain Ancient levee

Improved Subsynchronous Oscillation Parameter Identification with Synchrophasor Based on Matrix Pencil Method in Power Systems

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Journal of Modern Power Systems and Clean Energy 2024年第1期12卷 22-33页

作者： Xiaoxue Zhang Fang Zhang Wenzhong gao Jinghan He the School of Electrical Engineering Beijing Jiaotong UniversityBeijing 100044China the Department of Electrical and Computer Engineering University of DenverDenverUSA

The subsynchronous oscillations(SSOs)related to renewable generation seriously affect the stability and safety of the power *** realize the dynamic monitoring of SSOs by utilizing the high computational efficiency and noise-resilient features of the matrix pencil method(MPM),this paper propos es an improved MPM-based parameter identification with syn *** MPM is enhanced by the angular frequency fitting equations based on the characteristic polynomial coeffi cients of the matrix pencil to ensure the accuracy of the identi fied parameters,since the existing eigenvalue solution of the MPM ignores the angular frequency conjugation constraints of the two fundamental modes and two oscillation ***,the identification and recovery of bad data are proposed by uti lizing the difference in temporal continuity of the synchropha sors before and after noise *** proposed parameter identification is verified with synthetic,simulated,and actual measured phase measurement unit(PMU)*** with the existing MPM,the improved MPM achieves better accuracy for parameter identification of each component in SSOs,better real-time performance,and significantly reduces the effect of bad data.

关键词： Subsynchronous oscillations(SSOs) synchrophasor parameter identification matrix pencil method bad data

Cr-containing wastewater treatment based on Cr self-catalysis: a critical review

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Frontiers of Environmental Science & Engineering 2024年第1期18卷 1-22页

作者： Manshu Zhao Xinhua Wang Shuguang Wang Mingming gao School of Environmental Science and Engineering Shandong UniversityQingdao 266237China Shandong Key Laboratory of Environmental Processes and Health Shandong UniversityQingdao 266237China Shandong Key Laboratory of Water Pollution Control and Resource Reuse Shandong UniversityQingdao 266237China Weihai Research Institute of Industrial Technology of Shandong University Weihai 264209China

Chromium (Cr), as a transition metal material with multiple redox states, has exhibited the catalysis toward Fenton-like reactions over a wide pH range. Although it is not sensible to add Cr reagents as catalysts due to its toxicity, it is highly promising to remediate Cr-containing wastewater through Cr-initiated advanced oxidation processes (Cr-initiated AOPs), which are clean and low-cost. Moreover, the widely concerned Cr-complexes, considered as obstacles in the remediation process, can be effectively destroyed by AOPs. Cr self-catalysis is defined as Cr species is both substrate and catalyst. However, the full understanding of Cr self-catalysis, including the generation of intermediates Cr(IV)/Cr(V), the synergetic effects with co-existing ions, and the accumulation of toxic Cr(VI), remains a challenge for the practical application of Cr-initiated AOPs. In this review, relevant researches on Cr self-catalysis during Cr-initiated AOPs are summarized. Specifically, the Cr-Fenton-like reaction, Cr substituted materials, and Cr-sulfite reactions are explored as key mechanisms contributing to Cr self-catalysis. Moreover, Cr transformation processes, including synchronously Cr removal, Cr redox reactions, and Cr(VI) accumulation, in AOPs-based synergistic systems are systematically analyzed. Detailed approaches for the detection of active species in AOPs-based systems are also presented. The primary objective of this review is to explore the application of AOPs for Cr-containing wastewater remediation based on Cr self-catalysis, and provide fundamental insights and valuable information for future research on Cr-initiated AOPs.

关键词： Self-catalysis Cr-initiated AOPs Cr transformation Cr intermediates Cr-containing wastewater

Recovery of scandium from silicate minerals by high-pressure leaching in sulfuric acid

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Journal of Rare Earths 2024年第7期42卷 1375-1384,I0007页

作者： Peng Yan Xiaoming Chen Likun gao Bo Yang Faculty of Metallurgical and Energy Engineering Kunming University of Science and TechnologyKunming650093China Faculty of Land Resources Engineering Kunming University of Science and TechnologyKunming650093China School of Chemistry and Chemical Engineering Kunming UniversityKunming650214China

This study investigated the leaching of scandium from a Sc-bearing silicate *** Sc concentrate obtained by beneficiation pre-enrichment has 1.03×10^(−4) wt%Sc and 14.66 wt%*** main Sc-bearing minerals are limonite,chlorite,sericite,and hornblende,in the form of ***-pressure leaching(HPL)with sulfuric acid(98 wt%)and NaF was used to dispose this *** Sc leaching efficiency of 91.82%was obtained under the optimum conditions,which are pressure of 5.0×10^(5) Pa,A/O value of 1.1,L/S value of 1.8,NaF dosage of 2 wt%,at 130℃ for 6 *** X-ray diffraction(XRD)and scanning electron microscopy(SEM)results show that the residue is mainly quartz phase in the multihole *** with ordinary leaching for silicate,high-pressure leaching has significant advantages in saving acid and energy consumption.

关键词： Silicate minerals Scandium High-pressure Leaching Concentrated sulfuric acid Rare earths