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Tracklet-to-object Matching for Climbing Starlink Satellites through Recursive Orbit Determination and Prediction

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Research in Astronomy and Astrophysics 2022年第11期22卷 107-119页

作者： Bin Li lei liu Ji-Zhang Sang School of Geodesy and Geomatics Wuhan UniversityWuhan 430079China Collaborative Innovation Center for Geospatial Technology Wuhan 430079China

Concerns for the collision risk involving Starlink satellites have motivated the interest in obtaining their accurate orbit ***,accurate orbit determination(OD)and prediction(OP)of Starlink satellites confront two main challenges:mismatching or missed matching of sparse tracklets to maneuvering satellites,and unknown or unmodeled orbit *** to exactly associate a tracklet to the right satellite is the primary issue,since a maneuvering satellite does not follow the naturally evolving orbit during the maneuvering,while more tracklets are needed for developing an accurate orbit maneuver *** these two challenges are not well addressed,it may lead to catalog maintenance failure or even loss of *** paper proposes a method to correctly match tracklets to the climbing Starlink *** is based on the recursive OD and OP,in which the orbit maneuver is modeled and the thrust is estimated,such that the subsequent OP accuracy guarantees the correct match of tracklets shortly after the OD *** with climbing Starlink satellites demonstrate that the tracklets within three days of the last TLE(two-line element)are all correctly matched to the right *** the matched tracklets,the thrust accelerations of climbing Starlink satellites can be precisely estimated through an orbit control approach,and the position prediction accuracy over 48 hours is at the level of a few kilometers,providing accurate orbit knowledge for reliable collision warning involving Starlink satellites.

关键词： celestial mechanics methods:analytical miscellaneous

Variability of turbulence dispersion characteristics during heavy haze process: A case study in Beijing

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Journal of Environmental Sciences 2023年第2期124卷 440-450页

作者： lei liu Yu Shi Zhe Zhang Fei Hu LAPC Institute of Atmospheric PhysicsChinese Academy of SciencesBeijing 100029China University of Chinese Academy of Sciences Beijing 100049China

The turbulent standard deviations and the turbulent third-order and fourth-order moments are the key turbulence dispersion parameters in Lagrangian dispersion ***,the characteristics of these parameters under heavy haze conditions in urban areas have not been fully investigated,and the commonly used similarity relations of these parameters in modelswere based on observations in highly flat and sparsely populated *** this paper,the vertical profiles of these parameters and their local similarity relations under heavy haze conditions in the wintertime of Beijing have been analyzed by using data collected at a 325-m meteorological *** heavy haze process has been divided into three stages:transport stage(TS),cumulative stage(CS),and dispersion stage(DS).Results show that the turbulent dispersion parameters behave differently during three *** the TS and DS,the maxima appear in the profiles of the turbulent standard deviations above the urban canopy;in the CS,the turbulent standard deviation are almost constant with *** analysis of the third and fourth order moments shows that the wind velocities above the urban canopy in the TS deviate from the Gaussian distribution more significantly than those in the CS and *** local similarity relations of the turbulent dispersion parameters in the TS,especially for the longitudinal wind components,are normally different from those in the CS and ***,different from the common assumptions in Lagrangian models,the turbulence dispersion in horizontal directions is anisotropic and should be parameterized by multiple similarity relations under heavy haze conditions.

关键词： Heavy haze Turbulence dispersion Local similarity Lagrangian model

Redox potentials of trifluoromethyl-containing compounds

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Science China Chemistry 2015年第4期58卷 673-683页

作者： Yuanye Jiang Haizhu Yu Yao Fu lei liu Department of Chemistry University of Science and Technology of China Department of Polymer Science and Engineering University of Science and Technology Beijing Department of Chemistry Tsinghua University

Trifluoromethylation reactions are important transformations in the research and development of drugs, agrochemicals and functional materials. An oxidation/reduction process of trifluoromethyl-containing compounds is thought to be involved in many recently tested catalytic trifluoromethylation reactions. To provide helpful physical chemical data for mechanistic studies on trifluoromethylation reactions, the redox potentials of a variety of trifluoromethyl-containing compounds and trifluoro- methylated radicals were studied by quantum-chemical methods. First, eoB97X-D was found to be a reliable method in predicting the ionization potentials, electron affinities, bond dissociation enthalpies and redox potentials of trifluoromethylcontaining compounds. One-electron absolute redox potentials of 79 trifluoromethyl substrates and 107 trifluoromethylated radicals in acetonitrile were then calculated with this method. The theoretical results were found to be helpful for interpreting experimental observations such as the relative reaction efficiency of different trifluoromethylation reagents. Finally, the bond dissociation free energies （BDFE） of various compounds were found to have a good linear relationship with the related bond dissociation enthalpies （BDE）. Based on this observation, a convenient method was proposed to predict one-electron redox potentials of neutral molecules.

