Технико-технологические инновации. Рубрика в журнале - НБИ технологии
Статья научная
Из множества различных видов систем автоматического управления наибольший теоретический и прикладной интерес представляют дискретные динамические и логико-динамические системы управления. Объясняется это широкой востребованностью данных систем в промышленности, авиации, космонавтике, радиолокации, оборонном секторе и других сферах. Современная теория автоматического управления имеет достаточное количество эффективных методов расчета и проектирования линейных систем. Результаты, полученные для нелинейных и логико-динамических систем, имеют, как правило, частный характер и относятся к определенному классу нелинейностей или логических устройств. В связи с этим важной проблемой является формирование общей теории дискретных динамических, релейных и логико-динамических систем автоматического управления. В статье излагаются концептуальные основы общей теории дискретных динамических, релейных и логико-динамических систем на основе использования общих фундаментальных свойств рассматриваемых классов - дискретности структур и физической декомпозиции.
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Статья научная
Dynamic mechanical thermal analysis (DMTA) is an accessible and versatile analytical technique where a sample is submitted to an oscillating stress or strain as a function of oscillatory frequency and temperature. Through this non-destructive measurement, a comprehensive understanding of the dynamic mechanical properties of polymers may be obtained.
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Статья научная
Molecular dynamics simulation of glassy polymethylene (PM) plastic deformation is performed up to = 30 % in uniaxial compression and 60 % in tensile regimes at a temperature of 50 K, which is ~140 K below Tg of the polymer. All atoms of PM chains are represented explicitly. Calculations were performed for two series of samples with different molecular mass distribution of chains. Each sample contains 12 288 -CH2- monomeric units per computational sell. Contribution from various interactions to potential energy of the system was investigated. Nonaffine displacements of methylene groups and conformational rearrangements in chains during deformation are visualized and analyzed. The transformation of relative fragments of chains up to 16-20 monomer units length are basic structural units, nonconformational displacements of which control plastic process. Relatively large nonaffine displacements are observed even in the range of low strains, which are usually interpreted as Hookean strains. In the range of yield tooth and steady plastic flow, the number of these displacements increases along with their amplitude. Conformational set of PM chains does not show a serious change during deformation. Analysis had shown that the number of conformational rearrangements of trans-gauche type in PM chains during deformation is small and such rearrangements do not play decisive role in the considered range of PM plasticity, even at > 15 %, at the stage of the developed plastic flow.
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Molecular modeling of the 2-(pyridin-2-yl)-1H-benzimidazole intramolecular dynamics
Статья научная
The results of the DFT and MP2 theoretical investigation of 2-(pyridin-2-yl)- 1H-benzimidazole intramolecular dynamics are presented. The structural parameters of 2-(pyridin- 2-yl)-1H-benzimidazole conformers were obtained by these methods; barriers of internal rotation were estimated. GIAO-calculated NMR chemical shifts (1H and 13C) as obtained at various computational levels are reported for the 2-(pyridin-2-yl)-1H-benzimidazole conformers. The comparative analysis of experimental and computer NMR spectroscopy results revealed that the GIAO method with B3LYP/6-31G(d,p) level of theory and the PCM approach can be used to estimate the NMR 1H and 13C spectra parameters of the 2-(pyridin-2-yl)-1H-benzimidazole.
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Статья научная
GIAO-ca lculat ed NM R 13C chemical shifts as obtained at various computational levels are reported for the 1,1,3-trimethyl-3-(4-methylphenyl)butyl hydroperoxide. The data are compared with experimental solution data in chloroform-d, acetonitrile-d 3, and DMSO-d 6, focusing on the agreement with spectral patterns and spectral trends. Calculation of magnetic shielding tensors and chemical shifts for 13C nuclei of the 1,1,3-trimethyl-3-(4- methylphenyl)butyl hydroperoxide molecule in the approximation of an isolated particle and considering the solvent influence in the framework of the continuum polarization model (PCM) was carried out. Comparative analysis of experimental and computer NMR spectroscopy results revealed that the GIAO method with MP2/6-31G(d,p) level of theory and the PCM approach can be used to estimate the NMR 13C chemical shifts of the 1,1,3-trimethyl-3-(4- methylphenyl)butyl hydroperoxide.
