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Synergistic Effect in Mixed Capillary Gas Chromatographic Stationap Phases Containing Heptakis(2,3,6-tri-o-pentyl)-β-cyclodextrin and Dibenzo-18-crown-6

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Chinese Chemical Letters 1999年第3期10卷 223-226页

作者： Li Ming YUAN Ruo Nong FU xue xian chen Shi Hong GUl Rong Ji DAI (Chemistry Department of Yunnan Normal University.Kunming 650092)(Department of Chemical Engineering.Beijing institute of Technology,BEijing 100081)(Solar Energy Research Institute ofyunna Chemistry Department Yunnan Normal University Kunming 650092 China Department of Chemical Engineering Beijing Institute of Technology Beijing 100081 China Solar Energy Research Institute Yunnan Normal University Kunming 650092 China

used－silical capillary columns containing heptakis（2、3、6－tri－o－pentyl）-β-cyclodextrinand dibenzo-18-crown-6 were *** studying the selectivity of mixed stationary phases forsome solute *** well as comparing with the heptakis（2．3、6-tri-O-pentyl）-β-cyclodextrin and thedibenzo-18-crown-6 used as individual stationary phase、the synergistic effects were *** effects were affected by the column *** ratio and linear velocity of carrier gas．

关键词： Gas chromatography mixed stationary phase synergistic effect heptakis(2.3.6-tri-o-pentyl)-β-cyclodextrin dibenzo-18-crown-6

Volcanically Driven Terrestrial Environmental Perturbations during the Carnian Pluvial Episode in the Eastern Tethys

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Acta Geologica Sinica(English Edition) 2024年第3期98卷 753-770页

作者： Naveed Ur RAHMAN xian Benzhong FANG Linhao chen Sirui chen Peng Zaheen ULLAH WANG Pengyu National Key Laboratory of Petroleum Resources and Engineering Beijing 102249China College of Geosciences China University of PetroleumBeijing 102249China Centre for Earth and Space Sciences University of SwatSwat 19120Pakistan

The Carnian Pluvial Episode(CPE)fingerprints global environmental perturbations and biological extinction on land and oceans and is potentially linked to the Wrangellia Large Igneous Province(LIP).However,the correlation between terrestrial environmental changes and Wrangellia volcanism in the Ordos Basin during the CPE remains poorly *** of negative carbon isotopic excursions(NCIEs),mercury(Hg),Hg/TOC,and Hg enrichment factor(HgEF)from oil shales in a large-scale terrestrial Ordos Basin in the Eastern Tethys were correlated with marine and other terrestrial *** three significant NCIEs in the study section were consistently correlated with those in the CPE successions of Europe,the UK,and South and North *** U-Pb geochronology indicates a Ladinian-Carnian age for the Chang 7 Member.A comprehensive overview of the geochronology,NCIE correlation,and previous bio-and chronostratigraphic frameworks shows that the Ladinian-Carnian boundary is located in the lower part of Chang 7 in the Yishicun *** may be a more reliable proxy for tracing volcanic eruptions than the Hg/TOC ratio because the accumulation rates of TOC content largely vary in terrestrial and marine *** records of Hg,Hg/TOC,HgEF,and NCIEs in the Ordos Basin aligned with Carnian successions worldwide and were marked by similar anomalies,indicating a global response to the Wrangellia LIP during the ***,a warm-humid climate,enhancement of detrital input,and NCIEs are synchronous with the CPE interval in the Ordos Basin,which suggests that the CPE combined with the regional Qinling Orogeny should dominate the enhanced rate of terrigenous input and paleoenvironmental evolution in the Ordos Basin.

