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Automated estimation of stellar fundamental parameters from low resolution spectra: the PLS method

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Research in Astronomy and Astrophysics 2009年第6期9卷 712-724页

作者： jian-nan zhang A-Li Luo Yong-Heng Zhao National Astronomical Observatories Chinese Academy of Sciences Beijing 100012 China

PLS （Partial Least Squares regression） is introduced into an automatic estimation of fundamental stellar spectral parameters. It extracts the most correlative spectral component to the parameters （Teff, log g and [Fe/H]）, and sets up a linear regression function from spectra to the corresponding parameters. Considering the properties of stellar spectra and the PLS algorithm, we present a piecewise PLS regression method for estimation of stellar parameters, which is composed of one PLS model for Teff, and seven PLS models for log g and [Fe/H] estimation. Its performance is investigated by large experiments on flux calibrated spectra and continuum normalized spectra at different signal-to-noise ratios （SNRs） and resolutions. The results show that the piecewise PLS method is robust for spectra at the medium resolution of 0.23 nm. For low resolution 0.5 nm and 1 nm spectra, it achieves competitive results at higher SNR. Experiments using ELODIE spectra of 0.23 nm resolution illustrate that our piecewise PLS models trained with MILES spectra are efficient for O ～ G stars： for flux calibrated spectra, the systematic offsets are 3.8%, 0.14 dex, and -0.09 dex for Teff, log g and [Fe/H], with error scatters of 5.2%, 0.44 dex and 0.38 dex, respectively; for continuum normalized spectra, the systematic offsets are 3.8%, 0.12dex, and -0.13 dex for Teff, log g and [Fe/H], with error scatters of 5.2%, 0.49 dex and 0.41 dex, respectively. The PLS method is rapid, easy to use and does not rely as strongly on the tightness of a parameter grid of templates to reach high precision as Artificial Neural Networks or minimum distance methods do.

关键词： methods data analysis -- methods statistical -- stars fundamental param- eters (classification, temperatures, metallicity) -- techniques spectroscopic -- surveys

Photometric redshift estimation of galaxies with Convolutional Neural Network

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Research in Astronomy and Astrophysics 2020年第6期20卷 193-202页

作者： Yong-Huan Mu Bo Qiu jian-nan zhang Jun-Cheng Ma Xiao-Dong Fan School of Electronics and Information Engineering Hebei University of TechnologyTianjin 300401China CAS Key Laboratory of Optical Astronomy National Astronomical ObservatoriesChinese Academy of SciencesBeijing 100101China

The abundant photometric data collected from multiple large-scale sky surveys give important opportunities for photometric redshift ***,low accuracy is still a serious issue in the current photometric redshift estimation *** this paper,we propose a novel two-stage approach by integration of Self Organizing Map(SOM)and Convolutional Neural Network(CNN)methods *** SOM-CNN method is tested on the dataset of 150000 galaxies from Sloan Digital Sky Survey Data Release 13(SDSS-DR13).Inthe first stage,we apply the SOM algorithm to photometric data clustering and divide the samples into early-type and *** the second stage,the SOM-CNN model is established to estimate the photometric redshifts of ***,the precision rate and recall rate curves(PRC)are given to evaluate the models of SOM-CNN and Back Propagation(BP).It can been seen from the PRC that the SOM-CNN model is better than BP,and the area of SOM-CNN is 0.94,while the BP is ***,we provide two key error indicators:mean square error(MSE)and *** results show that the MSE of early-type is 0.0014 while late-type is 0.0019,which are better than the BP algorithm 22.2%and 26%,*** compared with Outliers,our result is optimally 1.32%,while the K-nearest neighbor(KNN)algorithm has 3.93%.In addition,we also provide the error visualization figures aboutΔZ andδ.According to the statistical calculations,the early-type with an error of less than 0.1 accounts for 98.86%,while the late-type is 99.03%.This result is better than those reported in the literature.

