With the aim of gathering temporal trends on bacterial epidemiology and resistance from multiple laboratories in China, the CHINET surveillance system was organized in 2005. Antimicrobial ...susceptibility testing was carried out according to a unified protocol using the Kirby-Bauer method or automated systems. Results were analyzed according to Clinical and Laboratory Standards Institute (CLSI) 2014 definitions. Between 2005 and 2014, the number of bacterial isolates ranged between 22 774 and 84 572 annually. Rates of extended-spectrum β-lactamase production among Escherichia coli isolates were stable, between 51.7 and 55.8%. Resistance of E. coli and Klebsiella pneumoniae to amikacin, ciprofloxacin, piperacillin/tazobactam and cefoperazone/sulbactam decreased with time. Carbapenem resistance among K. pneumoniae isolates increased from 2.4 to 13.4%. Resistance of Pseudomonas aeruginosa strains against all of antimicrobial agents tested including imipenem and meropenem decreased with time. On the contrary, resistance of Acinetobacter baumannii strains to carbapenems increased from 31 to 66.7%. A marked decrease of methicillin resistance from 69% in 2005 to 44.6% in 2014 was observed for Staphylococcus aureus. Carbapenem resistance rates in K. pneumoniae and A. baumannii in China are high. Our results indicate the importance of bacterial surveillance studies.
Abstract
We present the second release of value-added catalogues of the LAMOST Spectroscopic Survey of the Galactic Anticentre (LSS-GAC DR2). The catalogues present values of radial velocity Vr, ...atmospheric parameters – effective temperature Teff, surface gravity log g, metallicity Fe/H, α-element to iron (metal) abundance ratio α/Fe (α/M), elemental abundances C/H and N/H and absolute magnitudes MV and $M_{K_{\rm s}}$ deduced from 1.8 million spectra of 1.4 million unique stars targeted by the LSS-GAC since 2011 September until 2014 June. The catalogues also give values of interstellar reddening, distance and orbital parameters determined with a variety of techniques, as well as proper motions and multiband photometry from the far-UV to the mid-IR collected from the literature and various surveys. Accuracies of radial velocities reach 5 km s−1 for the late-type stars, and those of distance estimates range between 10 and 30 per cent, depending on the spectral signal-to-noise ratios. Precisions of Fe/H, C/H and N/H estimates reach 0.1 dex, and those of α/Fe and α/M reach 0.05 dex. The large number of stars, the contiguous sky coverage, the simple yet non-trivial target selection function and the robust estimates of stellar radial velocities and atmospheric parameters, distances and elemental abundances make the catalogues a valuable data set to study the structure and evolution of the Galaxy, especially the solar-neighbourhood and the outer disc.
Abstract
We present a three-dimensional (3D) extinction analysis in the region towards the supernova remnant (SNR) S147 (G180.0–1.7) using multiband photometric data from the Xuyi Schmidt Telescope ...Photometric Survey of the Galactic Anticentre (XSTPS-GAC), 2MASS and WISE. We isolate a previously unrecognized dust structure likely to be associated with SNR S147. The structure, which we term as ‘S147 dust cloud’, is estimated to have a distance d = 1.22 ± 0.21 kpc, consistent with the conjecture that S147 is associated with pulsar PSR J0538 + 2817. The cloud includes several dense clumps of relatively high extinction that locate on the radio shell of S147 and coincide spatially with the CO and gamma-ray emission features. We conclude that the usage of CO measurements to trace the SNR associated MCs is unavoidably limited by the detection threshold, dust depletion and the difficulty of distance estimates in the outer Galaxy. 3D dust extinction mapping may provide a better way to identify and study SNR–MC interactions.
We present a catalog of 5290 RR Lyrae stars (RRLs) with metallicities estimated from spectra of the LAMOST Experiment for Galactic Understanding and Exploration (LEGUE) and the Sloan Extension for ...Galactic Understanding and Exploration (SEGUE) surveys. Nearly 70% of them (3642 objects) also have systemic radial velocities measured. Given the pulsating nature of RRLs, metallicity estimates are based on spectra of individual exposures that have been matched with their synthetic templates. The systemic radial velocities are measured by fitting the observed velocity as a function of phase assuming an empirical pulsating velocity template curve. Various tests show that our analyses yield metallicities with a typical precision of 0.20 dex and systemic radial velocities with uncertainties ranging from 5 to 21 km s−1 (depending on the number of radial-velocity measurements available for a given star). Based on the well-calibrated near-infrared PMW1Z or , and MV-Fe/H relations, precise distances are derived for these RRLs. Finally, we include Gaia DR2 proper motions in our catalog. The catalog should be very useful for various Galactic studies, especially of the Galactic halo.
