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Access to High-Molecular-Weight Polyethylenes through High Temperature Ethylene Polymerization catalysed by Ethylene-Bridged ansa-(3-R-cyclopentadienyl)(Fluorenyl) Zirconocene complexes

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chinese Journal of Polymer Science 2024年第1期42卷 42-51,I0007页

作者： Bo Li Haiyan ma Jiling Huang Shanghai Key Laboratory of Functional materials chemistry and Laboratory of Organometallic chemistry School of Chemistry and Molecular EngineeringEast China University of Science and TechnologyShanghai 200237China

A series of c1-symmetric ethylene-bridged ansa-(3-R-cyclopentadienyl)(fluorenyl) metallocene complexes(Zr: 1-5;Hf: 6) have been synthesized, characterized and investigated as catalyst precursors for the high temperature ethylene polymerization. Using methylaluminoxane(maO) as the cocatalyst, zirconium complexes 1-5 bearing a bulky substituent on the 3-position of the cyclopendienyl ring showed high catalytic activities up to 1.48×10^(7) g PE·mol_(Zr)^(-1)·h^(-1) toward the polymerization of ethylene and afforded polyethylenes with high molecular weights(1.49×10^(5)-6.31×10^(5) g/mol), meanwhile exhibting great thermal stability at high temperatures up to 120 ℃ together with a long catalytic life time up to 2 h. By adopting low Al/Zr ratios, such as 125, polyethylenes with ultra high molecular weights up to 2.86×106 g/mol were obtained. It is worthy of noting that zirconium complexes 1-4 bearing a substituent with an aryl pendant showed temperature-dependent activities, which increased rapidly with the increase of polymerization temperature, thus weak interaction of the pendent aryl group with the cationic active center is proposed to account for the very low activities displayed at low temperatures. In contrast to zirconocene complexes 1-5, hafnocene complex 6 only displayed very low catalytic activities toward the polymerization of ethylene and afforded polyethylenes with molecular weights ten times smaller than those obtained by zirconocene complexes 1-5. Zirconocene complexes 1-5 were also able to catalyse the polymerization of propylene at high temperatures, but only afforded waxes with low molecular weights.

关键词： ansa-Metallocene Ethylene Propylene Polymerization High temperature

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Partial regularity and nonlinear potential estimates for Stokes systems with super-quadratic growth

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Science china mathematics 2024年第7期67卷 1525-1554页

作者： Lingwei ma Zhenqiu Zhang School of mathematical Sciences Tianjin Normal UniversityTianjin300387China School of mathematical Sciences and LPMc Nankai UniversityTianjin300071China

This paper builds a bridge between partial regularity theory and nonlinear potential theory for the following generalized stationary Stokes system with super-quadratic growth and continuous coefficients:-div A(x,Du)+■π=f,div u=0,where Du is the symmetric part of the gradient■*** first establish anε-regularity criterion involving both the excess functional of the symmetric gradient Du and Wolff potentials of the nonhomogeneous term f to guarantee the local vanishing mean oscillation(VMO)-regularity of Du in an open subset Ω_(u) of Ω with full *** anε-regularity criterion leads to a pointwise Wolff potential estimate of Du,which immediately infers that Du is partially c^(0)-regular under appropriate ***,we give a local continuous modulus estimate of Du.

关键词： nonlinear Stokes system partial regularity Wolff potential estimates continuous modulus estimates

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Supported Recyclable Metal-free Frustrated Lewis Pair catalyst for catalytic Hydrogenation of Substituted Pyridines to Piperidines

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chemical Research in chinese Universities 2024年第4期40卷 682-689页

作者： ma Shaohua TANG Zhiyong cAS Key Laboratory for Nanosystem and Hierarchical Fabrication CAS Center for Excellence in NanoscienceNational Center for Nanoscience and TechnologyBeijing100190P.R.China University of chinese Academy of Sciences Beijing100049P.R.China

The construction of heterogeneous frustrated Lewis pairs(FLPs)catalysts is crucial for realizing highly efficient and recyclable pyridines catalytic *** this work,we prepared a recyclable heterogenous FLPs catalyst cMP-BF with conjugated microporous polymer cMP-ethynyl as the support via self-catalyzed 1,1-carboboration reaction with commercial Lewis acid B(c_(6)F_(5))_(3).The as-synthesized cMP-BF demonstrates superior heterogenous catalytic hydrogenation performance(conversion>99%),and considerable stability(84%conversion after three cycles)in recyclable hydrogenation of 2,*** work provides insights into the fabrication and catalytic application of recyclable heterogenous FLP catalysts.

