Metal-deficient stars are regarded as fossils of the early generation of stars and therefore make crucial observational targets related to stellar astrophysics. They provide fundamental information and insights on pro...Metal-deficient stars are regarded as fossils of the early generation of stars and therefore make crucial observational targets related to stellar astrophysics. They provide fundamental information and insights on properties of the very early stage of the chemical history of the Galaxy and have been investigated for decades. The unique design of the Guoshoujing Telescope （LAMOST）, such as its large field and multi-object observational capability, enables it to be an excellent tool for searching for these metal-poor stars in the Milky Way. This work reports the result of test observations which search for metal-poor stars with LAMOST, during which nine candidate metal-poor stars with [Fe/H] ≤ - 1.0 were newly detected based on the low-resolution spectroscopic observations of the LAMOST commissioning data. The sample of stars demonstrates the efficiency of selecting from the input catalog, as well as the ability of LAMOST to enlarge the sample of metal-poor stars in the Milky Way. Furthermore, the sample of stars could be used for future calibrations of the LAMOST stellar pa- rameter pipeline.展开更多
To evaluate the effect of components in Guanxin Ⅱ prescription on the pharmacokinetic profiles of paeoniflorin. Plasma concentration of Paeoniflorin in rats after intravenous injection of Paronia Pall Extract （PPE）...To evaluate the effect of components in Guanxin Ⅱ prescription on the pharmacokinetic profiles of paeoniflorin. Plasma concentration of Paeoniflorin in rats after intravenous injection of Paronia Pall Extract （PPE） and oral administration of PPE and three types of decoctions in Guanxin Ⅱ prescription, respectively, were determined by HPLC analyses. NONMEM （nonlinear mixed-effect modeling） method was used to analyze full set of pharmacokinetic data directly. A two-compartment model with first-order degradation in absorption compartment was employed for the data analysis. The mean of population parameters, CL1, V1, CL2, V2, Ka0, and Kal, were measured to be 0.509 L/h, 0.104 L, 0.113 L/h, 0.123 L, 0.135/h, and 0.0135/h, respectively. Inter-individual variabilities were estimated and dose formulation （DF） was identified as a significant covariate of Ka 1, Ka0, and V1. It is concluded that the pharmacokinetic behaviors of paeoniflorin in rats can alter with different dose formulations.展开更多
We report the discovery of an extremely metal-poor（EMP） giant,LAMOST J110901.22＋075441.8, which exhibits a large excess of r-process elements with [Eu/Fe] ～ ＋1.16. The star is one of the newly discovered EMP star...We report the discovery of an extremely metal-poor（EMP） giant,LAMOST J110901.22＋075441.8, which exhibits a large excess of r-process elements with [Eu/Fe] ～ ＋1.16. The star is one of the newly discovered EMP stars identified from the LAMOST low-resolution spectroscopic survey and a highresolution follow-up observation with the Subaru Telescope. Stellar parameters and elemental abundances have been determined from the Subaru spectrum. Accurate abundances for a total of 23 elements including 11 neutron-capture elements from Sr through Dy have been derived for LAMOST J110901.22＋075441.8. The abundance pattern of LAMOST J110901.22＋075441.8 in the range of C through Zn is in line with the ＂normal＂ population of EMP halo stars, except that it shows a notable underabundance in carbon. The heavy element abundance pattern of LAMOST J110901.22＋075441.8 is in agreement with other well studied cool r-II metal-poor giants such as CS 22892-052 and CS 31082-001. The abundances of elements in the range from Ba through Dy match the scaled solar r-process pattern well.LAMOST J110901.22＋075441.8 provides the first detailed measurements of neutroncapture elements among r-II stars at such low metallicity with [Fe/H]-3.4, and exhibits similar behavior as other r-II stars in the abundance ratio of Zr/Eu as well as Sr/Eu and Ba/Eu.展开更多
