We propose an algorithm for comparative study of plastic smoking mixtures containing synthetic cannabinoids using gas chromatography in the following configuration: a Crystal 5000.2 chromatograph (Russia) with a quartz capillary column (L = 50 m,  = 0.32 mm) with a grafted phase based on polyethylene glycol modified with nitroterephthalic acid and a flame ionization detector. Plastic smoking mixtures (40 samples) seized from illegal circulation by officers of the Transport Department of the Ministry of Internal Affairs of Russia in the Siberian Federal District were used as test samples. Mathematical processing of chromatograms was performed using Chromatek Analytic 2.5 and Unscrambler 11.0 programs. It is shown that profiles of the volatile polar components of the fillers of plastic smoking mixtures containing synthetic cannabinoids are quite well manifested and reproduced, which gives them a very high identification value. To compare the profiles of impurities, 44 target compounds were selected, which provided the best reproducibility of the areas of chromatographic peaks during repeated measurements. The chromatographic peak areas of the target compounds were normalized, and the Pearson correlation coefficients and the Euclidean distances were calculated. A hierarchical clustering of the obtained data was carried out with construction of the dendrograms demonstrating the levels of the similarity of samples from different lots. It is shown that samples could be assigned to a single batch (recipe) if the Euclidean distances between the corresponding profiles do not exceed 0.14, and the Pearson distances — 0.12 rel.u. An algorithm procedure for the comparative study of plastic smoking mixtures containing synthetic cannabinoids using gas chromatography has been developed. This procedure includes profiling of the impurities, selection of the target compounds, normalization of the areas of their chromatographic peaks and subsequent mathematical processing using cluster analysis and calculation of Pearson correlation coefficients and Euclidean distances. The obtained results allow us to recommend the developed procedure for use in expert studies of smoking mixtures containing synthetic cannabinoids.

Water-propylene glycol extracts of medicinal plants are widely used as active components in therapeutic and cosmetic products for external use. However, sparse data on the extracting efficiency of water-propylene glycol mixtures and chemical composition of water-propylene glycol extracts of plant raw materials are available in the scientific literature. Usually the manufacturer documentation also provides information about characteristics of the products that are not related to their biological activity. The results of HPLC/MS/MS study of Matricaria chamomilla L. flowers have shown that water-propylene glycol and water-ethanol extracts are similar in the composition of phenolic compounds: the dominant compounds of water-propylene glycol extract of Matricaria chamomilla L. flowers are apigenin and its glycosides (apigenin-7-glucoside, apigenin-7-O-6-O-malonyl-D-glycoside, apigenin-7-acetylglycoside, acetyl-malonyl-apigenin-7-O-glycoside), as well as 5,4’-dioxy-3,6,7,3’-tetramethoxyflavone, cis- and trans-forms of 2-O-glucopyranoside 2-hydroxy-4-methoxycoric acid, 7-methoxycumarin. Spectral and analytical characteristics in the UV-visible range of the spectra of water-propylene glycol extracts of a number of medicinal plants most often used in the cosmetic industry were studied to reveal extracts with the highest protective properties against UV radiation in A and B areas (extracts of Salvia officinalis L. leaves, Matricaria chamomilla L. flowers, Achillea millefolium L. grass), free radicals (extracts of Camellia sinensis L. leaves, Hypericum perforatum L. herb), and the highest content of flavonoids (extracts of Hypericum perforatum L. herb, leaves of Salvia officinalis L.) were revealed. When extracting raw materials from the same batch, the optical density at a wavelength of 270 nm is associated with the content of flavonoids, antioxidants and dry matter by a functional relationship, which is very convenient for rapid control of extraction processes in order to obtain a product with reproducible characteristics. Formulas for calculating the content of antioxidants in extracts using the DPPH method in comparison with standard samples of rutin and gallic acid are derived. Interpretation of data on the antioxidant content in different extracts in comparison with other analytical parameters are also presented. Demonstrated high repeatability of the shape of the spectral curves of Matricaria chamomilla L. flowers extract, observed regardless of the source of raw materials can be used in combination with the individuality of the curve shape of the extracts of raw materials of different types as one of the authenticity criteria. The proposed UV-spectrometric method was used to study the dynamics of Matricaria chamomilla L. flower extraction under different process parameters (temperature, propylene glycol/water ratio in the extractant). It is shown that extraction of raw materials with 50% water-propylene glycol for 4 h at a temperature of 50°C is optimal.

