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Catalytic C-H activation-initiated transdiannulation:An oxygen transfer route to ring-fluorinated tricyclic γ-lactones

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Chinese Chemical Letters 2024年第9期35卷 145-149页

作者： Qiuyun Li Yannan Zhu Yining Wang Gang Qi Wen-Juan Hao Kelu Yan Bo Jiang School of Chemistry and Chemical Engineering Yancheng Institute of TechnologyYancheng 224051China School of Chemistry&Materials Science Jiangsu Normal UniversityXuzhou 221116China Key Laboratory of Life-Organic Analysis of shandong province School of Chemistry and Chemical EngineeringQufu Normal UniversityQufu 273165China

Catalytic C–H activation-initiated annulation reactions have emerged as a versatile strategy for the efficient construction of diverse ring structural units and complex cyclic molecules in synthetic ***,we describe a new Rh(Ⅲ)-catalyzed C–H activation-initiated transdiannulation reaction of N,Ndimethyl enaminones with gem-difluorocyclopropenes in the presence of H_(2)O,enabling a facile and oxygen transfer access to ring-fluorinated tricyclicγ-lactones with a 6-5 ring-junction tetrasubstituted *** approach features bond-forming/annulation efficiency,good functional group tolerance and complete regioselectivity,which may include a complex process consisting of Rh(Ⅲ)-catalyzed C(sp2)–H activation,cyclic alkene insertion,defluorinated ring-opening of gem-difluorocyclopropane,intramolecular oxygen transfer,intramolecular cyclization and oxidative hydration.

关键词： C-H bond activation Enaminones Transannulation Oxygen transfer Regioselectivity

Pushing the high-k scalability limit with a superparaelectric gate layer

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Journal of Advanced Ceramics 2024年第4期13卷 539-547页

作者： Kun Wang Chao Liu Yuan Zhang Fuyu Lv Jun Ouyang Houbing Huang Rui-Long Yang Yu-Yao Zhao Hongbo Cheng Hanfei Zhu Xiaoming Shi Yun Tian institute of Advanced Energy Materials and Chemistry Jinan Engineering Laboratory for Multi-scale Functional MaterialsSchool of Chemistry and Chemical EngineeringQilu University of Technology(Shandong Academy of Sciences)Jinan 250353China Key Laboratory for Liquid-Solid Structure Evolution and Processing of Materials(Ministry of Education) School of Materials Science and EngineeringShandong UniversityJinan 250061China China Tobacco shandong Industrial Co. Ltd.Jinan 250104China Department of Materials Science and Engineering Southern University of Science and TechnologyShenzhen 518055China Key Laboratory of Key Film Materials&Application for Equipments(Hunan province) School of Material Sciences and EngineeringXiangtan UniversityXiangtan 411105China Advanced research institute of Multidisciplinary Science and School of Materials Science and EngineeringBeijing Institute of TechnologyBeijing 100081China Key Laboratory of Magnetic Molecules and Magnetic Information Materials of Ministry of Education School of Chemistry and Materials ScienceShanxi Normal UniversityTaiyuan 030032China

To meet the expectation set by Moore’s law on transistors,the search for thickness-scalable high dielectric constant(k)gate layers has become an emergent research *** investigations have failed to solve the“polarizability–scalability–insulation robustness”*** this work,we show that this trilemma can be solved by using a gate layer of a high k ferroelectric oxide in its superparaelectric(SPE)*** the SPE,its polar order becomes local and is dispersed in an amorphous matrix with a crystalline size down to a few nanometers,leading to an excellent dimensional scalability and a good field-stability of the k *** an example,a stable high k value(37±3)is shown in ultrathin SPE films of(Ba_(0.95),Sr_(0.05))(Zr_(0.2),Ti_(0.8))O_(3)deposited on LaNiO_(3)-buffered Pt/Ti/SiO_(2)/(100)Si down to a 4 nm thickness,leading to a small equivalent oxide thickness of~0.46 *** aforementioned characteristic microstructure endows the SPE film a high breakdown strength(~10.5 MV·cm^(−1)for the 4 nm film),and hence ensures a low leakage current for the operation of the complementary metal oxide semiconductor(CMOS)***,a high electrical fatigue resistance is displayed by the SPE *** results reveal a great potential of superparaelectric materials as gate dielectrics in the next-generation microelectronics.

