Pharmaceuticals containing steroid hormones and their synthetic analogues are widely used in medicine. Accurate determination of the hormone content in biomedical objects is an urgent problem in modem analytical chemistry. A method for the selective and highly sensitive amperometric determination of adrenaline, melatonin, and cortisol in a flow-injection system has been developed. A scheme of a two-detector flow-injection system was proposed for the simultaneous determination of the adrenaline, melatonin, and cortisol content. Screen-printed carbon electrodes (SPE) with one or two working electrodes modified by gold-palladium binary system, which exhibited catalytic activity upon electrooxidation of organic compounds under study were used as detectors. A high sensitivity of the determination is attributed to the catalytic properties of the metal modifier: the transition between the metal and binary system leads to an increase in the catalytic current of hormones oxidation. The selectivity of the adrenaline determination in the presence of melatonin and cortisol is provided by the difference in the potentials of hormone oxidation at the developed electrode. For the selective determination of melatonin and cortisol the surface of the working electrode was modified by the Nation film. The potential difference between the oxidation peaks of adrenaline, melatonin and cortisol on the modified electrode was 300 mV. The proposed method was tested in analysis of real urine samples. The flow-injection scheme was supplemented with a dialyzer and a chromatographic mini-column to eliminate the interfering effect of electrophilic compounds. The linear logarithmic dependence of the analytical signal on the concentration of adrenaline, melatonin and cortisol is observed in the range from 5.0 x 10^-10 to 5.0 x 10^-3 M, from 5.0 x 10^-11 to 5.0 x 10^-3 M, and from 5.0 x 10^-12 to 5.0 x 10^-3 M, respectively. Amperometric determination of hormones in a flow-injection system leads to an increase in the productivity of analysis, decrease in the sample consumption and provides for automation of the process.

A novel enantioselective adsorbent was obtained by hybridization of microspherical polystyrene-divinylbenzene (PS-DVB) macroporous particles with eremomycin-stabilized gold nanoparticles (GNPs). Macrocyclic antibiotic eremomycin was used as a stabilization agent to obtain GNPs which were then characterized by transmission electron microscope. The average diameter of obtained nanoparticles is about 16.6 nm. Eremomycin-stabilized nanoparticles were successfully embedded into the porous polymer structure with a resulting chiral selector content of 37.5 pmol/g. The obtained PS-DVB composite containing GNPs with immobilized eremomycin was studied by scanning electron microscopy and diffuse reflectance spectroscopy. The values of the specific surface area (500 m²/g) and porosity of the adsorbent (0.39 cm³/g) are measured using nitrogen adsorption at low temperatures. The obtained composite material was used as a chiral stationary phase of liquid chromatography. A good separation enantio-selectivity to amino acids, their derivatives and beta-blockers under RPC (reversed-phase) and HILIC (Hidrophilic Interaction Liquid Chromatography) mode is demonstrated. The results obtained revealed that the prepared Eremo@GNP@PS-DVB composite is promising for use as a stationary phase in HPLC.

Methods of qualitative analysis are widely used in various spheres of public activity, including forensic examination. Making the right decisions based on the results of qualitative analysis, necessitates confirmation of the reliability (uncertainty) of the methods which can be provided by the validation procedure. However, the issues related to the validation of qualitative forensic methods are debatable in the absence general regulatory requirements for qualitative analysis methods. We consider a validation procedure of the qualitative forensic technique “Microscopic examination of textile fibers,” which consists in determining a complex of characteristic external features of natural and chemical textile fibers (color, color features, morphological features) using a microscope, as well as thickness and presence/absence of a matting agent for chemical fibers. These generic characteristics are used to differentiate the fibers under study in the forensic examination of fibrous materials. The reliability of the methodology and the competence of the performers were selected as validation parameters. The parameters were determined numerically by the likelihood ratio and by the values of the share of false and correct results in the total number of tests. Ten samples of natural and chemical textile fibers from the comparative collection of the Laboratory of forensic examination of fibrous materials of the RFCSE were used for validation. Three experts participated in the experiment independently identified the presence/absence of ten external signs in each of ten samples during a week. Each expert tested a set of one hundred different external features, 39 of them were present in the samples, and 61 were absent. When comparing the test results obtained by the expert with the corresponding regulated (known) external features, a conclusion was made about the level of true or false result for each sample. A low (1.7%) level of false results was revealed in relation to the total number of tests, as well as a low (2.6%) level of false results for each of the experts indicated the reliability of the methodology and competence of the experts. The calculation of the likelihood ratio (LR) showed that the probability of true results in the assessment of a set of features is about 60 times (significantly more than one) higher than the probability of false results, which also indicates the reliability of the technique. The results of the validation experiment allowed us to conclude that the method is suitable for use in solving expert problems in the forensic examination of fibrous materials.

