On the possible observational manifestation of supernova shock impact on the neutron star magnetosphere

Impact of supernova explosion on the neutron star magnetosphere in a massive binary system is considered. The supernova shock striking the NS magnetosphere filled with plasma can lead to the formation of a magnetospheric tail with significant magnetic energy. The magnetic field reconnection in the current sheet formed can convert the magnetic energy stored in the tail into kinetic energy of accelerated charged particles. Plasma instabilities excited by beams of relativistic particles can lead to the formation of a short pulse of coherent radio emission with parameters similar to those of the observed bright extragalactic millisecond radio burst (Lorimer et al. 2007).Comment: 8 pages, Astron. Lett. in pres

Modeling of the Interaction of GRB Prompt Emission with the Circumburst Medium

We present methodology and results of numerical modeling of the interaction of GRB prompt emission with the circumburst medium using a modified version of the multi-group radiation hydrocode STELLA. The modification includes the nonstationary photoionization, the photoionization heating and the Compton heating along with the hydrodynamics and radiation transfer. The lightcurves and spectra of the outcoming gamma-ray, X-ray and optical emission are calculated for a set of models (shells) of the circumburst environment, which differ in dimensions, density, density profile, composition, temperature. In some cases total bolometric and optical luminosities can reach 10^47 and 10^43 erg/s respectively. These effects can be responsible for irregularities which are seen on lightcurves of some GRB's X-ray and optical afterglows.Comment: 27 pages, 16 colour figures, this version is translated by authors, so it differs from that, which is published in Astronomy Letter

Broad-band gravitational-wave pulses from binary neutron stars in eccentric orbits

Maximum gravitational wave emission from binary stars in eccentric orbits occurs near the periastron passage. We show that for a stationary distribution of binary neutron stars in the Galaxy, several high-eccentricity systems with orbital periods in the range from tens of minutes to several days should exist that emit broad gravitational-wave pulses in the frequency range 1-100 mHz. The space interferometer LISA could register the pulsed signal from these system at a signal-to-noise ratio level $S/N>5\sqrt{5}$ in the frequency range $\sim 10^{-3}-10^{-1}$ Hz during one-year observational time. Some detection algorithms for such a signal are discussed.Comment: 17 pages, LATEX, 3 figures, Astronomy Letters, 2002, in press; typos corrected, refference adde

Новий метод синтезу атомоксетину та його взаємодія з азоловмісними сульфохло- ридами

A new approach to the synthesis of atomoxetine using the methods of enzymatic catalysis has been developed;the interaction of atomoxetine with a number of azole-containing heterocyclic sulfochlorides has been studied. Thecarbonyl group of 3-chloro-1-phenyl-propane-1-one was region-specifically reduced with NADPH-dependentcarbonylreductase (SSCR) in phosphate buffer solution. In Mitsunoby reaction with o-methylphenole the inversionof the final product configuration takes place and [R]-1-(3-chloro-1-phenypropoxy)-2-methylbenzene is formed.Its further treatment with methylamine results in the base of atomoxetine, which may be isolated from the solutionas a chloride. In order to develop the novel biologically active compounds the series of sufonyl chlorides withoxazole and isoxazole substituents were reacted with atomoxetine. The sulfonamides obtained fully comply withall criteria for the molecules – candidates for the biomedical study.Разработан метод синтеза атомоксетина с использованием стереоспецифичного ферментативного катализа. Карбонильная группа в структуре 3-хлор-1-фенил-пропан-1-она региоспецифично восстановлена с образованием NADPH-зависимой карбонилредуктазы (SSCR) в фосфатном буфере. В условиях реакции Мицунобу с о-крезолом происходит обращение конфигурации конечного продукта с образованием в ходе реакции [R]-1-(3-хлор-1-фенилпропокси)-2-метилбензола, который далее при обработке метиламином образует основание атомоксетина, выделяемое из раствора в виде соли с хлористоводородной кислотой. С целью поиска новых биологически активных соединений получен ряд сульфохлоридов с оксазольными и изоксазольными заместителями, которые далее вводились в реакцию с атомоксетином. Полученные в работе сульфонамиды удовлетворяют требованиям, предъявляемым к молекулам – кандидатам для биомедицинских исследований.Розроблено метод синтезу атомоксетину з використанням стереоспецифічного ферментативного каталізу. Карбонільна група в структурі 3-хлоро-1-феніл-пропан-1-ону регіоспецифічно відновлена з використанням NADPH-залежної карбонілредуктази (SSCR) в фосфатному буфері. В умовах реакції Міцунобу з о-крезолом відбувається обернення конфігурації кінцевого продукту з утворенням [R]-1-(3-хлоро-1-фенілпропокси)-2-метилбензолу, який далі при обробці метиламіном утворює основу атомоксетину, яка виділяється з розчину у вигляді солі з хлористоводневою кислотою. З метою пошуку нових біологічно активних сполук отримано ряд сульфохлоридів з оксазольними та ізоксазольними замісниками, які далі вводились в реакцію з атомоксетином. Отримані в роботі сульфонаміди відповідають вимогам, які висуваються до молекул – кандидатів для біомедичних досліджень

