Статьи журнала - НБИ технологии
Все статьи: 520
4D-модели в задачах экологического моделирования: проектирование информационной системы
Статья научная
Разработана информационная система для многомерной визуализации результатов численного моделирования нестационарных течений поверхностных вод.
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A new concept of photosynthesis
Статья научная
The history of the formation of a new concept of photosynthesis proposed by the author is considered for the period since 1966 to 2013. Its essence consists in the following facts: the photosynthetic oxygen (hydrogen) source is not water, but exo- and endogenous hydrogen peroxide; thermal energy is a necessary part of the photosynthetic process; along with the carbon dioxide the air (oxygen, inert gases) is included in the photosynthetic equation. The mechanism of the photovoltaic (Becquerel) effect in films of chlorophyll and its synthetic analogue - phthalocyanine are briefly touched upon in the article. The article presents the works on artificial photosynthesis performed in the laboratory of Photobionics of N.N. Semenov Institute of Chemical Physics, RAS.
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AB INITIO расчет мнимой части комплексной диэлектрической проницаемости наночастиц оксида титана
Статья научная
Из первых принципов произведен расчет мнимой части комплексной диэлектрической проницаемости наночастиц TiO2n (n = 1-3). Симуляция взаимодействия света с кластерами осуществлялась с помощью программы SIESTA. Полученные данные сравниваются со значениеми для объемного оксида титана.
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Статья научная
On a basis of the comparative analysis of the references data the correlated dependencies between the optical characteristics of aqueous sols of spherical nanoparticles and their diameter have been discovered. As a result, the empirical dependencies between the values of the square of wave frequency in the adsorption maximum of the surface plasmon resonance and average diameter of the nanoparticles were determined as well as between the values of the adsorption band width on a half of its height and silver nanoparticles distribution per size. Proposed dependencies are described by the linear equations with the correlation coefficients 0,97 and 0,84 correspondingly.
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Статья научная
Kinetics of the reaction of silver nitrate reduction by hydrazine in the presence of sodium citrate in alkaline medium was studied in a wide range of the reagents concentration variation. The orders of the reaction were determined and the effective constants of the silver nanoparticles nucleation process rate and of their propagation one were calculated. It was investigated the optical characteristics of the obtained sols of the silver nanoparticles. It was determined the empirical dependence of a size of the obtained silver nanoparticles on the kinetic parameters of a process.
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Analysis of the types of radar absorbing materials
Статья научная
The paper provides the analysis of modern radar absorbing materials. The authors describe the advantage of radar absorbing material on the basis of the metamaterial.
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Статья научная
The influence of a carbon nanomaterial obtained in a high-voltage discharge plasma on the endurance of elastomer compositions has been investigated. Complex tests of elastomeric compositions with highly dispersed carbon additives allowed us to confirm the model of nonlinear elastic deformation of macromolecules and adhesion between the elastomer and the nanoparticles. The results of these investigations comply with those obtained in determining the Mooney viscosity and relaxation, the parameters of the vulcanization kinetics of rubber mix, conventional tensile strength, relative breaking elongation of highly filled rubbers based on butadiene-nitrile caoutchoucs. To verify the assumed mechanism underlying the action of a carbon nanomaterial on elastomer compositions, the parameters of their vulcanizing network have been determined using the method of equilibrium swelling.
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Biodegradable blends based on polyhydroxybutyrate: structure and water diffusion
Статья научная
The present article focuses on the study of novel blends based on poly(3-hydroxybutyrate) (PHB) and polymers with different hydrophilicity (PELD, PA and PVA). Polymer blends were produced from five ratios of PHB/PELD in an effort to regulate the resistance to hydrolysis or (bio)degradation through the control of water permeability. The relation between the water transport and morphology (TEM data) shows the impact of polymer component ratio on the regulation of water flux in hydrophobic matrix. To elucidate the role of hydrophilicity of second component presenting in the PHB blends, we studied the PHB/PA blends where PA is the polyamide resin composed of statistical copolymer of hexamethyleneadipinate and -caprolactam in ratio 1 : 1. The complex of techniques including DCS and FTIR-imaging (for T-scale) demonstrates the interaction between PHB and PA in the temperature ranges of crystallization and melting. The general approach based on Flory- Huggins equation is presented as the way to choose the pairs of compatible or partly compatible polymers. Mechanical characteristics and water permeability of films on the basis of PVAPHB mixtures depending on their composition were investigated. It was shown that the additive of PHB increments water permeability of a polymeric matrix, but at major dosage of PHB the permeability of films can be reduced because of ability of PHB to fix water. It was determined by DSC, polarization IR-spectroscopy, WAXS and SAXS-experiments that there is a connection between structural architecture of films at crystalline (or at molecular) level with water permeability and mechanical performances. It was shown that the decreasing of strength of films occurs at PHB concentration more than 20 % (for PVA-PHB mixtures). Blending PHB with PA and PVA could be a simple and effective method to design new matrices for drug delivery in medicine, while the same procedure applied for PHB-PELD system with better resistance to hydrolysis and lower price than initial PHB could be used as novel bioerodible packaging materials.