关键词： high-k transistors Moore's law superparaelectric insulation robustness

An efficient approach for the equivalent linearization of frame structures with plastic hinges under nonstationary seismic excitations

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Earthquake Engineering and Engineering Vibration 2024年第3期23卷 677-690页

作者： Huang Huan Li Yingxiong Li Yuyu College of Water Conservancy and Civil Engineering South China Agricultural UniversityGuangzhou 510642China institute of Smart City and Intelligent transportation Southwest Jiaotong UniversityChengdu 611756China

An efficient approach is proposed for the equivalent linearization of frame structures with plastic hinges under nonstationary seismic *** concentrated plastic hinges,described by the Bouc-Wen model,are assumed to occur at the two ends of a linear-elastic beam *** auxiliary differential equations governing the plastic rotational displacements and their corresponding hysteretic displacements are replaced with linearized differential ***,the two sets of equations of motion for the original nonlinear system can be reduced to an expanded-order equivalent linearized equation of motion for equivalent linear *** solve the equation of motion for equivalent linear systems,the nonstationary random vibration analysis is carried out based on the explicit time-domain method with high ***,the proposed treatment method for initial values of equivalent parameters is investigated in conjunction with parallel computing technology,which provides a new way of obtaining the equivalent linear systems at different time *** on the explicit time-domain method,the key responses of interest of the converged equivalent linear system can be calculated through dimension reduction analysis with high *** examples indicate that the proposed approach has high computational efficiency,and shows good applicability to weak nonlinear and medium-intensity nonlinear systems.

关键词： nonstationary random vibration plastic hinge equivalent linearization method explicit time-domain method parallel computation

Laser constructed vacancy-rich TiO_(2-x)/Ti microfiber via enhanced interfacial charge transfer for operando extraction-SERS sensing

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Chinese Chemical Letters 2024年第9期35卷 187-192页

作者： Ying Hou Zhen Liu Xiaoyan Liu Zhiwei Sun Zenan Wang Hong Liu Weijia Zhou institute for Advanced Interdisciplinary research(iAIR) School of Chemistry and Chemical EngineeringUniversity of JinanJi’nan 250022China State Key Laboratory of Crystal Materials Shandong UniversityJi’nan 250100China Shenzhen institute of Advanced Technology Chinese Academy of SciencesShenzhen 518055China

Semiconductor-molecule surface-enhanced Raman scattering(SERS),especially the stronger interfacial charge transfer process(ICTP),represents a frontier in the field of SERS with spectral reproducibility and unparalleled ***,through a laser microfabrication method in situ,the free-standing,super hydrophilic and vacancy-rich TiO_(2-x)/Ti is successfully *** blue TiO_(x)/Ti(B-TiO_(x)/Ti)as preconcentrated substrate,a nanomolar-level limit of detection of 12 nmol/L at 1385 cm–1,is confirmed using crystal violet(CV)bacteriostat as a model under 532 nm ***,the results demonstrate that the SERS enhancement mechanism is via the moderate adulteration of oxygen vacancy,which leads to a narrow value of band gap and increases the ICTP of substrate to *** a hand-held extractor assembled with B-TiO_(x)/Ti microfiber,the operando analysis of mixtures distributed information excited in different parts of Asian carp is facilely *** work guides the controlled synthesis of vacancy-rich TiO_(2-x)/Ti nanostructure and its application in ultrasensitive extraction-SERS *** also provides the direction for the rapid and operando transmission of biological information with temporal and spatial concentration distribution in human tissues by highly sensitized materials.