Алюмооксидный носитель для катализатора низкотемпературной изомеризации углеводородов

Objectives. Determine the necessary conditions for obtaining a granulated η-Al2O3 carrier, investigate its structural and strength properties, and evaluate its activity for the model n-butane isomerization reaction.Methods. Samples containing bayerite structure aluminum trihydroxide were synthesized by precipitation from aqueous solutions of aluminum nitrate with ammonia under isothermal conditions at a constant pH value. The samples of the granulated carrier were obtained using an extrusion method when the composition of molding pastes was varied by tuning the ratio of bayerite- and η-Al2O3 -containing components and introducing polyvinyl alcohol.Results. The influence of the preparation conditions on the structural and strength properties of the active Al2O3 granules is evaluated. Samples of the aluminum oxide carrier were tested for a model reaction of low-temperature isomerization of n-butane, demonstrating a sufficiently high selectivity and reasonable prospects for use as catalysts for low-temperature isomerization of hydrocarbons.Conclusions. Increasing the content of the polyvinyl alcohol in the molding paste from 0.4 to 1.8 wt % is accompanied by an increase in the predominant sizes of the mesopores in the range of 10–50 nm and pores in the range of 50–80 nm, explaining the high values of all recorded parameters for the process of isomerization of n-butane.Цели. Определение условий получения гранулированного η-Al2O3 -носителя, исследование его структурно-прочностных свойств и оценка активности в модельном процессе изомеризации н-бутана.Методы. Образцы, содержащие тригидроксид алюминия байеритной структуры, синтезированы осаждением из водных растворов нитрата алюминия аммиаком в изотермических условиях при постоянном значении рН. Экструзионным методом получены образцы гранулированного носителя при варьировании состава формовочных паст: соотношения количеств байерит- и η-Al2О3 -содержащих компонентов и введения поливинилового спирта.Результаты. Оценено влияние условий приготовления на структурно-прочностные свойства гранул активного Al2О3. Образцы алюмооксидного носителя испытаны в модельной реакции низкотемпературной изомеризации н-бутана, показана их достаточно высокая селективность и перспективность при получении катализаторов низкотемпературной изомеризации углеводородов.Выводы. Увеличение содержания поливинилового спирта в формовочной пасте от 0.4 до 1.8 масс. % сопровождается смещением преобладающих размеров мезопор в интервале 10–50 нм и пор в интервале 50–80 нм в большую сторону, что объясняет высокие значения всех регистрируемых показателей процесса изомеризации н-бутана

Magnetic fileds of coalescing neutron stars and the luminosity function of short gamma-ray burst

Coalescing neutron star binaries are believed to be the most reliable sources for ground-based detectors of gravitational waves and likely progenitors of short gamma-ray bursts. In the process of coalescence, magnetic fields of neutron stars can induce interesting observational manifestations and affect the form of gravitational wave signal. In this papaer we use the population synthesis method to model the expected distribution of neutron star magnetic fields during the coalescence under different assumptions on the initial parameters of neutron stars and their magnetic field evolution. We discuss possible elecotrmagnetic phenomena preceding the coalescence of magnetized neutron star binaries and the effect of magnetic field on the gravitational wave signal. We find that a log-normal (Gaussian in logarithms) distribution of the initial magnetic fields of neutron stars, which agrees with observed properties of radio pulsars, produces the distribution of the magnetic field energy during the coalescence that adequately describes the observed luminosity function of short gamma-ray bursts under different assumptions on the field evolution and initial parameters of neutron stars. This agreement lends further support to the model of coalescing neutron star binaries as progenitors of gamma-ray bursts.Comment: v.2, LATEX, 25 pages, inc. 7 ps figures, Astron. Lett., in press. Typos corrected, reference adde

Supernovae - Optical Precursors of Short Gamma-Ray Bursts

The probability of observing "supernova - gamma-ray burst" (GRB) pair events and recurrent GRBs from one galaxy in a time interval of several years has been estimated. Supernova explosions in binary systems accompanied by the formation of a short-lived pair of compact objects can be the sources of such events. If a short GRB is generated during the collision of a pair, then approximately each of ~300 short GRBs with redshift z must have an optical precursor - a supernova in the observer's time interval <2(1+z)yr. If the supernova explosion has the pattern of a hypernova, then a successive observation of long and short GRBs is possible. The scenario for the generation of multiple GRBs in collapsing galactic nuclei is also discussed.Comment: 12 pages, 1 figure; this paper has the e-precursor arXiv:1101.3298 [astro-ph.HE

Search for pre-burst emission from binary neutron star mergers with Spectrum-Roentgen-Gamma

Close binary systems consisting of two neutron stars (BNS) emit gravitational waves, that allow them to merge on timescales shorter than Hubble time. It is widely believed, that NS-NS mergers in such systems power short gamma-ray bursts (GRB). Several mechanisms which could lead to electromagnetic energy release prior to a merger have been proposed. We estimate the ability to observe the possible pre-burst emission with telescopes of Spectrum-Roentgen-Gamma. We also investigate first such event, GRB210919A, which fell into the field of view of the SRG telescopes less than two days before the burst.Comment: Accepted for publication in Astronomy Letter