关键词： Chang 7 Member oil shale Carnian Pluvial Episode volcanism environmental perturbations

Dynamic changes in physicochemical property,biogenic amines content and microbial diversity during the fermentation of Sanchuan ham

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Food Science and Human Wellness 2024年第1期13卷 506-516页

作者： Zhongai chen Hong chen Huan Du Cong chen Kaixiang Lu Qiaoli xue Yongjin Hu College of Food Science and Technology Yunnan Agricultural UniversityKunming 650000China Institute of Food Processing Guizhou Academy of Agricultural SciencesGuiyang 550006China Editorial Department of Journal of Yunnan Agricultural University Yunnan Agricultural UniversityKunming 650000China

Sanchuan ham is appreciated in Yunnan Province,China,for its characteristic flavor and taste,while the microbial community structure and biogenic amines content remain unclear during fermentation *** this study,we explored the physicochemical property,biogenic amines concentration and microbial diversity of external and internal Sanchuan ham by high-throughput sequencing during the processing of Sanchuan *** showed that the nitrite remained at a stable level of 0.15 mg/kg which was significantly lower than the national health standard safety level of 20 mg/*** addition,compared with fresh hams,the content of total free amino acids in ripe Sanchuan ham has grown 14 folds;sour and bitter were the main tastes of Sanchuan ***,the concentration of cadaverine was the highest of all biogenic amines during the entire fermentation *** the bacterial phyla level,Firmicutes and Actinobacteria were the two main phyla,while at the genus level,Staphylococcus was a significant strain throughout the whole ***,the dry stage has a great impact on the succession change of microbial community ***,the change trends and composition of bacteria in the interior have slight discrepancies with those of the exterior of Sanchuan ham.

关键词： Sanchuan ham Nitrite cont ent Free amino acids Cadaverine Staphylococcus

Sm^(2+)ions boost ammonia electrooxidation reaction on samarium oxide anode for hydrogen generation in non-aqueous electrolyte

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Nano Research 2024年第7期17卷 5856-5862页

作者： Xingyu Liu xue Yang Han Sun Zekai Yang Haijun chen Tianjin Key Laboratory of Optoelectronic Thin Film Devices and Technology College of Electronic Information and Optical EngineeringNankai UniversityTianjin 300350China

Ammonia has garnered recognition as a zero-carbon fuel due to its high-density hydrogen storage capacity and its convenience for storage and *** address the challenges associated with the direct usage of ammonia,the development of NH_(3)-to-H_(2)conversion technologies has emerged as a promising and effective ***,we present for the first time that crystallized Sm_(2)O_(3−x)electrodes demonstrate high and stable electrocatalytic activities,including N_(2)evolution rate and Faradaic efficiency,for ammonia electrolysis in a non-aqueous *** was observed that Sm^(2+)ions in samarium oxide play an indispensable role in the ammonia electrooxidation reaction on the ***,the mechanism of ammonia electrooxidation has also been elucidated,laying the foundation for a better understanding of the relationship between local structure and electrochemical properties in order to facilitate research on Pt-free electrocatalysts for the electrolysis of ammonia into H_(2).

关键词： NH_(3)-to-N_(2)conversion ammonia electrooxidation reaction ammonia electrolysis non-aqueous electrolyte samarium oxide

Intermetallic Compounds Formation in Dissimilar Friction Stir Welding of Mg/Cu Alloys

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Acta Metallurgica Sinica(English Letters) 2024年第9期37卷 1523-1532页

作者： xue Li Qingzhen Zhao Hao Su Ji chen Chuansong Wu MOE Key Lab for Liquid-Solid Structure Evolution and Materials Processing Institute of Materials JoiningShandong UniversityJinan250061China

Joining dissimilar Mg/Cu alloys was still an intractable problem because of the excessive intermetallic compounds(IMCs)and poor mechanical properties using conventional welding *** the present study,friction stir welding was employed for the butt joining of dissimilar AZ31B Mg-alloy and T2 pure Cu ***-free Mg/Cu joints were obtained with Mg-RS and Cu-AS configuration,at a welding speed of 50 mm/min and tool rotating speeds of 325 r/min,625 r/min and 925 r/*** the joining interface,both Mg_(2)Cu and MgCu_(2) IMC phases were observed,with a clear,uniform and continuous IMCs layer composed of two sub-layers,layer-A of Mg+Mg_(2)Cu and layer-B of Mg_(2)Cu+MgCu_(2).The maximum ultimate tensile strength of the Mg/Cu friction stir welding joint reached 130 MPa at 925 r/min due to enhanced mechanical interlocking between Mg and Cu,as well as sufficient metallurgical bonding at the joining interface with an IMCs layer thickness in the range of 1.0-2.0μm.