The goal of the study is developing a methodology for determination of the residual amounts of quaternary ammonium compounds (QAC) in food products by UHPLC/high-resolution mass spectrometry after water-acetonitrile extraction of the determined components from the analyzed samples. The identification and determination of QAC was carried out on an «UltiMate 3000» ultra-high-performance liquid chromatograph (Thermo Scientific, USA) equipped with a «maXis 4G» high-resolution quadrupole-time-of-flight mass spectrometric detector and an ion spray «ionBooster» source (Bruker Daltonics, Germany). Samples of milk, cheese (upper cortical layer), dumplings, pork, chicken skin and ground beef were used as working samples. Optimal conditions are specified for chromatographic separation of the mixture of five QAC, two of them being a mixture of homologues with a linear structure (including isomeric forms). The identification of QAC is carried out by the retention time, exact mass of the ions, and coincidence of the mSigma isotopic distribution. The limits for QAC detection are 0.1 – 0.5 ng/ml, the determination limits are 1 ng/ml for aqueous standard solutions. The determinable content of QAC in food products ranges within 1 – 100 ng/g. The results of analysis revealed the residual amount of QAC present in all samples, which confirms data of numerous sources of information about active use of QAC-based disinfectants in the meat and dairy industry. The correctness of the obtained results is verified by introduction of the additives in food products at a level of 10 ng/g for each QAC. The relative standard deviation of the analysis results does not exceed 0.18. The duration of the analysis is 30 – 40 min.

Nickel films formed on the surface of zirconium alloys are often used to protect materials against hydrogen penetration. Hydrogen adsorption on nickel is faster since the latter actively interacts with hydrogen, oxidizes and forms a protective film. The goal of the study is to develop a method providing control of hydrogen absorption by nickel films during vacuum-magnetron sputtering and hydrogenation via measuring thermoEMF. Zirconium alloy E110 was saturated from the gas phase with hydrogen at a temperature of 350°C and a pressure of 2 atm. A specialized Rainbow Spectrum unit was used for coating. It is shown that a nickel film present on the surface significantly affects the hydrogen penetration into the alloy. A coating with a thickness of more than 2 μm deposited by magnetron sputtering on the surface of a zirconium alloy with 1% Nb, almost completely protects the alloy against hydrogen penetration. The magnitude of thermoemf depends on the hydrogen concentration in the zirconium alloy and film thickness. An analysis of the hysteresis width of the thermoEMF temperature loop and a method for determining the effective activation energy of the conductivity of a hydrogenated material coated with a nickel film are presented. The results of the study can be used in assessing the hydrogen concentration and, hence, corrosion protection of the material.

Improvement of the physical and mechanical properties of hard alloys based on WC – Co widely used in manufacturing of structural and tool products nowadays results from the use of novel technologies providing formation of a homogeneous high-density structures. Slight deviations of the carbon content from the equilibrium state lead to the formation of brittle η-phases (in particular, Co3W3C) and, accordingly, to deterioration of the mechanical properties of the product. We present the results of studying the homogeneity of the phase composition of the samples of hard alloys WC + 10% Co, obtained using advanced technologies of plasma-chemical synthesis and spark plasma sintering (SPS). The layer-by-layer X-ray phase analysis revealed the heterogeneity of the phase composition in depth: the brittle η-phase (Co₃W₃C) appears at a depth of ≥100 μm and reaches a constant value of 18 ± 1 wt.% at >200 μm, which indirectly confirms the hypothesis of carbon diffusion from graphite punches contacting with the surface of sintered samples and makes it possible to expand the range of parameters affecting the process of spark plasma sintering.

Development of the technologies simulating optical processes in an arbitrary dispersed medium is one of the important directions in the field of optical instrumentation and can provide computer simulation of the processes instead of using expensive equipment in physical experiments. The goal of the study is simulation of scattering of optical radiation by aerosol media using the finite element method to show a practical significance of the results of virtual experiments. We used the following initial conditions of the model: radius of a spherical particle of distilled water is 1 μm, wavelength of the incident optical radiation is 0.6328 μm, air is a medium surrounding the particle. An algorithm for implementation of the model by the finite element method is proposed. A subprogram has been developed which automates a virtual experiment for a group of particles to form their random arrangement in the model and possibility of changing their geometric shape and size within predetermined intervals. Model dependences of the radiation intensity on the scattering angle for single particle and groups of particles are presented. Simulation of the light transmission through a dispersed medium provides development of a given photosensor design and determination of the minimum number of photodetectors when measuring the parameters of the medium under study via analysis of the indicatrix of scattering by a group of particles.