We report on a pilot study on identifying metal-poor stars pre-enriched by Pair-Instability Supernovae（PISNe）.Very massive,first generation（Population Ⅲ） stars（140 M⊙≤M≤260 M⊙）end their lives as PISNe,which...We report on a pilot study on identifying metal-poor stars pre-enriched by Pair-Instability Supernovae（PISNe）.Very massive,first generation（Population Ⅲ） stars（140 M⊙≤M≤260 M⊙）end their lives as PISNe,which have been predicted by theories,but no relics of PISNe have been observed yet.Among the distinct characteristics of the yields of PISNe,as predicted by theoretical calculations,are a strong odd-even effect,and a strong overabundance of Ca with respect to iron and the solar ratio.We use the latter characteristic to identify metal-poor stars in the Galactic halo that have been pre-enriched by PISNe,by comparing metallicites derived from strong, co-added Fe lines detected in low-resolution（i.e.,R=λ/△λ～2000）spectra of the Sloan Digital Sky Survey（SDSS）,with metallicities determined by the SDSS Stellar Parameters Pipeline（SSPP）.The latter are based on the strength of the CaⅡ K line and assumptions on the Ca/Fe abundance ratio.Stars are selected as candidates if their metallicity derived from Fe lines is significantly lower than the SSPP metallicities.In a sample of 12 300 stars for which SDSS spectroscopy is available,we have identified 18 candidate stars.Higher resolution and signal-to-noise ratio spectra of these candidates are being obtained with the Very Large Telescope of the European Southern Observatory and the XSHOOTER spectrograph,to determine their abundance patterns,and to verify our selection method.We plan to apply our method to the database of several million stellar spectra to be acquired with the Guo Shou Jing Telescope （LAMOST）in the next five years.展开更多
Aphis glycines （Hemiptera： Aphididae） is considered as a cosmopolitan pest of cultivated soybean, major difficulties in its control measures may be due to its higher genetic diversity; however, the knowledge about ...Aphis glycines （Hemiptera： Aphididae） is considered as a cosmopolitan pest of cultivated soybean, major difficulties in its control measures may be due to its higher genetic diversity; however, the knowledge about population genetic diversity of this species is limited. This study aimed to represent the genetic differentiation among different geographic populations of soybean aphid in Northeast China. In order to investigate and assess the genetic diversity, genetic differentiation, molecular variance, population structure, ecological importance and evolutionary history of A. glycines, we sequenced a fragment of one protein-coding gene, the cytochrome c oxidase I/of mitochondrial DNA gene. The results showed that four haplotypes were defined among CO 11 gene of 180 sequences of soybean aphid in Northeast China including H1 shared by all the populations. Lower haplotype diversity （Hd=0.3590± 0.0420） and nucleotide diversity （Pi=0.0012±0.0002） were observed and high gene flow was detected in every two populations, while most of the variation （80.81%） arose from variability within A. glycines from individuals. Low genetic differentiation and high gene flow （Nm=2.106） indicated a high migration rate between the populations, which might reveal that gene flow in different geographic populations did not affect by geographical distance. The phylogenetic tree and the haplotype network ofA. glycines were obtained based on sequences of CO Ⅱ gene, there were no significant genealogical branches or clusters recognized in NJ tree, and no clear distribution, delineation of haplotypes were demonstrated in the haplotype network according to geographical location. This study rejected the vicariance hypothesis： geographic isolation could be a barrier and it restricted A. glycines gene flow among 10 populations.展开更多
基金The Large Sky Area Multi-Object Fiber Spectroscopic Telescope (LAMOST,now called the Guoshoujing Telescope) is a National Major Scientific Project built by the Chinese Academy of Sciencessupported by the National Natural Science Foundation of China (NSFC) (Grant No.10821061)+2 种基金the National Basic Research Program of China (Program 973Grant No.2007CB815103),and it has made use of the CAS database of SDSS3the Global Networks program of the University of Heidelberg,and from Deutsche Forschungsgemeinschaft under grant CH 214/5-1
文摘Metal-deficient stars are regarded as fossils of the early generation of stars and therefore make crucial observational targets related to stellar astrophysics. They provide fundamental information and insights on properties of the very early stage of the chemical history of the Galaxy and have been investigated for decades. The unique design of the Guoshoujing Telescope （LAMOST）, such as its large field and multi-object observational capability, enables it to be an excellent tool for searching for these metal-poor stars in the Milky Way. This work reports the result of test observations which search for metal-poor stars with LAMOST, during which nine candidate metal-poor stars with [Fe/H] ≤ - 1.0 were newly detected based on the low-resolution spectroscopic observations of the LAMOST commissioning data. The sample of stars demonstrates the efficiency of selecting from the input catalog, as well as the ability of LAMOST to enlarge the sample of metal-poor stars in the Milky Way. Furthermore, the sample of stars could be used for future calibrations of the LAMOST stellar pa- rameter pipeline.
