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Extremely metal-poor star candidates in the SDSS

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Research in Astronomy and Astrophysics 2013年第3期13卷 313-322页

作者： Si-Yao Xu Hua-wei Zhang xiao-wei liu Department of Astronomy School of Physics Peking University Kavli Institute of Astronomy and Astrophysics Peking University

For a sample of metal-poor stars （-3.3 ≤ [Fe/H] ≤-2.2） that have highresolution spectroscopic abundance determinations, we have measured equivalent widths of the Ca II K, Mg I b and near-infrared Ca II triplet lines using low-resolution spectra from the Sloan Digital Sky Survey （SDSS）, calculated effective temperatures from （g - z）o color, deduced stellar surface gravities by fitting stellar isochrones, and determined metallicities based on the aforementioned quantities. Metallicities thus derived from the Ca II K line are in much better agreement with the results deter- mined from high-resolution spectra than the values given in the SDSS Data Release 7. The metallicities derived from the Mg I b lines have a large dispersion owing to the large measurement errors, whereas those deduced from the Ca II triplet lines are too high due to both non-local thermodynamical equilibrium （NLTE） effects and mea- surement errors. Abundances after correction for the NLTE effect for the Mg I b lines and Ca II triplet lines are also presented. Following this method, we have identified six candidates of ultra-metal-poor stars with [Fe/H] - -4.0 from a sample of 166 metal-poor star candidates. One of them, SDSS J102915＋172927, was recently con- firmed to be an ultra-metal-poor （[Fe/H] 〈 -4.0） star with the lowest metallicity ever measured. Follow-up high-resolution spectroscopy for the other five ultra-metal-poor stars in our sample will therefore be of great interest.

关键词： stars: abundances -- stars: Population -- techniques: spectroscopic

Solidification crack characteristics and sensitivity of peritectic steel

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Journal of Iron and Steel Research(International) 2024年第7期31卷 1668-1679页

作者： Ya-qiang Li Jian-hua liu Zi-ming Wang Ying-ying Li Yang He xiao-wei Li Department of Automotive Engineering Hebei Vocational University of Technology and EngineeringXingtai 054000HebeiChina Hebei Special Vehicle Modification Technology Innovation Center Hebei Vocational University of Technology and EngineeringXingtai 054000HebeiChina Institute of Engineering Technology University of Science and Technology BeijingBeijing 100083China School of Petroleum and Natural Gas Engineering Changzhou UniversityChangzhou 213164JiangsuChina

The characteristics and sensitivity of solidification cracks in peritectic steels were investigated using directional solidifi-cation *** cracks were observed in both hypoperitectic steels(12CrlMoV,15CrMo)and hyper-peritectic steel(20CrMo)during solidification at growth velocities of 15,50,and 80 pm/*** the dendritic boundaries,sulphide precipitates were found,promoting crack *** on the statistical analysis of interdendritic cracks in peritectic steels,the area ratio(RA)of interdendritic cracks in a directional solidification structure was proposed to evaluate the crack sensitivity of peritectic ***,the crack sensitivities of peritectic steels(12CrlMoV,15CrMo,and 20CrMo)were tested,evaluated,and compared with the surface crack rates of three types of steels produced from a steel *** results demonstrated that RA was in good agreement with that of the steel plant,and the crack sensitivity of 12CrlMoV steel was the strongest,followed by that of 15CrMo and 20CrMo ***,RA can be used to evaluate the crack sensitivity of peritectic steel.

关键词： Peritectic steel-Directional solidification Growth velocity Dendritic structure Solidification crack Crack sensitivity

Research advances in neuroimaging and genetic characteristics of the non-fluent/agrammatic variant of primary progressive aphasia

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Chinese Medical Journal 2021年第6期134卷 665-667页

作者： Yi-Jing Bai xiao-wei liu wei-Dong Le Liaoning Provincial Center for Clinical Research on Neurological Diseases the First Affiliated Hospital of Dalian Medical UniversityDalianLiaoning 116021China Liaoning Provincial Key Laboratory for Research on the Pathogenic Mechanisms of Neurological Diseases the First Affiliated HospitalDalian Medical UniversityDalianLiaoning 116021China Institute of Neurology Sichuan Academy of Medical Science-Sichuan Provincial HospitalChengduSichuan 610072China Department of Neurology the First Affiliated Hospital of Dalian Medical UniversityDalianLiaoning 116021China

Primary progressive aphasia(PPA),which typically refers to a neurodegenerative disease,such as frontotemporal lobar degeneration(FTLD)or Alzheimer disease(AD),is characterized by gradual loss of the brain systems that govern language,with relative sparing of other cognitive domains.[1]Based on specific speech and language features,clinical consensus criteria published in 2011 for the classification of the PPAs divided them into three subtypes:the semantic variant(svPPA),the non-fluent/agrammatic variant(naPPA),and the logopenic variant(lvPPA)[Supplementary Table 1;http://***/CM9/A522].The naPPA or"progressive non-fluent aphasia",as a form of progressive language disorder that is different from the other subtypes,was first described in 1996 by Grossman et al.

