Статьи журнала - НБИ технологии
Все статьи: 520
Influence of hydrolysis on diffusion of electrolytes
Статья научная
Experimental mutual diffusion coefficients of potassium chloride, magnesium nitrate, cobalt chloride and beryllium sulphate in aqueous solutions have been compared with those estimated by the Onsager-Fuoss. From the observed deviations, we are proposing a model that allows to estimate the percentages of H3O+ (aq) resulting of hydrolysis of some ions (i.e. beryllium, cobalt, potassium and magnesium ions), contributing in this way to a better knowledge of the structure of these systems.
Бесплатно
Influence of rolling on behaviour of polystyrene films
Статья научная
The effect of cold rolling of the isotropic and preliminary oriented polystyrene films on their properties has been investigated. It was found that the film modification by the cold rolling is necessary to conduct for only the isotropic films but not for the oriented ones. To achieve the optimal state of rolling and to reduce the side stresses at drawing, the process should be performed in several consecutive stages.
Бесплатно
Innovative application of some coordination compounds of arsenic and stibium
Статья научная
Based on arsenic compounds obtained by transformation of arsenic industrial waste and natural resources (arsenic (III) oxide, arsenic (III) chlorides, alkoxides, stibium (III) oxide), we obtained and studied new coordination compounds, “white arsenic”, hyperpure metallic arsenic and various materials with specific properties. By using obtained non-volatile inorganic-organic complexes we created and tested new cheap anti-microbe substances and fungicides for protection of archaelogical items and museum exhibits and biological stuff. Based on the organic hetero-chain polymers modified by carbo-functional siliconorganic oligomers we created anti-biocorrosive covers for woodwork, goods from plastics and leather. We discussed the possibility of obtaining siloxane-arsenic oligomeric additions for under-water hydrophobic bioactive dye composites. We have shown the real perspective to manufacture madications, anti-helmintes, semi-conductors, optical glass-fibers and bio-medical nano composites based on Georgian region arsenic industrial waste and natural resources.
Бесплатно
Innovative equipment for modernization of system of flue gases cleaning
Статья научная
Gas-cleaning installations of various principles of action are observed: rotational, impact-sluggish and centrifugal. Experiment by definition efficiency of cleaning gas emissions is executed. The characteristic for optimisation of hydrodynamic conditions of its work is given each aspect of scrubbers. It will allow designers of the equipment to make sampling of the necessary build. The modified row of apparatuses for wet cleaning of gas emissions is devised. Designs on modernisation of system of cleaning gases of refire kilns are devised. The data obtained by means of apparatuses confirm the patent for an invention.
Бесплатно
Introduction to ceramizable polymer composites
Статья научная
In this paper ceramization (ceramification) of polymer composites is presented as a promising method for gaining flame retardancy of the materials. Because of its passive fire protecting character, ceramization effect can be applied in polymer composites, which are dedicated for work in public places like shopping centers, sport halls, galleries and museums, office buildings, theatres or cinemas and public means of transport. In case of fire, ceramizable polymer composites turn into barrier ceramic materials, ensuring integrity of objects like electrical cables, window frames, doors, ceilings, etc., exposed on flames and heat, preventing from collapsing of materials and making electricity working, enabling effective evacuation. Moreover, ceramization process decreases emission of toxic or harmful gaseous products of polymer matrix degradation as well as its smoke intensity. The paper describes the mechanisms of ceramization for various polymer composites, especially focusing on silicone rubber-based ones, basic characteristics of the materials and ways of their testing.
Бесплатно
Investigation of magnetic properties of Rb3C60 single crystal fullerene using torque experiments
Статья научная
For the first time, magnetic properties of fullerides have been studied using a torque technique. A Rb3C60 single crystal has been investigated in these experiments. It was shown that this method is sensitive to the structural phase transition in both superconducting and normal states. In the superconducting state a transition at Tc = 28 K was observed and a pinning force of the magnetic vortices has been estimated. In the normal state, the transition from s.c. to f.c.c. structure has been indicated. A very strong magnetic response has also been observed at temperatures T ~ 200-250 K, which may be explained in terms of the rearrangement on the magnetic system in the material.
Бесплатно
Investigation of reaction of ethylene telomerization
Статья научная
The interest towards radical telomerization is conditioned by the fact that it enables to obtain comparably low-molecular long-chain organic substances with various functional groups that are hard to obtain with ordinary methods and that can be widely applied in practice. The reaction of telomerization of ethylene and trichloracetic acid ethyl ester [3] is especially interesting. The reaction proceeds in the following way: nCH2 = CH2 +CCl3COOEt Cl (CH2CH2)nCCl2COOEt Telomers, received from ethylene and trichloracetic acid esters, are utilized to obtain the psychotropic drug
Бесплатно
Investigation of the physical and mechanical properties of radio-absorbing materials
Статья научная
The paper studies the physical and mechanical properties of radio-absorbing materials. It is shown that to ensure an effective level of material absorption, it is necessary to introduce carbon fibers in the amount of at least 0.25% by weight.
Бесплатно
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.
Бесплатно
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.
Бесплатно
Modification of epoxy resins by polyisocyanates
Статья научная
Epoxy resin compositions modified by compounds containing isocyanate fragments are recently of considerable scientific and practical interest. However, only some of them are widely used. Urethane fragments in the molecular structure of epoxy units of oligomeric molecules cause the improvement of the deformation-strength properties of polymer materials. The aim of this work is the development and study of film-forming composites with improved physical, mechanical and chemical properties by modifying the epoxy oligomers by the polyisocyanates.
Бесплатно
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.
Бесплатно
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.
Бесплатно
Статья научная
For the first time in the world practice the results of simulation by Monte Carlo method of the kinetics of three-dimensional free-radical polymerization of tetrafunctional monomers (TFM) have been obtained in the framework of the formation of a unitary three-dimensional structural element (UTDSE) and its structure formation on the simple cubic lattice, depending on the length l of molecules tetrafunctional monomers (l = 1 to 40 ribs of the lattice). Peculiarities of kinetics of changes in parameters such as the degree of polymerization of the Pn UTDSE, the number of radicals, the number of cross-links and cycles, and other characteristics are revealed. It is established that UTDSE are characterized by low levels of Pn, and an explanation of this phenomenon is given.
Бесплатно
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.
Бесплатно
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.
Бесплатно
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.
Бесплатно
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.
Бесплатно
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.
Бесплатно
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.
Бесплатно
