Detection of white dwarf spin period variability in the intermediate polar V2306 Cygni

Magnetic cataclysmic variables are close binaries which consist of a compact object - a white dwarf - and a red dwarf filling its Roche Lobe. Such systems are physical laboratories which enable study of the influence of magnetic fields on matter flows. They often exhibit spin-up or spin-down of the white dwarf, while some systems exhibit more complex behaviour of the spin period change. We monitor changes of the spin periods of white dwarfs in a sample of close binary systems to study interaction of the magnetic field and accretion processes as well as evolution of intermediate polars. Within the framework of our intermediate polar monitoring program, we obtained photometric CCD observations at several observatories. Two-period trigonometric polynomial fitting was used for determination of extrema timings. The (O-C) analysis was performed to study the variability of the orbital and spin periods of the systems. Using data taken during 9 years of observations of the magnetic cataclysmic variable V2306 Cygni (formerly known as 1WGA J1958.2+3232), we detected the spin period variability which shows a spin-up of the white dwarf with a characteristic time of $(53\pm5)\cdot10^4$ years. The value of the spin period was $733.33976$ seconds with the formal accuracy of $0.00015$ seconds. We derived an improved value of the orbital period of the system to be $4.371523\pm0.000009$ hours.Comment: Accepted to MNRAS 2019 July 23. 5 pages, 3 figures, supporting data onlin

Plasma measurements conducted in the vincinity of Venus on the spacecraft VENERA-4

Plasma flux measurements in vicinity of Venus by charged particle traps on Venera-4 spacecraf

Sorption of volatile organic compounds and their mixtures on montmorillonite at different humidity

The vapor-phase sorption of volatile organic compounds (VOCs), i.e. n-hexane, benzene and methanol, along with sorption of their binary mixtures, i.e. benzene/n-hexane and benzene-methanol, on montmorilllonite with different water content was studied. The absolutely dry mineral did not exhibit selectivity towards the studied VOCs sorbed separately. The hydration inhibited sorption of hydrocarbons and promoted that of methanol because of intercalation of its molecules to the interlayer space of the swelling mineral and dissolution in the water films on the external mineral surface. Unlike separate sorption of benzene and n-hexane, sorption of their binary mixture on the montmorillonite, even equal by volume, was selective. The components shared the same sorption sites with benzene being more active due to its ability to form the donor-acceptor complexes with the mineral surface in addition to Van-der-Waals interactions. Opposite, in the benzene/methanol mixture the undoubted predominance of hydrophilic methanol over benzene was revealed, which increased with increasing humidity and was significantly stronger compared to the differences in sorption of methanol and benzene sorbed separately. In the binary mixtures unequal by volume, preadsorption played an important role in VOCs competition with sorption of aliphatic n-hexane being suppressed stronger than that of aromatic benzene. In the benzene/methanol mixture, methanol was predominantly sorbed at all the studied volume ratios and hydration degrees, occupying its specific sorption sites. Hydration of the montmorillonite caused the reverse impact on the sorption of benzene and methanol. As a result, at the full hydration state methanol sorption in the mixture reached that of the pure methanol. © 2014 Elsevier B.V

Effect of the Soil Dehydration Temperature on the Vapor-Phase Sorption of p-xylene

The effect of two methods for the preparation of soil samples for sorption experiments-hard (dehydration at 105°C) and mild (drying over P2O5 at 20°C in vacuum) drying-on the values of the vaporphase sorption of p-xylene was studied depending on the content of organic matter in the soil. It was shown with dark gray forest and chernozemic soils as examples that the hard drying of soil samples taken from the upper layer of the humus profile with a high content (>4%) of organic carbon decreased their sorption capacity in the range of 0-5% by 7-81%. Therefore, the method is unsuitable for these soils. It was also found that the mild method of soil preparation had obvious analytical advantages. © 2010 Pleiades Publishing, Ltd

Use of geoinformation and neurotechnology to assess and to forecast the humus content variations in the steppe soils

This paper reports the results obtained using the systemic basin approach, geoinformation, and neurotechnology for modeling and forecasting of the humus spatial inhomogeneity and content variations in the steppe and dry steppe zones (Kherson oblast, Ukraine

Effect of organic matter on the sorption activity of heavy loamy soils for volatile organic compounds under low moisture conditions

© 2014, Pleiades Publishing, Ltd. The diverse effect of the organic matter content on the sorption of vapors of aromatic and aliphatic hydrocarbons in soils under low moisture (<10.5%) has been revealed in sorption experiments using profile samples from two virgin heavy loamy dark gray forest soils characterized by relatively stable contents of finely dispersed mineral components. The decrease of the hydrocarbon sorption with increasing the content of organic matter under dry conditions (in the moisture range from 0 to 5–6%) indicates its lower sorption activity than that of the clay components and the blocking of the sorption sites on soil minerals by organic matter. At moisture contents above 5–6%, the effect of the soil composition on the sorption activity changes radically: it increases with increasing the content of organic matter. This is due to the inversion of the ratio between the activities of the soil components because of the hydrophilization of the surface of the mineral soil component. As a result, the sorption of water on the minerals reduces the mineral sorption activity to hydrocarbons to a lower level than the activity of organic matter. The maximum manifestation of the revealed blocking effect has been observed for the low-humus soils and this effect decreased with the accumulation of soil organic matter

Mathematical Modelling of Astrophysical Objects and Processes

In this review, we present some advanced algorithms and programs used in our scientific school with short description of types of astrophysical systems, which we study. However, we discuss mainly mathematical methods, which may be applied to analysis of signal of any nature - in computer science, engineering, economics, social studies, decision making etc. The variety of types of signals need a diversity of adequate complementary specific methods, in an addition to common algorithms. As an example, one may refer to vibrations, stability of mechanisms. Many mathematical equations are common in Science, Technics and Humanities.Comment: 20 pages. A review devoted to the 90-th anniversry of the Odessa National Maritime University. Chapter of a monograp

Sorption of hydrocarbons by leached chernozem

The sorption of n-octane, n-nonane, n-decane, decalin, and p-xylene on oven-dried and differently wetted leached chemozem, zeolite-bearing rock, and limestone was studied using static headspace-gas chromatography. It was found that leached chernozem exhibits a high capacity for selective sorption of hydrocarbons and has significantly heterogeneous sorption sites. Thermodynamic parameters of sorption, specific surface of sorbents, and the fractal dimension of soil surface were determined. An increase in the soil moisture content significantly inhibited the sorption of the hydrocarbons studied. Copyright © 2003 by MAIK "Nauka/Interperiodica" (Russia)