关键词： semantic such progressive

A Numerical Calculation Algorithm of the Inclination Function Based on the Representation of SO(3) Group

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Acta Mathematicae Applicatae Sinica 2024年第1期40卷 137-148页

作者： Yu-xiao wei Wen-lin Tang Department of Geophysics School of Geology Engineering and GeomaticsChang’An UniversityXi’an710064China Key Laboratory of Electronics and Information Technology for Space Systems National Space Science CenterChinese Academy of SciencesBeijing100190China

In the determination of the Earth gravity field in satellite geodesy, the inclination functions represent the projection of data observed along the orbital plane of a satellite orbit into the sphere in the terrestial reference frame. The inclination functions in this work is studied from a group theoretical perspective. The inclination functions are proved to generate a representation of the SO(3) group. An orthogonal relation of the inclination functions is derived and some recurrence relations for the inclination functions are given, based on which an algorithm to calculate the inclination functions is proposed.

关键词： SO(3)group inclination function satellite geodesy representation of SO(3)

Trace formula of the integro-differential operator on a quantum graph

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Applied Mathematics(A Journal of Chinese Universities) 2024年第2期39卷 311-318页

作者： wei Li-xiao YANG Chuan-fu School of Mathematics and Statistics Nanjing University of Science and TechnologyNanjing 210094China.

In this paper we study the eigenvalue problem for integro-differential operators on a lasso *** trace formula of the operator is established by applying the residual technique in complex analysis.

关键词： integro-differential operators eigenvalue trace formula

Differences in and factors controlling organic matter enrichment in the Ziliujing Formation shale in the Sichuan Basin

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Petroleum Science 2024年第1期21卷 77-86页

作者： Peng Li Zhong-Bao liu He Bi Tao Jiang Rui-Kang Bian Peng-wei Wang xiao-Yu Shang State Key Laboratory of Shale Oil and Gas Enrichment Mechanisms and Efficient Development Beijing102206China Key Laboratory of Shale Oil/Gas Exploration and Production Technology SINOPECBeijing102206China Petroleum Exploration and Production Research Institute SINOPECBeijing102206China Research Institute of Petroleum Exploration and Development PetroChinaBeijing100083China Chinese Academy of Geological Sciences Beijing100037China No.4 Oil Production Plant in Daqing Oilfield Co Ltd. Daqing163511HeilongjiangChina

Lacustrine shale oil and gas are important fields for unconventional exploration and development in China,and organic-rich shale deposition lays down the critical foundation for hydrocarbon *** are two sets of shale,the Dongyuemiao and Da’anzhai Members,in the Ziliujing Formation in the Sichuan *** identify the differential enrichment characteristics of organic matter and clarify its controlling factors,geochemical analyses of organic and inorganic geochemical analyses were *** results showed that the total organic carbon content of the Dongyuemiao shale(1.36%)is slightly higher than that of the Da’anzhai shale(0.95%).The enrichment of organic matter in the two shales resulted from the comprehensive controls of paleoproductivity,paleoenvironment,and terrigenous input,but different factors have different *** addition,driven by climate,the change in the sulfate concentration in the bottom water further led to the different intensities of bacterial sulfate reduction in early *** made a great difference regarding organic matter accumulation in the two *** general,climate may have played a dominant role in organic matter enrichment in the two sets of shale.

关键词： Lacustrine shale Ziliujing Formation Sichuan Basin Enrichment mechanism of organic matter

Key role of electron accessibility at the noble metal-free catalytic interface in hydrogen evolution reaction

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Nano Research 2024年第4期17卷 2538-2545页

作者： Dongchen Han Nanxing Gao Yuyi Chu Zhaoping Shi Ying Wang Junjie Ge Meiling xiao Changpeng liu wei Xing State Key Laboratory of Electroanalytical Chemistry Changchun Institute of Applied ChemistryChinese Academy of SciencesChangchun 130022China School of Applied Chemistry and Engineering University of Science and Technology of ChinaHefei 230026China Laboratory of Advanced Power Sources Changchun Institute of Applied ChemistryChinese Academy of SciencesChangchun 130022China Jilin Province Key Laboratory of Low Carbon Chemical Power Sources Changchun 130022China State Key Laboratory of Rare Earth Resource Utilization Changchun Institute of Applied ChemistryChinese Academy of SciencesChangchun 130022China

The reactant concentration at the catalytic interface holds the key to the activity of electrocatalytic hydrogen evolution reaction(HER),mainly referring to the capacity of adsorbing hydrogen and electron *** hydrogen adsorption free energy(ΔGH)as a reactivity descriptor,the volcano curve based on Sabatier principle is established to evaluate the hydrogen evolution activity of ***,the role of electron as reactant received insufficient attention,especially for noble metal-free compound catalysts with poor conductivity,leading to cognitive gap between electronic conductivity and apparent catalytic *** we successfully construct a series of catalyst models with gradient conductivities by regulating molybdenum disulfide(MoS_(2))electronic bandgap via a simple solvothermal *** demonstrate that the conductivity of catalysts greatly affects the overall catalytic *** further elucidate the key role of intrinsic conductivity of catalyst towards water electrolysis,mainly concentrating on the electron transport from electrode to catalyst,the electron accumulation process at the catalyst layer,and the charge transfer progress from catalyst to *** and experimental evidence demonstrates that,with the enhancement in electron accessibility at the catalytic interface,the dominant parameter governing overall HER activity gradually converts from electron accessibility to combination of electron accessibility and hydrogen adsorbing *** results provide the insight from various perspective for developing noble metal-free catalysts in electrocatalysis beyond HER.