Treatment of cellulose with ionizing radiation (γ-rays, accelerated electrons) provides the possibility to reduce its molecular weight, change the molecular weight distribution, increase the esterification reactivity and affect other physical and chemical characteristics. The acquired properties, in turn, make it possible to obtain then esters with the desired characteristics. We present the results of studying the effect of γ-irradiation of industrial grades of cellulose on the esterification products, i.e., lacquer colloxylins and xanthogenates. It is found that γ-irradiation at a dose of 3 - 5 kGy prior to mercerization leads to an increase in the reactivity of the polymer in the reaction of xanthogenation by more than 30%. Nitro derivatives corresponding to the technical characteristics (conditional viscosity and nitrogen content) of colloxylins of different grades were obtained by irradiation at a dose of 20 and 30 kGy. It is shown that the stages of prehydrolysis and reduction of nitrocellulose viscosity during its treatment in autoclaves can be excluded when producing colloxylins. It appeared possible to reduce significantly the consumption of carbon disulfide in the technology of xanthocarbon production. The results obtained can be used in developing optimal modes and performance criteria for radiation pretreatment of cellulose of different grades during nitration and xanthogenation proceeding from changes in their physical and chemical properties upon γ-irradiation.

Data on the parameters of suspended particles are required in the electronic, optical, chemical and mining industries, powder metallurgy, atmospheric physics, medicine, etc. We present the results of determining the parameters of suspended particles of arbitrary shape using a combined optoelectronic approach, including a photoelectric method and a digital method of image processing. The results of both methods were used to correct the particle parameters and operational control of the laser emitter radiation. The operation of an optoelectronic device used to determine the parameters is based on the analysis of particle images in four projections, as well as on the registration of radiation scattered by particles and collected by an elliptical mirror. Spectrometry of the disperse composition of aerosols was carried out using a photomultiplier tube. The images of suspended particles for digital processing were obtained using a CCD array. It is shown that the applied image processing algorithms make it possible to remove noise, correct a background, improve the boundaries, determine the binarization threshold, exclude small particles, select closed areas and boundaries, split the image into the parts and count the number of particles in each of them, determine the parameters and classify the particles. Moreover, it becomes possible to restore the volumetric shape of a suspended particle and display the main characteristics on a digital indicator with an accuracy of 1%, which is significantly better than that of known similar devices. The results obtained can be used to control air pollution and improve the accuracy of identification of suspended particles of arbitrary shape.

Heterogeneities of the crystal structure and chemical composition, as well as the impurity elements forming inclusions cause deviations of the properties of test object from the required physical and mechanical parameters which significantly affects the reliability and service life of the product. We present the results of studying the susceptibility of structural steels to corrosion in aggressive environment using their magnetic characteristics. Structural-phase transformations occurred in steels under the effect of heat treatment change their properties, including magnetic and corrosion ones. Heat-treated 09G2S, St3, 15XSND steel samples were studied. In addition to the main magnetic parameter — coercive force, we also used spectral characteristics of the samples obtained using a remagnetization curve, magnetic hysteresis loop. The multi-parameter approach with harmonic components was used to identify the corrosion rate and coercive force correlation. Determination of the corrosion rate in this case can be reduced to classical problems of technical diagnostics. It is shown that a complex parameter based on harmonic components obtained using a magnetic hysteresis loop and the corrosion rate exhibit a pronounced correlation which provide developing a non-destructive method for predicting the corrosion resistance of structural steels. The results obtained can be used to improve the rapid method for determining the corrosion-hazardous zones of steels using the magnetic parameters.