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Nanocomposites based on polyethylene and nanocrystalline silicon films
Статья научная
High-strength polyethylene films containing 0.5-1.0 wt. % of nanocrystalline silicon (nc-Si) were synthesized. Samples of nc-Si with an average core diameter of 7-10 nm were produced by plasmochemical method and by laser-induced decomposition of monosilane. Spectral studies revealed almost complete (up to ~95 %) absorption of UV radiation in 200-400 nm spectral region by 85 micron thick film if the nc-Si content approaches to 1.0 wt. %. The density function of particle size in the starting powders and polymer films containing immobilized silicon nanocrystallites were obtained using the modeling a complete profile of X-ray diffraction patterns, assuming spherical grains and the lognormal distribution. The results of X-ray analysis shown that the crystallite size distribution function remains almost unchanged and the crystallinity of the original polymer increases to about 10 % with the implantation of the initial nc-Si samples in the polymer matrix.
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Neutralization of gas emissions in the production of polystyrene plastics
Статья научная
The assessment of the cost-effectiveness of measures to protect the environment was carried out. Relations are obtained to calculate the damage caused by atmospheric emissions in the production of polystyrene. Criteria for technical and economic evaluation of the effectiveness of gas purification system were developed. A method for estimating gas treatment facilities, allowing the design stage to make a comparative analysis of competing systems, taking into account the costs of implementation of environmental measures.
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Ozone decomposition on the surface of metal oxide catalyst
Статья научная
The catalytic decomposition of ozone to molecular oxygen over catalytic mixture containing manganese, copper and nickel oxides was investigated in the present work. The catalytic activity was evaluated on the basis of the decomposition coefficient which is proportional to ozone decomposition rate, and it has been already used in other studies for catalytic activity estimation. The reaction was studied in the presence of thermally modified catalytic samples operating at different temperatures and ozone flow rates. The catalyst changes were followed by kinetic methods, surface measurements, temperature programmed reduction and IR-spectroscopy. The phase composition of the metal oxide catalyst was determined by X-ray diffraction. The catalyst mixture has shown high activity in ozone decomposition at wet and dry O3/O2 gas mixtures. The mechanism of catalytic ozone degradation was suggested.
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Peculiarities of mineral nutrition of cereals in aluminum-acid soil conditions
Статья научная
The influence of aluminum ions on requirements of plants of cereal crops (wheat Triticum aestivum L. and oats Avena sativa L.) in macronutrients is studied. In the first series of experiments it is revealed that doubling of a dose of phosphorus in the acid media has caused doubling of its inclusion in metabolic processes in aluminum-resistant wheat Irgina at early stages of development, but in aluminum-sensitive wheat Priokskaya - only at a flowering stage. The development of root systems in wheat varieties differ in their Al-resistance level in the conditions of full supply with nitrogen and potassium does not depend on the presence of ions of hydrogen, aluminum or phosphorus in soil. Aluminum-sensitive wheat variety is characterized by considerable dependence of photosynthesis on conditions of a mineral nutrition whereas the intensity of photosynthetic processes of aluminum-resistant variety is influenced basically by a development stage. In the second series of experiments rather different reaction of the investigated wheat varieties on input of calcium into acid growth media is pointed out. These differences are related with transformation of absorbed phosphorus into mineral and organic acid-soluble fractions. Decreasing of ratio organic: mineral phosphorus indicates less intensiveness of metabolic processes in aluminum-resistant wheat Irgina at early stage of growth and following increasing of these processes under liming. Opposite, sensitive wheat Priokskaya displays sharp decrease of metabolic activity by the termination of experiment under calcium input. In the third plants of aluminum-resistant oats variety Krechet were capable to support metabolic processes with participation of nitrogen, phosphorus and potassium in the conditions of action of the stressful factor at the same level as in the neutral growth media. Changes of relative requirements in macronutrients specifies in considerable reorganizations of metabolic reactions in plants of Al-sensitive oats variety Argamak under stressor action. The biochemical processes related with action of the photosynthetic apparatus of leaves in stressful conditions have a priority in their supply with macronutrients, that is specified by smaller variability of the triple ratio N:P:K necessary for the maximum development of the leaves of oats in comparison with root systems at aluminum influence.
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Статья научная
The role of chemical elements with a valence of two or more is important for the living organism, as just they ensure the action of enzymes - proteins, catalysts of biochemical reactions. The atoms of such elements are components of the active groups of complex proteins. Accordingly, in low amounts, such elements are necessary for plants and all living things. At the same time, increased concentrations of these elements are disastrous for living organisms. Therefore, the study of the heavy metal biological action became a separate branch of the science. Trophic chains contribute to the increase of the concentration and accumulation of heavy metals in organisms - consuments. That affects adversely both animals and human beings. Human activity creates the processes of the environmental contamination by heavy metals and undesirable chemical compounds. For example, the derricks of power and transport systems are powerful sources of atmospheric heavy metals: Pb, Mn, Fe, and others, as well as of such compounds as benspiren, oxides of nitrogen and carbon, and the like. The monitoring of the heavy metals concentration in the environment, particularly in the food and feeds is very important, for it makes it possible to take steps timely aimed at preserving the purity of the environment and human health. The information about the content of heavy metals in dry vegetative mass and other medicinal plants components is of great importance as well.
