Comptomization and radiation spectra of X-ray sources. Calculation of the Monte Carlo method

The results of computations of the Comptomization of low frequency radiation in weakly relativistic plasma are presented. The influence of photoabsorption by iron ions on a hard X-ray spectrum is considered

On the application of the effective action approach to amplitudes with reggeon splitting

Application of the effective action approach to amplitudes with loop integration is studied for collisions on two and three centers with possible gluon emission. A rule is formulated for the integration around pole singularities in the induced vertices which brings the results in agreement with the QCD. It is demonstrated that the amplitudes can be restored from the purely transverse picture by introducing the standard Feynman propagators for intermediate gluons and quarks.Comment: 16 pages, 9 figures; submitted to Eur.Phys.Jour.

Diffractive scattering on the deuteron projectile in the NLO: triple interaction of reggeized gluons

High-mass diffractive production of protons on the deuteron target is studied in the next-to-leading order (NLO) of the perturbative QCD in the BFKL approach. The non-trivial part of the NLO contributions coming from the triple interactions of the exchanged reggeons is considered. Analytic formulas are presented and shown to be infrared free and so ready for practical calculation.Comment: 28 pages, 2 figures; to be published in Eur.Phys.Jour.

Endothelotropic activity of 4-hydroxy-3,5-di-tret-butylcinnamic acid in the conditions of experimental cerebral ischemia

The aim of the study was to evaluate the endothelioprotective activity of 4-hydroxy-3,5-di-tret-butylcinnamic acid in conditions of experimental cerebral ischemia. The brain ischemia was reproduced by the method of irreversible right-sided thermocoagulation of the middle cerebral artery. As comparative drugs, mexidol (30 mg/kg) and sulodexide (30 U/kg) were use

X-ray Spectral Signatures of the Photon Bubble Model for Ultraluminous X-ray Sources

The nature of ultraluminous X-ray sources in nearby galaxies is one of the major open questions in modern X-ray astrophysics. One possible explanation for these objects is an inhomogeneous, radiation dominated accretion disk around a $\sim 10 M_{\odot}$ black hole -- the so-called ``photon bubble'' model. While previous studies of this model have focused primarily on its radiation-hydrodynamics aspects, in this paper, we provide an analysis of its X-ray spectral (continuum and possible edge and line) characteristics. Compton reflection between high and low density regions in the disk may provide the key to distinguishing this model from others, such as accretion onto an intermediate mass black hole. We couple a Monte Carlo/Fokker-Planck radiation transport code with the XSTAR code for reflection to simulate the photon spectra produced in a photon bubble model for ULXs. We find that reflection components tend to be very weak and in most cases not observable, and make predictions for the shape of the high-energy Comptonizing spectra. In many cases the Comptonization dominates the spectra even down to $\sim$ a few keV. In one simulation, a \sim 9 \kev feature was found, which may be considered a signature of photon bubbles in ULXs; furthermore, we make predictions of high energy power-laws which may be observed by future instruments.Comment: Accepted for publication in the Astrophysical Journa

Synthesis and evaluation of cerebroprotective activity of novel 6,7-dimethoxyquinazolin-4(3H)-one derivatives containing residues of amino acids and dipeptides

Neurodegenerative processes of the central nervous system are an important socially significant problem of modern society. They cause many diseases, such as Alzheimer's disease and cerebral ischemia, which significantly reduce the quality of human life and can lead to disability or death. The aim of this study was to synthesize novel 6,7-dimethoxyquinazolin-4(3H)-one derivatives with the remains of neuroactive amino acids and dipeptides in order to investigate their cerebroprotective properties. As a result of the study, 13 novel 6,7-dimetho-xyquinazolin-4(3H)-one derivatives were synthesized. Cerebral ischemia in rats was reproduced by irreversible right-sided occlusion of the middle cerebral artery using the Tamura method, and the area of brain necrosis was evaluated. Cognitive functions were evaluated in the Y-maze test. Among the studied quinazolinone derivatives, compounds 3i, 3j and 3k have the most pronounced cerebrotropic activity, which is not inferior to ethylmethylhydroxypyridine succinate in terms of pharmacological activity, making them promising objects for further research