关键词： Defect engineering TiO_(2-x)/Ti microfiber Laser microfabrication Surface-enhanced Raman scattering Solid phase microextraction Operando sensing

Responses of nitrogen cycling and related microorganisms to brackish wetlands formed by evapotranspiration

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Pedosphere 2024年第1期34卷 252-266页

作者： Jiaohui FANG Tianshu LU Jian LIU Shangbin HE Xiufeng YANG Huashan DOU Honghai ZHANG School of Life Sciences Qufu Normal UniversityQufu 273100China Environment research institute Shandong UniversityQingdao 266237China Hulunbuir Academy of Inland Lakes in Northern Cold&Arid Areas Hulunbuir 021000China

Elevated evapotranspiration due to warmer air temperature could raise salinity and nutrient levels of some inland wetlands, potentially impacting nitrogen cycling. To characterize the impact of high evapotranspiration on soil microbial nitrogen cycling in inland wetlands, we compared freshwater and brackish marsh(or non-marsh) wetlands in terms of sediment ammonia-oxidizing rate(AOR), denitrifying rate(DR), and related microbial communities in a typical inland basin, the Hulun Lake basin, in China. Results showed that marsh ecosystems(ME) exhibited 31% higher AOR and 65% higher DR than non-marsh ecosystems(NE). For NE, freshwater non-marsh wetland exhibited 12% higher AOR than brackish non-marsh wetland. This was probably due to the inhibitory effects of high NH_4~+ and salinity levels on ammonia-oxidizing archaea in brackish non-marsh wetland. Conversely, DR in brackish non-marsh wetland was 23% higher than that in freshwater non-marsh wetland, with total organic carbon(TOC) significantly influencing this difference,suggesting that the higher DR in brackish non-marsh wetland was mainly due to its higher TOC level. For ME, due to the direct and indirect interference of salinity, brackish marsh wetland displayed 26% lower AOR and 19% lower DR than freshwater marsh wetland. Besides, brackish wetlands harbored distinct ammonia-oxidizing and denitrifying microbial communities compared to freshwater wetlands. The assembly of these communities was dominated by stochastic processes, while brackish wetlands exhibited more prominent deterministic processes than freshwater wetlands. Overall, high evapotranspiration altered activities and community characteristics of ammonia oxidizers and denitrifiers in inland brackish wetlands by enhancing salinity and nutrient levels,while emergent plants occurring in ME could mitigate the adverse effects of salt stress of inland brackish wetlands on nitrogen cycling.

关键词： ammonia-oxidizing archaea ammonia-oxidizing bacteria aquatic plants denitrifying bacteria nitrogen transformation inland wetlands

Microstructure,Corrosion and Mechanical Properties of Medium-Thick 6061-T6 Alloy/T2 Pure Cu Dissimilar Joints Produced by Double Side Friction Stir Z Shape Lap-Butt Welding

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Chinese Journal of Mechanical Engineering 2024年第2期37卷 385-400页

作者： Jiuxing Tang Guoxin Dai Lei Shi Chuansong Wu Sergey Mironov Surendra Kumar Patel Song Gao Mingxiao Wu MOE Key Lab for Liquid-Solid Structure Evolution and Materials Processing Shandong UniversityJinan 250061China Laboratory of Mechanical Properties of Nanoscale Materials and Superalloys Belgorod State UniversityBelgorod 308015Russia School of Mechanical Engineering Qilu University of Technology(Shandong Academy of Sciences)Jinan 250353China State Grid Henan Electric Power research institute Zhengzhou 450052China

