Optical study of the polar BM CrB in low accretion state

This paper presents a spectral and photometric study of the poorly studied polar BM CrB. Three states of the polar brightness and signs of transition from one-pole to two-pole accretion mode were found by an analysis of ZTF data. It is shown that the transition from the low state to the high state changes the longitude of the main accretion spot (by $\approx 17^{\circ}$) and increases its elongation (by $\approx 10^{\circ}$). The spectra contain Zeeman absorptions of the H$\alpha$ line which are formed at a magnetic field strength of $15.5\pm1$ MG. These absorptions are likely produced by a cold halo extending from the accretion spot at $\approx {^1/_4}$ of the white dwarf radius. Modeling of the behavior of the H$\alpha$ emission line shows that the main source of emission is the part of the accretion stream near the Lagrangian point L$_1$, which is periodically eclipsed by the donor star. The spectra exhibit a cyclotron component formed in the accretion spot. Its modeling by a simple accretion spot model gives constraints on the magnetic field strength $B=15-40$ MG and the temperature $T_e\gtrsim15$ keV

Triple molybdates one-, one - and three(two)valence metals

The authors thank Ph. D. M. K. Alibaeva, Ph. D. I. A. Gudkova and Ph. D. I. V. Korolkova for participation in the research.The review summarizes experimental data on the phase formation, structure and properties of new complex oxide compounds group - triple molybdates containing tetrahedral molybdate ion, two different singly charged cation, together with tri- or divalent cation. The several structural families of these compounds were distinguished and it shown that many of them are of interest as luminescent, laser, ion-conducting or nonlinear optical materials.The work is executed at partial support of the Russian Foundation for basic research (projects No. 08-03-00384, 13-03-01020 and 14-03-00298)

PN G068.1+11.0: A young pre-cataclysmic variable with an extremely hot primary

© 2016, Pleiades Publishing, Ltd.An analysis of spectroscopic and photometric data for the young pre-cataclysmic variable (PCV) PN G068.1+11.0, which passed through its common-envelope stage relatively recently, is presented. The spectroscopic and photometric data were obtained with the 6-m telescope and Zeiss-1000 telescope of the Special Astrophysical Observatory. The light curves show sinusoidal brightness variations with the orbital-period time scale and brightness-variation amplitudes of Δm = 1.m41, 1.m62, and 1.m57 in the B, V, and R bands, respectively. The system’s spectrum exhibits weak HI (Hβ–Hδ) andHeII λλ4541, 4686, 5411 Å absorption lines during the phases of minimum brightness, as well as HI, HeII, CIII, CIV, NIII, and OII emission lines whose intensity variations are synchronized with variations of the integrated brightness of the system. The emission-line formation in the spectra can be fully explained by the effects of fluorescence of the ultraviolet light from the primary at the surface of the cool star. All the characteristics of the optical light of PN G068.1+11.0 confirm that it is a young PCV containing sdO subdwarf. The radial velocities were measured from a blend of lines of moderately light elements, CIII+NIII λ4640 Å, which is formed at the surface of the secondary due to reflection effects. The ephemeris of the system has been improved through a joint analysis of the radial-velocity curves and light curves of pre-cataclysmic variable, using modelling of the reflection effects. The fundamental parameters of PN G068.1+11.0 have been determined using two evolutionary tracks for planetary-nebula nuclei of different masses (0.7 M⊙and 0.78M⊙). The model spectra for the system and a comparison with the observations demonstrate the possibility of refining the components’ effective temperatures if the quality of the spectra used is improved

