Multidrug efflux pumps:structure, function and regulation

Infections arising from multidrug-resistant pathogenic bacteria are spreading rapidly throughout the world and threaten to become untreatable. The origins of resistance are numerous and complex, but one underlying factor is the capacity of bacteria to rapidly export drugs through the intrinsic activity of efflux pumps. In this Review, we describe recent advances that have increased our understanding of the structures and molecular mechanisms of multidrug efflux pumps in bacteria. Clinical and laboratory data indicate that efflux pumps function not only in the drug extrusion process but also in virulence and the adaptive responses that contribute to antimicrobial resistance during infection. The emerging picture of the structure, function and regulation of efflux pumps suggests opportunities for countering their activities

Broadband Multi-wavelength Properties of M87 during the 2017 Event Horizon Telescope Campaign

Abstract: In 2017, the Event Horizon Telescope (EHT) Collaboration succeeded in capturing the first direct image of the center of the M87 galaxy. The asymmetric ring morphology and size are consistent with theoretical expectations for a weakly accreting supermassive black hole of mass ∼6.5 × 109 M ⊙. The EHTC also partnered with several international facilities in space and on the ground, to arrange an extensive, quasi-simultaneous multi-wavelength campaign. This Letter presents the results and analysis of this campaign, as well as the multi-wavelength data as a legacy data repository. We captured M87 in a historically low state, and the core flux dominates over HST-1 at high energies, making it possible to combine core flux constraints with the more spatially precise very long baseline interferometry data. We present the most complete simultaneous multi-wavelength spectrum of the active nucleus to date, and discuss the complexity and caveats of combining data from different spatial scales into one broadband spectrum. We apply two heuristic, isotropic leptonic single-zone models to provide insight into the basic source properties, but conclude that a structured jet is necessary to explain M87’s spectrum. We can exclude that the simultaneous γ-ray emission is produced via inverse Compton emission in the same region producing the EHT mm-band emission, and further conclude that the γ-rays can only be produced in the inner jets (inward of HST-1) if there are strongly particle-dominated regions. Direct synchrotron emission from accelerated protons and secondaries cannot yet be excluded

The Blue‐LED‐Sensitive Naphthoquinone‐Imidazolyl Derivatives as Type II Photoinitiators of Free Radical Photopolymerization

In this work, new naphthoquinone-based photoinitiators (PIs) were synthesized and applied for the first time in free radical photopolymerization. In the presence of acrylate monomers, these PIs displayed excellent photoinitiation capabilities under blue-light (LED@405nm) irradiation in a two-component photoinitiating system where the additive was a common iodonium salt (bis-(4-tert-butylphenyl)iodonium hexafluorophosphate-Iod) or a tertiary amine (ethyl 4-dimethylaminobenzoate-EDB). In controlled tests, the polymerization performance of dye4/Iod was equal to or better than that of common commercial Type II photoinitiators (2-isopropylthioxanthone and benzophenone). Meanwhile, only a trace amount of photoinitiator was required (as low as 0.05%) to initiate the photopolymerization. It is worth noting that some of these compounds can also be used in one-component photoinitiating system (monocomponent Type II behavior) and exhibited high photoinitiation ability. A series of complementary characterization analyses of two new naphthoquinone dyes (i.e. dye 1 and dye 4) with very similar chemical structures were carried out to investigate the relevant photochemical mechanism. The results indicated that the interaction between the newly developed PIs and the additives could occur effectively, which can lead to the free radical photopolymerization. Finally, 3D printing experiments using the developed photoinitiating system were carried out by a simple and convenient Direct Laser Write (DLW) technique