Long-Lived Electron Capture Dissociation Product Ions Experience Radical Migration via Hydrogen Abstraction

To explore the mechanism of electron capture dissociation (ECD) of linear peptides, a set of 16-mer peptides were synthesized with deuterium labeled on the α-carbon position of four glycines. The ECD spectra of these peptides showed that such peptides exhibit a preference for the radical to migrate to the α-carbon position on glycine via hydrogen (or deuterium) abstraction before the final cleavage and generation of the detected product ions. The data show c-type fragment ions, ions corresponding to the radical cation of the c-type fragments, c·, and they also show c·-1 peaks in the deuterated peptides only. The presence of the c·-1 peaks is best explained by radical-mediated scrambling of the deuterium atoms in the long-lived, metastable, radical intermediate complex formed by initial electron capture, followed by dissociation of the complex. These data suggest the presence of at least two mechanisms, one slow, one fast. The abundance of H· and −CO losses from the precursor ion changed upon deuterium labeling indicating the presence of a kinetic isotope effect, which suggests that the values reported here represent an underestimation of radical migration and H/D scrambling in the observed fragments

Performance of a cryogenic system prototype for the XENON1T Detector

We have developed an efficient cryogenic system with heat exchange and associated gas purification system, as a prototype for the XENON1T experiment. The XENON1T detector will use about 3 ton of liquid xenon (LXe) at a temperature of 175K as target and detection medium for a dark matter search. In this paper we report results on the cryogenic system performance focusing on the dynamics of the gas circulation-purification through a heated getter, at flow rates above 50 Standard Liter per Minute (SLPM). A maximum flow of 114 SLPM has been achieved, and using two heat exchangers in parallel, a heat exchange efficiency better than 96% has been measured

Dynamic fibrils in H-alpha and C IV

Aim: To study the interaction of the solar chromosphere with the transition region, in particular active-region jets in the transition region and their relation to chromospheric fibrils. Methods: We carefully align image sequences taken simultaneously in C IV with the Transition Region and Coronal Explorer and in H-alpha with the Swedish 1-m Solar Telescope. We examine the temporal evolution of "dynamic fibrils", i.e., individual short-lived active-region chromospheric jet-like features in H-alpha. Results: All dynamic fibrils appear as absorption features in H-alpha that progress from the blue to the red wing through the line, and often show recurrent behavior. Some of them, but not all, appear also as bright features in C IV which develop at or just beyond the apex of the H-alpha darkening. They tend to best resemble the H-alpha fibril at +700 mA half a minute earlier. Conclusions: Dynamic chromospheric fibrils observed in H-alpha regularly correspond to transition-region jets observed in the ultraviolet. This correspondence suggests that some plasma associated with dynamic fibrils is heated to transition-region temperatures.Comment: 8 pages, 8 figure

Influence of Preparative Form on the Target Efficiency and Toxicity of the Solid Insecticide Based on Pyrethroid and Neonicatinoid

Received: 24.11.2021. Revised: 11.01.2022. Accepted: 11.01.2022. Available online: 13.01.2022.The authors declare that they have no known competing financial interests or personal relationships that could have appeared to influence the work reported in this paper.The influence of solid preparative form was studied on the «GET Dry» insecticide based on alpha-cypermethrin and imidacloprid. The target efficiency as acute and residual impact was studied when agent was applied against the bedbugs (Cimex hemipterus), German cockroach (Blatella germanica), common house flies (Musca domestica) and larvae of the leather beetles (Attagenus smirnovi). The agent demonstrated strong acute effect (about 100%) when applied against the cockroaches, bugs, and flies. Moreover, the agent demonstrates the residual impact on the cockroaches, flies, fleas for 45 days, and on the bugs for 30 days. The slight insecticidal activity was observed when the agent was applied against the larvae. We studied toxicity of the agent, LD50, when swallowed (moderately hazardous substances, class III) and when applied to the skin (low-hazard substance, class IV) as well as studied its inhalation hazard according to its volatility С 20 °C, irritant action when applied to the skin (slight) and eye irritation (moderate). Sensibilizing action was not observed

Explosive events - swirling transition region jets

In this paper, we extend our earlier work to provide additional evidence for an alternative scenario to explain the nature of so-called `explosive events'. The bi-directed, fast Doppler motion of explosive events observed spectroscopically in the transition region emission is classically interpreted as a pair of bidirectional jets moving upward and downward from a reconnection site. We discuss the problems of such a model. In our previous work, we focused basically on the discrepancy of fast Doppler motion without detectable motion in the image plane. We now suggest an alternative scenario for the explosive events, based on our observations of spectral line tilts and bifurcated structure in some events. Both features are indicative of rotational motion in narrow structures. We explain the bifurcation as the result of rotation of hollow cylindrical structures and demonstrate that such a sheath model can also be applied to explain the nature of the puzzling `explosive events'. We find that the spectral tilt, the lack of apparent motion, the bifurcation, and a rapidly growing number of direct observations support an alternative scenario of linear, spicular-sized jets with a strong spinning motion.Comment: 9 pages, 3 figures, accepted for publication in Solar Physic

