This article examines the bioclimatic potential (BCP) (according to S.A. Sapozhnikova) and agroclimatic characteristics of the Central Chernozem Region, including the Oryol oblast, with ...spatiotemporal trends of their variability analyzed from 1980 to 2021. In the early 2000s, compared to the late 20th century, there was a 10% increase in the BCP, a 13% rise in the sum of active temperatures, and a 6% longer active growing season. Furthermore, shifts in the isolines of the sum of active temperatures and the hydrothermal coefficient (HTC) occurred. The active temperature isotherm of 3000°C moved northward, and it is now running through the Belgorod and Voronezh oblast. As a result of the observed hydrothermal conditions, a significant part of the Central Chernozem transitioned from the zone with sufficient moisture (1.3 ≥ HTC > 1) to an arid zone (1 ≥ HTC > 0.7). The overall growth of the BCP in the Central Chernozem Region can be associated with a considerable rise in the sum of active temperatures and a reduction in moisture supply.
Airborne Conical Antenna Arrays Ponomarev, L. I.; Vasin, A. A.; Terekhin, O. V. ...
Journal of communications technology & electronics,
10/2020, Volume:
65, Issue:
10
Journal Article
Peer reviewed
The study presents an algorithm and the results of analysis of the sum-and-difference directional characteristics of an airborne conical antenna arrays (AAs) of slot radiators located on the ...conductive surface of the cone. It is shown that the maximum directivity of such antennas in the radiation mode and the steepness of the difference radiation pattern (in the
E
-plane) in the receive mode for pointed cones can significantly exceed similar parameters of the equivalent planar aperture.
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EMUNI, FIS, FZAB, GEOZS, GIS, IJS, IMTLJ, KILJ, KISLJ, MFDPS, NLZOH, NUK, OILJ, PNG, SAZU, SBCE, SBJE, SBMB, UKNU, UL, UM, UPUK, VKSCE, ZAGLJ
The requirements for the characteristics of phased antenna arrays of radar systems designed to probe the Earth’s surface from an aircraft are determined. The design features of an onboard ...pass-through phased array antenna with a monopulse irradiator are considered. The results of the calculation of the directivity characteristics and the magnitude of the gain coefficient losses of the phase-controlled antenna array are presented.
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EMUNI, FIS, FZAB, GEOZS, GIS, IJS, IMTLJ, KILJ, KISLJ, MFDPS, NLZOH, NUK, OILJ, PNG, SAZU, SBCE, SBJE, SBMB, UKNU, UL, UM, UPUK, VKSCE, ZAGLJ
A two-stage method for calculation of the input crosstalk of two airborne radars is considered. Electromagnetic compatibility of two closely located onboard X- and Ka-band radars is evaluated and a ...possibility of simultaneous work is assessed.
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EMUNI, FIS, FZAB, GEOZS, GIS, IJS, IMTLJ, KILJ, KISLJ, MFDPS, NLZOH, NUK, OILJ, PNG, SAZU, SBCE, SBJE, SBMB, UKNU, UL, UM, UPUK, VKSCE, ZAGLJ
A onestage method has been developed for phase transfer of gold nanoparticles (NPs) with a diameter of 17.2 ± 0.5 nm from a hydrosol to an organic medium (chloroform). The method is based on the high ...affinity of thiolated poly(ethylene glycol) (TPEG) for nonpolar solvents and the capability of its molecules for chemisorption on a gold NP surface with the formation of a dense monolayer. Results of thermo-gravimetric analysis have been used to determine the maximum packing density (≈0.85 nm
−2
) of TPEG molecules on the surface of Au NPs with the aforementioned diameter. It has been shown that TPEG can play the roles of both an NP stabilizer and a phase transfer agent. Therewith, the degree of NP transfer from water to chloroform is ≈90%. The stability to aggregation of the obtained organosols has been found to increase with the chemisorption value of PEG molecules. It has been demonstrated that these organosols can be used to form two-dimensional ensembles of gold NPs on planar substrates.
The results of experimental studies devoted to the formation of highly ordered nanoparticle assemblies on planar substrates of various nature using block copolymer lithography methods are presented. ...The structure and properties of such assemblies and the design of thin-film polymer-metal composites based thereon are discussed. The attention is focused on the assemblies obtained by nanoparticle synthesis in the micelles of amphiphilic diblock copolymers.