关键词： galaxies distances and redshifts-techniques photometric-method data analysis

Relative flux calibration for the Guoshoujing Telescope (LAMOST)

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Research in Astronomy and Astrophysics 2012年第4期12卷 453-464页

作者： Yi-Han Song A-Li Luo Georges Comte Zhong-Rui Bai jian-nan zhang Wei Du Hao-Tong zhang jian-Jun Chen Fang Zuo Yong-Heng Zhao National Astronomical Observatories Chinese Academy of SciencesBeijing 100012China Key Laboratory of Optical Astronomy National Astronomical ObservatoriesChinese Academy of SciencesBeijing 100012China Graduate University of Chinese Academy of Sciences Beijing 100049China Observatoire Astronomique Marseille-Provence and Laboratoire d'Astrophysique de Marseille F-13388 Marseille CedexFrance

This paper presents a relative flux calibration method for the Guoshoujing Telescope （LAMOST）, which may be applied to connect a blue spectrum to a red spectrum to build the whole spectrum across the total wavelength range （3700 ～ 9000 A）. In each spectrograph, we estimate the effective temperatures of selected stars using a grid of spectral line indices in the blue spectral range and a comparison with stellar atmosphere models. For each spectrograph, stars of types A and F are selected as pseudo-standard stars, and the theoretical spectra are used to calibrate both the blue （3700 ～ 5900 A） and red spectrograph arms （5700 ～ 9000 A）. Then the spectral response function for these pseudo-standard stars could be used to correct the raw spectra provided by the other fibers of the spectrograph, after a fiber efficiency function has been derived from twilight flat-field exposures. A key problem in this method is the fitting of a pseudo stellar continuum, so we also give a detailed description of this step. The method is tested by comparing a small sample of LAMOST spectra calibrated in this way on stars also observed by the Sloan Digital Sky Survey. The result shows that the T eff estimation and relative flux calibration method are adequate.

关键词： techniques: spectroscopic — calibration: methods:data analysis

Lipid metabolism-related long noncoding RNAs:A potential prognostic biomarker for hepatocellular carcinoma

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World Journal of Gastroenterology 2024年第33期30卷 3799-3802页

作者： Rui-nan zhang jian-Gao Fan Department of Gastroenterology Xinhua Hospital Affiliated to Shanghai Jiao Tong University School of MedicineShanghai 200092China

The incidence rates of hepatocellular carcinoma(HCC)have increased in recent *** advancements in therapy and early diagnosis improving shortterm prognosis,long-term outcomes remain *** noncoding RNAs(lncRNAs)and lipid metabolism play crucial roles in the development and progression of *** lipid synthesis promotes HCC progression,and lncRNAs can reprogram the expression of lipogenic ***,lipid metabolism-related(LMR)-lncRNAs regulate lipid anabolism,accelerating the onset and progression of *** suggests that LMR-lncRNAs could serve as novel prognostic biomarkers and therapeutic targets.

关键词： Long noncoding RNAs Lipid metabolism Hepatocellular carcinoma Prognosis Biomarker

Automatic determination of stellar atmospheric parameters and construction of stellar spectral templates of the Guoshoujing Telescope (LAMOST)

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Research in Astronomy and Astrophysics 2011年第8期11卷 924-946页

作者： Yue Wu A-Li Luo Hai-Ning Li jian-Rong Shi Philippe Prugniel Yan-Chun Liang Yong-Heng Zhao jian-nan zhang Zhong-Rui Bai Peng Wei Wei-Xiang Dong Hao-Tong zhang jian-Jun Chen National Astronomical Observatories Chinese Academy of Sciences Beijing 100012 China Universitede Lyon Universite Lyon 1 Villeurbanne F-69622 France CRAL Observatoire de Lyon CNRS UMR 5574 69561 Saint-Genis Laval France Key Laboratory of Optical Astronomy NAOC Chinese Academy of Sciences Graduate University of Chinese Academy of Sciences Beijing 100049 China Shandong University at Weihai Weihai 264209 China

A number of spectroscopic surveys have been carried out or are planned to study the origin of the Milky Way. Their exploitation requires reliable automated methods and softwares to measure the fundamental parameters of the stars. Adopting the ULySS package, we have tested the effect of different resolutions and signal-to- noise ratios （SNR） on the measurement of the stellar atmospheric parameters （effective temperature Teff, surface gravity log g, and metaUicity [Fe/H]）. We show that ULySS is reliable for determining these parameters with medium-resolution spectra （R ～2000）. Then, we applied the method to measure the parameters of 771 stars selected in the commissioning database of the Guoshoujing Telescope （LAMOST）. The results were compared with the SDSS/SEGUE Stellar Parameter Pipeline （SSPP）, and we derived precisions of 167 K, 0.34dex, and 0.16dex for Teff, logg and [Fe/H] respectively. Furthermore, 120 of these stars are selected to construct the primary stellar spectral template library （Version 1.0） of LAMOST, and will be deployed as basic ingredients for the LAMOST automated parametrization pipeline.