Control of the stress-strain state, compressive and tension stresses, accumulated fatigue damage is one of the goals of non-destructive testing. We consider data of current research in the field of eddy current and electromagnetic methods of non-destructive testing aimed at solving the problem of monitoring the accumulated damage in structural steels and alloys. Developments for practical implementation of the coercive force method, the eddy current structurescopy of non-magnetic materials, the method of higher harmonics and remanence-based control, the method of magnetic noise (Barkhausen noise) are considered. The physical foundations of non-destructive testing methods are considered along with their brief comparative analysis. Examples of non-destructive testing of critical units, such as operating oil and gas pipelines, aircraft parts, bearing parts, pressure vessels, crane parts, etc. are given. The possibility of using the eddy current method for control of the austenitic phase of cold rolled austenitic steels (AISI 304, AISI 321, AISI 316) is analyzed. The examples of static and fatigue tests of the samples of various steels and alloys are given: St3, St20, St45, D16T, AMg6, AMg6N, 12Kh18N9T, 08Kh18N9, 40Kh, R91. Metrology issues and the impact of interfering parameters affecting the measurement error are considered. The equipment used for a number of methods is discussed. Conclusions regarding the limits of applicability and limitations of the considered methods are drawn. The review provides links to both the fundamental works in the field of electromagnetic structurescopy and to modern research in this area which is important for the practical implementation of the devices based on electromagnetic and magnetic methods of non-destructive testing.

The fracture toughness which reflects change in the elastic deformation energy of the structural element with an increase in the crack area per unit at the onset of straining is one of the crack resistance parameters of carbon fiber plastics (CFRPs). When studying the fracture toughness, the position of the crack front is determined: both the initial one and that obtained as a result of crack growth. Currently existing test standards (STO TsAGI, ASTM D7905) determine the viscosity by the shear mode G_IIc using the samples with a crack initiator. However, the method does not reflect the real conditions of crack initiation in CFRPs structures and can lead to a decrease in the accuracy of determining the load of crack initiation. A new technique of the fracture viscosity determination free of the standard delamination initiator has been developed in TsAGI. We present the results of developing the proposed methodology. The G_IIc values were determined for a shear crack under three-point bending conditions after wedging. To determine the position and shape of the crack front, as well as to assess the dynamics of its propagation under subsequent loads, we used ultrasonic methods — ultrasonic flaw detection (ultrasonic NDT) and acoustic microscopy instead of the standard visual observation of the crack boundaries from the end surface of the samples. It is shown that acoustic microscopy at a frequency of 50 MHz provides determination of the crack front position in CFRP samples at a depth of 3.0 – 3.5 mm with a high resolution about 100 μm. The features of the crack growth under shear conditions are discussed. The results of the study show that high accuracy of acoustic microscopy in comparison with traditional ultrasonic NDT diagnostics is strongly sought for determining the shape of the cracks, as well as for analyzing the dynamics of crack growth and revealing the mechanisms of interlayer crack propagation in a composite material.

A compact and simple in design device (friction machine) for testing materials for friction and wear is developed. The device is intended for determination of the wear resistance and friction coefficient of structural, frictional and antifriction materials, as well as the tribological characteristics of lubricants. The measurement system of the device includes spring helical and flat spiral elastic elements, combined in one node and designed to measure the normal force and friction torque, respectively. Metal-cutting machines can be used as an external drive of the device. The friction machine was tested when measuring the wear rate and the value of the friction coefficient of the samples of cast iron SCh20, brass L63, technical aluminum A7, as well as modified aluminum A7 with improved mechanical characteristics. The materials were tested in tandem with a counter-sample made of hardened steel 95Kh18 according to the ball-ring scheme in dry friction mode and in boundary lubrication mode using I-20A industrial oil at a normal load of 50 N and a linear velocity in the contact zone of 0.5 m/sec. The wear degree was estimated by the weight loss. The obtained results are characterized by the sufficient accuracy and reproducibility. A severe wear of brass is observed at a given testing load. Tests of the aluminum samples modified with ultrafine diamond-graphite powder UDP-AG obtained from explosives showed an increase in the tribological characteristics by 10 – 18%.

The study continues the research previously published in the article «Validation of analytical methods: the international requirements» (Zavod. Lab. Diagn. Mater. 2018. Vol. 84. No. 12, pp. 25 – 31). We consider the procedure and the results of validation of the measurement procedure for determination of the residual content of enrofloxacin in food using high performance liquid chromatography with mass spectrometric detection. The program of experimental studies and calculation formulas necessary to assess the metrological characteristics of the method are presented. Validation included assessment of the detection limit, quantitation limit, decision limit, capability of enrofloxacin detection in food samples in accordance with GOST 32797–2014 «Food products, food raw materials. Method for the determination of the residual content of quinolones using high performance liquid chromatography with a mass spectrometric detector». The linearity of the calibration characteristic within the measurement range is demonstrated using the regression analysis procedure. The values of the accuracy indicators and the measurement range specified in GOST 32797–2014 were confirmed when the method was implemented in a testing laboratory.