Analysis of fundamental parameters for V477 Lyr

We analyze the photometric and spectroscopic observations of the young pre-cataclysmic variable (pre-CV) V477 Lyr. The masses of both binary components have been corrected by analyzing their radial velocity curves. We show that agreement between the theoretical and observed light curves of the object is possible for several sets of its physical parameters corresponding to the chosen temperature of the primary component. The final parameters of V477 Lyr have been established by comparing observational data with evolutionary tracks for planetary nebula nuclei. The derived effective temperature of the O subdwarf is higher than that estimated by analyzing the object's ultraviolet spectra by more than 10000 K. This is in agreement with the analogous results obtained previously for the young pre-CVs V664 Cas and UU Sge. The secondary component of V477 Lyr has been proven to have a more than 25-fold luminosity excess compared to main-sequence stars of similar mass. Comparison of the physical parameters for the cool stars in young pre-CVs indicates that their luminosities do not correlate with the masses of the objects. The observed luminosity excesses in such stars show a close correlation with the post-common-envelope lifetime of the systems and should be investigated within the framework of the theory of their relaxation to the state of main-sequence stars. © 2008 Pleiades Publishing, Ltd

Spectral types of four binaries based on photometric observations

We present results of photometric and spectroscopic observations of four close binaries with subdwarf B components: PG 0918+029, PG 1000+408, PG 1116+301, PG 0001+275. We discovered that PG 1000+408 is a close binary, with the most probable orbital period being Porb = 1.041145 day. Based on a comparison of the observed light curves at selected orbital phases and theoretical predictions for their variations, all the systems are classified as doubly degenerate binaries with low-luminosity white-dwarf secondaries. © 2008 Pleiades Publishing, Ltd

The intermediate-age pre-cataclysmic variables SDSS J172406+562003 and RE J2013+4002

We have analyzed the physical status of the pre-cataclysmic variables SDSSJ172406+562003 and RE J2013+4002, which have evolved after their common-envelope stage a time t = 10 6-10 7 years. Spectroscopy and photometry of these systems were performed with the 6-m and 1-m telescopes of the Special Astrophysical Observatory. We demonstrate that emission lines in the spectra were formed solely by the reflection of radiation emitted by the white dwarfs on the surfaces of their cool companions, under conditions close to local thermodynamic equilibrium. These effects are also responsible for most of the objects' photometric variability amplitude. However, comparing the light curves of SDSS 172406 from different epochs, we find aperiodic brightness variations, probably due to spottedness of the surface of the secondary. Jointly analyzing the spectra, radial-velocity curves, and light curves of the pre-cataclysmic variables and modeling the reflection effects, we have derived their fundamental parameters. We demonstrate that the secondaries in these systems are consistent with evolutionary models for main-sequence stars and do not have the luminosity excesses characteristic of cool stars in young pre-cataclysmic variables. © 2012 Pleiades Publishing, Ltd

Development of Fluorescent Isocoumarin‐Fused Oxacyclononyne – 1,2,3‐Triazole Pairs

Fluorescent isocoumarin-fused cycloalkynes, which are reactive in SPAAC and give fluorescent triazoles regardless of the azide nature, have been developed. The key structural feature that converts the non-fluorescent cycloalkyne/triazole pair to its fluorescent counterpart is the pi-acceptor group (COOMe, CN) at the C6 position of the isocoumarin ring. The design of the fluorescent cycloalkyne/triazole pairs is based on the theoretical study of the S1 state deactivation mechanism of the non-fluorescent isocoumarin-fused cycloalkyne IC9O using multi-configurational ab initio and DFT methodologies. The calculations revealed that deactivation proceeds through the electrocyclic ring opening of the α-pyrone cycle and is accompanied by a redistribution of electron density in the fused benzene ring. We proposed that the S1 excited state deactivation barrier could be increased by introducing a pi-acceptor group into a position that is in direct conjugation with the formed C=O group and has a reduced electron density in the transition state. As a proof of concept, we designed and synthesized two fluorescent isocoumarin-fused cycloalkynes IC9O-COOMe and IC9O-CN bearing pi-acceptors at the C6 position. The importance of the nature of a pi-acceptor group was shown by the example of much less fluorescent CF$_3$-substituted cycloalkyne IC9O-CF$_3$

Стандартные образцы для градуировки анализатора водорода при высокой концентрации

