Traditionally, the X-ray analysis (XRD) method is used to study the phase composition of a solid. But phases with structural defects, poorly crystallized (with disordered structure and amorphous), microphases, phases of variable composition, surface phases and phases, distributed in various ways throughout the entire volume of the sample, often turn out to be X-ray amorphous. In these situations, the stochiographic DR method proves to be more effective, since it allows qualitatively and quantitatively to detect both the crystalline and X-ray amorphous phases listed above. The phase compositions of the spinel type catalysts Cu₁Cr₂O₄ and Cu₁Fe₂O₄ were studied by the stoichiographic method of differentiating dissolution (DR). It is established that the nature of the element and temperature influence the formation of the spinel structure, creating new shapes. The paper describes phase transformations occurring in the synthesis of catalysts, which was carried out by coprecipitation from a mixture of solutions of nitrate salts. It was found that the temperature of 85°C forms various stoichiometric formations, which are precursors of spinels. The 600°C temperature in the case of copper-chromium systems forms stoichiometric compounds of the spinel composition Cu₁²⁺Cr₂³⁺O₄ and structures with different degree of ordering. In the case of copper-iron systems at 600 °C, stoichiometric compounds of the Cu_1-x²⁺Fe₂³⁺O₄ spinel composition and structure are defective in copper. The 900°C temperature pro­vides the formation of compounds of a given spinel composition Me₁²⁺Me₂³⁺O₄ and structures in both systems. The results by the DR method were compared with the results of the XRD method. A comparative analysis has shown that the ordered or crystallized forms of spinels and oxides are detected by both methods, while disordered and defective forms of spinels, the shapes of disordered solid solutions, and also small amounts of oxides show only the DR method.

Introduction of a substance into medical practice requires the  indispensable evidence of the  substance purity as early as the stage of preclinical testing. The content of residual organic solvents, which can affect the  pharmacological activity of the  drug, is one of the  indicators of the  substance quality control. Four solvents are used during synthesis and isolation of the substance: dichloromethane, ethyl  acetate, methyl tert-butyl ether (MTBE), and n-hexane. Two methods of determining residual organic solvents in (2R,4R,4aR,7R,8aR)-4,7-dimethyl-2-(thiophen-2-yl)octahydro-2H-chromen-4-ol using gas  chromatography are offered: i) introduction of a gas sample and separation of the components on a commercial HP-5ms capillary column (30 m × 0.35 mm × 0.25 ìm); ii) introduction of a liquid  sample and separation  on a capillary column (30 m × 0.32 mm × 0.30 ìm) filled with  a modified poly(1-trimethylsilyl-1- propyne) (PTMS). Since  the  first method provides only determination of n-hexane and  ethyl  acetate, the  procedure was developed and  validated for determination of four  residual solvents, i.e., dichloromethane, ethyl  acetate, methyl n-butyl ether, and  n-hexane in test substance using gas chromatography on the  column with  a modified PTMSP-based phase. We detected trace amounts of ethyl  acetate and  methyl n-butyl ether; the  content of dichloromethane and  n-hexane in the  substance appeared below the  detection limits. The average content of ethyl  acetate and MTBE in the  substance for 9 parallel determinations (0.10 and 0.20 ppm) appeared 5 and 2.5 × 104 times lower than maximum permissible content (5000 ppm),  respectively. The  developed technique was assessed for: specificity, linearity of the calibration curve,  correctness, precision at the level of the repeatability and intralaboratory precision, and stability of the  chromatographic system. Standard deviations in the  determination of ethyl acetate and MTBE in the substance do not exceed 0.03 and 0.09, respectively. The procedure is specific, accurate and  reliable for determination of the  residual organic solvents in the  substance.

The widespread use of polyethylene terephthalate packaging (PET) in the food market can be a threat to the  health of people.  In the  process of manufacturing these polymeric materials, various substances are used that improve the properties of the finished package. In particular, phthalates are considered to be one of these dangerous pollutants because their molecules are  not  chemically attached to polymer chains, these substances can  easily  pass  from  plastic containers to food, beverages and  water during packaging or production processes. The study was carried out by ultrahighperfomance liquid  chromatography with  a tandem quadrupole-time-of-flight mass  spectrometric high-resolution detector. The concentrations of phthalates was  varies widely  in  foodstuffs purchased  in  food  market, diisooctyl phthalate has been  found  in the  highest concentration in almost every category of specimens studied. The same  phthalic acid ester proved to be the  most  common, followed by dibutyl phthalate, diisobutyl phthalate and diethyl phthalate. The ranges of detectable contents for phthalates were 15 – 3000 ng/ml (R² > 0,99). Limit of detection were from 0.5 to 15 ng/ml.  The relative standard deviation of the  analysis results did not exceed 15%.

