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Physical properties and chemical composition of the cores in the California molecular cloud
Zhang, Guo-Yin,Xu, Jin-Long,Vasyunin, A. I.,Semenov, D. A.,Wang, Jun-Jie,Dib, Sami,Liu, Tie,Liu, Sheng-Yuan,Zhang, Chuan-Peng,Liu, Xiao-Lan,Wang, Ke,Li, Di,Wu, Zhong-Zu,Yuan, Jing-Hua,Li, Da-Lei,Gao, Springer-Verlag 2018 Astronomy and astrophysics Vol.620 No.-
<P><I>Aims.</I> We aim to reveal the physical properties and chemical composition of the cores in the California molecular cloud (CMC), so as to better understand the initial conditions of star formation.</P><P><I>Methods.</I> We made a high-resolution column density map (18.2′′) with <I>Herschel</I> data, and extracted a complete sample of the cores in the CMC with the fellwalker algorithm. We performed new single-pointing observations of molecular lines near 90 GHz with the IRAM 30m telescope along the main filament of the CMC. In addition, we also performed a numerical modeling of chemical evolution for the cores under the physical conditions.</P><P><I>Results.</I> We extracted 300 cores, of which 33 are protostellar and 267 are starless cores. About 51% (137 of 267) of the starless cores are prestellar cores. Three cores have the potential to evolve into high-mass stars. The prestellar core mass function (CMF) can be well fit by a log-normal form. The high-mass end of the prestellar CMF shows a power-law form with an index <I>α</I> = −0.9 ± 0.1 that is shallower than that of the Galactic field stellar mass function. Combining the mass transformation efficiency (<I>ε</I>) from the prestellar core to the star of 15 ± 1% and the core formation efficiency (CFE) of 5.5%, we suggest an overall star formation efficiency of about 1% in the CMC. In the single-pointing observations with the IRAM 30m telescope, we find that 6 cores show blue-skewed profile, while 4 cores show red-skewed profile. [HCO<SUP>+</SUP>]/[HNC] and [HCO<SUP>+</SUP>]/[N2H<SUP>+</SUP>] in protostellar cores are higher than those in prestellar cores; this can be used as chemical clocks. The best-fit chemical age of the cores with line observations is ~5 × 10<SUP>4</SUP> yr.</P>
Fazhi Xie,Feng-Jun Zhang,Han Xuan,Yejun Ge,Yin Wang,Guolian Li,Lei Zhu,오원춘 한국세라믹학회 2014 한국세라믹학회지 Vol.51 No.5
In this work, a new method that utilizes L-cysteine salicylaldehyde Schiff-base modified macroporous polystyrene resin (PSCSC)as an effective sorbent has been developed for preconcentration of trace cadmium and lead in environmental water samples. The effect of pH, the contact time, the elution conditions, the flow rate, the initial concentration of target metal ions, andthe effects of interfering ions on the preconcentration of the analytes were investigated. The maximum adsorption capacity of PSCSCunder optimum conditions for cadmium and lead were found to be 6.03 - 18.17 mg/g and 12.58 - 36.13 mg/g when the initialconcentration of metal ions between 5.0 - 90 mg/L. The limits of detection for cadmium and lead were 2.46 ng/L and 0.52 μg/L,with a preconcentration factor of 200. The developed method has been validated by analyzing certified reference material andsuccessfully applied for the enrichment and determination of trace cadmium and lead from environmental water samples.
( Qiu Chun Li ),( Ya Chen Hu ),( Yin Fei Wu ),( Xiao Chun Wang ),( Xiao Lei Xie ),( Ming Xin Tao ),( Jun Lei Yin ),( Zhi Jie Lin ),( Yang Jiao ),( Li Juan Xu ),( Xinan Jiao ) 한국미생물 · 생명공학회 2015 Journal of microbiology and biotechnology Vol.25 No.5
As Salmonella enterica serovar Pullorum remains a major economic problem for the poultry industries of countries with no efficient control measures, we presented a multidrug resistance strain S06004 (isolated from a clinically sick chicken in China in 2006) for genome sequencing. The genome comparison showed that the strain contained two prophages, the ST104 and prophage-4 (Fels2) of E. coli LF82, which were not detected in the only published genomes of S. Pullorum RKS5078 and CDC1983-67. In addition, the GyrA Ser83 point mutation, drugresistant genes, and many antibiotic pump systems that are present in S06004 may be contributing to the multidrug resistance of this strain.