The study discusses the issues of improving the accuracy of measuring high hydrogen concentrations in the development of storage materials in the hydrogen energy industry. The purpose of the study was to develop reference materials for calibration of the hydrogen analyzers at high concentrations. The main methods for determining the hydrogen content in materials were analyzed. It was established that the extraction method in an inert gas medium has found the widest application. The main methods for determining the hydrogen content in materials are analyzed, it is established that the extraction method in an inert gas medium has found the widest application. The need for calibration of analyzers on reference materials with a high hydrogen concentration was noted. Reference materials of titanium alloy VT-1-0 with hydrogen concentration up to (4.0±0.1) wt.% have been developed. The optimal parameters for the analysis were selected. On the example of the hydrogen analyzer RHEN602 (LECO, USA), calibration was carried out on the developed reference materials to obtain a calibration dependence. The reliability of the obtained calibration curve with the application of stoichiometric zirconium hydride was estimated. The confidence interval of the resulting calibration curve was ±10 %. It has been established that the calibration on the developed materials makes it possible to analyze materials with a hydrogen content of 0.5 to 4.0 wt.%. The practical significance of the study lies in the development of reference materials that can be applied to calibrate hydrogen analyzers operating on the principle of melting in an inert gas medium at a high hydrogen concentration.В данном исследовании рассматриваются вопросы повышения точности при измерении высоких концентраций водорода при разработке материалов-накопителей в водородной энергетике. Цель исследования – разработка стандартных образцов для градуировки анализаторов водорода при высоких концентрациях. Проанализированы основные методы определения содержания водорода в материалах, установлено, что экстракционный метод в среде инертного газа нашел наиболее широкое применение. Отмечена необходимость градуировки анализаторов по стандартным образцам с высокой концентрацией водорода. Разработаны стандартные образцы из титанового сплава ВТ-1-0 с концентрацией водорода до (4,0±0,1) масс.%. Подобраны оптимальные параметры проведения анализа. На примере анализатора водорода RHEN602 (LECO, США) проведена градуировка по разработанным стандартным образцам с получением градуировочной зависимости. Оценена надежность полученной градуировочной прямой с использованием стехиометрического гидрида циркония. Доверительный интервал полученной градуировочной прямой составил ±10 %. Установлено, что проведение градуировки по разработанным образцам позволяет проводить анализ материалов с содержанием водорода от 0,5 до 4,0 масс.%. Практическая значимость исследования заключается в разработке стандартных образцов, которые могут быть применены для проведения градуировки анализаторов водорода, работающих по принципу плавления в среде инертного газа, при высокой концентрации водорода.

Results of investigating the characteristics of bone marrow in patients with squamous cell carcinoma of the head and neck, their clinical value

To reveal the specific features of hematopoiesis in patients with head and neck squamous cell carcinoma (HNSCC), the authors analyzed the indicators of 41 bone marrow aspirates in relation to the clinical and morphological characteristics of the tumor and micrometastases detected in bone marrow. Puncture samples were morphologically and molecularly examined at the Laboratory of Hematopoiesis Immunology, N.N. Blokhin Russian Cancer Research Center. The found changes in the bone marrow cell composition in HNSCC patients showed themselves as an increase in the relative count of segmented neutrophils and a decrease in the level of immature granulocytes with no alternations in the neutrophil maturation index and in the percentage of granulocyte lineage cells. Bone marrow hypocellularity is a characteristic feature of high-grade HNSCC. The significantly enhanced leuko-erythroblastic ratio was due to a reduction in red blood cells: the erythroid cell maturation index rose, by increasing the percentage of bone marrow oxyphilic normoblasts in patients with locally advanced HNSCC. A highly sensitive method for detecting mRNA of the specific squamous cell carcinoma protein E48 was perfected using reverse-transcription polymerase chain reaction and Southern blotting, followed by an enzyme immunoassay that could recognize bone marrow micrometastases in 35 % of the patients with HNSCC. The patients with found bone marrow micrometastases showed a significant decrease in the proportion of polychromatophilic normoblasts and a significant increase in granulocytes in the presence of normal values of lymphocytes and other cellular elements of myelograms. It was established that in the presence of regional lymph node involvement, bone marrow micrometastases were significantly more frequently in the patients with HNSCC and tumor progression over a period of up to 9 months