关键词： Pyridine hydrogenation Frustrated Lewis pair conjugated microporous polymer

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comparative Study on Microstructure and Mechanical Properties of coarse-grained Wc-based cemented carbides Sintered with Ultrafine Wc or (W+c) as Additives

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Journal of Wuhan University of Technology(materials Science) 2024年第2期39卷 399-409页

作者：于淞百闵凡路 LI De NOUDEM Guillaume Jacques ZHANG Hailong ma Jichang ZHAO Kui YAO Zhanhu 张建峰 college of Mechanics and materials Hohai UniversityNanjing 210098China Key Laboratory of Geomechanics and Embankment Engineering Hohai UniversityMinistry of EducationNanjing 210098China cRISmaT-ENSIcAEN(UMR-cNRS 6508) Universitéde Caen-Basse-NormandieF-14050 CaenFrance Shaanxi Aeronautic carbide Tool co.Ltd. Hanzhong 724200China cccc Tunnel Engineering co.Ltd. Beijing 100102China

The effects of ultrafine Wc(Wc_(UF),0.5μm) or W(1μm) and c(0.3μm)(W+c)_(UF) additives on the densification,microstructure and mechanical properties of coarse-grained cemented carbides were compared ***,the cemented carbides with Wc_(UF)/(W+c)_(UF) additives are almost fully densification to be higher than 99%,and the average grain size is kept above 2.8μ*** Wc_(UF) additive assists grains to(truncated)trigonal prism shape by two dimensional(2D) growth,whereas the(W+c)_(UF) additive assists grains to rounded shape by three dimensional(3D) growth,lowers Wc contiguity and increases face-centered-cubic *** hardness and bending strength of(75Wc_(c)-15Wc_(UF))-10co are 86.6 HRA and 2 272 MPa,respectively,both higher than those of(75Wc_(c)-15(W+c)_(UF))-10co,which could be ascribed to the enhanced densification and unblemished ***,the fracture toughness of the(75Wc_(c)-15(W+c)_(UF))-10co is 23.5 MPa·m^(1/2),higher than that of the(75Wc_(c)-15Wc_(UF))-10co due to the uniform Wc-co structure and flexible binder phase.

关键词： coarse-grained Wc-based cemented carbide ultrafine Wc ultrafine(W+c) microstructure mechanical properties

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The diagnostic value of tenascin-c in acute aortic syndrome

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Journal of Geriatric cardiology 2024年第3期21卷 359-368页

作者： Ming ma Wei cHEN Hai-Long cAO Jun PAN Qing ZHOU Xin-Long TANG Dong-Jin WANG Department of Thoracic and cardiovascular Surgery Nanjing Drum Tower Hospital Clinical College of Nanjing Medical UniversityNanjingChina Department of Thoracic and cardiovascular Surgery Nanjing Drum Tower HospitalAffiliated Hospital of Medical SchoolNanjing UniversityNanjingChina Department of Thoracic surgery Kunshan Hospital of Traditional Chinese MedicineJiangsuChina

OBJEcTIVES Misdiagnosis of acute aortic syndrome(AAS)significantly increases ***-c(TN-c)is an extracellular matrix glycoprotein related to cardiovascular *** elevation of TN-c in AAS and whether it can discriminate suddenonset of acute chest pain in chinese remains *** We measured the plasma concentration of TN-c by ELISA in a cohort of 376 patients with chest or back *** to discriminate AAS from acute coronary syndrome(AcS)were compared and *** From October 2016 to September 2021,376 undiagnosed patients with chest or back pain were enrolled.166 of them were finally diagnosed as AAS,100 were AcS and 110 without cardiovascular diseases(NcV).TN-c was significantly elevated in AAS at 18.18 ng/mL(IQR:13.10–27.68)compared with 7.51 ng/mL(IQR:5.67–11.38)in AcS(PcV(Pcant difference in TN-c level among the subtypes of *** the 166 AAS patients,the peaked level of TN-c was at acute stage(P=0.012),then a slight of decrease was observed at subacute *** area under receiver operating characteristic curve for AAS patients versus NcV was 0.979(95%cI:0.964-0.994)for *** a cutoff level of 11.474 ng/mL,TN-c has a sensitivity of 76.0%,specificity of 85.5%,accuracy of 82.0%,positive predictive value(PPV)of 76.0%,negative predictive value(NPV)of 85.5%.Diagnostic performance of TN-c was superior to D-dimer and *** The concentration of serum TN-c in AAS patients was significantly higher than that in AcS patients and ***-c could be a new biomarker to distinguish AAS patients in the early stage after symptoms onset from other pain diseases.