The possibility of using diantipyrylpropylmethane (DAPPM) as an electrode-active membrane component of the mercury-selective electrode (Hg-SE) is shown. To clarify the mechanism of membrane functioning we studied the equilibrium in the “membrane-solution” system as a function of the medium acidity and amount of the ionophore. The potentiometric selectivity coefficients of Hg-SE are determined with respect to some anions and cations by the method of bionic potentials. DAPPM at pH 0 - 1.5 is in the cation form, and mercury ions in 0.1 M HCl — in the form of a trichloromercurium ion. The ion associate DAPPM + [HgCl₃]^- formed under these conditions is the most stable at pH 1 and pCl 1, and the membrane responds only to trichloromercurate ions.. A mercury-selective electrode with an optimized membrane composition (in wt. %) contains: PVC — 32.32; o-NPOE — 64.63; DAPPM — 3.05 (DAPPM concentration 100 mM). The electrochemical characteristics are determined: the linear range (1 x 10^-4 - 1 x 10^-2 M) and slope of the electrode function (50 mV/dec). The operating range (pH 0 - 1.5), detection limit (6.3 x 10^-5 M), and the response time (15 - 20 sec) are determined. For optimal operation of the flow-injection system, a selection of the carrier stream has been made, which affects the stability of the line, the sensitivity and the performance of the analysis. The proposed electrode is used as a detector in the flow-injection determination of mercury in sewage water and “Achromin” cream. Optimum operation conditions of the flow-injection system which ensure the stability of the baseline, as well as the maximum sensitivity and performance of the analysis, are found. The correctness of the results of the determination of mercury is confirmed in spike tests.

The  analytical review  and  determining method of the  morphology of structure inhomogeneities of selectively-permeable surface of polymer membranes are  presented in this  article. The  aim of the  work was   the    developing  and   research  of   automated  method  for   calculating  the    morphology  of microstructure   inhomogeneities  of  selectively  permeable  surface  of  nanofiltration  membranes OPMN-P and OFAM-K. The developed method of calculation allows to identify surface microstructural inhomogeneity of semi-permeable membranes and  the  contamination coefficient. The  obtained data about the microstructural inhomogeneities and the ratio of clogging of the membranes allow for the actual conditions of the  factory laboratories to  predict and  define  the  term of effective operation of nanofiltration by porous membranes OPMN-P and OFAM-K, which are equipped by roller elements of a baromembrane and  electrobaromembrane plants for concentration and  purification of technological solutions and  wastewater in the  electroplating, chemical and  food industries. Implementation of this method is  confirmed by  developed software  package for  identification of  surface microstructure inhomogeneities of semi-permeable membranes and the contamination coefficient. There is a methodology for automated calculation of the  average diameter value  of semi-permeable membranes clogging and  the  contamination coefficient of the  porous objects  in this  paper. The  software complex  based  on the  proposed method is developed and  allows  to determine the  microstructural inhomogeneity of the surface of  the   polymer membranes  OPMN-P and   OFAM-K  No.  2018611402RU. The  calculation method is based on the developed program that allows to study the description of the main functions of “imaging processing toolbox”. The use of modern tools to achieve the goal of this  work is shown by using the capabilities of the software package Matlab 2017. Practically, the method is implemented on the example of  the   process of  nanofiltration with   the   using of  semi-permeable  polymer membranes OPMN-P and  OFAM-K.

