Sequential dissociation of ionized benzonitrile: New pathways to reactive interstellar ions and neutrals

Since benzonitrile’s discovery in the interstellar medium (ISM) in 2018, several studies have explored the strongest unimolecular dissociations of its radical cation (C6H5CN•+). However, sequential dissociation processes, which become important when ionization occurs with significant excess energy transfer, have received almost no attention to date. The present metastable dissociative ionization experiments reveal 14 different dissociations, of which 11 have never been observed before. Nine of these new reactions involve the dissociation of a fragment ion. A notable result shows that C4H2 •+ production (the second most intense fragment ion in conventional mass spectra without metastable dissociation analysis) derives from sequential dissociation via C6H4 •+ , as well as from the previously reported unimolecular dissociation of C6H5CN •+ . Furthermore, our experiments demonstrate new pathways that produce astrochemically important neutrals including HCN/CNH and CN• , as well as revealing CH• and C3H• production from ionized benzonitrile for the first time. In addition to the metastable dissociation experiments, we applied density functional theory to calculate two sequential dissociation routes and report the results of our detailed analysis of the peak shapes in a conventional mass spectrum of benzonitrile. The latter enabled the dominant ion to be identified in peaks with nearest-integer m/z values that match two conceivable ions. The present identification of C6H2N+ production using this approach allows its presence in the ISM to be inferred for the first time. This paper extends our understanding of how the dissociative ionization of benzonitrile can contribute to the abundances of radicals and other reactive species in interstellar environments

Elastic Differential Cross Sections for Electron Scattering with Dichloromethane

In the present study joint experimental and theoretical elastic differential cross sections for electron scattering from dichloromethane in the incident electron energy region 7 to 50eV are discussed

An Interferon-Related Signature in the Transcriptional Core Response of Human Macrophages to Mycobacterium tuberculosis Infection

The W-Beijing family of Mycobacterium tuberculosis (Mtb) strains is known for its high-prevalence and -virulence, as well as for its genetic diversity, as recently reported by our laboratories and others. However, little is known about how the immune system responds to these strains. To explore this issue, here we used reverse engineering and genome-wide expression profiling of human macrophage-like THP-1 cells infected by different Mtb strains of the W-Beijing family, as well as by the reference laboratory strain H37Rv. Detailed data mining revealed that host cell transcriptome responses to H37Rv and to different strains of the W-Beijing family are similar and overwhelmingly induced during Mtb infections, collectively typifying a robust gene expression signature (“THP1r2Mtb-induced signature”). Analysis of the putative transcription factor binding sites in promoter regions of genes in this signature identified several key regulators, namely STATs, IRF-1, IRF-7, and Oct-1, commonly involved in interferon-related immune responses. The THP1r2Mtb-induced signature appeared to be highly relevant to the interferon-inducible signature recently reported in active pulmonary tuberculosis patients, as revealed by cross-signature and cross-module comparisons. Further analysis of the publicly available transcriptome data from human patients showed that the signature appears to be relevant to active pulmonary tuberculosis patients and their clinical therapy, and be tuberculosis specific. Thus, our results provide an additional layer of information at the transcriptome level on mechanisms involved in host macrophage response to Mtb, which may also implicate the robustness of the cellular defense system that can effectively fight against genetic heterogeneity in this pathogen

Elastic Differential Cross Sections for Electron Scattering with Dichloromethane

1 pag., 1 fig. -- International Conference on Photonic, Electronic, and Atomic Collisions (ICPEAC) (30th. 2017. Cairns, Australia). -- Open Access funded by Creative Commons Atribution Licence 3.0In the present study joint experimental and theoretical elastic differential cross sections for electron scattering from dichloromethane in the incident electron energy region 7 to 50eV are discussed

Mycobacterium ulcerans and Buruli Ulcer

Buruli Ulcer (BU) is the third most common mycobacterium disease following only tuberculosis and leprosy. Though BU is thought to be associated with large-and small-scale disturbances to the landscape and bodies of water frequented by human populations, primary prevention of BU is difficult because the mode of transmission is not known. This chapter reviews the most common environmental risk factors for BU and recent research into understanding its transmission. It is predicted that the proteins affected by mycolactone may share an underlying mechanism of production that could explain their co-regulation. Early work on the mechanism of suppression by mycolac-tone was carried out in Jurkat T cells using ASLs and focused on the suppression of IL-2 production. A multidisciplinary approach to treatment and patient care is essential for optimizing treatment outcomes. Physiotherapy is paramount minimizing and/or preventing disabilities

Decomposition of protonated ronidazole studied by low-energy and high-energy collision-induced dissociation and density functional theory

International audienceNitroimidazoles are important compounds in medicine, biology, and the food industry. The growing need for their structural assignment, as well as the need for the development of the detection and screening methods, provides the motivation to understand their fundamental properties and reactivity. Here, we investigated the decomposition of protonated ronidazole [Roni+H]+ in low-energy and high-energy collision-induced dissociation (CID) experiments. Quantum chemical calculations showed that the main fragmentation channels involve intramolecular proton transfer from nitroimidazole to its side chain followed by a release of NH2CO2H, which can proceed via two pathways involving transfer of H+ from (1) the N3 position via a barrier of TS2 of 0.97 eV, followed by the rupture of the C–O bond with a thermodynamic threshold of 2.40 eV; and (2) the –CH3 group via a higher barrier of 2.77 eV, but with a slightly lower thermodynamic threshold of 2.24 eV. Electrospray ionization of ronidazole using deuterated solvents showed that in low-energy CID, only pathway (1) proceeds, and in high-energy CID, both channels proceed with contributions of 81% and 19%. While both of the pathways are associated with small kinetic energy release of 10–23 meV, further release of the NO• radical has a KER value of 339 meV