A novel double side friction stir Z shape lap-butt welding(DS-FSZW)process was proposed to achieve excellent mechanical properties of Al/Cu medium-thick dissimilar *** influence of welding parameters on weld microstructure and properties of DS-FSZW joint were systematically *** indicated that defect-free medium-thick Al/Cu DS-FSZW joint could be achieved under an optimal welding ***-FSZW joint was prone to form void defects in the bottom of the second-pass *** recrystallization mechanisms at the top and middle of the weld nugget zone(WNZ)were continuous dynamic recrystallization(CDRX)and geometric dynamic recrystallization(GDRX).While the major recrystallization mechanism at the bottom of the WNZ was ***-FSZW joint of the optimal welding condition with 850 r/min-400 mm/min was produced with a continuous thin and crack-free IMCs layer at the Al/Cu interface,and the maximum tensile strength of this joint is 160.57 MPa,which is equivalent to 65.54%of pure Cu base ***,the corrosion resistance of Al/Cu DS-FSZW joints also achieved its maximum value at the optimal welding parameter of 850 r/min-400 mm/*** demonstrates that the DS-FSZW process can simultaneously produce medium-thick Al/Cu joints with excellent mechanical performance and corrosion resistance.

关键词： DS-FSZW Al/Cu dissimilar joint Corrosion behaviour Intermetallic compounds Microstructure Mechanical properties

Numerical Study of Flow Features Around Submerged Circular and Square Piles at Flat and Scoured Beds Using OpenFOAM

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Journal of Ocean University of China 2024年第4期23卷 897-914页

作者： WANG Chaolin WU Guoxiang WANG Dianhe DU Shengtao ZHANG Zhiyong JIN Heng ZHU David Z. LIANG Bingchen Donghai Academy School of Civil&Environmental Engineering and Geography ScienceNingbo UniversityNingbo 315211China Key Laboratory of Estuary and Coast of Zhejiang province and Zhejiang Institute of Hydraulics and EstuaryHangzhou 310020China shandong Provincial Key Laboratory of Ocean Engineering and College of EngineeringOcean University of ChinaQingdao 266100China shandong Water Conservancy Vocational College Rizhao 276826China School of Mechanical and Energy Engineering Ningbotech UniversityNingbo 315211China

Elucidating the flow features around piles in local scouring processes is crucial for studies of local scouring mechanisms and scour depth *** study details the flow turbulence characteristics of two submerged piles that are determined by solving the Navier-Stokes equations with the improved delayed detached eddy simulation *** model is verified by comparing experimental and numerical results for hydrodynamic parameters with the literature for both square-crossing piles(SCPs)and circular-crossing piles(CCPs).Original topographies of flat and scoured beds(i.e.,the initial and equilibrium scouring stages)are based on experimental results obtained by the authors in the present *** and CCP flow features in the scouring process are *** results indicate that during the scouring process,the time-averaged drag coefficient and root mean square(rms)of the lift coefficient increase linearly in the CCP test,while the rms of the lift coefficient in the SCP test decreases ***,the minimum pressure coefficient is always located in the upstream corners in the SCP case but moves from 72.5°to 79.5°when the scour hole is completely developed in the CCP *** flow behind the pile,which is generated by separated boundary layers above the top face of the pile,can reach the sand bed and turn the separated shear layers into patches of small vortices in the near-wake ***,the high shear stress zones are mainly at the scour edges under scoured-bed conditions.

关键词： flat bed scoured bed local scour OpenFOAM bed shear stress

Characterization of alpine meadow surface crack and its correlation with root-soil properties

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Journal of Arid Land 2024年第6期16卷 834-851页

作者： WU Yuechen ZHU Haili ZHANG Yu ZHANG Hailong LIU Guosong LIU Yabin LI Guorong HU Xiasong School of Geological Engineering Qinghai UniversityXining 810016China Key Laboratory of the Cenozoic Resources and Environment on the North Rim of the Qinghai-Tibet Plateau Xining 810016China Qinghai Provincial transportation Planning and Design research institute Co.Ltd. Xining 810002China

