Vol 485, No 3 (2019)

For high-order ordinary differential equations containing terms with lower order derivatives, sufficient conditions for the absence of rapidly growing solutions are obtained.

New estimates for the independence numbers of distance graphs with vertices in B {-1, 0, 1}ⁿ are obtained.

A derivation of the Vlasov-Poisson-Poisson equation is proposed for studying stationary solutions of a system of gravitating charged particles in vicinity of triangular libration points (Kordylevsky cloud). Stationary solutions are sought as functions of integrals, which leads to elliptic nonlinear equations for the potentials of the gravitational and electrostatic fields. This gives a critical mass: for bodies with large masses dominates gravitation forces, and for bodies with smaller masses - electrostatic forces.

A differential two-photon method of measuring the temperature of ⁴⁰Ca atoms in a continuously operating magneto-optical trap is demonstrated. Coherent two-photon resonances at the 4s^{2 1}S₀-50 ¹S₀ Rydberg transition have been investigated experimentally using resonance laser beams propagating at different angles. The tempera­ture of the cloud of ⁴⁰Ca atoms was measured depending on the frequency detuning of the cooling laser radiation.

In this paper we consider the control of the motion of a dynamically asymmetric unbalanced ball (Chaplygin top) by means of two perpendicular rotors. We propose a mechanism for control by periodically changing the gyrostatic momentum of the system, which leads to an unbounded speedup. We then formulate a general hypothesis of the mechanism for speeding up spherical bodies on a plane by periodically changing the system parameters.

The dependence of rolling friction on velocity for various contact conditions is discussed. The principal difference between rolling and other types of relative motion (sliding and spinning) is that the points of the body in contact with the support change over time. Due to deformations, there is a small contact area and, entering into contact, the body points have a normal velocity proportional to the diameter of this area. For describing the dependence of the friction coefficient on the angular velocity in the case of “pure” rolling, a linear dependence is proposed that admits a logical explanation and experimental verification. Under the combined motion, the rolling friction retains its properties, the sliding and spinning friction acquiring the properties of viscous friction.

A terpolymer with a molecular weight of 45 kDa containing 7 mol.% of vinylamine units, 80 mol.% of vinylpyrrolidone, and 3 mol.% of vinyliminodiacetic acid units has been synthesized. Its complexation with Ga³⁺ ion has been studied by HPLC. The resulting metal–polymer complex has been characterized by exclusion chromatography and spectral (IR, ¹H NMR) data. The complex has a monomolecular structure where the metal ion acts as an anchor fragment between vinyliminodiacetic acid units and is stable in the reaction of interligand exchange with histidine.

New 4,5-diaza-9,9'-spirobifluorene derivative 8 with two electron-accepting perylene diimide moieties has been prepared. The compound 8 was characterized by NMR spectroscopy, elemental analysis, UV-spectroscopy and cyclic voltammetry. Energies of HOMO/LUMO levels are of -5.81 eV/-3.89 eV; Egopt and Egech values are of 1.75 eV and 1.92 eV, respectively. Low-lying energy levels and strong absorption in the visible region of UV- spectrum indicate the potential use of the compound 8 as a new promising electron acceptor in nonfullerene polymer solar cells.

Self-oscillating neck propagation of amorphous polybutylene succinate was studied. The neck propagated by regular neck front jumps at the stretching speeds from 0.05 to 1000 mm/min. Self-oscillations at extremely low stretching speeds contradicts to the theory of this phenomenon. The instability of the neck propagation was explained by the deformation softening of the polymer.

It was established that the age of hydrothermal ore metasomatites of the Burinda gold-silver deposit, one of the most famous in eastern Asia, can be estimated in the interval 126-128 Ma. It is shown that the formation of this deposit is due to hydrothermal processes in the final stages of the formation of the Taldan volcanic complex.

Analysis of the data of seismoacoustic investigation and geotechnical drilling in the western Barents Sea has shown the following. The Upper Weichselian glacial deposits cover spread regionally. It represents seismostratigraphic complex (SSK) SSK III, unconformity occurs on the Mezozoic deposits, partly – on the Lower Weichselian moraine (SSK V) and is overlain unconformity by the Late Glacial glaciomarine (SSK II) – Holocene marine (SSK I) sediments. SSK III consists of two seismofacies (SF). Predominant SSF III-C are formed by the ordinary moraine almost solely, and SF III-T – by the M-moraine. The presence of these moraines determine of SSK III thicknesses distribution nearly completely. The ordinary moraine thickness fluctuates from < 10 m to 10–25 m. The M-moraine forms huge in plan, positive accumulation bodies in which its thickness > 25 m and arrives at 50–75 m. The other grandiosity structure-morphological elements of the Upper Weichselian deposits cover are: end moraines (the giant form was discovered) and powerful subglacial cuts, which represents unique unburied analog of the known so-called tunnel valleys. Structure, composition, thicknesses particularities of SSK III deposits cover were conditioned by specific character of process of the Last Glaciation development in the region.