关键词： trifluoromethylation redox potential density functional theory

Nickel(Ⅱ)-catalyzed asymmetric alkylation of acyclic oxocarbenium ions with carboxylic acid derivatives

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Chinese Chemical Letters 2021年第3期32卷 1237-1240页

作者： Pengbo Ye Xuan liu Gang Wang lei liu School of Chemistry and Chemical Engineering Shandong UniversityJi'nan 250100China

A nickel(Ⅱ)-catalyzed asymmetric alkylation of acyclic oxocarbenium ions generated in situ from corresponding acetals with carboxylic acid derivatives to prepareβ-alkoxyl carbonyl moieties with diverseα-substituents has been *** method exhibited broad scope of acetals and carboxylic acid derivatives with excellent enantioselectivity and good functional group compatibility,and can be conducted in a gram-scale without obvious loss of efficiency.

关键词： Oxocarbenium ion Acyclic Nickel Asymmetric catalysis Alkylation

Existence of Solutions for a Parabolic System Modelling Chemotaxis with Memory Term

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Journal of Partial Differential Equations 2020年第2期33卷 158-170页

作者： WU Shaohua liu lei School of Mathematics and Statistics Wuhan UniversityWuhan 430072China

In this paper,we come up with a parabolic system modelling chemotaxis with memory term,and establish the local existence and uniqueness of weak *** main methods we use are the fixed point theorem and semigroup theory.

关键词： Parabolic system chemotaxis memory term fixed point theorem

Early Triassic Silicic Volcanics of South China:Petrogenesis and Constraints on the Geodynamic Evolution of the Paleo-Tethys Ocean Region

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Acta Geologica Sinica(English Edition) 2024年第3期98卷 617-629页

作者： WANG Yabo liu lei ZHAO Zengxia liu Xijun HUANG Wenmin Guangxi Key Laboratory of Hidden Metallic Ore Deposits Exploration College of Earth SciencesGuilin University of TechnologyGuilinGuangxi 541004China Collaborative Innovation Center for Exploration of Nonferrous Metal Deposits and Efficient Utilization of Resources Guilin University of TechnologyGuilinGuangxi 541004China

The only occurrence of Lower Triassic silicic volcanic rocks within the South China Block is in the Qinzhou Bay area of Guangxi ***-ICP-MS zircon U-Pb dating reveals that volcanic rocks of the Beisi and Banba formations formed between 248.8±1.6 and 246.5±1.3 Ma,coeval with peraluminous granites of the Qinzhou Bay Granitic *** studied rhyolites and dacites are characterized by high SiO_(2),K_(2)O,and Al_(2)O_(3),and low MgO,CaO,and P_(2)O_(5) contents and are classified as high-K calc-alkaline S-type rocks,with A/CNK=*** volcanic rocks are depleted in high field strength elements,e.g.,Nb,Ta,Ti,and P,and enriched in large ion lithophile elements,e.g.,Rb,K,Sr,and *** the analyzed volcanic rocks have extremely enriched zircon Hf isotopic compositions(ε_(Hf)(t)=-29.1 to-6.9),source discrimination indicators and high calculated Ti-in-zircon temperatures(798-835℃)reveal that magma derived from enriched lithospheric mantle not only provided a heat source for anatectic melting of the metasedimentary protoliths but was also an endmember component of the S-type silicic *** studied early Triassic volcanics are inferred to have formed immediately before closure of the Paleo-Tethys Ocean in this region,as the associated subduction would have generated an extensional setting in which the mantle-derived upwelling and volcanic activity occurred.

