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What is the right way to quench star formation in semi-analytic models of galaxy formation?

Research in Astronomy and Astrophysics 2017年第2期17卷 7-16页

作者： Yu Luo xi kang Purple Mountain Observatory the Partner Group of MPI für Astronomie Graduate School University of the Chinese Academy of Sciences

Semi-analytic models of galaxy formation are powerful tools to study the evolution of a galaxy population in a cosmological context. However, most models overpredict the number of low- mass galaxies at high redshifts and the colors of model galaxies are not right in the sense that low-mass satellite galaxies are too red and centrals are too blue. The recent version of the L-Galaxies model by Henriques et al. （H15） is a step forward to solve these problems by reproducing the evolution of stellar mass function and the overall fraction of red galaxies. In this paper we compare the two model predictions of L-Galaxies （the other is Guo et al., G13） to SDSS data in detail. We find that in the H15 model the red fraction of central galaxies now agrees with the data due to their implementation of strong AGN feedback, but the stellar mass of centrals in massive halos is now slightly lower than what is indicated by the data. For satellite galaxies, the red fraction of low-mass galaxies （log M./M~ 〈 10） also agrees with the data, but the color of massive satellites （10 〈 logM,/M~ 〈 11） is slightly bluer. The correct color of centrals and the bluer color of massive satellites indicate that quenching in massive satellites is not strong enough. We also find that there are too many red spirals and less bulge-dominated galaxies in both H15 and G13 models. Our results suggest that additional mechanisms, such as more minor mergers or disk instability, are needed to slightly increase the stellar mass of the central galaxy in massive galaxies, mainly in the bulge component, and bulge dominated galaxies will be quenched not only by minor mergers, but also by some other mechanisms.

关键词： galaxies: evolution -- galaxies: formation- galaxies: star formation

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Support interaction of Pt/CeO2 and Pt/SiC catalysts prepared by nano platinum colloid deposition for CO oxidation

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Journal of Rare Earths 2020年第4期38卷 376-383页

作者： kang xi Yong Wang kang Jiang Jing xie Ying Zhou Hanfeng Lu Innovation Team of Air Pollution Control Institute of Catalytic Reaction EngineeringCollege of Chemical EngineeringZhejiang University of TechnologyHangzhou 310014China

The interaction between Pt and its various supports can regulate the intrinsic electronic structure of Pt particles and their catalytic ***,Pt/CeO2 and Pt/SiC catalysts were successfully prepared via a facile Pt colloidal particle deposition method,and their catalytic performance in CO oxidation was ***,TEM,XPS and H2-TPR were used to identify the states of Pt particles on the support surface,as well as their effect on the performance of the *** of the Pt-O-Ce interaction is one of the factors controlling catalyst *** the oxidative treatment at low temperature,the Pt-O-Ce interaction plays an important role in improving the catalytic *** calcining at high temperature,enhanced Pt-O-Ce interaction results in the absence of metallic Pt0 on the support surface,as evidenced by the appearance of Pt2+*** is consistent with the XPS data of Pt/CeO2,and is the main reason behind the deactivation of the *** contrast,either no interaction is formed between Pt and SiC or Pt nanoparticles remain in the metallic Pt0 state on the SiC surface even after aging at 800℃in an oxidizing ***,the Pt/SiC shows better thermal stability than Pt/*** interaction between Pt and the active support may be concluded to be essential for CO oxidation at low temperature,but strong interactions may induce serious deactivation of catalytic activity.

关键词： Nano platinum colloid CO oxidation Pt-O-Ce interaction CeO2 SiC Rare earths

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Hierarchical structural complexity in atomically precise nanocluster frameworks

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National Science Review 2021年第3期8卷 88-98页

作者： xiao Wei xi kang Zewen Zuo Fengqi Song Shuxin Wang Manzhou Zhu Department of Chemistry and Centre for Atomic Engineering of Advanced Materials Anhui Province Key Laboratory of Chemistry for Inorganic/Organic Hybrid Functionalized Materials Anhui University National Laboratory of Solid State Microstructures Collaborative Innovation Center of Advanced MicrostructuresSchool of PhysicsNanjing University Atomic Manufacture Institute Key Laboratory of Structure and Functional Regulation of Hybrid Materials(Anhui University) Ministry of Education