关键词： acute cardiovascular elevated

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combined Effect of Outdoor Time and Other Modifiable Factors on Myopia Incidence Among children and Adolescents—9 PLADs,china,2020

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china cDc weekly 2024年第9期6卷 151-156,I0001,I0002页

作者： Panliang Zhong Yunfei Liu Ning ma Jiajia Dang Di Shi Shan cai Ziyue chen Yanhui Dong Peijin Hu Jun ma Patrick W.c Lau Randall S.Stafford Yi Song Institute of child and Adolescent Health School of Public HealthPeking UniversityNational Health Commission Key Laboratory of Reproductive HealthBeijingChina Department of Sport Physical Education&HealthHong Kong Baptist UniversityKowloon TongHong Kong Special Administrative RegionChina Department of Medicine Stanford Prevention Research CenterStanford University School of MedicineStanfordCAUnited States

Summary What is already known about this topic?Myopia has been identified as a significant emerging challenge and policy priority among children and adolescents in china by the Ministry of Education and seven other *** research has been conducted to investigate the collective impact of outdoor time and other modifiable factors on the incidence of myopia.

关键词： Incidence collective policy

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Effects of gravel on the water absorption characteristics and hydraulic parameters of stony soil

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Journal of Arid Land 2024年第7期16卷 895-909页

作者： ma Yan WANG Youqi ma chengfeng YUAN cheng BAI Yiru Breeding Base for State Key Laboratory of Land Degradation and Ecological Restoration in Northwest china Ningxia UniversityYinchuan 750021China School of Geography and Planning Ningxia UniversityYinchuan 750021China School of Ecology and Environment Ningxia UniversityYinchuan 750021China

The eastern foothills of the Helan Mountains in china are a typical mountainous region of soil and gravel,where gravel could affect the water movement process in the *** study focused on the effects of different gravel contents on the water absorption characteristics and hydraulic parameters of stony *** stony soil samples were collected from the eastern foothills of the Helan Mountains in April 2023 and used as the experimental materials to conduct a one-dimensional horizontal soil column absorption *** experimental groups with gravel contents of 0%,10%,20%,30%,40%,and 50%were established to determine the saturated hydraulic conductivity(K_(s)),saturated water content(θ_(s)),initial water content(θ_(i)),and retention water content(θ_(r)),and explore the changes in the wetting front depth and cumulative absorption volume during the absorption *** Philip model was used to fit the soil absorption process and determine the soil water absorption *** the length of the characteristic wetting front depth,shape coefficient,empirical parameter,inverse intake suction and soil water suction were derived from the van Genuchten ***,the hydraulic parameters mentioned above were used to fit the soil water characteristic curves,unsaturated hydraulic conductivity(K_(θ))and specific water capacity(c(h)).The results showed that the wetting front depth and cumulative absorption volume of each treatment gradually decreased with increasing gravel *** with control check treatment with gravel content of 0%,soil water absorption rates in the treatments with gravel contents of 10%,20%,30%,40%,and 50%decreased by 11.47%,17.97%,25.24%,29.83%,and 42.45%,*** the gravel content increased,inverse intake suction gradually increased,and shape coefficient,K_(s),θ_(s),andθ_(r)gradually *** the same soil water content,soil water suction and K_(θ)gradually decreased with increasing gravel *** the same soil water s

关键词： stony soil gravel content water absorption characteristics hydraulic parameters one-dimensional horizontal soil column absorption experiment van Genuchten model eastern foothills of Helan Mountains

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Electrochemical and colorimetric dual-signal detection of Staphylococcus aureus enterotoxin B based on AuPt bimetallic nanoparticles loaded Fe-N-c single atom nanocomposite

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Food Science and Human Wellness 2024年第4期13卷 2025-2035页

作者： Huan Liang Hongcheng Liu Haojian Lin Guobao Ning Xiaokang Lu Siying ma Fei Liu Hui Zhao canpeng Li School of chemical Science and Technology Yunnan UniversityKey Laboratory of Medicinal Chemistry for Natural ResourceMinistry of EducationKunming 650091China Institute of Quality Standard and Testing Technology Yunnan Academy of Agricultural ScienceSupervision and Testing Center for Farm Product QualityMinistry of AgricultureKunming 650223China State Key Laboratory of Optoelectronic materials and Technologies Guangdong Province Key Laboratory of Display Material and TechnologySchool of Electronics and Information TechnologySun Yat-sen UniversityGuangzhou 510275China Laboratory for conservation and Utilization of Bio-resource Yunnan UniversityKunming 650091China

