Fine Chemical Technologies

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Vol 10, No 6 (2015)
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5-36 273
The solid state of samples (crystal, paracrystal, nanocrystal, amorphous), the main features of nanoobjects, their dimensional hierarchy and peculiarities of properties are considered. The main methods of studying the сomposition, substructure and microstructure characteristics of nanosized compounds are proved. The basic method is X-ray study with specific effects on a diffraction picture. By the example of samples with anatase and η-phase structures obtained by the sulfate method the results of a complex of techniques (wide-angle and small-angle X-ray diffraction, synchrotron radiation, low temperature absorption of nitrogen, IR-spectroscopy, Raman spectroscopy) for the determination of the composition and structure of nanoparticles and their functional characteristics are shown. A relationship of some characteristics and preparation conditions of samples with parameters of the adsorption and photocatalytic properties is found.
37-43 246
Many techniques for high-resolution surface analysis of semiconductors are known, such as optical-, X-ray-, transmission electron microscopy etc. However, atomic-force microscopy and scanning electron microscopy are generally used. In this article, basic principles of scanning electron and atomic-force microscopy are considered. This article shows advantages and disadvantages of each technique. These techniques can be used for quality assessment of semiconductors wafers and structures at different stages of production such as incoming inspection, interoperation inspection and functional control. For AFM study we used “tapping mode” which is well suited for epitaxial structures. SEM images were obtained in secondary electrons imaging mode. These two techniques were compared with respect to the following factors: surface morphology, working environment and the determination of composition. Specific defects for each semiconductor structure and substrates for epitaxy were studied in detail. One of the main advantages of AFM is 3D imaging of the surface together with a “true” vertical resolution less than 0.1 nm. On the contrary, lateral resolution in SEM is better. AFM works under atmospheric environmental conditions that exclude sample preparation. SEM requires vacuum conditions, but at the same time, this “disadvantage” helps to realize its excellent analytical potential. The applicability of these methods for surface morphology investigations of semiconductors such as Ge, MCT, InSb, AlGaN, InGaAs is shown. These materials are commonly used for IR imaging systems in military and civil applications, and their quality is very important. In summary, we conclude that both techniques complement each other. In a modern laboratory it is better to use these techniques side-by-side to achieve satisfactory results.
44-52 183
Nonlocal relativistic hydrodynamic equations describing the motion of photons in a gravitational field are derived. Numerical self-similar wave solutions of these equations for one-dimensional motion of photons of the same energy in a longitudinal gravitational field are found. The influence of the gravitational field on the frequency and number of photons per unit volume is considered.
53-57 187
The methods of calculation of the minimum reflux ratio for actual binary mixtures with the possibility of formation of the pinch modes was considered. It is proved that in the presence of the pinch mode in the product-concentrating column the value of the minimum reflux ratio doesn't depend on the aggregate state of the initial mixture. In the case of pinch mode in the stripping column a formula for calculating the minimum reflux ratio taking into account the energy level of the initial mixture is obtained.
58-63 194
Photonic crystals are fabricated on two different substrates. The first structure consists of a PDMS-covered photonic crystal which is deposited on a PTFE film. The other one consists of a PDMS-covered photonic crystal which is deposited on a glass surface. Diffuse reflective spectra of both structures were analyzed. It was found that spectral shift induced by adding of the organic compound on a PDMS layer occurs only in the first structure. Estimations indicate the connection of diffuse spectral shifts with the effective refractive index and lattice parameter changing.
64-70 201
The possibility of using heat pumps of the open and closed type when carrying out vacuumevaporating (adiabatic) crystallization is analysed. The influence of technological parameters on the efficiency of the use of thermal pumps is considered. Thus, areas of change of technological parameters in which it is profitable to use such heat pumps are established. It is shown that the power efficiency of using closed-type heat pumps is higher than that of open-type heat pumps when carrying out adiabatic crystallization.
71-78 176
Analytical evaluation the effective thermal conductivity of porous and fibrous materials is difficult due to the complexity of the structures, which leads to idealization and simplification of its parameters. Macro-quantum thermodynamic calculation method (MQTM) uses well known fundamental constants and requires no approximate factors. This ensures accuracy of calculations. MQTM also makes it possible to determine the internal (effective) specific surface for heat or mass transfer, which could not be evaluated experimentally. The results of the analysis calculation are given in graphical form. The calculation results confirm the efficiency of the method and demonstrate the basic relationship between physical constants and macroscopic quantum parameters. The presented information opens up a new approach for the evaluation and modeling of heat and mass transfer processes for various purposes.


79-82 253
During the production of PVC articles a composition was prepared with different additives that give the required exploitation properties. Among these additives there are viscosity regulators which are capable of changing PVC pastes viscosity over a broad range. There is quite a large variety of viscosity regulators, though in recent times a growing interest is generated by viscosity regulators made of renewable plant-based raw materials that feature high environmental indicators. Mostly, these are fatty acid methyl esters obtained through transesterification of vegetable oils with methanol. However, it is possible to use ethyl, propyl and butyl esters of fatty acids as viscosity regulators. In this connection it leads to a problem of chemical compounds identification. The most simple and effective method to identify such compounds is to use retention indexes based on gas-liquid chromatography. Experimental identification of retention indexes of 18 methyl, ethyl, propyl and butyl esters of fatty acids С16-С22 within a temperature range of 240-280°C was carried out. It shows the linear dependence of retention indexes on temperature for all esters. Equations to predict retention indexes of fatty acids esters were found.
83-87 229
Polymethylphenylsiloxane liquid PFMS-5 is used as a high temperature heat transfer fluid and a working fluid in the high-vacuum pumps. It is one of the most high-temperature stationary phases in gas chromatography. However, some samples have an upper temperature limit of 280 to 350°С. The composition of this fluid was studied by HPLC. For identification a set of compounds isolated by preparative gas chromatography was obtained. A previously synthesized product consisting of linear polymethylphenylsiloxanes with the number of silicon atoms from 3 to 120 was used. By using a diode array detector the UV-spectra of all the components in the obtained chromatogram were recorded. On the basis of these data it can be concluded that the liquid PFMS-5 consists of polymer homologues with the number of silicon atoms from 3 to 13. In addition to linear methylphenyloligosiloxanes methylphenylsiloxanes of other structure are present in the liquid. Linear methylphenyloligosiloxanes were identified


88-95 236
The possibility of simultaneous determination of the title compounds and coumatetralyl derivatives (coumatetralyl, flocumaphen and brodifacoum) in rodenticide means was considered. The conditions of direct analytical determination and stages of preparation were adapted, which will provide determination of the isomeric composition of difenacoum in rodenticide compositions. Using less polar mobile phases on the basis of acetonitrile is preferable as compared to mixtures on the basis of methanol. Conditions allowing the separation of enantiomers with the limit of sensitivity of the method for difenacoum level 0.0002% were found, which allows to monitor the content of more active trans isomers of the title compound both in the original rodenticide substances and in the end poisoned baits. Implementation of the analytical stage of the determination of the isomeric composition of difenacoum involves the use of simpler equipment due to the implementation of the isocratic mode afterwards.


96-98 179
The mineral filler dispersity is shown to affect significantly the adsorption and strength properties of diene-styrene copolymers. Expressions for combinatorial entropy of mixing non-interacting particles in a multicomponent system were obtained, taking into account the contribution due to the difference in component size.

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