关键词： astronomical data bases: atlases -- stars: fundamental parameters techniques: spectroscopic -- surveys

Carbon coated LaFe_(0.92)Pd_(0.08)O_(3) composites for catalytic transfer hydrogenation:Balance in the ability of substrates adsorption and conversion

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nano Research 2024年第5期17卷 3724-3732页

作者： Bowen Wang nan zhang Ping Xiao jian zhang Sónia A.C.Carabineiro Junjiang Zhu Hubei Key Laboratory of Biomass Fibers and Eco-dyeing&Finishing College of Chemistry and Chemical EngineeringWuhan Textile UniversityWuhan 430200China College of Chemistry and Materials Engineering Wenzhou UniversityWenzhou 325035China LAQV-REQUIMTE Department of ChemistryNOVA School of Science and TechnologyUniversidade NOVA de LisboaLargo da Torre2829-516 CaparicaPortugal

Catalytic transfer hydrogenation(CTH)is a green and efficient pathway for selective hydrogenation of unsaturated aldehydes and ***,managing the abilities of solid catalysts to adsorb substrates and to convert them into desired products is a challenging ***,we report the synthesis of carbon coated LaFe_(0.92)Pd_(0.08)O_(3) composites(LFPO-8@C)for CTH of benzaldehyde(BzH)into benzyl alcohol(BzOH),using isopropanol(IPA)as hydrogen *** coating with carbon improves the ability to adsorb/transfer reactants from solution to active sites,and the doping of Pd2+at Fe3+site strengthens the ability of LaFeO_(3) to convert BzH into BzOH.A balanced point between them(i.e.,abilities to adsorb BzH and to convert BzH into BzOH)is obtained at LFPO-8@C,which exhibits a BzOH formation rate of 3.88 mmol·gcat^(-1)·h^(-1) at 180℃ for 3 h,which is 1.50 and 2.72 times faster than those of LFPO-8 and LaFeO_(3)@C.A reaction mechanism is proposed,in which the acidic sites(e.g.,Fe^(4+),oxygen vacancy)are used for the activation of C=O bond of BzH and O-H bond of IPA,and the basic sites(e.g.,lattice oxygen)for the activation ofα-H(O-H)bond of IPA.

关键词： LaFe_(0.92)Pd_(0.08)O_(3) porous carbon catalytic transfer hydrogenation isopropanol reaction mechanism

Quasars in the Galactic Anti-Center Area from LAMOST DR3

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Research in Astronomy and Astrophysics 2017年第4期17卷 7-10页

作者： Zhi-Ying Huo Xiao-Wei Liu jian-Rong Shi Mao-Sheng Xiang Yang Huang Hai-Bo Yuan jian-nan zhang Wei zhang jian-Ling Wang Yu-Zhong Wu Zi-Huang Cao Yong zhang Yong-Hui Hou Yue-Fei Wang National Astronomical Observatories Chinese Academy of Sciences Beijing 100012 China Department of Astronomy Peking University Beijing 100871 China Kavli Institute for Astronomy and Astrophysics Peking University Beijing 100871 China Department of Astronomy Beijing Normal University Beijing 100875 China nanjing Institute of Astronomical Optics & Technology Chinese Academy of Sciences Nanjing 210042 China

Abstract We present a sample of quasars discovered in an area near the Galactic Anti-Center covering 150°≤l≤ 210° and ｜b｜ ≤ 30°, based on LAMOST Data Release 3 （DR3）. This sample contains 151 spectroscopically confirmed quasars. Among them 80 are newly discovered with LAMOST. All these quasars are very bright, with i magnitudes peaking around 17.5 mag. All the new quasars were discovered serendipitously from objects that were originally targeted with LAMOST as stars having bluer colors, except for a few candidates targeted as variable, young stellar objects. This bright quasar sample at low Galactic latitudes will help fill the gap in the spatial distribution of known quasars near the Galactic disk that are used to construct an astrometric reference frame for the purpose of accurate proper motion measurements that can be applied to, for example, Gala. They are also excellent tracers to probe the kinematics and chemistry of the interstellar medium in the Milky Way disk and halo via absorption line spectroscopy.