The supramolecular chemistry of nanoclusters is a flourishing area of nano-research;however,the controllable assembly of cluster nano-building blocks in different arrays remains *** this work,we report the hierarchical structural complexity of atomically precise nanoclusters in micrometric linear chains(1 D array),grid networks(2 D array) and superstructures(3 D array).In the crystal lattice,the Ag(SSR)(PPh)nanoclusters can be viewed as unassembled cluster dots(Ag-OD).In the presence of Cs~+ cations,the Ag(SSR)nano-building blocks are selectively assembled into distinct arrays with different oxygen-carrying solvent molecules—Cs@Ag(SSR)(DMF)as 1 D linear chains(Ag-1 D),Cs@Ag(SSR)(NMP)as 2 D grid networks(Ag-2 D),and Cs@Ag(SSR)(TMS)as 3 D superstructures(Ag-3 D).Such self-assemblies of these Ag(SSR)units have not only been observed in their crystalline state,but also in their amorphous *** to the diverse surface structures and crystalline packing modes,these Ag-based assemblies manifest distinguishable optical absorptions and emissions in both solutions and crystallized ***,the surface areas of the nanocluster crystals are evaluated,the maximum value of which occurs when the cluster nano-building blocks are assembled into 2 D arrays(***-2 D).Overall,this work presents an exciting example of the hierarchical assembly of atomically precise nanoclusters by simply controlling the adsorbed molecules on the cluster surface.

关键词： hierarchical structural complexity atomically precise nanocluster 1D linear chain 2D grid network 3D superstructure

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The formation of a blue cluster in the local Universe

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Research in Astronomy and Astrophysics 2020年第12期20卷 337-346页

作者： Qing-xin Wen Yu Luo xi kang Purple Mountain Observatory Chinese Academy of SciencesNanjing 210033China School of Astronomy and Space Sciences University of Science and Technology of ChinaHefei 230026China Zhejiang University-Purple Mountain Observatory Joint Research Center for Astronomy Zhejiang UniversityHangzhou 310037China

It is well known from the Butcher-Oemler effect that galaxies in dense environment are mostly red with little star formation and the fraction of blue galaxies in galaxy groups/clusters also declines rapidly with redshifts.A recent work by Hashimoto et *** a local ‘blue cluster’ with a high fraction of blue galaxies(∼0.57),higher than the model *** ascribed this blue cluster to the feeding of gas along a filamentary structure around the *** this work we use group catalog from the Sloan Digital Sky Survey Data Release 7(SDSS DR7) and the state-of-art of semi-analytic model(SAM) to investigate the formation of blue clusters in the local *** total,we find four blue clusters with halo mass ∼10^14 M⊙ at 0.02 xies are recently *** conclude that the formation of blue clusters is mainly governed by newly accreted blue satellites,rather than the effect of large-scale environment.

关键词： galaxies:clusters:statistical galaxies:evolution galaxies:formation galaxies:blue fraction

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Bibliometric analysis about compassion fatigue based on Web of Science database

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Frontiers of Nursing 2019年第2期6卷 151-156页

作者： xi-Liang kang xiao Gao Operating Room of Affiliated Hospital of Taishan Medical University

Objective: To analyze the related foreign literature about compassion fatigue (CF) and to provide the basis for further improving the level of research in this field. Methods: Based on the Web of Science core database and its own analysis function, HistCite analysis software was used to study the diploma research about CF. Results: A total of 652 paper were retrieved, the output of literature showed an increasing trend year by year. The United States ranked first, and China ranked eleventh. The “Oncology Nursing Forum” had the largest number of articles (4.0%). The main research direction was in nursing (29.6%), and the main research output was from articles (73.2%). The key words highly cited were “compassion” and “fatigue”. Figley was the author of the high-yield field, and mainly research institutions were universities. The highly cited article was entitled “Compassion fatigue: Psychotherapists’ chronic lack of self-care”. Conclusions: In recent years, the related heat of CF has been high fever. Our research in this field is still in the primary stage, and it needs to be further excavated and promoted.