Quantifying surface cracks in alpine meadows is a prerequisite and a key aspect in the study of grassland crack *** characterization indices are crucial for the quantitative characterization of complex cracks,serving as vital factors in assessing the degree of cracking and the development *** far,research on evaluating the degree of grassland degradation through crack characterization indices is rare,especially the quantitative analysis of the development of surface cracks in alpine meadows is relatively ***,based on the phenomenon of surface cracking during the degradation of alpine meadows in some regions of the Qinghai-Tibet Plateau,we selected the alpine meadow in the Huangcheng Mongolian Township,Menyuan Hui Autonomous County,Qinghai province,China as the study area,used unmanned aerial vehicle(UAV)sensing technology to acquire low-altitude images of alpine meadow surface cracks at different degrees of degradation(light,medium,and heavy degradation),and analyzed the representative metrics characterizing the degree of crack development by interpreting the crack length,length density,branch angle,and burrow(rat hole)distribution density and combining them with in situ crack width and depth ***,the correlations between the crack characterization indices and the soil and root parameters of sample plots at different degrees of degradation in the study area were analyzed using the grey relation *** results revealed that with the increase of degradation,the physical and chemical properties of soil and the mechanical properties of root-soil composite changed significantly,the vegetation coverage reduced,and the root system aggregated in the surface layer of alpine *** the degree of degradation increased,the fracture morphology developed from"linear"to"dendritic",and eventually to a complex and irregular"polygonal"*** crack length,width,depth,and length density were identified as the crack char

关键词： alpine meadow grassland degradation grassland cracks crack characterization index crack morphology root length density grey relation analysis

Quantitative geochemical reconstruction of Eocene paleoenvironment in Fushun Basin,northeast China

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Acta Geochimica 2024年第3期43卷 571-587页

作者： Yuanji Li Pingchang Sun Qiang Zhang Junxian Wang Department of Safety Engineering Heilongjiang University of Science and TechnologyHarbin 150022China National Professional Center Lab of Safety Basic research for Hydrocarbon Gas Pipeline transportation Network Harbin 150022China College of Earth Sciences Jilin UniversityChangchun 130061JilinChina Beijing research institute of Uranium Geology Beijing 100029China

The quantitative estimation of key parameters of paleotemperature and paleoprecipitation is crucial for paleoclimate *** data from mod-ern sediments are highly consistent with climate data,and their relationship can provide an important reference for the quantitative reconstruction of the *** this study,detailed inorganic geochemical analysis was carried out using high-precision sampling of the Paleogene(LFD-1 well)Guchengzi,Jijuntun and Xiloutian Formations in the Fushun Basin located in the mid-latitudes of the Northern *** Eocene Guchengzi Formation(54.51–47.8 Ma)and Jijuntun Formation(47.8–41.2 Ma)in the Fushun Basin were found to have been deposited under a humid *** lower(41.2–40.1 Ma)and upper(40.1–37.8 Ma)parts of the Xiloutian Formation were character-ized by semiarid and semihumid–semiarid climates,respec-tively,which is very similar to the paleoclimatic information reflected by organic carbon *** Eocene Thermal Maximum 2(ETM2,~53.7 Ma),Early Eocene Climatic Optimum(EECO,~53.1–46.5 Ma),Eocene Thermal Maxi-mum 3(ETM 3,~52.8 Ma),and Middle Eocene Climatic Optimum(MECO,~40.7–40.1 Ma)events significantly enhanced chemical weathering during these *** rapid increase in pCO_(2)concentration leads to an increase in temperature,precipitation,and surface runoff,exhibiting strong chemical *** mean annual temperature(MATa)and mean annual precipitation(MAPa,MAPb,and MAPc)were estimated using parameters,such as the corrosion index without potassium(CIA-K),CaO/Al_(2)O_(3),and(Na_(2)O+K_(2)O)/Al_(2)O_(3).Comparing MAPa,MAPb,and MAPc with the MAP estimated using pollen data,MAPa and MAPb were found to be more sensitive to the climate during high precipitation periods(precipitation>1000 mm,Guchengzi Formation),and the recovered average precipi-tation was similar to *** contrast,MAPc was more sensitive to the climate during low precipitation periods(precipitation<1000 mm,Jijuntun,and Xilouti

关键词： Eocene Fushun Basin Major element Paleoclimate Geochemical reconstruction