Physical Drivers of Emission-line Diversity of SDSS Seyfert 2s and LINERs after Removal of Contributions from Star Formation

Ionization sources other than H ii regions give rise to the right-hand branch in the standard ([N ii]) BPT diagram, populated by Seyfert 2s and LINERs. However, because the majority of Seyfert/LINER hosts are star-forming (SF), H ii regions contaminate the observed lines to some extent, making it unclear if the position along the branch is merely due to various degrees of mixing between pure Seyferts/LINERs and SF, or whether it reflects the intrinsic diversity of Seyfert/LINER ionizing sources. In this study, we empirically remove SF contributions in ∼100,000 Seyferts/LINERs from SDSS using the doppelganger method. We find that mixing is not the principal cause of the extended morphology of the observed branch. Rather, Seyferts/LINERs intrinsically have a wide range of line ratios. Variations in ionization parameter and metallicity can account for much of the diversity of Seyfert/LINER line ratios, but the hardness of the ionization field also varies significantly. Furthermore, our k-means classification on seven decontaminated emission lines reveals that LINERs are made up of two populations, which we call soft and hard LINERs. The Seyfert 2s differ from both types of LINERs primarily by higher ionization parameter, whereas the two LINER types mainly differ from each other (and from star-forming regions) in the hardness of the radiation field. We confirm that the [N ii] BPT diagram more efficiently identifies LINERs than [S ii] and [O i] diagnostics, because in the latter many LINERs, especially soft ones, occupy the same location as pure starformers, even after the SF has been removed from LINER emission.

Observation of Intact and Proteolytically Cleaved Amyloid-Beta (1–40)-Oleuropein Noncovalent Complex at Neutral pH by Mass Spectrometry

Mass spectrometry analyses carried out on mass spectrometers equipped with soft ionization sources demonstrated their utility in the assessment of the formation of noncovalent complexes and the localization of the binding sites. Direct analyses by mass spectrometry of the noncovalent complex formed in acidic and mildly acidic environments by amyloid beta (1–40) peptide and oleuropein have been previously described, and, in several studies, the absorption, metabolism, excretion, and the implications in the prevention and therapy of Alzheimer’s disease of oleuropein have been investigated. Our paper presents modifications of the method previously employed for noncovalent complex observation, namely, the amyloid beta (1–40) pretreatment, followed by an increase in the pH and replacement of the chemical environment from ammonium acetate to ammonium bicarbonate. The formation of noncovalent complexes with one or two molecules of oleuropein was detected in all chemical solutions used, and the amyloid beta (17–28) binding site was identified via proteolytic experiments using trypsin prior to and after noncovalent complex formation. Our results highlight the importance of further studies on the effect of oleuropein against amyloid beta aggregation.

Long Short Term Memory Networks (LSTM)-Monte-Carlo Simulation of Surface Ionization using Radon

Earthquake events are usually associated with the atmospheric processes modification. Some of the important events in seismic periods include the atmospheric electricity/conductivity modification, which is often related to the ion population in the earthquake preparation area vicinity. Radon, together with cosmic radiation is the major ionization sources in the lower troposphere. The ion-pair production rate is estimated as caused by radon in Erzincan, a city along the North Anatolian Fault Zone, Turkey. Long short term memory and Monte Carlo methods are proposed to account for uncertainty in the estimations and also in the radon data to simulate the ion production rate. The advantage of the LSTM model is taken to study radon anomalies during the M=5 Girlevik earthquake, Erzincan. Radon concentration in Erzincan is found to be very high when compared to other regions, and this might relate to the geological settings of the region. Radon concentration is found to increase prior to the 5.0 Girlevik earthquake. According to estimations, 23×109 ion-pairs m-3s-1 were generated during the earthquake. The ion production estimation rate due to radon and its progeny in Erzincan is at the order of 109 ion-pairs m-3s-1. When added to other ionization sources more pronounced conditions could favor ionospheric perturbations. Ionospheric disturbance simulations would be significant in regions with high radon concentration for understanding atmospheric processes.

Radially Resolved Optical Emission Spectral Imaging Study of an Atmospheric Pressure µDBD Jet for Elucidating the Effect of Sample Surface Material on the Underlying Mechanisms

Dielectric barrier discharges are receiving increasing attention as sampling/ionization sources for ambient mass spectrometry. Nevertheless, the underlying mechanisms are not completely understood, particularly when the plasma plume is exposed to...

Особенности описания импульсной электрической прочности полимерных диэлектриков

The scenario based on the macro molecules field ionization model is proposed to describe the polymer dielectrics pulse breakdown. The decisive role of the real dielectric space-field inhomogeneity on formation of the ionization “sources” and redistribution of charge carries is taken into account. The justification of the choice of the defining model parameters - energy gap width and frequency factor is carried out. The possibility of using these parameters to describe the pulse electric strength of polymers in both uniform and sharply non-uniform electric fields (on the example of polymethylmethaacrylate) is shown.