关键词： geochemistry silicic volcanic rocks mantle contribution Olenekian-Anisian Paleo-Tethys oceanic plate subduction

Expression and function of WNT4 involved in larvae development and limb regeneration in Portunus trituberculatus

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Journal of Oceanology and Limnology 2021年第1期39卷 306-316页

作者： Zhiming REN Yuanyuan FU lei liu Xiao liu Chunlin WANG Key Laboratory of Applied Marine Biotechnology Ministry of EducationNingbo UniversityNingbo 315832China Collaborative Innovation Center for Zhejiang Marine High-effi ciency and Healthy Aquaculture Ningbo UniversityNingbo 315832China

The wingless-related integration site(WNT)proteins are a family of secreted glycoproteins that are evolutionarily conserved and are believed to be involved in evolution in vertebrates and *** signaling pathways may be associated with limb regeneration and development in ***,the detail mechanisms remain ***,the distribution of WNT4 in the hepatopancreas,muscle,hemocyte,ganglion,heart,eyestalk,gill tissue,and diff erent larvae development stages of the swimming crab(Portunus trituberculatus)were characterized using immunofl uorescence,real-time PCR,and Western *** cant PtWNT4 expression was detected in heart and *** addition,PtWNT4 was expressed in all larval stages of *** with a dynamic expression pattern,especially in the eyestalk and other organs in the carapace *** injection of WNT4 dsRNA into regenerative limbs signifi cantly decreased PtWNT4 mRNA levels in the eyestalk,heart,and muscle,resulting in 1.9-fold,2.2-fold,and 2.7-fold decreases compared with those detected in the group injected with crab saline(P<0.05),respectively,indicating successful gene ***,expression analysis on the WNT4 using RNAi provides an insight to its functional mechanism during limb regeneration in *** results not only demonstrated the requirement for WNT4 in limb regeneration of Crustaceans,but also suggested its ability to promote larval development at specifi c stages.

关键词： wingless-type MMTV integration site family member-4(WNT4) limb regeneration larvae development Portunus trituberculatus expression pattern RNAi

Bibliometric study of diabetic retinopathy during 2000-2010 by ISI

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International Journal of Ophthalmology(English edition) 2011年第4期4卷 333-336页

作者： liu, lei Jiao, Jing-Hua Chen, lei China Med Univ Affiliated Hosp 1 Dept Ophthalmol Shenyang 110001 Liaoning Provin Peoples R China Shengyang Med Coll Fengtian Hosp Dept Anesthesiol Shenyang 110024 Liaoning Provin Peoples R China

AIM: To analyze the progress in diabetic retinopathy (DR) researches between 2000 and 2010 through bibliometric study. METHODS: Using ISI Web of Science database for statistical sources, we retrieved DR literatures during 2000-2010, analyzed 'the number of published articles per year, authors, source publications, subject category, document type, document language, institution and country/region' by bibliometric statistical methods. RESULTS: The total number of published articles that were retrieved for the years during 2000-2010 was 8590. DR researches changed as a linear upward trend, the main researches focused on ophthalmology, endocrine and metabolic diseases. Article was the main document type. Harvard University was the major research institution. CONCLUSION: There has achieved a significant increase in the number of ISI publications and collaborations in DR literatures from 2000 to 2010. With the rising of the number of diabetes in the world, diabetic retinopathy has become a focus of scientific researches.

关键词： bibliometric study diabetic retinopathy ISI web of science database

Effect of metformin on stem cells:Molecular mechanism and clinical prospect

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World Journal of Stem Cells 2020年第12期12卷 1455-1473页

作者： Lin-Li Jiang lei liu State Key Laboratory of Oral Diseases&National Clinical Research Center for Oral Diseases&Department of Oral and Maxillofacial Surgery West China Hospital of StomatologySichuan UniversityChengdu 610041Sichuan ProvinceChina

Metformin is a first-line medication for type II *** studies have shown that metformin not only has hypoglycemic effects,but also modulates many physiological and pathological processes ranging from aging and cancer to fracture *** these different physiological activities and pathological changes,stem cells usually play a core ***,many studies have investigated the effects of metformin on stem *** affects cell differentiation and has promising applications in stem cell *** exerts anti-aging effects and can be applied to gerontology and regenerative *** potential anticancer stem cell effect of metformin indicates that it can be an adjuvant therapy for ***,metformin has beneficial effects against many other diseases including cardiovascular and autoimmune *** this review,we summarize the effects of metformin on stem cells and provide an overview of its molecular mechanisms and clinical prospects.

关键词： Metformin Stem cells Differentiation Anti-aging Anti-cancer Mechanism