关键词： Friction stir welding Magnesium Copper Intermetallic compounds Mechanical properties

Ant-nest-inspired porous structure for MXene composites with high-performance energy-storage and actuating multifunctions

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Nano Research 2024年第7期17卷 6673-6685页

作者： Yi Wang Guanfeng xue Zhiling Luo Wei Zhang Luzhuo chen Fujian Provincial Key Laboratory of Quantum Manipulation and New Energy Materials College of Physics and EnergyFujian Normal UniversityFuzhou 350117China Fujian Provincial Collaborative Innovation Center for Advanced High-Field Superconducting Materials and Engineering Fuzhou 350117China

Integrating energy-storage devices(supercapacitors)and shape-deformation devices(actuators)advances the miniaturization and multifunctional development of soft ***,soft robots necessitate supercapacitors with high energy-storage performance and actuators with excellent actuation ***,inspired by ant nests,we present a porous structure fabricated by MXene-graphene-methylcellulose(M-GMC)composite,which overcomes the self-stacking of MXene nanosheets and offers a larger specific surface *** porous structure provides more channels and active sites for electrolyte ions,resulting in high energy storage *** areal capacitance of the M-GMC electrode reaches up to 787.9 mF·cm^(−2),significantly superior to that of the pristine MXene electrode(449.1 mF·cm^(−2)).Moreover,the M-GMC/polyethylene bilayer composites with energy storage and multi-responsive actuation functions are *** M-GMC is used as the electrode and the polyethylene is used as the encapsulation layer of the quasi-solid-state ***,the actuators fabricated by the bilayer composites can be driven by light or low voltage(≤9 V).The maximum bending curvature is up to 5.11 cm^(−1).Finally,a smart gripper and a fully encapsulated smart integrated circuit based on the M-GMC/polyethylene are *** smart gripper enables programmable control with multi-stage *** applications realize the intelligence and miniaturization of soft *** ant-nest-inspired M-GMC composites would provide a promising development strategy for soft robots and smart integrated devices.

关键词： MXene graphene ant nest supercapacitor actuator multi-functional

Exploring multiple phases and first-order phase transitions in Kármán Vortex Street

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Science China(Physics,Mechanics & Astronomy) 2024年第11期67卷 47-54页

作者： Xu Li Xing xiang Tingting xue Limin Wang Xiaosong chen School of Systems Science and Institute of Nonequilibrium Systems Beijing Normal UniversityBeijing 100875China State Key Laboratory of Multiphase Complex Systems Institute of Process EngineeringChinese Academy ofSciencesBeijing 100190China School of Chemical Engineering University of Chinese Academy of SciencesBeijing 100049China

Kármán Vortex Street, a fascinating phenomenon of fluid dynamics, has intrigued the scientific community for a long time. Many researchers have dedicated their efforts to unraveling the essence of this intriguing flow pattern. Here, we apply the lattice Boltzmann method with curved boundary conditions to simulate flows around a circular cylinder and study the emergence of Kármán Vortex Street using the eigen microstate approach, which can identify phase transition and its order-parameter. At low Reynolds number, there is only one dominant eigen microstate W_(1) of laminar flow. At Re_(c)^(1)= 53.6, there is a phase transition with the emergence of an eigen microstate pair W^(2,3) of pressure and velocity fields. Further at Re_(c)^(2)= 56, there is another phase transition with the emergence of two eigen microstate pairs W^(4,5) and W^(6,7). Using the renormalization group theory of eigen microstate,both phase transitions are determined to be first-order. The two-dimensional energy spectrum of eigen microstate for W^(1), W^(2,3) after Re_(c)^(1), W^(4-7) after Re_(c)^(2) exhibit-5/3 power-law behavior of Kolnogorov's K41 theory. These results reveal the complexity and provide an analysis of the Kármán Vortex Street from the perspective of phase transitions.