The Structure and Dynamics of the Upper Chromosphere and Lower Transition Region as Revealed by the Subarcsecond VAULT Observations

The Very high Angular resolution ULtraviolet Telescope (VAULT) is a sounding rocket payload built to study the crucial interface between the solar chromosphere and the corona by observing the strongest line in the solar spectrum, the Ly-a line at 1216 {\AA}. In two flights, VAULT succeeded in obtaining the first ever sub-arcsecond (0.5") images of this region with high sensitivity and cadence. Detailed analyses of those observations have contributed significantly to new ideas about the nature of the transition region. Here, we present a broad overview of the Ly-a atmosphere as revealed by the VAULT observations, and bring together past results and new analyses from the second VAULT flight to create a synthesis of our current knowledge of the high-resolution Ly-a Sun. We hope that this work will serve as a good reference for the design of upcoming Ly-a telescopes and observing plans.Comment: 28 pages, 11 figure

Comment on "On the subtleties of searching for dark matter with liquid xenon detectors"

In a recent manuscript (arXiv:1208.5046) Peter Sorensen claims that XENON100's upper limits on spin-independent WIMP-nucleon cross sections for WIMP masses below 10 GeV "may be understated by one order of magnitude or more". Having performed a similar, though more detailed analysis prior to the submission of our new result (arXiv:1207.5988), we do not confirm these findings. We point out the rationale for not considering the described effect in our final analysis and list several potential problems with his study.Comment: 3 pages, no figure

Virtual Planetary Space Weather Service offered by the Europlant H2O2O Research Infrastructure

Under Horizon 2020, the Europlanet 2020 Research Infrastructure (EPN2020-RI) will include an entirely new Virtual Access Service, ?Planetary Space Weather Services? (PSWS) that will extend the concepts of space weather and space situational awareness to other planets in our Solar System and in particular to spacecraft that voyage through it. PSWS will make twelve new services accessible to the research community, space agencies, and industrial partners planning for space missions. These services will in particular be dedicated to the following key planetary environments: Mars (in support of the NASA MAVEN and European Space Agency (ESA) Mars Express and ExoMars missions), comets (building on the outstanding success of the ESA Rosetta mission), and outer planets (in preparation for the ESA JUpiter ICy moon Explorer mission), and one of these services will aim at predicting and detecting planetary events like meteor showers and impacts in the Solar System. This will give the European planetary science community new methods, interfaces, functionalities and/or plugins dedicated to planetary space weather as well as to space situational awareness in the tools and models available within the partner institutes. A variety of tools (in the form of web applications, standalone software, or numerical models in various degrees of implementation) are available for tracing propagation of planetary and/or solar events through the Solar System and modelling the response of the planetary environment (surfaces, atmospheres, ionospheres, and magnetospheres) to those events. But these tools were not originally designed for planetary event prediction and space weather applications. PSWS will provide the additional research and tailoring required to apply them for these purposes. PSWS will be to review, test, improve and adapt methods and tools available within the partner institutes in order to make prototype planetary event and space weather services operational in Europe at the end of 2017. To achieve its objectives PSWS will use a few tools and standards developed for the Astronomy Virtual Observatory (VO). This paper gives an overview of the project together with a few illustrations of prototype services based on VO standards and protocolsauthorsversionPeer reviewe

Search for Event Rate Modulation in XENON100 Electronic Recoil Data

We have searched for periodic variations of the electronic recoil event rate in the (2-6) keV energy range recorded between February 2011 and March 2012 with the XENON100 detector, adding up to 224.6 live days in total. Following a detailed study to establish the stability of the detector and its background contributions during this run, we performed an un-binned profile likelihood analysis to identify any periodicity up to 500 days. We find a global significance of less than 1 sigma for all periods suggesting no statistically significant modulation in the data. While the local significance for an annual modulation is 2.8 sigma, the analysis of a multiple-scatter control sample and the phase of the modulation disfavor a dark matter interpretation. The DAMA/LIBRA annual modulation interpreted as a dark matter signature with axial-vector coupling of WIMPs to electrons is excluded at 4.8 sigma.Comment: 6 pages, 4 figure