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Biopolymers for application in photonics
Статья научная
The possibilities of utilization of biopolymers, the deoxyribonucleic acid (DNA) in particular, are reviewed and discussed. The ways of their functionalization with photoresponsive molecules to get desired properties are described and illustrated on several examples as well as the processing of materials into thin films. Their room- and photo-thermal stability, studied by spectroscopic techniques is reported, together with optical damage thresholds. Physical properties, and more particularly linear, nonlinear and photo-luminescent properties of obtained materials are also reviewed and discussed.
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Статья научная
The article studies the properties of calcium stearate (CaSt2) and lubricants produced on its basis. These lubricants were prepared using sodium stearate and calcium chloride by subsidence from aqueous solutions. The CaSt2 and the light fraction of crude oil were mixed together to obtain lubricating substances. The article shows that CaSt2 had the melting temperature of 142.8 C that is higher than the melting temperature of crude oil (128 C). The compositions of obtained lubricants were studied with optical microscopes. The article shows that the sizes of dispersed particles amount to 1.88 mcm and 0.11 mcm for lubricants having 1 % and 2 % CaSt2 concentration, respectively. As a result of wear trials, it was shown that the friction and wear coefficients of crude oil amounted to 0.099 and 1402 nm, respectively. For the lubricant with 1 % CaSt2 concentration, these coefficients were reduced to 0.0730 and 627.61 nm. Lower wear coefficient (540 nm) was obtained for the lubricant with 2 % CaSt2 concentration. The CaSt2 improved the lubricating property of crude oil but did not improve its oxidative and thermal stability.
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Catalytic activity of titania-supported manganese oxide catalyst in ozone decomposition
Статья научная
The titania-supported Mn oxide system made by incipient wetness impregnation method was investigated in the reaction of heterogeneous catalytic decomposition of ozone. The catalytic activity of the catalysts containing 6, 8 and 10 wt % manganese oxide was found using the decomposition coefficient g which is proportional to ozone decomposition rate. It was established that all catalytic samples are active towards ozone decomposition but the catalyst possessing 10 t % MnOx/TiO2 was the most active. The calculated values of g were in the range of 0.05´10-4-0.4´10-4. The experiments were performed at the temperature range of 258 K to 313 K in a tube glass reactor. It was determined that the activation energy of the process is 11 kJ/mol. The catalyst was characterized by TPR, XRD, AFM, FT-IR spectroscopy and surface measurements. A catalytic cycle of ozone decomposition on MnOx/TiO2 catalyst was proposed.
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Characterization of a pearlescent biaxially oriented multilayer polypropylene film
Статья научная
The morphology, composition, optical, thermal and mechanical properties of a commercial pearlescent and multilayer BOPP film were determined in the present study. The film was polypropylene and it was biaxially oriented as shown by FTIR spectroscopy and X-ray diffraction. FTIR spectroscopy indicated carbonate ions, EDX analysis indicated the presence of Ca element, X-ray diffraction showed the presence of calcite and thermal gravimetric analysis indicated that 11.2 % calcite was present in the film. The 30 μm film consisted of a core layer filled with calcite and 4 μm thick upper and lower layers without any filler and from different polymers. There were long air cavities in the core layer with aspect ratios of 23 and 19 in machine and transverse directions making the film pearlescent. The surfaces of the film were very smooth and had surface roughness in the range of 3.052 nm and 11.261 nm as determined by AFM. The film melted at 163.6 oC had 51% crystallinity and had 6.3 nm polymer crystals when heated at 10 oC/min rate. The film thermally degraded in two steps. They consist in polymer fraction and decomposition of calcite, respectively. For 10 oC/min heating rate the onset of polypropylene degradation was 250 oC and calcite decomposition was 670 oC. The activation energies for polypropylene degradation and calcite decomposition were 64.8 kJ/mol and 204.8 kJ/mol. The tensile strength of the film in machine and transverse directions was 97.7 and 35.9 MPa, respectively.
