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.
Methane monooxygenases (MMOs) mediate the facile conversion of methane into methanol in methanotrophic bacteria with high efficiency under ambient conditions. Because the selective oxidation of ...methane is extremely challenging, there is considerable interest in understanding how these enzymes carry out this difficult chemistry. The impetus of these efforts is to learn from the microbes to develop a biomimetic catalyst to accomplish the same chemical transformation. Here, we review the progress made over the past two to three decades toward delineating the structures and functions of the catalytic sites in two MMOs: soluble methane monooxygenase (sMMO) and particulate methane monooxygenase (pMMO). sMMO is a water-soluble three-component protein complex consisting of a hydroxylase with a nonheme diiron catalytic site; pMMO is a membrane-bound metalloenzyme with a unique tricopper cluster as the site of hydroxylation. The metal cluster in each of these MMOs harnesses O2 to functionalize the CH bond using different chemistry. We highlight some of the common basic principles that they share. Finally, the development of functional models of the catalytic sites of MMOs is described. These efforts have culminated in the first successful biomimetic catalyst capable of efficient methane oxidation without overoxidation at room temperature.
Context. Deep far-infrared (FIR) cosmological surveys are known to be affected by source confusion, causing issues when examining the main sequence (MS) of star forming galaxies. In the past this has ...typically been partially tackled by the use of stacking. However, stacking only provides the average properties of the objects in the stack. Aims. This work aims to trace the MS over 0.2 ≤ z < 6.0 using the latest de-blended Herschel photometry, which reaches ≈10 times deeper than the 5σ confusion limit in SPIRE. This provides more reliable star formation rates (SFRs), especially for the fainter galaxies, and hence a more reliable MS. Methods. We built a pipeline that uses the spectral energy distribution (SED) modelling and fitting tool CIGALE to generate flux density priors in the Herschel SPIRE bands. These priors were then fed into the de-blending tool XID+ to extract flux densities from the SPIRE maps. In the final step, multi-wavelength data were combined with the extracted SPIRE flux densities to constrain SEDs and provide stellar mass (M⋆) and SFRs. These M⋆ and SFRs were then used to populate the SFR-M⋆ plane over 0.2 ≤ z < 6.0. Results. No significant evidence of a high-mass turn-over was found; the best fit is thus a simple two-parameter power law of the form log(SFR) = αlog(M⋆) − 10.5 + β. The normalisation of the power law increases with redshift, rapidly at z ≲ 1.8, from 0.58 ± 0.09 at z ≈ 0.37 to 1.31 ± 0.08 at z ≈ 1.8. The slope is also found to increase with redshift, perhaps with an excess around 1.8 ≤ z < 2.9. Conclusions. The increasing slope indicates that galaxies become more self-similar as redshift increases. This implies that the specific SFR of high-mass galaxies increases with redshift, from 0.2 to 6.0, becoming closer to that of low-mass galaxies. The excess in the slope at 1.8 ≤ z < 2.9, if present, coincides with the peak of the cosmic star formation history.
Mesenchymal stem cells (MSCs) are multi-potent progenitor cells that are isolated from the bone marrow and several adult organs and tissues. These cells possess remarkable immunosuppressive ...properties and can inhibit the proliferation and function of the major immune cell populations, including T cells, B cells and natural killer (NK) cells; modulate the activities of dendritic cells (DCs); and induce regulatory T cells both in vivo and in vitro. These unique properties make MSCs ideal candidates for clinical application as immunosuppressants. The immunomodulatory effect of MSCs is mediated by a non-specific anti-proliferative action of these cells, which is dependent on cell-cell contact or secreted soluble factors such as indoleamine 2,3-dioxygenase (IDO), prostaglandin E₂ (PGE₂), nitric oxide (NO), histocompatibility leucocyte antigen-G (HLA-G), transforming growth factor (TGF)-β, interferon (IFN)-γ and interleukin (IL)-1β. Considerable progress has been obtained in preclinical studies on MSCs, including those on their ability to activate allogeneic cells. This review examines the current understanding of the immunomodulatory properties of MSCs and its therapeutic implication for immune-mediated diseases and transplant rejection.
In this work, A four-dimensional (4D) discrete chaotic map model based on quantum-Cournot duopoly game is proposed, and the dynamics of this map using bounded rationality are studied. It is observed ...that the stable region of mapping equilibrium increases with the increase of quantum entanglement γ. and the occurrence time of bifurcation and chaos delays with the increase of mapped Nash equilibrium. In addition, A novel synchronization control approach which adopts both linear and nonlinear feedback strategies is proposed by constructing a dynamic controller. The simulation results verify the effectiveness of the proposed method.