Sensitive detection of Staphylococcus aureus enterotoxin B(SEB)is of importance for preventing food poisoning from threatening human *** this work,an electrochemical and colorimetric dual-signal detection assay of SEB was *** probe(Ab2/AuPt@Fe-N-c)was bound to SEB captured by Ab1,where the Ab2/AuPt@Fe-N-c triggered methylene blue degradation and resulted in the decrease of electrochemical ***,the probe catalyzed the oxidation of 3,3’,5,5’-tetramethyl biphenyl to generate a colorimetric absorbance at 652 *** the target was captured and formed a sandwich-like complex,the color changed from colorless to *** detection by colorimetric and electrochemical methods showed a linear relationship in the concentration ranges of 0.0002-10.0000 and 0.0005-10.0000 ng/mL,with limits of detection of 0.0667 and 0.1670 pg/mL,*** dual-signal biosensor was successfully used to detect SEB in milk and water samples,which has great potential in toxin detection in food and the environment.

关键词： Staphylococcus aureus enterotoxin Electrochemical immunosensor colorimetric assay MOF@borophene composite Dual-functional Fe-N-c signal atom catalyst

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Integration of earth-abundant cocatalysts for high-performance photoelectrochemical energy conversion

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Journal of Energy chemistry 2024年第1期88卷 336-355,I0008页

作者： Joonhee ma Sang Hyun Ahn Soo Young Kim Department of materials Science and Engineering Korea UniversitySeoul 02841Republic of Korea School of chemical Engineering and materials Science Chung-Ang University84 Heukseok-roDongjak-guSeoul 06974Republic of Korea

Photoelectrochemical(PEc)energy conversion has emerged as a promising and efficient approach to sustainable energy harvesting and *** utilizing semiconductor photoelectrodes,PEc devices can harness solar energy and drive electrochemical reactions such as water splitting or carbon dioxide(cO_(2))reduction to generate clean fuels and value-added ***,PEc energy conversion faces several challenges such as high overpotential,sluggish reaction kinetics,charge carrier recombination,and stability issues,which limit its practical ***,significant research has been conducted to improve the overall conversion efficiency of PEc *** particularly promising approach is the use of cocatalysts,which involves introducing specific cocatalysts onto the photoelectrode surface to promote charge separation,improve reaction kinetics,and reduce the overpotential,thereby enhancing the overall performance of PEc energy *** review provides a comprehensive overview of the recent developments in the earth-abundant cocatalysts for PEc water splitting and cO_(2) *** main earth-abundant catalysts for the PEc water splitting include transition-metal dichalcogenide(TMD)-based materials,metal phosphides/carbides,and metal oxides/***,PEc-cO_(2)RR was divided into c_(1) and c_(2+)based on the final product since various products could be produced,focusing on diverse earth-abundant materials-based *** addition,we provide and highlight key advancements achieved in the very recent reports on novel PEc system design engineering with ***,the current problems associated with PEc systems are discussed along with a suggested direction to overcome these obstacles.

关键词： Solar energy Photo-electrochemical Water splitting cO_(2)reduction cocatalysts

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Enhanced properties of stone coal-based composite phase change materials for thermal energy storage

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International Journal of Minerals,Metallurgy and materials 2024年第1期31卷 206-215页

作者： Baoshan Xie Huan ma chuanchang Li Jian chen Key Laboratory of Renewable Energy Electric-Technology of Hunan Province School of Energy and Power EngineeringChangsha University of Science and TechnologyChangsha 410114China State Key Laboratory of Disaster Prevention and Reduction for Power Grid Changsha University of Science and TechnologyChangsha 410114China

Phase change materials (PcMs) can be incorporated with low-cost minerals to synthesize composites for thermal energy storage in building *** coal (Sc) after vanadium extraction treatment shows potential for secondary utilization in composite *** prepared Sc-based composite PcMs with Sc as a matrix,stearic acid (SA) as a PcM,and expanded graphite (EG) as an *** combined roasting and acid leaching treatment of raw Sc was conducted to understand the effect of vanadium extraction on promoting loading *** showed that the combined treatment of roasting at 900℃ and leaching increased the Sc loading of the composite by 6.2%by improving the specific surface *** loading capacity and thermal conductivity of the composite obviously increased by 127%and 48.19%,respectively,due to the contribution of 3wt% *** data were supported by the high load of 66.69%and thermal conductivity of 0.59 W·m^(-1)·K-1of the designed *** obtained composite exhibited a phase change temperature of 52.17℃,melting latent heat of 121.5 J·g^(-1),and good chemical *** Sc-based composite has prospects in building applications exploiting the secondary utilization of minerals.

关键词： thermal energy storage phase change material stone coal vanadium extraction secondary utilization

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