A highly pathogenic pig disease emerged in China in 2006, which was characterized by prolonged high fever, red discoloration of the body, and blue ears associated with high mortality. Porcine ...reproductive and respiratory syndrome virus (PRRSV) was isolated as the single most prominent virus in the samples collected from affected pigs. The full-length genomic sequence of the virus revealed two distinct deletions in the non-structural protein 2 (NSP2) in comparison to all previously reported North American genotype PRRSV. Through extensive surveys in 14 different provinces, 56 additional PRRSV isolates were obtained from affected farms. All of the isolates were found to contain identical deletions in NSP2. To confirm the etiology, eight 60-day-old PRRSV-free pigs were divided into two groups and the test group was intranasally infected at a titer of 2 x 10⁵.⁰ tissue culture infectious dose 50 per pig. The inoculated pigs all died at 7, 8, 12, 16, or 21 days post-inoculation with their clinical and pathological findings similar to those in the field. The viruses recovered from dead pigs were identical to the inoculated virus in NSP2 and GP5 genes. Our study shows that the recently emerged PRRSV in China is characterized by two discontiguous deletions in NSP2 and is the cause for the current epizootics in China.
Single-phase equiatomic CoCrFeMnNi high-entropy alloy (HEA) specimens with three different grain sizes (0.65 μm, 2.1 μm and 105 μm) were processed by cold rolling and annealing treatment. Tensile ...properties were investigated over a broad temperature range from 77 K to 873 K. Superior strength-ductility balance can be achieved by refining grain size and decreasing temperature. The Hall-Petch relationship was well fitted, and the fitting parameters have a negative relation with temperature. The thermal and athermal contributions to the yield strength were revealed. This work has unveiled the superior mechanical property of HEAs at cryogenic temperatures.
•The Hall-Petch relationships for CoCrFeMnNi high-entropy alloys (HEAs) were well fitted in large temperature range.•The Hall-Petch slope and friction stress of the CoCrFeMnNi HEAs have a negative relation with temperature.•Athermal contribution and grain size (d) follow a Hall-Petch relation, while thermal part is related to temperature and d.•Superior strength and ductility for CoCrFeMnNi HEAs were achieved by refining grain size and decreasing temperature.
We present a new catalog of 18080 radial velocity (RV) standard stars selected from the APOGEE data. These RV standard stars are observed at least three times and have a median stability (3 RV) ...around 240 m s−1 over a time baseline longer than 200 days. They are largely distributed in the northern sky and could be extended to the southern sky by the future APOGEE-2 survey. Most of the stars are red giants (J − Ks ≥ 0.5) owing to the APOGEE target selection criteria. Only about 10 per cent of them are main-sequence stars. The H-band magnitude range of the stars is 7-12.5 mag with the faint limit much fainter than the magnitudes of previous RV standard stars. As an application, we show the new set of standard stars to determine the RV zero points of the RAVE, the LAMOST, and the Gaia-RVS Galactic spectroscopic surveys.
The tensile and high-cycle fatigue tests of Fe-30Mn-0.9C twinning-induced plasticity (TWIP) steel after 30%, 60% and 70% pre-straining were performed. Meanwhile, the surface damage morphologies of ...post-fatigue specimens and microstructure evolutions of pre-strained and post-fatigue pre-strained specimens were also investigated. It is found that the fatigue properties of the TWIP steel can be effectively improved through pre-straining, because the pre-straining can change the fatigue strength coefficient and exponent, respectively. The improvement of fatigue strength coefficient may be attributed to the strengthening mechanisms induced by both twin boundaries and dislocations; while the variation of fatigue strength exponent should be resulted from the combined effects of deformation homogeneity and slip reversibility, as well as the internal damages. Furthermore, the detailed mechanisms associated with the variations of fatigue strength coefficient and exponent were discussed. This study may enrich the fundamental knowledge about how to improve the high-cycle fatigue properties of TWIP steels.
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