The paper discusses environmentally friendly ways to improve the productivity of crop production. Drugs made from plants containing terpenes are capable to protect crops from various diseases and ...stimulate their development. Outer bark of birch may contain triterpene alcohol betulin up to 40% of the mass, which allows to obtain environmentally friendly plant protection products. Experimental studies are devoted to studying the process of extracting betulin from birch bark, creating a betulin-containing preparation "Stimulin" for treating seeds and vegetative plants, as well as testing "Stimulin" on various agricultural cultures. The results of the use of the drug showed a significant increase in yield (by 8-35 %%) of crops such as wheat, barley, buckwheat, soybeans, and watermelons. The test of the fungicidal activity of "Stimulin" was carried out on sea buckthorn, the main causative agent of diseases and the cause of drying of which is the Fusarium mushroom. The fungicidal activity of "Stimulin" is comparable to potent synthetic agrochemicals.
ABSTRACT
Statistical analysis of samples of the orbits of celestial bodies is complicated by the fact that the Keplerian orbit is a multidimensional object, the coordinate representation of which ...non-linearly depends on the choice of orbital elements. In this work, using the construction of the Fréchet mean, concepts of mean orbit and dispersion of the orbit family are introduced, consistent with the distance function on the orbit set. The introduced statistical characteristics serve as analogues of sample mean and variance of a one-dimensional random variable. Exact formulas for calculating the elements of mean orbits and dispersion quantities with respect to two metrics on the orbit space are derived. For a large sample of meteoroid orbits from the Geminid stream, numerical simulations of orbit evolution over 20 000 yr in the past were conducted. By analysing the dependency of statistical characteristics on time, estimates for the age of the stream and the gas outflow velocity are obtained under the assumption of the birth of the Geminids due to the rapid destruction of the cometary nucleus. The estimate of the age of the stream lies in the interval from 1200 to 2400 yr, and the speed of gas outflow at perihelion should have been more than 1.2 km s−1.
A computational-experimental method for studying the packaging and unfolding of shell structures made of composite material is proposed. The construction consists of rigid elements interconnected by ...elastic hinges made of uncured prepreg. This material is elastic and therefore it can store an elastic energy during the structure packaging, and later a stored energy will facilitate unfolding. The hinge's material is modelled by a hyper elastic isotropic medium, the Neo-Hookean potential is applied. The parameters of the potential are determined by the computational-experimental method. The viscous and viscoelastic characteristics of the binder are determined by the rheological method with a Physica MCR 501 rotational rheometer. The calculated effective properties of the hinge's material are used to demonstrate the packaging of the cylindrical shell. Three different packaging methods for a cylindrical shell with six prepreg hinges are considered. The article studies the dependence of the load required for packaging on the type of packaging and the curing degree of the binder.
At present, the vesuvianite group of minerals consists of eight members, six of which are distinguished by the dominant cation in the Y1(A,B) five-coordinated site. We investigated two vesuvianite ...samples from the type locality by electron microprobe analysis, Mössbauer and infrared spectroscopy, TGA/DSC, MAS NMR, single-crystal and powder X-ray diffraction. The crystal structures of these samples (# 27844 and 51062 from the Vesuvius collection, Fersman Mineralogical Museum, Moscow) have been refined to R1 = 0.027 and R1 = 0.035, respectively. Both samples have the space group P4/nnc; a = 15.5720(3) and 15.5459(3), c = 11.8158(5) and 11.7988(4), respectively. In both samples low-occupied T1 and T2 sites are populated by minor B and Al, which agrees with their high-temperature origin. According to our experimental results, the general revised crystal-chemical formula of vesuvianite can be written as VII−IXX19VY1VIY12(Z2O7)4(ZO4)10(W)10, where X are seven- to nine-coordinated sites of Ca with minor Na, K, Fe2+ and REE impurities; VY has a square pyramidal coordination and is occupied predominantly by Fe3+ with subordinate Mg, Al, Fe2+ and Cu2+; VIY has octahedral coordination and is predominantly occupied by Al with subordinate Mg, Fe2+, Fe3+, Mn2+, Mn3+, Ti, Cr and Zn; ZO4 = SiO4, sometimes with subordinate AlO4 and/or (OH)4, and W = OH, F, with minor O and Cl. The idealized charge-balanced formula of the vesuvianite end-member without subordinate cations is Ca19Fe3+(Al10Me2+2)(Si2O7)4(SiO4)10O(OH)9, where Ме = Fe2+, Mg2+, Mn2+.
