Gamma-radiation with E gamma 5 MeV detected from Seyfert galaxy 3C120 and region with 1" = 190 deg and b" = 20 deg

The observation of the Galaxy anticenter region in gamma-rays with E gamma = 5 / 100 MeV was made by gamma-telescope Natalya-1 in a balloon flight. The flight was performed at the ceiling 5.1 + or - 0.1 g/sq cm, magnetic cutoff being 17 GV. The description of the instrument and the analysis of the experiment conditions are given. The tracks of electron-positron pairs generated by gamma-quanta in the convertors were detected by wire spark chambers. The recorded events were classified manually by an operator using a graphic display into three classes: pairs, single and bad events. The arrival angle of gamma-quanta and their energy for selected gamma-ray events (pairs and singles) were determined through multiple scattering of pair components in the convertors. On the basis of the data obtained the celestial maps were made in gamma-rays for E sub gamma 5 MeV and E gamma 20 MeV energy ranges

Search for broad absorption lines in spectra of stars in the field of supernova remnant RX J0852.0-4622 (Vela Jr.)

Supernova remnant (SNR) RX J0852.0-4622 is one of the youngest and is most likely the closest among known galactic supernova remnants (SNRs). It was detected in X-rays, the 44Ti gamma-line, and radio. We obtain and analyze medium-resolution spectra of 14 stars in the direction towards the SNR RX J0852.0-4622 in an attempt to detect broad absorption lines of unshocked ejecta against background stars. Spectral synthesis is performed for all the stars in the wavelength range of 3740-4020AA to extract the broad absorption lines of Ca II related to the SNR RX J0852.0-4622. We do not detect any broad absorption line and place a 3-sigma upper limit on the relative depths of <0.04 for the broad Ca II absorption produced by the SNR. We detect narrow low and high velocity absorption components of Ca II. High velocity |V(LSR)|=100-140 km/s components are attributed to radiative shocks in clouds engulfed by the old Vela SNR. The upper limit to the absorption line strength combined with the width and flux of the 44Ti gamma-ray line 1.16 MeV lead us to conclude that SNR RX J0852.0-4622 was probably produced by an energetic SN Ic explosion.Comment: 9 pages, 8 figures, accepted in A&

Are Ti44-Producing Supernovae Exceptional?

According to standard models supernovae produce radioactive $^{44}$Ti, which should be visible in gamma-rays following decay to $^{44}$Ca for a few centuries. $^{44}Ti production is believed to be the source of cosmic$^{44}$Ca, whose abundance is well established. Yet, gamma-ray telescopes have not seen the expected young remnants of core collapse events. The$^{44}$Ti mean life of$\tau \simeq$89 y and the Galactic supernova rate of$\simeq$3/100 y imply$\simeq$several detectable$^{44}Ti gamma-ray sources, but only one is clearly seen, the 340-year-old Cas A SNR. Furthermore, supernovae which produce much $^{44}Ti are expected to occur primarily in the inner part of the Galaxy, where young massive stars are most abundant. Because the Galaxy is transparent to gamma-rays, this should be the dominant location of expected gamma-ray sources. Yet the Cas A SNR as the only one source is located far from the inner Galaxy (at longitude 112 degree). We evaluate the surprising absence of detectable supernovae from the past three centuries. We discuss whether our understanding of SN explosions, their$^{44}Ti yields, their spatial distributions, and statistical arguments can be stretched so that this apparent disagreement may be accommodated within reasonable expectations, or if we have to revise some or all of the above aspects to bring expectations in agreement with the observations. We conclude that either core collapse supernovae have been improbably rare in the Galaxy during the past few centuries, or $^{44}Ti-producing supernovae are atypical supernovae. We also present a new argument based on$^{44}$Ca/$^{40}$Ca ratios in mainstream SiC stardust grains that may cast doubt on massive-He-cap Type I supernovae as the source of most galactic$^{44}$Ca.Comment: 23 pages, 14 figures, accepted for publication in Astronomy and Astrophysics 2006. Correcting the SN type of Tycho in Table B.1. and add its associated reference

Spermine Induces Autophagy in Plants: Possible Role of NO and Reactive Oxygen Species

© 2018, Pleiades Publishing, Inc. This is the first study to show that polyamine spermine, a low-molecular-weight nitrogen-containing compound, can induce autophagy in plants. This process is accompanied by an increased generation of reactive oxygen species and nitric oxide, which play a signal role and are required for triggering autophagy

EPR study of nitric oxide production in rat tissues under hypokinesia

EPR spectroscopy was used to study the intensity of nitric oxide (NO) production upon modeling 60-day progressive hypokinesia (restriction of motor activity) in rats and estimating the content of (DETC)2-Fe2+-NO complexes in heart and liver tissues. In 30 days of hypokinesia, there was a 2-3-fold increase in tissue NO. Administration of a nonspecific inhibitor of NO synthases, L-NAME, to hypokinetic rats prior to measurement decreased their NO level even below the untreated control. Our results show that the intensified NO production in hypokinesia is mainly due to NO synthases, rather than to the nitrite reductase pathway. © 2013 Pleiades Publishing, Ltd

Changes of Nitric Oxide Content in the Rat Hippocampus, Heart and Liver in Acute Phase of Ischemia

© 2016, Springer-Verlag Wien.Electron paramagnetic resonance (EPR) was used as a method to record nitric oxide (NO) production in the tissues of the brain, heart and liver of healthy rats, and rats after modeling of ischemic stroke. Direct measurement of the dynamics of NO production by EPR spectroscopy in our experiments showed that after the emergence of signs of ischemic stroke, 5 h after the start of ischemia, the content of NO in the hippocampus decreased two- to threefold and this decrease was maintained at 24 and 72 h. Deserving special attention is the data demonstrating that there is a greater decrease of NO production in the tissues of the heart and liver than in the brain. Consequently, the change in intensity of NO production in the modeling of ischemic events in the brain has a systemic, not a local character

EPR Detection of Iron Storage in Rat Tissues After Simulated Microgravity Model

© 2016, Springer-Verlag Wien.By a method of spectroscopy of electron paramagnetic resonance the tissues of rats after exposure of microgravity simulation (model of hindlimb unloading) were investigated. In the tissues of heart, lung, liver and muscles the signals of electron magnetic resonance (EMR) depending on orientation were detected. The temperature and orientation dependences of the signals were studied. Comprehensive analysis of the characteristics of the EMR signals made it possible to identify the source of the signals as a crystalline magnetite. Three types of anisotropic EMR signals corresponding to a variety of spatial forms of accumulation of biogenic magnetite were detected. The appearance of the signals after microgravity simulation indicates an alteration in iron metabolism and an abnormal accumulation of iron in the rat tissues

Changes in nitric oxide in heart of intact and sympathectomized rats of different age

Nitric oxide production in heart tissues of rats of different age in the norm and after pharmacological sympathectomy was studied by electron spin resonance spin-trapping. Rats at the age of 14, 21, 70, and 100 days were used in the experiment. The concentration of nitric oxide produced in rat heart tissues proved to considerably decrease during ontogeny. Pharmacological sympathectomy notably decreased nitric oxide production in the heart in 14-and 21-day-old rats: the nitric oxide concentration in the spin trap as well as the level of R and T conformers of hemoglobin nitrosyl complexes decreased. In 70-day-old rats, pharmacological sympathectomy had no notable effect on the level of nitric oxide-containing paramagnetic complexes. © 2008 MAIK Nauka