Wear of 16MnCrS5 steel surface layers in the pulsing contact loads

Approaches to actualizing the use of modern alloy steels that are in demand in the Eurasian technological space are proposed. According to the criterion of resistance to contact fatigue, quantitative indicators of wear of the surfacehardened layers of steel 16MnCrS5 were revealed. With the contact stress amplitude up to 950 MPa, the composite material of carbonized and nitrocemented layers is characterized by a period of high resistance with minimal manifestations of structural hardening by the mechanism of softening of the material. The obtained composite material with carbonized and nitrocemented layers is characterized by a period of high resistance up to 15 000 cycles

Evolution of the Low-Energy Photon Spectra in Gamma-Ray Bursts

We report evidence that the asymptotic low-energy power law slope alpha (below the spectral break) of BATSE gamma-ray burst photon spectra evolves with time rather than remaining constant. We find a high degree of positive correlation exists between the time-resolved spectral break energy E_pk and alpha. In samples of 18 "hard-to-soft" and 12 "tracking" pulses, evolution of alpha was found to correlate with that of the spectral break energy E_pk at the 99.7% and 98% confidence levels respectively. We also find that in the flux rise phase of "hard-to-soft" pulses, the mean value of alpha is often positive and in some bursts the maximum value of alpha is consistent with a value > +1. BATSE burst 3B 910927, for example, has a alpha_max equal to 1.6 +/- 0.3. These findings challenge GRB spectral models in which alpha must be negative of remain constant.Comment: 12 pages (including 6 figures), accepted to Ap

Synthesis, in vitro and docking studies of 2-substituted 5,6,7,8-tetrahydrobenzo[4,5]thieno[2,3-d]pyrimidine-4(3H)-one derivatives as agents for the treatment of Alzheimer's disease

Alzheimer's disease is a chronic neurodegenerative disease, which is characterized mainly by a progressive decrease in intellectual abilities, memory impairment and a change in a person's personality. Unfortunately, there are practically no medicines that act on pathogenesis of Alzheimer's disease. The development of new highly effective medicines for the treatment of this pathology is an actual area of pharmaceutical research. The aim of this work is to search among 2-substituted 5,6,7,8-tetrahydrobenzo[4,5]thieno[2,3-d]pyrimidine-4(3H)-one effective compounds with an anticholinesterase and an antiamyloid activities. As a result, it was found that compounds 4d, 4e and 4f have the high anticholinesterase ability, which in their structure contain residues of hydroxy-methoxyphenyl fragments. Structures 4c, 4g, 4h, 4j, 4k, 4m, 4n and 4p showed slightly less activity, the effect of which did not differ statistically from that of Donepezil. Compounds 4c, 4e, 4k and 4m have the greatest ability to inhibit the formation of the amyloid, comparable to GV-971. It should be noted that the molecular docking data are consistent with the results of the determination of the anticholinesterase activity of the studied compounds obtained in vitro. Thus, the prospects for future studies of these compounds in the possibility of creating a pharmaceutical active substance for the treatment of neurodegenerative diseases have been revealed

Wear of 16MnCrS5 steel surface layers in the pulsing contact loads

Approaches to actualizing the use of modern alloy steels that are in demand in the Eurasian technological space are proposed. According to the criterion of resistance to contact fatigue, quantitative indicators of wear of the surfacehardened layers of steel 16MnCrS5 were revealed. With the contact stress amplitude up to 950 MPa, the composite material of carbonized and nitrocemented layers is characterized by a period of high resistance with minimal manifestations of structural hardening by the mechanism of softening of the material. The obtained composite material with carbonized and nitrocemented layers is characterized by a period of high resistance up to 15 000 cycles