•A four-dimensional discrete chaotic map model based on quantum game is proposed.•The stable region of mapping equilibrium increases with the increase of quantum entanglement γ and the occurrence time of bifurcation and chaos delays with the increase of mapped Nash equilibrium.•A novel synchronization control approach which adopts both linear and nonlinear feedback strategies is proposed by constructing a dynamic controller. The simulation results verify the effectiveness of the proposed method.
A (2+1)-dimensional variable coefficient nonlinear Schrödinger equation (NLSE) is described under strongly nonlocal nonlinear media. The soliton cluster solutions are obtained by using the improved ...self-similar reduction and F-expansion method. The regulation of nonlinear coefficients on the dynamics of spatial optical solitons and the self-similar propagation characteristics of the optical soliton clusters are investigated. It is observed that dark solitons transmitted in nonlinear media show two different spatial distributions. It is also found that the peak intensity of the soliton cluster only fluctuates in a small range during the propagation process, but the soliton cluster after harmonic potential modulation has some loss during the propagation process. But the loss is not as dramatic as when bright solitons are modulated. A new kind of soliton cluster is formed after the modulation of dark solitons, which has great practical significance such as application in logic gates, all-optical devices.
•A (2 + 1)-dimensional variable coefficient nonlinear Schrödinger equation is studied.•The soliton cluster solutions are derived by using the self-similar method.•The proposed method has a certain significance for relevant nonlinear physics.
Summary Objective To determine whether autophagy contributes to the pathogenesis of degenerative disc disease (DDD) or retards the intervertebral disc (IVD) degeneration, and investigate the possible ...relationship between compression-induced autophagy and intracellular reactive oxygen species (ROS) in nucleus pulposus (NP) cells in vitro. Methods The autophagosome and autophagy-related markers were used to explore the role of autophagy in rat NP cells under compressive stress, which were measured directly by electronic microscopy, monodansylcadaverine (MDC) staining, immunofluorescence, western blot, and indirectly by analyzing the impact of pharmacological inhibitors of autophagy such as 3-methyladenine (3-MA) and chloroquine (CQ). And the relationship between autophagy and apoptosis was investigated by Annexin-V/propidium iodide (PI)-fluorescein staining. In addition, ROS were measured to determine whether these factors are responsible for the development of compression-induced autophagy. Results Our results indicated that rat NP cells activated autophagy in response to the same strong apoptotic stimuli that triggered apoptosis by compression. Autophagy and apoptosis were interconnected and coordinated in rat NP cells exposed to compression stimuli. Compression-induced autophagy was closely related to intracellular ROS production. Conclusions Enhanced degradation of damaged components of NP cells by autophagy may be a crucial survival response against mechanical overload, and extensive autophagy may trigger autophagic cell death. Regulating autophagy and reducing the generation of intracellular ROS may retard IVD degeneration.
We investigate the ultrafast terahertz response of electrostatically gated graphene upon optical excitation. We observe that the photoinduced terahertz absorption increases in charge neutral graphene ...but decreases in highly doped graphene. We show that this transition from semiconductor-like to metal-like response is unique for zero bandgap materials such as graphene. In charge neutral graphene photoexcited hot carriers effectively increase electron and hole densities and increase the conductivity. In highly doped graphene, however, photoexcitation does not change net conducting carrier concentration. Instead, it mainly increases electron scattering rate and reduce the conductivity.
By using homotopic mapping method, a functional is first introduced to construct the iterative relation of the equation, and the approximate expansion on the soliton solution of the corresponding ...equation is presented. The perturbation solution of the perturbed Burgers equation (PBE) is derived. In addition, the nested breather and bright–dark solitons are constructed by using auxiliary functions and the local excitation structure of the solution are considered This proposed method overcomes the limitation of classical variational iterative methods to find Lagrange factors for PDEs and can quickly approximate the exact solution of the perturbed equation. This method is simple and effective, and it has a wide range of application prospects.
•A functional is first introduced to construct the iterative relation.•The approximate expansion of the perturbed Burgers equation (PBE) is derived.•The nested breather and bright–dark solitons are constructed by auxiliary functions.•This method is simple and effective, and has a wide range of application prospects.
The nonlinear Schrödinger equation (NLSE) under nonlocal nonlinear media (NNM) is described and the approximate analytical solutions of the vector multipole solitons and vortex optical soliton ...clusters are obtained via the variational method. The results show that the structure of the optical solitons is determined by modulation depth and topological charge. In the propagation process, the spatial soliton has an observable rotation property. Under certain conditions, the rotating space modulated vortex optical solitons degenerate into circular symmetric vortex optical solitons. The results can be extended to other physical systems.
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