A new method has been proposed for designing composite materials that represent highly ordered two-dimensional metal nanoparticles ensembles having variable geometric parameters and being embedded ...into the surface layer of a polymer matrix to a predetermined depth. The method is based on diblock copolymer micellar lithography and the effect of decreased glass-transition temperature of a polymer surface as compared with its bulk value. The possibility of independent variations in the depth of embedding of metal nanoparticles (by system annealing) and their size (by seeded growth) has resulted in the systematic study of the influence of the temperature and time of annealing on the kinetics of nanoparticle embedding into a polymer. For the first time, the plasmon-resonant properties of hexagonally ordered ensembles of gold nanoparticles located at a polymer-air interface have been experimentally studied. It has been established that the embedding of an ensemble of nanoparticles into a polymer is accompanied by a bathochromic shift of the maximum of its localized surface plasmon resonance due to a growth in the effective dielectric permittivity of the environment of the nanoparticles. An empirical equation has been proposed, which satisfactorily describes these experimental data.
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EMUNI, FIS, FZAB, GEOZS, GIS, IJS, IMTLJ, IZUM, KILJ, KISLJ, MFDPS, NLZOH, NUK, OILJ, PILJ, PNG, SAZU, SBCE, SBJE, SBMB, UKNU, UL, UM, UPUK, VKSCE, ZAGLJ
A new approach to creating highly ordered two-dimensional ensembles of nanoparticles with variable geometric parameters is proposed. It combines diblock copolymer micellar lithography and controlled ...deformation of a polymer substrate. The key feature of the approach is the formation of a monolayer of hexagonally packed metal precursor-containing micelles of an amphiphilic diblock copolymer on the surface of an isotropically stretched polymer plate. The average distance between micelle centers is 140 nm. Subsequent thermal treatment (or isotropic stretching) of the sample results in the shrinkage (or elongation) of the substrate, which enables one to vary the distance between micelle centers in a range of 80–200 nm while retaining hexagonal packing of the micelles in the monolayer. At the final stage, ensembles of hexagonally ordered gold nanoparticles are obtained by exposing the micellar films to air plasma. It is demonstrated that gold nanoparticles in these ensembles can be enlarged by seeded growth. The systematic study of the plasmon-resonant properties of the resulting ensembles shows that the gradual increase in the distance between 35-nm gold particles from 80 to 200 nm leads to an unexpected nonmonotonic shift of the maximum of localized surface plasmon resonance, which is, from our point of view, caused by the high degree of organization of nanoparticles on the substrate.
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EMUNI, FIS, FZAB, GEOZS, GIS, IJS, IMTLJ, IZUM, KILJ, KISLJ, MFDPS, NLZOH, NUK, OILJ, PILJ, PNG, SAZU, SBCE, SBJE, SBMB, UKNU, UL, UM, UPUK, VKSCE, ZAGLJ
Optical spectroscopy and atomic force microscopy are used to study the formation of silver shells on gold nanoparticles in their highly ordered two-dimensional ensembles produced by the method of ...block copolymer micellar lithography. The shells are synthesized using formaldehyde or hydroquinone as a reducing agent. The spectral characteristics of the nanoparticle ensemble are shown to be essentially sensitive to the silver shell thickness. As a result, working units of solid-state optical sensors for detecting trace amounts of metal ions and different reductants may be created based on highly ordered 2D ensembles of gold nanoparticles.
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EMUNI, FIS, FZAB, GEOZS, GIS, IJS, IMTLJ, IZUM, KILJ, KISLJ, MFDPS, NLZOH, NUK, OILJ, PILJ, PNG, SAZU, SBCE, SBJE, SBMB, UKNU, UL, UM, UPUK, VKSCE, ZAGLJ
The formation of reverse micelles of amphiphilic diblock copolymers of styrene and 2-vinylpyridine in selective (for one of the blocks) solvent (toluene) is studied by dynamic light scattering and ...atomic force and transmission electron microscopies, as well as by absorption spectroscopy and X-ray photoelectron spectroscopy techniques. It is revealed that the behavior of micelles of block copolymers with different ratios of block lengths and absolute molecular masses in solution is fundamentally different depending on the amount of added metal salt. The possibility of controlled variations in the characteristic sizes of two-dimensional ordered ensembles of micelles on the surface of silicon wafers is demonstrated. It is shown that, in some cases, the distance between the centers of micelles in ensemble depends on the concentration of copolymer solution and the amount of metal salt preliminarily added to the solution.
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EMUNI, FIS, FZAB, GEOZS, GIS, IJS, IMTLJ, IZUM, KILJ, KISLJ, MFDPS, NLZOH, NUK, OILJ, PILJ, PNG, SAZU, SBCE, SBJE, SBMB, UKNU, UL, UM, UPUK, VKSCE, ZAGLJ