The results of studies of obtaining nanoparticles in laser ablation of solids in liquids are presented, an experimental facility for obtaining nanoparticles has been developed. The facility uses a ytterbium pulse fiber laser YLP (Russia) with a radiation wavelength of 1064 nm, a pulse duration of 100 ns, a separate radiation power control unit (up to 20 W) and pulse repetition rate (20 – 60 kHz), as well as an automated target transfer system based on the motorized biaxial linear translator 8MTF (Lithuania) and controller CNC USB TB6560 (China), allowing uniform evaporation of the material from the target surface, reducing the size changes of the formed craters, thereby increasing effect the ablation efficiency with prolonged irradiation and the narrowing of the scatter in the sizes of the nanoparticles obtained. The scanning parameters are set and controlled via the computer, the scanning process is displayed on the monitor. The particle size was studied on a laser particle size analyzer SALD-7500nano (Japan). The obtained materials were studied by scanning electron microscopy, energy dispersive X-rayspectroscopy using a scanning electron microscope JCM-6000 (Japan). The facility allows produce colloidal solutions of nanoparticles, for example Ag and Si in ethyl alcohol (C₂H₅OH) with an average size of 45 and 33 nm, respectively, to be obtained by laser ablation of volumetric metal and semiconductor targets in liquid, respectively, and the resulting solution of coagulated Si particles was dispersed in an ultrasonic bath. To study the optical properties of the obtained colloidal solutions of Ag and Si, a spectrophotometer SF-56 (Russia) and quartz cuvettes with an optical path length of 10 mm was used, ethanol was used as a comparison. For a solution of silver nanoparticles, a minimum of light transmission at a wavelength of 390 nm is observed, this is due to the absorption of radiation at this wavelength as a result of surface plasmon resonance. A solution of silicon nanoparticles transmits radiation starting at a wavelength of more than 300 nm, and is almost completely (up to 95% in the 600 – 1100 nm region) transparent in the visible red and infrared regions of the spectrum.

Now development and creation of polymeric composites is a serious scientific problem. Introduction of natural excipients to a polymeric matrix allows to create material with new properties. The nature of the entered excipient can affect set of physicomechanical and physical and chemical properties of composites. In work physicomechanical and rheological properties of compositions on the basis of secondary polymeric raw materials and filler of natural origin — a rice peel are studied. The sample of secondary polypropylene corresponding to primary polypropelene of the FF/3350 brand and a rice peel of various dispersion have been considered as objects of a research. Modeling of process of processing of polymeric materials carried out at the laboratory station (plastograf) of PlastographEC (Germany). Deformation and strength properties of material defined on the pressed samples of material 1 mm thick. Pressing was carried out on an automatic hydraulic press of AutoMH-NE (USA). Physicomechanical properties of polymeric composites at a gap defined by explosive ShimadzuAGS-X car (Japan) at a temperature of 20°C and speeds of the movement of mobile hijacking of the explosive car of 1 mm/min. Rheological measurements of polypropelene fusion and compositionally the filled materials on its basis carried out on a modular dynamic reometr of HaakeMarsIII at 220°C. It is established that introduction of filler leads to increase in size of torque, reduction of value of an indicator of fluidity of fusion, growth of dynamic viscosity of fusion, but is not followed by increase in elasticity. To increase in viscosity it is obviously connected with adsorption of polymer on the surface of filler. It is shown that during filling of secondary polypropylene minor change and deformation and strength properties of composition happens a rice peel. At introduction to composition up to 10 mass part a rice peel will allow to form the materials which aren’t conceding on the physicomechanical indicators to initial secondary polypropylene and capable at the same time to biodegradation. Besides the higher dispersion of filler, the all mentioned indicators change stronger.

A method for assessing the selectivity of active centers upon sorption of sorbates from multicomponent solutions containing three or more pollutants is proposed. The method is based on comparison of the values of specific sorbent capacity for each of the sorbates when they are extracted from single-pollutant (one pollutant) and multipollutant (all contaminants simultaneously) solutions. Both stationary and flowing solutions to be studied contained close and significantly different initial concentrations of eco-pollutants. At the first stage, stationary solutions contained a single pollutant (then all three at the same time) at a given equal (close) initial concentration, the sorbent mass in them being fixed strictly. At a given moment of time фi, the capacity of the sorbent Qi for each sorbate is estimated. Then the same experiment is carried out with the solutions containing all three pollutants simultaneously. If Qi (фi = const) does not depend on the presence of other pollutants, then the selectivity of the active centers of the sorbent takes place. If it decreases with the introduction of other pollutants, the selectivity isabsent. At the second stage, the same experiment is carried out in the flow solutions, and at the third stage at the concentration of one the sorbate (10 – 100 times) lower than that of others (flow media). In all cases, the value Qi of each i-th sorbate is also estimated and the same theoretical analysis is carried out. Results of sorption of metal cations (Me (II)) (iron group) on glauconite at practically identical their initial concentrations and Ni (II) from media with high (more than 100-fold) content of hardness cations (Ca (II) and Mg (II)) are presented as an example. The high selectivity of the active sorbent centers is shown.