This study is aimed at comparative analysis of the chemical evolution, age, and petrogenetic features of the Li–F granites from various zones of the Early Mesozoic magmatic areal. The newly obtained geochemical data preclude the formation of rare-metal Li–F granites by processes of magmatic differentiation of a palingenic granitic magma, parental to the Baga–Khentei Pluton. The rare-metal granites of the peripheral zone of the Early Mesozoic magmatic areal, compared to their counterparts from the central part (the Baga–Khentei Pluton), are more enriched in some elements that accumulated intensively during fluid-magmatic differentiation (Li, Rb, Sn, Ta, and F), often forming a concentrated mineralization. This corroborates the potential of rifted fringes of batholiths in the context of the connection of rare-metal mineralization and magmatism. The geochemical specifics of the Khentei intrusion granite from the central part of the Early Mesozoic magmatic areal may imply a deeper source related to the mantle plume.

This paper presents the results of a Raman spectroscopic study of shock melt veins in L6 chondritic meteorites Dhofar 717 and 864, and conclusions about the PT-parameters recorded in these meteorites after the impact event. The primary minerals of the host chondrite include olivine, orthopyroxene, clinopyroxene, plagioclase, chromite, phosphates, troilite, and kamasite. Shock melt veins up to 1 cm thick contain fragments of the high- pressure minerals ringwoodite, wadsleyite, majorite, akimotoite, jadeite, lingunite, and tuite and quenched melt consisting of majorite, ringwoodite, troilite, and kamasite. The mineral associations of the Dhofar 717 and 864 chondrites indicate high peak PT-parameters of the impact in the region of stability of majorite (>20 GPa and >2500 K) and bridgmanite (>25 GPa and >2500 K). The presence of lingunite also directly indicates a peak pressure in the area of stability of the bridgmanite.

This article is devoted to a study of variations in the U isotopic composition (²³⁸U/²³⁵U) in the section of clas- tic-carbonate Ediacaran sediments exposed along the Chaya River in the southern part of Central Siberia (Russia). Measurements of ²³⁸U/²³⁵U in the rocks were performed using a high-precision (±0.07%o, 2SD) MC-ICP- MS with a ²³³U-²³⁶U double isotope spike. The total variation range of S²³⁸U in the studied carbonate rocks was -0.91 to -0.01%. Extremely low values of S²³⁸U (-0.91%, -0.9%, and -0.84%), which were found in a number of samples from the lower part of the section, are interpreted as the result of postsedimentation processes affecting the rocks. In the overlying sediments, the range of S²³⁸U variations is smaller from -0.49 to -0.01%. Here, regular “weighting” of the U isotopic composition observed upwards through the section indicates an increase in the reduction conditions at this time (about 550 Ma) in the paleobasin. This conclusion is consistent with the elevated concentrations of U, Mo, and V in the Late Ediacaran sedimentary rocks of the region studied.

Based on the Chelyabinsk (February 13, 2013) and Lipetsk (June 21, 2018) events, disturbances in the Earth's geomagnetic field, which were induced by the fall of these meteorites, were studied. Based on the data provided by geomagnetic observatories of the INTERMAGNET network and the mid-latitude Mikhnevo geophysical observatory (IDG RAS), it was established that the fall of meteorites through the Earth's atmosphere, in general, induces geomagnetic disturbances of up to 5 nT at distances up to 2700 km from the impact point of a cosmic body; the maximum effect is reached with a delay time ranging from ~5 to ~10 min, and the duration of the period of the induced geomagnetic field disturbances varies from ~5 to ~20 min. The estimation dependencies of the amplitude and duration of induced geomagnetic disturbances from a distance from the meteorite impact points are proposed.

Previously, we synthesized a dimeric dipeptide mimetic of the brain-derived neurotrophic factor (BDNF) loop 4, GSB-106, which, similarly to BDNF, activated TrkB, PI3K/AKT, and MAPK/ERK. When administered systemically, it exhibited neuroprotective, antidepressant, and antidiabetic activities and stimulated neurogenesis and synaptogenesis. In this study, we established that GSB-106 also exhibits the analgesic activity, typical for BDNF, which was revealed in rats in hot plate and tail flick tests 0.5–48 h after intraperitoneal injection at doses of 0.1 and 1 mg/kg.

This is the first study to isolate the taxoid taxuyunnanin C (group of 14-hydroxylated taxoids) from the biomass of suspension cell culture of the Canadian yew (Taxus canadensis). According to available data, this is the first report of the presence of nonpolar (polyacylated) forms of 14-hydroxylated taxoids, including taxuyunnanin C, in T. canadensis.

A study of the association of vertebrates from the Pleistocene deposits of the Taurida karst cave discovered in 2018 in the central Crimea (Belogorsky district, Zuya village) showed its correlation with the Late Villafranchian faunas of the Eastern Mediterranean and an approximate age of 1.8–1.5 Ma.