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Clearing and cooling of smoke fumes in the production of pottery
Статья научная
Smoke emissions from refire kilns are the source of air pollution in the process of ceramic materials manufacture. In this connection, the modernized systems for purifying polluted air were designed. The authors suggest experimental research of the efficiency of clearing the gas emissions. The program of computing the hydrodynamics - Ansys CFX - allows modeling the process of gas and liquid stream. The ecological result of implementation of this system consists highly in utilization of waste-heat and betterment of ecological conditions in industrial zones.
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Evaluation of the effectiveness of radio-absorbing coatings for information security problems
Статья научная
The paper investigates the weakening effects of screens of various kinds on the electromagnetic waves passing through them. With such solutions, it is possible to make estimates for the weakening effect of electromagnetic screens of arbitrary shape and for radiation with arbitrarily given characteristics.
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Статья научная
The author specifies the technique of estimating internal combustion engine of valve mechanism on the example of VAZ engine, obtained by means of developed simulation model of studying valve train dynamics research. Experimental research of valve spring coil oscillations by high-speed motion-picture technique is being considered as well.
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Halophilic microorganisms from saline wastes of starobin potash deposit
Статья научная
3 cultures of halophilic phosphate-solubilizing bacteria isolated from solid saliferous wastes of Starobin potash mines run by Belaruskali concern are capable to grow in the presence of 10-15 % sodium chloride and to promote germination and growth of alfalfa (Medicago sativa).
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High-molecular weight of biopolymer
Статья научная
Hyaluronan (HA) is a linear polysaccharide has a high-molecular weight, naturally occurring and found in all tissues and body fluids of higher animals. The excellent properties of HA such as biodegradability, biocompatibility, safety, excellent mucoadhesive capacity and high water retaining ability make it well-qualified for using in various bio-medical applications. In addition, HA is non-toxic, non-inflammatory and non-immunogenic. Because of all these advantages, HA has received much attention as a matrix for drug delivery system. This review will summarize our present knowledge about HA, its properties and development in some pharmaceutical applications.
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High-strength reinforced plastics
Статья научная
A historical excursus is presented on the participation of the Laboratory of Reinforced Plastics (LRP) of the N. N. Semenov Institute of Chemical Physics of RAS in the development of scientific and technological foundations of producing and refining these materials. The main directions of research include studying the extent of realization of the fiber properties in unidirectional composites and determining the roles of the fibers, polymer matrix, and material structure. The most effective directions for application of these materials are identified.
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Hydrosilylation of hydrophobic material supported by platinum catalysts
Статья научная
Catalytic activity of platinum supported on styrene-divinylbenzene copolymer and fluorinated carbons was tested in reactions of hydrosilylation of several olefins and the way of platinum binding to the support surface as well as platinum oxidation states were determined. Catalysts based on the above hydrophobic materials make it possible to obtain high yields of desirable reaction products and in most cases the highest activity was shown by polymer-supported platinum catalyst. In addition to hydrophobicity, another factor appeared to influence catalytic activity, namely the kind of the catalyst precursor. It was established that some amount of unpolymerized vinyl groups that were present on the polymeric support surface was involved in the interaction with platinum. XPS spectra enabled to determine that platinum was present on the catalyst surface in 0 and +2 oxidation states, however Pt0 clearly predominated.
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Influence of hydrodynamic regimes of oil and gas mixtures on the efficiency of heat exchange
Статья научная
The results of experimental studies identify the degree of intensification of the processes of oil and gas mixtures heating in horizontal pipe due to changes in hydrodynamic regimes. So, at oil and gas mixtures heating processes it is desirable to consider their implementation in a turbulent flow, which will help to develop energy-saving technology of thermal preparation of hydrocarbons to the primary distillation in refineries by optimizing the hydrodynamic conditions in tubular heat exchangers.
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