Thermal barrier coatings (TBC) are widely used to protect the hot section structural components, such as aircraft gas turbine, against hot corrosion and large thermal gradients during the service life. The resistance to interfacial debonding (adhesion) is one of the key factors for predicting the TBC durability during operation. The goal of the study is analysis of the existing approaches to quantification of the interfacial adhesion for multi-layered thermal barrier coating systems and thermally-grown oxide on Ni-based superalloys and discussion of the problem regarding the reasons for a large spread of the adhesion characteristics. Theoretical prerequisites for determining the adhesion characteristics are considered to provide a theoretical background for quantification of the interfacial adhesion. The absence of national standard tests applicable to TBC is marked along with a significant scatter of the values obtained using international test-regulating documents and proprietary technologies. The values of the intensity of the strain energy release are found to vary from 0.3 to 230 J/m² depending on the method for measuring adhesion, experimental details and type of the system considered. The factors that determine a large spread of the interfacial adhesion values were divided into two groups: 1 — intrinsic, attributed to the features of TBC layer formation and temperature affecting the value and distribution of residual strains and stresses and direction of the failure initiation; 2 — extrinsic, which are related to test conditions and technique of experimental data processing. A complex approach involving both intrinsic and extrinsic parameters is required to address the problem of interfacial adhesion quantification.

Creation of the new generation of power equipment (nuclear reactors, gas turbine plants, special power plants) with increased operational parameters and meeting high safety requirements, entails the goal of creating novel domestic methods for determining stresses and strains that occur in the most critical elements during operation of such installations. The new approaches, including the restoration and development of domestic competencies in the creation of means for experimental control of deformations in elements of the equipment at high temperatures are proposed. The results of developing indirect methods providing determination of the deformations at the most critical points of the structure based on solutions of the inverse problems of experimental mechanics are presented. Improved algorithms for processing experimental information and determining strains from measured stresses are considered for the case of inelastic behavior of the structural material in the zones of tensometric measurements. The improved hermetic strain gauges resistant to lead and sodium coolant are proposed for experimental determination of the deformations that occur on the internal surfaces of the liquid metal coolant circulation circuit of new nuclear reactors of BN and BREST types. The results of tests of the developed measuring instruments in liquid sodium medium at a temperature of 540°C during bench tests are presented. In conditions of increased requirements for assessing the effect of the strain gauge creep on the measurement results obtained at high temperatures, a stand design has been developed that makes it possible to determine the boundaries of a possible error at temperatures up to 600°C under dynamic loading of the structure. To determine the stresses arising at dangerous points of the heat exchange equipment of BN type reactors located in inaccessible areas of the inner surface of the facility, an iterative algorithm for solving the inverse problem of thermoelasticity is proposed, using the measured values of stresses and temperatures on the outer surface of the structure. A set of improvements to the traditional method of full-scale tensometric study is proposed proceeding from of the analysis and implementation of the data obtained.

A number of well-known methods of accelerated testing for relative wear resistance are considered including a procedure based on the Brinell-Howarth method for laboratory studies and implemented on a IM-01 facility (designed at WISHOM) in which a powder abrasive is used. The shortcomings of those methods are discussed. A new VIM LTDP installation is developed in which an abrasive tape (320 mm and 15 mm in length and width, respectively) with a grain size of P60 is used as an abrasive material. The degree of wear was determined by a decrease of the sample mass using weighing on a balance before and after testing with an accuracy of 0.0001 g. The test results were obtained as a relative wear resistance e equal to the ratio of the values of the wear resistance of the test and standard samples. Consideration of the relative wear resistance makes it possible to increase the accuracy of the results due to the exclusion of the effect of changes in external parameters which determine the wear rate during testing. The installation ensures accelerated testing of the samples, i.e., the time for testing one sample is about 5 min. The structure and the grain size of the working body, the load value in the contact zone and the speed of interaction between the sample and tool are preserved. The use of an abrasive tape with different grain size provides for application of the unit to a wide range of tasks using samples without any preliminary grinding, but with the obligatory preliminary cleaning of the samples from slags and large particles after application of wear-resistant coatings.