The analysis of failure criteria and limit states for thin-wall pressure vessels is carried out, taking into account the influence of plastic deformations. The introduction describes the main problems of operation of thin-walled vessels operating under internal excess pressure, associated with technological defectiveness and reduction of the residual life. Typical technological and operational defects in welded joints of vessels and statistical data on their number and types are presented, their grouping and statistical processing are carried out. The share of welding defects was 62 % of the total number of defects, the remaining types of defects are much smaller. The histograms of the dimensions of welding defects were constructed and the distribution laws were determined: the length of the cuts was described by the lognormal distribution law, the depth by the normal distribution law. Further, the limiting states and criteria for the destruction of vessels in the presence of defects and cracks in the conditions of elastoplastic deformation of the material are indicated. The advantages of using generalized equations of the form «J-curves» when calculating for fracture toughness are shown. A formula is given for the calculation of «J-curves» connecting a dimensionless J-integral with a dimensionless load. An analysis is made of the stress-strain state of a thin-walled vessel with a external half-elliptical and internal elliptical cracks, in a volumetric setting. The peculiarities of the stress and strain fields in the local region of the crack zone under elastoplastic deformation were investigated. The accountings are performed and the results of evaluation of the fracture mechanics energy criterion — J-integral for vessel model with the external half-elliptical and internal elliptical cracks in elastic-plastic deformation — are presented. The results are presented as graphs of the dimensionless J-integral dependency on the geometrical sizes of the vessel and crack. The equations of «J-curve» were obtained and the ultimate load for thin-wall pressure vessels were determined. That ultimate load depends on the geometrical dimensions, loading parameters, structural behaviors of material, the characteristics of crack strength and deformation. On the «J-curves» and the deformation curve, a formula is obtained for determining the dependence of the ultimate load on the crack size, loading parameters and material characteristics. Using this formula, we plotted the dependences of the vessel’s limiting pressure for elastoplastic deformations on the ratio a/S for surface and internal cracks for different ratios R/S and Jc, which allow estimating the levels of limiting pressure for the safe operation of thin-walled vessels.

The issues regarding improving the quality of low-rigid shafts are considered through studying the stressed state of their surface layer. The depth of hardening, value and distribution of the residual stresses in the surface layer have a direct impact on the geometrical stability of low-rigid shafts. The main goal of hardening consists in providing the uniformity of the stressed state in the bulk. A novel design of a centrifugal roller is proposed to ensure effective hardening of low-rigid shafts. A notion of a mutual impact zone is introduced. Theoretical dependences providing determination of the optimal depth of the hardened layer of low-rigid shafts are presented. The experimental results regarding determination of the hardening depth as a function of the rotational frequency of a centrifugal roller are presented. The experimental data show that the quality of treating low-rigid shafts with a centrifugal roller depends on the characteristics and thickness of the mutual impact zone, which is determined by the average grain size of the microstructure. The developed design of a centrifugal roller provides an unchanged value of the working force, stability of deformation and stresses along the workpiece length. The optimal depth of hardening of the surface layer of low-rigid shafts attained upon finishing-hardening by surface plastic deformation (SPD), which is proved both theoretically and experimentally, should not exceed the size of the mutual impact zone.

The purpose of this work is to study possible schemes of loading double-cantilever beam (DCB) specimens to replenish the arsenal of the methods used in their testing. Mathematical analysis of ten different modes of specimen loading is carried out for different methods of immobilizing and loading of the cantilever including splitting force, deformational and combined loading. Analytical expressions for the stress intensity factor (SIF), as well as the dependence of the beam spread angle θ (rotation angle of the beam head) on the crack length are derived. Those dependences form a basis for developing the methods for measuring the dynamics of the crack length changes during testing. The energy approach is used in determination of the stress intensity factors. The classical scheme of force loading of the DCB specimen by a pair of forces is supplemented with a loading scheme with two pairs of forces applied to different cross sections. A modification of the DCB specimen by rigid binding of the ends of its consoles when each shoulder of the specimen is considered a singly statically indeterminable beam and DCB specimen becomes a double-beam specimen is also considered. The possibility of rearranging the sections of the load application and position of the rigid support-link is also studied. The deformational loading is simulated by inserting a wedge in one or two sites along the specimen length. The wedge effect is modeled by a preset deformation in one of the sections and binding of the specimen consoles in the other. Formulas of the stress intensity factor for the DCB specimen asymmetric with respect to the crack propagation line upon pure force loading by the forces applied in one section are presented. References to the reports on experimental implementation of a number of proposed and considered load configurations are presented.