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.
The natural resonance appears at 16
GHz for (Fe, Ni)/C nanocapsules with (Fe, Ni) alloys as cores and graphite as shells. Reflection loss (RL) exceeding −10
dB was obtained in the whole Ku-band ...(12.4–18
GHz) for an absorber thickness of 2.0
mm, while it exceeds −20
dB over the 13.6–16.6
GHz range. In addition, the bandwidth does not change dramatically for the thicknesses of 1.87–2.1
mm for the RL values exceeding −10
dB. The (Fe, Ni)/C nanocapsules with wide bandwidth absorption can be used as excellent electromagnetic-wave-absorption materials in the whole Ku-band.
An ideal semiconducting material should simultaneously hold a considerable direct band gap and a high carrier mobility. A 2D planar compound consisting of zigzag chains of C–C and B–N atoms, denoted ...as BC2N, would be a good candidate. It has a direct band gap of 2 eV, which can be further tuned by changing the layer number. At the same time, our first-principles calculations show that few-layer BC2N possesses a high carrier mobility. The carrier mobility of around one million sqaure centimeters per volt-second is obtained at its three-layer. As our study demonstrated, few-layer BC2N has potential applications in nanoelectronics and optoelectronics.
The topological phases in materials have been studied in recent decades for their unique boundary states and transport properties. Photonic systems with band structures embrace the topological phases ...closely, where they not only provide platforms to testify the topological band theory, but also shed light on designing novel optical devices. In this review, we present exciting developments, supported by brief descriptions of prominent milestones of topological phases in photonic systems in recent years. These studies may sustain further developments of optical devices and offer novel methods for light manipulations.
An essential starting point when investigating the potential role of human expired aerosols in the transmission of disease is to gain a comprehensive knowledge of the expired aerosol generation ...process, including the aerosol size distribution, the various droplet production mechanisms involved and the corresponding sites of production within the respiratory tract. In order to approach this level of understanding we have integrated the results of two different investigative techniques spanning 3 decades of particle size from 700
nm to 1
mm, presenting a single composite size distribution, and identifying the most prominent modes in that distribution. We link these modes to specific sites of origin and mechanisms of production. The data for this were obtained using the Aerodynamic Particle Sizer (APS) covering the range 0.7≤
d≤20
μm and Droplet Deposition Analysis (DDA) covering the range
d≥20
μm.
In the case of speech three distinct droplet size distribution modes were identified with count median diameters at 1.6, 2.5 and 145
μm. In the case of voluntary coughing the modes were located at 1.6, 1.7 and 123
μm. The modes are associated with three distinct processes: one occurring deep in the lower respiratory tract, another in the region of the larynx and a third in the upper respiratory tract including the oral cavity. The first of these, the Bronchiolar Fluid Film Burst (BFFB or B) mode contains droplets produced during normal breathing. The second, the Laryngeal (L) mode is most active during voicing and coughing. The third, the Oral (O) cavity mode is active during speech and coughing. The number of droplets and the volume of aerosol material associated with each mode of aerosol production during speech and coughing is presented. The size distribution is modeled as a tri-modal lognormal distribution dubbed the Bronchiolar/Laryngeal/Oral (B.L.O.) tri-modal model.
► We investigate the role of human expired aerosols in disease transmission. ► Three droplet size distribution modes were identified during speech and coughing. ► We present the number of droplets and volume of aerosol material for each mode. ► Results provide insight into expired aerosol generation process.
Blood-circulating microRNAs (miRNAs) have been reported to be used as potential biomarkers in various cancers. MiR-101 has been found to act as a tumor suppressor in many tumor types, but little is ...known for osteosarcoma. The purpose of this study was to investigate miR-101 expression in osteosarcoma patients and assess its correlation with clinical features and prognosis. Serum samples from 152 osteosarcoma patients and 70 healthy controls were detected using quantitative reverse-transcription polymerase chain reaction (qRT-PCR). The data showed that miR-101 expression levels were remarkably underexpressed in serum samples from osteosarcoma patients compared to controls, and the post-treatment serum miR-101 expression was significantly higher than that in the pre-treatment expression. Low serum miR-101 expression was positively associated with advanced clinical stage and distant metastasis. Receiver operating characteristic (ROC) curve analysis showed that serum miR-101 could serve as a useful marker for osteosarcoma diagnosis, with a high sensitivity and specificity. Moreover, patients with high miR-101 expression had longer overall survival and recurrence free survival than those with low miR-101 expression. In addition, both univariate and multivariate analyses showed that serum miR-101 downregulation was associated with shorter overall survival and recurrence free survival. Our present results implicated serum miR-101 might be a useful biomarker for the clinical diagnosis and prognosis of osteosarcoma.
