For determination of mold fungus antigen (Ag) Aspergillus niger, amperometric biosensors based on a printed graphite electrode modified with multi-walled carbon nanotubes (MWCNT), reduced graphene oxide (RGO), and gold nanoparticles (Au NP) were developed. Tyrosinase enzyme was used as a biosensitive component. It was found that Aspergillus niger Ag is an activator of tyrosinase in the concentration range of 1 × 10–8 – 1 × 10–5 μg/mg with LOD = 7 × 10–9 μg/mg. Modification of the electrode surface with carbon nanomaterials and the MWCNT/Au NPs nanocomposite allowed us to improve a number of analytical characteristics: expand the range of detectable concentrations to 1 × 10–10 – 1 × 10–3 μg/mg in the case of MWCNTs and MWCNTs/Au NPs, 5 × 10–10 – 1 × 10–3 μg/mg in the case of RGO, reduce the LOD to 7 × 10–11 μg/mg (MWCNT modifier), 1 × 10–10 μg/mg (RGO), 5 × 10–11 μg/mg (MWCNTs/Au NPs). Kinetic parameters of the reaction of enzymatic transformation of phenol in the presence of Ag Aspergillus niger were studied: regardless of the presence or absence of the modifier two-parameter coordinated activation of the enzyme-substrate tyrasinase – phenol system was observed. The developed biosensors were tested for the quantitative assessment of Aspergillus niger Ag content in a sample of agricultural crop (onion) and in a sample of bronchoalveolar lavage (BAL). The accuracy of the obtained results was confirmed by reference methods — microbiological (sample of onion) and using amperometric enzyme immunoassay sensor (BAL).

For the first time, the possibility of running in a bimodal HPLC based on combination of the dispersion interactions and hydrophobic effect (reversed phase mode) and stacked parallel-displaced π-interactions (quasi-normal phase mode) for the developed stationary phase AWE-241 with an N-alkyl-substituted 2,4-dinitroaniline selector is demonstrated. Hydrophobic nature of the aromatic selector substituted with two nitro-groups allows it to run in reversed-phase mode, and its electron-deficient character provides additional retention due to stacking parallel-displaced π-interactions, as well as dipole-dipole interactions and interactions via hydrogen bonds. This combination of types of chemical interactions makes it possible to selectively determine substances containing an aromatic group, including polar ones, when operating in the reverse-phase HPLC mode, as well as simultaneously determine polar and hydrophobic compounds with an aromatic group without the need for gradient elution. This advantage of AWE-241 is demonstrated in comparison with commercially available analogues for reverse-phase liquid chromatography (octylsilyl and octadecylsilyl phases), as well as the most common phases containing aromatic groups (phenylhexyl, pentafluorophenyl and pyrenethyl), using the example of simultaneous determination of Paracetamol and Ibuprofen, the active ingredients of the two-component drug «Ibuklin». The metrological characteristics of the developed method for the determination of Paracetamol and Ibuprofen using the AWE-241 stationary phase were evaluated: the range of detectable concentrations was from 0.02 to 0.5 mg/mL, the detection limits were 0.3 and 0.7 μg/mL for Paracetamol and Ibuprofen, respectively. The trueness of the determination was confirmed by the spike solutions method

Methods for determining elements contained in suspended particles of different sizes in atmospheric air by inductively coupled plasma mass spectrometry are proposed. Cascade impactors with sulfate cellulose filters with an average pore size of 15, 10, 5, 2.5, and 1 μm are recommended for the selection of aerosol particles (PM) with a size of >1 μm, as well as the quartz perfilters complete with nitrate cellulose filters with an average pore diameter of 0.2 μm with a paper base plate with coarse grain 500 g/m2 for the selection of particles with a size of <1 μm. The following requirements have been established for air sampling when monitoring maximum single concentrations: air flow values υd = 1.2 dm3/min, υf = 1.0 dm3/min, time of sampling tmin = 20 min for PM >1 μm, and υd = 2.0 dm3/min, υf = 1.8 dm3/min, tmin = 11 min for PM <1 μm. The effectiveness of the techniques in monitoring average daily concentrations has been proven. The developed analysis methods are used to determine the elemental composition of fractional dust of atmospheric air in the area of a metallurgical enterprise for the production of steel pipes. Based on the results of the research and metrological examination of materials for the development of measurement methods, their certification was carried out: the methods were included in the unified register of certified methods in the territory of the Russian Federation (MUK 4.1.4060-24 (FR.1.31.2023.45935); MUK 4.1.4159-25 (FR.1.31.2024.500365)). A new approach to the multiparametric analysis of atmospheric air is shown. A multiparametric analysis can be used to determine air pollution standards.