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The physical properties of an epoxy resin doped with C
60
fullerenes at concentrations from 0.02 to 1 wt. % have been investigated by the methods of computer modeling and full-scale experiments. A ...percolation model of the fullerene-filled epoxy resin is proposed. The main result of the computer modeling is the critical concentration of fullerene in the epoxy at which the material changes its properties. This concentration corresponds to the percolation threshold. In full-scale experiments, the Young’s modulus and refraction index of material were determined. The identical nonmonotonic behavior of the Young’s modulus and refraction index at a maximum fullerenes concentration of 0.153 wt.% is revealed. On further increasing the concentration, the properties of the material returned to the initial ones. The relation between material properties and the average size and power of percolation cluster is determined.
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DOBA, EMUNI, FIS, FZAB, GEOZS, GIS, IJS, IMTLJ, IZUM, KILJ, KISLJ, MFDPS, NLZOH, NUK, OBVAL, OILJ, PILJ, PNG, SAZU, SBCE, SBJE, SBMB, SBNM, UILJ, UKNU, UL, UM, UPUK, VKSCE, ZAGLJ
The formulation of the system of equations of the mechanics of a gas as a continuous medium is completed. This describes the non-stationary slow laminar flow of a mixture of gases (the Mach number ...being much less than unity), for a Reynolds number and relative drops in temperature and molar fractions of the order of unity. The distribution with respect to the internal energies of the molecules is close to Boltzmann (the case of rapid exchanges of translational and internal energies of the molecules). The difference from the similar system of equations in the Navier–Stokes approximation is the fact that in the equation of motion the Burnett stresses, expressed in terms of the second differential and paired products of the first derivatives with respect to the temperature and molar fractions (concentrations) are taken into account. A consequence of the action of these stresses is thermal-stress and concentration-stress convection. Special cases and possible extensions are considered.
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The present study includes experimental investigations of rheological properties of the epoxy composite matrix based on epoxy resin L and hardener EPH 161. It is shown that the temperature ...dependences of the oligomer viscosity and the hardener can be satisfactorily described by the Arrhenius equation. Dependence of epoxy resin viscosity on temperature and volume concentration of the hardener at the initial stage of the polymerization process is investigated. It is shown that the experimental results can be generalized with one universal dependence of concentration and temperature.
We investigate the curing of large shell construction made of epoxy resin/carbon fibers prepreg under free space conditions in solar synchronous Low Earth Orbit. The curing kinetics is described by ...first order kinetic equation with auto-acceleration and deceleration parameters based on the experimental data. Heating of the shell is provided by solar radiation. The heat distribution in the shell is modelled based on partial absorbance of the solar radiation, the prepreg thermal conductivity and thermal capacity, radiation heat transfer between inner surfaces of the shell and the gas thermal conductivity. The iterated algorithm of curing was developed. Three flight regimes based on the circular motion of a construction have been considered: 1 – the axis of a shell lies in the tangent plane to the orbit and makes a constant angle with the tangent; 2 – under conditions (1), a shell rotates around its axis with a constant angular velocity; 3 – under conditions (2), the axis of the shell precesses around the tangent to the orbit. It was found, that the parameters of the motion (i.e. angular velocity of the rotation around the axis, precession angular velocity and precession angle) could be optimised in such way, that the whole shell can be completely cured under the solar radiation.
•Curing of epoxy composite in space is proposed for large space construction.•Solar synchronous Low Earth Orbit is considered for a curing orbit.•Orbital motion with the axis of the shell precesses around the tangent is optimised.
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The accuracy of model kinetic equations is analyzed using the exact moment solutions of the Boltzmann–Maxwell equation for homoenergetic affine flows of a monatomic gas of Maxwellian molecules in the ...absence of external forces. Solutions of the third-order kinetic-moment equations for homogeneous shear flow and one-dimensional homogeneous expansion-collapse flow are considered. The principal advantages of the domestic Shakhov and, especially, Larina–Rykov models are demonstrated.
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The paper studies the patterns and snowmelt regime on the case of several river catchments of the Kama Region. Based on the temperature coefficient method, detailed digital maps and GIS-technologies, ...a model of spring snow melting has been developed. This model makes it possible to take into account the spatial distribution of meteorological information, features of the relief and soil-vegetation cover more accurately. The estimation of the slope aspect influence on the spring snow melting processes by means of correction coefficients and the technique of determining their optimal values is proposed. A method for verifying the results of calculations of the snow cover spatial distribution based on space monitoring data is proposed. To perform a quantitative comparison of model maps with interpreted images, the choice of the value of the fraction of remaining snow in each cell of the map (information on the presence or absence of snow cover) was justified. If the value of fraction ≥ 0.5, then 1 is assigned – snow is present, if < 0.5, then 0 is assigned – no snow. The simulation results of snow melting for the Kosa–Kosa catchment area during the spring periods of 2004, 2010 and 2015 showed that the average overlap of snow-covered area on the model maps and decoded satellite images is 73.67%. Validation of the proposed snowmelt model was carried out in the Kama–Gainy and the Vishera–Ryabinino catchments. The average overlap area between the model maps and interpreted satellite images was 72.56 and 88.56%, respectively.
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