关键词： compassion fatigue Web of Science literature measurement

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Baseline optimization for scalar magnetometer array and its application in magnetic target localization

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Chinese Physics B 2018年第6期27卷 213-219页

作者： Li-Ming Fan Quan Zheng xi-Yuan kang xiao-Jun Zhang Chong kang College of Science Harbin Engineering University Harbin 150001 China College of Mechanical and Electrical Engineering Harbin Engineering University Harbin 150001 China College of Computer Science and Technology Harbin Engineering University Harbin 150001 China

Generally, a magnetic target can be described with six parameters, three describing the position and three describing the magnetic moment. Due to a lack of sufficient components from one magnetometer, we need more than one magnetometer when locating the magnetic target. Thus, a magnetometer array should be designed. The baseline of the array is an important factor that affects the localization accuracy of the target. In this paper, we focus on the localization of a static target by using a scalar magnetometer array. We present the scalar magnetometer array with a cross-shaped *** propose a method of determining the optimal baseline according to the parameters of the magnetometer and detection requirements. In the method, we use the traditional signal-to-noise ratio（SNR） as a performance index, and obtain the optimal baseline of the array by using the Monte Carlo method. The proposed method of determining the optimal baseline is verified in simulation. The arrays with different baselines are used to locate a static magnetic target. The results show that the location performance is better when using the array with the optimal baseline determined by the proposed method.

关键词： scalar magnetometer array baseline optimization Monte Carlo simulation magnetic anomaly

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Modeling the dynamical friction timescale of a sinking satellite

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Research in Astronomy and Astrophysics 2010年第12期10卷 1242-1254页

作者： Jian-Ling Gan xi kang Jin-Liang Hou Rui-xiang Chang Key Laboratory for Research in Galaxies and Cosmology Shanghai Astronomical Observatory Chinese Academy of Sciences Shanghai 200030 China jlgan@*** Purple Mountain Observatory Chinese Academy of Sciences Nanjing 210008 China Graduate University of Chinese Academy of Sciences Beijing 100049 China

When a satellite galaxy falls into a massive dark matter halo, it suffers from the dynamical friction force which drags it into the halo＇s center, where it finally merges with the central galaxy. The time interval between entry and merger is called the dynamical friction timescale （Tdf）. Many studies have been dedicated to deriving Tdf using analytical models or N-body simulations. These studies have obtained qualitative agreements on how Zdf depends on the orbital parameters, and the mass ratio between the satellite and the host＇s halo. However, there are still disagreements on deriving an accurate form for Tdf. We present a semi-analytical model to predict Tdf and we focus on interpreting the discrepancies among different studies. We find that the treatment of mass loss from the satellite by tidal stripping dominates the behavior of Tdf. We also identify other model parameters which affect the predicted Tdf.

关键词： methods: analytical -- methods: numerical-- galaxies: haloes -- galax-ies: evolution -- galaxies: interactions -- cosmology: dark matter

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Effect of Ni-V loading on the performance of hollow anatase TiO2 in the catalytic combustion of dichloromethane

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Journal of Environmental Sciences 2019年第10期31卷 59-68页

作者： Bing Zhou xixiong Zhang Yong Wang Jing xie kang xi Ying Zhou Hanfeng Lu College of Chemical Engineering Institute of Catalytic Reaction Engineering Zhejiang University of Technology Hangzhou 310014 China College of Environment Zhejiang University of Technology Hangzhou 310014 China

A catalyst based on mixed V-Ni oxides supported on TiO2(Ni-V/TiO2)was obtained using the sol-gel *** catalytic performance relative to dichloromethane(DCM)degradation was *** and analysis were conducted using transmission electron microscopy,H2 temperature-programmed reduction,pyridine-Fourier transform infrared spectroscopy(FTIR)characterization,and X-ray *** showed that the original hollow anatase structure of pure TiO2 was well-maintained after Ni-V *** loading of NiO-VOx not only significantly improved the stability of pure TiO2 but also inhibited the formation of the by-product monochloromethane(MCM).Among the series of Ni-V/TiO2 catalysts,4%Ni-V/TiO2 possessed the highest catalytic activity,with 90%DCM conversion at only 203℃.No by-products and no significant changes in the catalytic activity were observed during combustion of DCM after 100 hr of a continuous stability ***,thermogravimetric analysis(O2-TG)and energy dispersive spectrometer(EDS)characterization of the used 4%Ni-V/TiO2 catalyst revealed that no coke deposition or chlorine species could be detected on the catalyst surface.