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Prospective production ways of new heat-resisting materials based on polyimides
Статья научная
The article is devoted to production and study of materials based on different kinds of industrially manufactured polyimides, including chemical modification of reactivity of multifunctional compounds. The presence of reactive carboxyl, amide and amino groups, capable to interact with multifunctional monomeric and oligomeric modifiers, in macromolecules of polyamide acids, gives the chance of receiving the polyimide materials possessing properties of polymers. As a result, we observe improvement of strength properties and thermal characteristics of new polymeric materials for practical aims.
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Recent advances on montmorillonite-based fire retardant composites in polymer matrices
Статья научная
Fire retardancy in the future will likely involve a combination of materials that all function as fire retardants but each offers something different. In this paper, it is suggested that a nano-dimensional material, possibly and organically-modified montmorillonite, will be one of the components. Drawing examples from a number of different systems, this is elucidated in this paper.
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Rhizospheric trophic chain: the role and stability in soil processes and ecosystems
Статья научная
The authors have investigated the problems of interactions in the rhizosphere in the context of changing trophic connections, their resilience in ecosystems. It is shown that the dynamics of rhizosphere interactions with changes in environmental conditions becomes the focus of intensive research and the development of continuum enrichment area at the roots and the formation of systems of their interaction in the soil profile.
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Self-organization and entropic s-lines
Статья научная
The concept of the entropy of spatial-energy interactions is used similarly to the ideas of thermodynamics on the static entropy. The idea of entropy appeared on the basis of the second law of thermodynamics and ideas of the adduced quantity of heat. Such rules are general assertions independent of microscopic models. Therefore, their application and consideration can result in a large number of consequences which are most fruitfully used in statistic thermodynamics. In this research we are trying to apply such regularities to self-organization assessing the degree of spatial-energy interactions using their graphic dependence in the form of S-lines. The nomogram to assess the entropy of different processes is obtained. The variability of entropic S -line demonstrations is discussed, in biophysical processes and engineering systems, as well.
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Solution of the diffusion problem in thermocyclic nitrocementation of steel
Статья научная
It is shown that cyclic heating and cooling considerably accelerate the kinetics of chemical thermal processing of steels. The author studies the laws of formation of the strengthened layers at thermocyclic nitrocementation of steel 20 Kh. Production tests of machine parts after chemical thermal and chemical-thermocyclic processings were performed. The structure, phase composition and intensity of wear process of a blanket depending on a number of cycles are investigated.
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Статья научная
Currently the reinforcement of steel surface treatment is widely used in various industries, especially in the automobile. The paper discusses the new economical methods of processing the steel surface, which can significantly improve the properties of the metal.
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Статья научная
The paper deals with structural, morphological and optical properties of nanoproducts which undergone zirconium laser ablation in water and in aqueous SDS solutions. Depending on experiment conditions the indicated products can appear as different crystalline phases of zirconia and organic-inorganic composites, which include SDS alkyl chains intercalated between layers of zirconium oxides or hydroxides. The formation of zirconium dioxide-based hollow nano- and microstructures is demonstrated. It is suggested that ablation-formed gasvapor bubbles can serve as templets for generation of hollow structures.
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Статья научная
It has been shown that the parameters of formation of carbon nanotubes (nanofibers) ring-like structures can be described in the scope of fractal kinetics. In this case the main feature is represented by interactions in polymer matrix at the level of nanofiller. The indicated model explained relatively high degree of bonds between the nanocomposites of polymer/carbon nanotubes at ultra small nanofiller contents.
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Surface-modified magnetic nanoparticles for cell labeling
Статья научная
High potential of the polymer-coated magnetic nanoparticles can be envisioned for many biological applications. The particles can be easily magnetically separated and redispersed in water solutions upon removing of the external magnetic field.
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The aggregation process as a cause of large-scale disorder in nanocomposites of polymer/organoclay
Статья научная
It has been shown that organoclay platelets aggregation in "packets" (tactoids) results in large-scale disorder intensification. It reduces the nanofiller anisotropy degree. In its turn, this factor decreases essentially the nanocomposites reinforcement degree. The interfacial adhesion role in anisotropy level definition has been shown.
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