Broadband multi-wavelength properties of M87 during the 2018 EHT campaign including a very high energy flaring episode

Context. The nearby elliptical galaxy M87 contains one of only two supermassive black holes whose emission surrounding the event horizon has been imaged by the Event Horizon Telescope (EHT). In 2018, more than two dozen multi-wavelength (MWL) facilities (from radio to γ-ray energies) took part in the second M87 EHT campaign. Aims. The goal of this extensive MWL campaign was to better understand the physics of the accreting black hole M87*, the relationship between the inflow and inner jets, and the high-energy particle acceleration. Understanding the complex astrophysics is also a necessary first step towards performing further tests of general relativity. Methods. The MWL campaign took place in April 2018, overlapping with the EHT M87* observations. We present a new, contemporaneous spectral energy distribution (SED) ranging from radio to very high-energy (VHE) γ-rays as well as details of the individual observations and light curves. We also conducted phenomenological modelling to investigate the basic source properties. Results. We present the first VHE γ-ray flare from M87 detected since 2010. The flux above 350 GeV more than doubled within a period of ≈36 hours. We find that the X-ray flux is enhanced by about a factor of two compared to 2017, while the radio and millimetre core fluxes are consistent between 2017 and 2018. We detect evidence for a monotonically increasing jet position angle that corresponds to variations in the bright spot of the EHT image. Conclusions. Our results show the value of continued MWL monitoring together with precision imaging for addressing the origins of high-energy particle acceleration. While we cannot currently pinpoint the precise location where such acceleration takes place, the new VHE γ-ray flare already presents a challenge to simple one-zone leptonic emission model approaches, and it emphasises the need for combined image and spectral modelling

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

Development of Potential Antitumor Agents. Synthesis and Biological Evaluation of a New Set of Sulfonamide Derivatives as Histone Deacetylase Inhibitors

A series of sulfonamide hydroxamic acids and anilides have been synthesized and studied as histone deacetylase (HDAC) inhibitors that can induce hyperacetylation of histones in human cancer cells. The inhibition of HDAC activity represents a novel approach for intervening in cell cycle regulation. The lead candidates were screened in a panel of human tumor and normal cell lines. They selectively inhibit proliferation, cause cell cycle blocks, and induce apoptosis in human cancer cells but not in normal cells. The structure−activity relationships, the antiproliferative activity, and the in vivo efficacy are described