关键词： Galaxy: disk -- quasars: emission lines -- reference systems -- proper motions -- ISM:kinematics and dynamics

Collapsin response mediator protein-2 plays a major protective role in acute axonal degeneration

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Neural Regeneration Research 2017年第5期12卷 692-695页

作者： jian-nan zhang Jan C.Koch Department of Neurology University Medicine GottingenGottingenGermany Department of Neurobiology Beijing Institute for Brain Disorders and Key Laboratory for Neurodegenerative Disease of the Ministry of EducationCapital Medical UniversityBeijingChina Center for nanoscale Microscopy and Molecular Physiology of the Brain(CNMPB) GottingenGermany

Axonal degeneration is a key pathological feature in many neurological diseases. It often leads to persistent deficits due to the inability of axons to regenerate in the central nervous system. Therefore therapeutic approaches should optimally both attenuate axonal degeneration and foster axonal regeneration. Compelling evidence suggests that collapsin response mediator protein-2（CRMP2） might be a molecular target fulfilling these requirements. In this mini-review, we give a compact overview of the known functions of CRMP2 and its molecular interactors in neurite outgrowth and in neurodegenerative conditions. Moreover, we discuss in detail our recent findings on the role of CRMP2 in acute axonal degeneration in the optic nerve. We found that the calcium influx induced by the lesion activates the protease calpain which cleaves CRMP2, leading to impairment of axonal transport. Both calpain inhibition and CRMP2 overexpression effectively protected the proximal axons against acute axonal degeneration. Taken together, CRMP2 is further characterized as a central molecular player in acute axonal degeneration and thus evolves as a promising therapeutic target to both counteract axonal degeneration and foster axonal regeneration in neurodegenerative and neurotraumatic diseases.

关键词： collapsin response mediator protein-2 CRMP2 axonal regeneration optic nerve cruch axonaldegeneration calpain axonal transport

Metal-organic nanosheet assembly ions sieving membrane for precise lithium ion and anion/solvent separation toward robust lithium metal battery

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Science China Chemistry 2024年第10期67卷 3320-3327页

作者： jian-Qiang Shen Tian-Tian Zhao Ying-Li Song Lingjuan zhang Ya-nan Gao Xiao-nan Cui Peng Zhao Xian-Ming zhang Key Laboratory of Magnetic Molecules&Magnetic Information Materials Ministry of EducationSchool of Chemistry&Material ScienceShanxi Normal UniversityTaiyuan 030031China College of Chemistry and Chemical Engineering Taiyuan University of TechnologyTaiyuan 030024China

Metal-organic nanosheets(MONs)as a novel material with tunable pore structures and low mass transfer resistance,have emerged as molecular sieves for the separation of gases and *** theory,they can also serve as ion sieves for lithium metal batteries(LMBs),realizing the high-energy and dendritic free ***,there are rarely relevant reports,because it is difficult to simultaneously balance efficient ion sieving ability,high ion passing rate and high electrochemical ***,we synthesized a stable ultrathin MON[Zn_(2)(Bim)_(4)]([Zn_(2)(Bim)_(4)]nanosheet,HBim=benzimidazolate),which can achieve both efficient lithium ion sieving ability,high lithium ion passing rate and high electrochemical stability at the same *** separator assembled by this MON exhibits high Li^(+)transfer number of 0.81 due to the accurate lithium ion and anion/solvent *** battery containing such separator shows high lithium ionic conductivity of 0.74 m S cm^(-1)and low activation energy of 0.099 eV,which can be attributed to the nanometer level thickness and the ion sieving *** is more,we realized the application of MONs-based ion sieves in LMBs with intercalation cathodes for the first *** the LiFePO_(4)|Li battery with as-assembled separator demonstrates improved Coulombic efficiency(>99%)and significantly extended cycling life(>1600 cycles)with 80%capacity retention.

关键词： lithium sieving membrane metal-organic nanosheets lithium metal battery lithium ion and anion separation lithium ion and solvent separation

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