关键词： conductivity molybdenum disulfide catalytic interface electron accessibility hydrogen evolution charge transfer.

Poly(3-hexylthio) thiophene Field-effect Transistor Device Performance: Impact of the Content of Hexylthio Side Chain on Backbone

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Chinese Journal of Polymer Science 2024年第1期42卷 14-23,I0005页

作者： Hao-Yu liu Lian-He Han Ling-wei Kong Li-Ping Zhu xiao-Lan Qiao Mei-Fang Zhu State Key Laboratory for Modification of Chemical Fibers and Polymer Materials College of Materials Science and EngineeringDonghua UniversityShanghai 201620China School of Electronic Information and Electrical Engineering Shanghai Jiao Tong UniversityShanghai 200240China

Regioregular poly(3-hexylthio)thiopene(P3HTT) has emerged tremendous potential in organic electronic applications due to the strong noncovalent interactions from the sulfur atom linked to thiophene. However, P3HTT generally exhibits low charge mobility mostly due to poor solution processability attributed to dense arrangement of hexylthio side chain in polymer, which led to strong noncovalent interactions among sulfur atoms. To balance the nonvalent interaction and aggregation for P3HTT, herein, we systematically study the effect of hexylthio side chain content in polymer backbone on the structure and properties. A series of regioregular P3HTT-based homopolymers(P3HTT, P3HTT-50,P3HTT-33 and P3HTT-25) were prepared via Kumada catalyst transfer polycondensation method from a set of mono-, bi-, ter-and quarterthiophenes containing different contents of hexylthio side chain. The DFT calculation shows the planarity of polymers backbone could be improved through reducing the density of hexylthio side chain in polymer mainchain. And significant changes in their crystallinity, aggregation and optical properties were observed with the content of hexylthio side chain reducing. The P3HTT-33 displayed the highest field-effect transistor hole mobility of 2.83×10^(-2) cm^(2)·V^(-1)·s^(-1) resulting from a balance between the crystallinity and planarity. This study demonstrates modulating the content of hexylthio side chain in P3HTT is an effective strategy to optimize the opto-electronic properties of polymer obtaining excellent semiconductor device performance.

关键词： Conjugated polymer Polythiophene Noncovalent interaction Molecular aggregation Organic field-effect transistor

Quantification of Central and Eastern China's atmospheric CH_(4) enhancement changes and its contributions based on machine learning approach

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Journal of Environmental Sciences 2024年第4期138卷 236-248页

作者： Xinyue Ai Cheng Hu Yanrong Yang Leying Zhang Huili liu Junqing Zhang Xin Chen Guoqiang Bai wei xiao College of Biology and the Environment Joint Center for sustainable Forestry in Southern ChinaNanjing Forestry UniversityNanjing 210037China Collaborative Innovation Center on Forecast and Evaluation of Meteorological Disasters(CIC-FEMD) Nanjing University of Information Science&TechnologyNanjing 210044China Guang’an Vocational&Technical College Guangan 638550China HuaNan Meteorological Administration Huanan 154400China

Methane is the second largest anthropogenic greenhouse gas,and changes in atmospheric methane concentrations can reflect the dynamic balance between its emissions and ***,the monitoring of CH_(4) concentration changes and the assessment of underlying driving factors can provide scientific basis for the government’s policy making and *** is the world’s largest emitter of anthropogenic ***,due to the lack of ground-based observation sites,little work has been done on the spatial-temporal variations for the past decades and influencing factors in China,especially for areas with high anthropogenic emissions as Central and Eastern *** to quantify atmospheric CH_(4) enhancements trends and its driving factors in Central and Eastern China,we combined the most up-to-date TROPOMI satellite-based column CH_(4)(xCH_(4))concentration from 2018 to 2022,anthropogenic and natural emissions,and a random forest-based machine learning approach,to simulate atmospheric xCH_(4) enhancements from 2001 to *** results showed that(1)the random forest model was able to accurately establish the relationship between emission sources and xCH_(4) enhancement with a correlation coefficient(R^(2))of 0.89 and a root mean-square error(RMSE)of 11.98 ppb;(2)The xCH_(4) enhancement only increased from 48.21±2.02 ppb to 49.79±1.87 ppb from the year of 2001 to 2018,with a relative change of 3.27%±0.13%;(3)The simulation results showed that the energy activities and waste treatment were the main contributors to the increase in xCH_(4) enhancement,contributing 68.00% and 31.21%,respectively,and the decrease of animal ruminants contributed-6.70% of its enhancement trend.

关键词： TROPOMI Methane column concentrations Anthropogenic sources Random Forest model