Inspiration for molecular design and construction can be derived from mathematically based structures. In the quest for new materials, the adaptation of new building blocks can lead to unexpected ...results. Towards these ends, the quantitative single‐step self‐assembly of a shape‐persistent, Archimedean‐based building block, which generates the largest molecular sphere (a cuboctahedron) that has been unequivocally characterized by synchrotron X‐ray analysis, is described. The unique properties of this new construct give rise to a dilution‐based transformation into two identical spheres (octahedra) each possessing one half of the molecular weight of the parent structure; concentration of this octahedron reconstitutes the original cuboctahedron. These chemical phenomena are reminiscent of biological fission and fusion processes. The large 6 nm cage structure was further analyzed by 1D and 2D NMR spectroscopy, mass spectrometry, and collision cross‐section analysis. New routes to molecular encapsulation can be envisioned.
Bigger and bigger: A giant, 6 nm, shape‐persistent, Archimedean‐inspired cuboctahedron was quantitatively assembled and characterized by synchrotron X‐ray analysis. The structure consists of one type of X‐shaped, terpyridine‐based ligand and 24 metal ions (Zn2+ or Cd2+). A fusion–fission switching process between a cuboctahedron and an octahedron could be induced by changing the concentration or the counterions.
Size distributions of expiratory droplets expelled during coughing and speaking and the velocities of the expiration air jets of healthy volunteers were measured. Droplet size was measured using the ...interferometric Mie imaging (IMI) technique while the particle image velocimetry (PIV) technique was used for measuring air velocity. These techniques allowed measurements in close proximity to the mouth and avoided air sampling losses. The average expiration air velocity was 11.7
m/s for coughing and 3.9
m/s for speaking. Under the experimental setting, evaporation and condensation effects had negligible impact on the measured droplet size. The geometric mean diameter of droplets from coughing was 13.5
μm and it was 16.0
μm for speaking (counting 1–100). The estimated total number of droplets expelled ranged from 947 to 2085 per cough and 112–6720 for speaking. The estimated droplet concentrations for coughing ranged from 2.4 to 5.2
cm
−3 per cough and 0.004–0.223
cm
−3 for speaking.
ABSTRACT
High time resolution and accuracy are of critical importance in the studies of timing analysis and time delay localization of gamma-ray bursts (GRBs), soft gamma-ray repeaters (SGRs) and ...pulsars. The Gravitational wave high-energy Electromagnetic Counterpart All-sky Monitor (GECAM) consisting of two micro-satellites, GECAM-A and GECAM-B, launched on 2020 December 10, is aimed at monitoring and locating X-ray and GRBs all over the sky. To achieve its scientific goals, GECAM is designed to have the highest time resolution (0.1 $\mu {\rm s}$) among all GRB detectors ever flown. Here, we make a comprehensive time calibration campaign including both on-ground and on-orbit tests to derive not only the relative time accuracy of GECAM satellites and detectors, but also the absolute time accuracy of GECAM-B. Using the on-ground calibration with a $\rm ^{22}Na$ radioactive source, we find that the relative time accuracy between GECAM-A and GECAM-B is about 0.15 $\mu {\rm s}$ (1σ). To measure the relative time accuracy between all detectors of a single GECAM satellite, cosmic-ray events detected on orbit are utilized since they could produce many secondary particles simultaneously record by multiple detectors. We find that the relative time accuracy among all detectors onboard GECAM-B is about 0.12 $\mu {\rm s}$ (1σ). Finally, we use the novel Li-CCF method to perform the absolute time calibration with Crab pulsar and SGR J1935+2154, both of which were jointly observed by GECAM-B and Fermi/GBM, and obtain that the time difference between GECAM-B and Fermi/GBM is 3.06 ± 6.04 $\mu {\rm s}$ (1σ).
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