基金National Natural Science Foundation (Grant No. 30472165)
文摘To evaluate the effect of components in Guanxin Ⅱ prescription on the pharmacokinetic profiles of paeoniflorin. Plasma concentration of Paeoniflorin in rats after intravenous injection of Paronia Pall Extract （PPE） and oral administration of PPE and three types of decoctions in Guanxin Ⅱ prescription, respectively, were determined by HPLC analyses. NONMEM （nonlinear mixed-effect modeling） method was used to analyze full set of pharmacokinetic data directly. A two-compartment model with first-order degradation in absorption compartment was employed for the data analysis. The mean of population parameters, CL1, V1, CL2, V2, Ka0, and Kal, were measured to be 0.509 L/h, 0.104 L, 0.113 L/h, 0.123 L, 0.135/h, and 0.0135/h, respectively. Inter-individual variabilities were estimated and dose formulation （DF） was identified as a significant covariate of Ka 1, Ka0, and V1. It is concluded that the pharmacokinetic behaviors of paeoniflorin in rats can alter with different dose formulations.
基金the paper.H.N.L.and G.Z.acknowledge supports by the National Natural Science Foundation of China (Grant Nos.11103030, 11233004 and 11390371)W.A.and T.S.are supported by the JSPS Grant-in-Aid for Scientific Research (S: 23224004)+1 种基金S.H.is supported by the JSPS Grant-in-Aid for Scientific Research (c:26400231)N.C.acknowledges support from Sonderforschungsbereich 881 "The Milky Way System" (subproject A4) of the German Research Foundation (DFG)
文摘We report the discovery of an extremely metal-poor（EMP） giant,LAMOST J110901.22＋075441.8, which exhibits a large excess of r-process elements with [Eu/Fe] ～ ＋1.16. The star is one of the newly discovered EMP stars identified from the LAMOST low-resolution spectroscopic survey and a highresolution follow-up observation with the Subaru Telescope. Stellar parameters and elemental abundances have been determined from the Subaru spectrum. Accurate abundances for a total of 23 elements including 11 neutron-capture elements from Sr through Dy have been derived for LAMOST J110901.22＋075441.8. The abundance pattern of LAMOST J110901.22＋075441.8 in the range of C through Zn is in line with the ＂normal＂ population of EMP halo stars, except that it shows a notable underabundance in carbon. The heavy element abundance pattern of LAMOST J110901.22＋075441.8 is in agreement with other well studied cool r-II metal-poor giants such as CS 22892-052 and CS 31082-001. The abundances of elements in the range from Ba through Dy match the scaled solar r-process pattern well.LAMOST J110901.22＋075441.8 provides the first detailed measurements of neutroncapture elements among r-II stars at such low metallicity with [Fe/H]-3.4, and exhibits similar behavior as other r-II stars in the abundance ratio of Zr/Eu as well as Sr/Eu and Ba/Eu.