关键词： Kármán Vortex Street first-order phase transition eigen microstate approach renormalization group theory of eigen microstate

Relationship between the Stratospheric Arctic Vortex and Surface Air Temperature in the Midlatitudes of the Northern Hemisphere

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Journal of Meteorological Research 2024年第1期38卷 39-52页

作者： xue RAN Dingzhu HU Yang ZHANG Mei-chen LIU Key Laboratory of Meteorological Disaster Ministry of Education(KLME)/Joint International Research Laboratory of Climate and Environmental Change(ILCEC)/Collaborative Innovation Center on Forecast and Evaluation of Meteorological Disasters(CIC-FEMD)Nanjing University of Information Science&TechnologyNanjing 210044 School of Atmospheric Sciences Nanjing UniversityNanjing 210023

It is known that different relationships exist between the strength and displacement of the stratospheric polar vortex(SPV),and the surface air temperature(SAT)patterns in Eurasia and North America,but the mechanisms behind these relationships remain unclear,especially on an interannual *** on empirical orthogonal function(EOF)analysis using NCEP reanalysis data over 1958–2018,this study attempts to ascertain the relationship between the SPV intensity and displacement over the Arctic and the SATs in the midlatitudes of the Northern *** results indicate that a strengthened SPV corresponds to an SAT increase in Eurasia and a decrease in eastern North America and *** the SPV is shifted towards Eurasia,however,a corresponding SAT increase occurs in both North America and Eurasia,with a larger increase in North America than in ***,a strengthened SPV tends to correspond to a positive North Atlantic Oscillation-like circulation in the troposphere with negative geopotential height(GH)anomalies in Greenland and eastern North American continent and positive GH anomalies to the north of 45°N in Eurasia,which corresponds to lower SATs in North America than in ***,when the SPV shifted towards Eurasia,it was accompanied by a positive Pacific/North American-like pattern with a deepened Aleutian low,which corresponds to the increasing SATs in North *** tropospheric circulation changes are related to the response of tropospheric planetary wave activity to the SPV.A strengthened SPV corresponds to the weakening of tropospheric planetary wave-1 waves,which is accompanied by a negative GH in North America but a positive GH in *** the SPV shifted towards Eurasia,the tropospheric planetary wave-1(-2)waves strengthened(weakened),and the combined effects of the planetary wave-1 and wave-2 waves would cause positive GH anomalies in both Eurasia and North America.

关键词： stratospheric polar vortex surface air temperature teleconnection patterns planetary waves

A data-driven approach for predicting the fatigue life and failure mode of self-piercing rivet joints

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Advances in Manufacturing 2024年第3期12卷 538-555页

作者： Jian Wang Qiu-Ren chen Li Huang chen-Di Wei Chao Tong xian-Hui Wang Qing Liu Nanjing University of Science and Technology Nanjing210094People’s Republic of China Material Academy JitriSuzhou215100JiangsuPeople’s Republic of China Key Laboratory for Light-weight Materials Nanjing Tech UniversityNanjing210009People’s Republic of China Xi’an Jiaotong-Liverpool University Suzhou215123JiangsuPeople’s Republic of China

In lightweight automotive vehicles,the application of self-piercing rivet(SPR)joints is becoming increasingly *** the importance of automotive service performance,the fatigue performance of SPR joints has received considerable ***,this study proposes a data-driven approach to predict the fatigue life and failure modes of SPR *** dataset comprises three specimen types:cross-tensile,cross-peel,and *** ensure data consistency,a finite element analysis was employed to convert the external loads of the different *** selection was implemented using various machine-learning algorithms to determine the model *** Gaussian process regression algorithm was used to predict fatigue life,and its performance was compared with different kernel functions commonly used in the *** results revealed that the Matern kernel exhibited an exceptional predictive capability for fatigue *** the data points,95.9%fell within the 3-fold error band,and the remaining 4.1%exceeded the 3-fold error band owing to inherent dispersion in the fatigue *** predict the failure location,various tree and artificial neural network(ANN)models were *** findings indicated that the ANN models slightly outperformed the tree *** ANN model accurately predicts the failure of joints with varying dimensions and ***,minor deviations were observed for the joints with the same ***,this data-driven approach provided a reliable predictive model for estimating the fatigue life and failure location of SPR joints.

关键词： Self-piercing rivet(SPR)joints Fatigue life prediction Failure mode prediction Machine learning