关键词： Catalytic combustion Dichloromethane(DCM) TiO2 catalyst Ni-V/TiO2 catalyst

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Analysis of Translocation of the CagA Protein and Induction of a Scattering Phenotype in AGS Cells Infected with Helicobacter pylori

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Biomedical and Environmental Sciences 2009年第5期22卷 394-400页

作者： xiAN-HONG LIANG YA-NAN ZHANG YONG-JUN WANG xi-xiONG kang Department of Neurology Beijing Tiantan Hospital Capital Medical University Beijing 100050 China Department of Microbiology Peking University Health Science Center Beijing 100191 China Department of Laboratory Beijing Tiantan Hospital Capital Medical UniversityBeijing 100050 China

Objective To investigate whether the presence of structured CagA proteins in Western- and Eastern-type Helicobacter pylori （H. pylori） induces different incidences of gastric diseases. Methods CagA and phosphorylatd CagA were expressed in AGS gastric epithelial cells infected with wild type and mutant strains. The ability of individual CagA was determined by immunoprecipitation and Western blot assay. Morphological changes of these cells were observed under microscope to evaluate the appearance of elongation hummingbird phenotype. Results The sizes of CagA proteins in different strains were different, and no phosphorylated CagA proteins were detected in wild-type strains. Meanwhile, the kinetics of CagA status in AGS infected with H. pylori was detected. The molecular weight of phosphorylated CagA with the same size of CagA proteins in H. pylori was different in infections with different wild-type strains. CagA and phosphorylated CagA increased in a time-dependent manner after the infection. The hummingbird phenotype with H. pylori for time-course was observed under microscope. Instead of HPK5 strain, the wild-type 26695 strain induced hummingbird phenotype in a time-dependent manner. Conclusion Translocation and phosphorylation of CagA are necessary, but not sufficient, for the induction of hummingbird phenotype in AGS cells.

关键词： CagA Western CagA-specific sequence (WSS) Eastern CagA-specific sequence (ESS) Hummingbird phenotype

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A Morphological Study of Two Young Multipolar Planetary Nebulae

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Research in Astronomy and Astrophysics 2023年第3期23卷 170-182页

作者： Shi-Bo Wen Chih-Hao Hsia xiao-xi kang Rui Chen Tao Luo State Key Laboratory of Lunar and Planetary Sciences Macao University of Science and Technology.MacaoChina The Laboratory for Space Research Faculty of ScienceThe University of Hong KongChina Deep Space Exploration Laboratory Beijing 100043China Lunar Exploration and Space Engineering Center China National Space AdministrationBeijing 100190China Shien-Ming Wu School of Intelligent Engineering South China University of TechnologyGuangzhou 511442China Zhuhai Bojay Electronics Co. Ltd.Zhuhai 519075China

We carry out an optical morphological and infrared spectral study for two young planetary nebulae(PNs)Hen2-158 and Pe 1-1 to understand their complex shapes and dust *** Space Telescope optical images reveal that these nebulae have several bipolar-lobed structures and a faint arc with a clear boundary is located at the northwestern side of Pe *** presence of this arc-shaped structure suggests that the object interacts with its nearby interstellar *** IRS spectroscopic observations of these young nebulae clearly show prominent unidentified infrared emission features and a weak silicate band in Pe 1-1,indicating that Hen 2-158 is a carbonrich nebula and Pe 1-1 has a mixed chemistry dust ***,we construct two three-dimensional models for these PNs to realize their intrinsic *** simulated models of the nebulae suggest that multipolar nebulae may be more numerous than we *** analyses of spectral energy distributions for Hen 2-158 and Pe 1-1 show that they have low luminosities and low stellar effective temperatures,suggesting that these nebulae are young PNs.A possible correlation between typical multipolar young PNs and nested nebulae is also discussed.

关键词： northwestern stellar planetary

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