基金J.R.and N.C.acknowledge financial support by the Global Networks program of Universitt Heidelbergby Deutsche Forschungsgemeinschaft through grant CH 214/5-1+3 种基金Sonderforschungsbereich SFB 881"The Milky Way System"(subproject A4)J.Ren and G.Zhao acknowledge the support by the National Natural Science Foundation of China(Grant Nos.11233004 and 11243004)J.Ren acknowledges partial financial support from the Shandong University Fund for Graduate Study AbroadFunding for the SDSS and SDSS-II has been provided by the Alfred P.Sloan Foundation,the Participating Institutions,the National Science Foundation,the U.S.Department of Energy,the National Aeronautics and Space Administration,the Japanese Monbukagakusho,the Max Planck Society,and the Higher Education Funding Council for England
文摘We report on a pilot study on identifying metal-poor stars pre-enriched by Pair-Instability Supernovae（PISNe）.Very massive,first generation（Population Ⅲ） stars（140 M⊙≤M≤260 M⊙）end their lives as PISNe,which have been predicted by theories,but no relics of PISNe have been observed yet.Among the distinct characteristics of the yields of PISNe,as predicted by theoretical calculations,are a strong odd-even effect,and a strong overabundance of Ca with respect to iron and the solar ratio.We use the latter characteristic to identify metal-poor stars in the Galactic halo that have been pre-enriched by PISNe,by comparing metallicites derived from strong, co-added Fe lines detected in low-resolution（i.e.,R=λ/△λ～2000）spectra of the Sloan Digital Sky Survey（SDSS）,with metallicities determined by the SDSS Stellar Parameters Pipeline（SSPP）.The latter are based on the strength of the CaⅡ K line and assumptions on the Ca/Fe abundance ratio.Stars are selected as candidates if their metallicity derived from Fe lines is significantly lower than the SSPP metallicities.In a sample of 12 300 stars for which SDSS spectroscopy is available,we have identified 18 candidate stars.Higher resolution and signal-to-noise ratio spectra of these candidates are being obtained with the Very Large Telescope of the European Southern Observatory and the XSHOOTER spectrograph,to determine their abundance patterns,and to verify our selection method.We plan to apply our method to the database of several million stellar spectra to be acquired with the Guo Shou Jing Telescope （LAMOST）in the next five years.
基金Supported by the Special funds for Construction of Modern Agricultural Technology System(CARS-04)Public Welfare Industry(Agriculture)Special Fund(201103002)
文摘Aphis glycines （Hemiptera： Aphididae） is considered as a cosmopolitan pest of cultivated soybean, major difficulties in its control measures may be due to its higher genetic diversity; however, the knowledge about population genetic diversity of this species is limited. This study aimed to represent the genetic differentiation among different geographic populations of soybean aphid in Northeast China. In order to investigate and assess the genetic diversity, genetic differentiation, molecular variance, population structure, ecological importance and evolutionary history of A. glycines, we sequenced a fragment of one protein-coding gene, the cytochrome c oxidase I/of mitochondrial DNA gene. The results showed that four haplotypes were defined among CO 11 gene of 180 sequences of soybean aphid in Northeast China including H1 shared by all the populations. Lower haplotype diversity （Hd=0.3590± 0.0420） and nucleotide diversity （Pi=0.0012±0.0002） were observed and high gene flow was detected in every two populations, while most of the variation （80.81%） arose from variability within A. glycines from individuals. Low genetic differentiation and high gene flow （Nm=2.106） indicated a high migration rate between the populations, which might reveal that gene flow in different geographic populations did not affect by geographical distance. The phylogenetic tree and the haplotype network ofA. glycines were obtained based on sequences of CO Ⅱ gene, there were no significant genealogical branches or clusters recognized in NJ tree, and no clear distribution, delineation of haplotypes were demonstrated in the haplotype network according to geographical location. This study rejected the vicariance hypothesis： geographic isolation could be a barrier and it restricted A. glycines gene flow among 10 populations.