Synthetic oxide pyrochlores are characterized by a wide range of unique properties. Multi-element pyrochlores doped with several transition elements are of particular interest in terms of the mutual influence of dopants on each other and on the functional properties of the compound. This paper presents the results of a study of the electrical and optical properties of oxide pyrochlore based on bismuth niobate doped with cobalt, chromium, and manganese cations in equimolar amounts. XPS was used to study the charge state of cations in the oxide pyrochlore Bi_1.73Mn_1/3Cr_1/3Co_1/3Nb₂O₉ + δ, synthesized by a solid-phase reaction. The XPS spectral parameters for the multi-element pyrochlore were compared with those of transition element oxides. It was shown that pyrochlore exhibits a characteristic shift of the Bi4f and Nb3d spectra toward lower energies by 0.20 and 0.65 eV, respectively. The cobalt and manganese cations are in a mixed charge state, predominantly with an effective charge of +2 and +3. The Cr2p spectrum is a superposition of the spectra of chromium ions in charge states of +3, +4, and +6. It was also established that the ceramic microstructure is low in porosity, formed by fused grains measuring 2 μm. The band gap for the direct allowed transition is 1.85 eV. At 24 °C, the permittivity of the pure and doped samples in the range of 104 – 106 Hz depends weakly on frequency and is 70 and 80, respectively. The dielectric loss tangent for both samples at 1 MHz is 0.002, and the activation energy for high-temperature conductivity is 0.78 and 0.71 eV, respectively. The obtained results can be used to improve the methodology for using the material as, for example, a photocatalyst in the visible spectrum.

When using powder metallurgy technology, the challenge arises of preserving the original microstructure and grain size in a compact material as a result of sintering (powder consolidation). This is particularly relevant for powders of heavy tungsten-based alloys and refractory metal carbides (tungsten, hafnium, tantalum, etc.). This problem is solved by applying approaches that utilize high-intensity, short-term, high-temperature exposure combined with mechanical pressure on the powder blank. The objective of this study is to investigate the high-voltage consolidation (HVC) process of powder materials using the developed measuring system. HVC involves simultaneously applying a short, powerful current pulse to the powder, generated by a high-voltage current pulse generator, and external mechanical pressure, generated by a pneumatic press. The measuring system included systems for recording the high-voltage current pulse and the intensity of thermal radiation from the consolidated material using pulse photometry with photodiode sensors, as well as a matching and control system. During the tests, the parameters of the high-voltage pulse current and the thermal radiation intensity of the consolidated materials were recorded under high-voltage electric pulse exposure. Optimal values for the high-voltage pulse current parameters were determined for VK20, VNZh-90, and VNM 3-2 alloys, and the structure and physical and mechanical properties of the consolidated samples were analyzed. The results can be used to improve the high-voltage consolidation methodology for refractory powder materials.

The aim of the research is to develop a method for evaluating the effect of high-temperature corrosion damage on the thermal fatigue resistance of samples made of heat-resistant alloys on the nickel bas used for blades and disks of gas turbine units. For preliminary application of corrosion damage, the specimens were exposed to a corrosive environment at high temperatures. The metal microstructure of the samples before thermal fatigue tests (after accumulation of corrosion damage and production of one polished surface) was studied by digital metallography. Thermal fatigue tests were carried out in vacuum on plane corset specimens. Heating of the axially fixed specimens is performed by passing electric current. The specified cyclic heating/cooling program was maintained automatically during the entire test. Test programs with temperature changes within the cycle in the ranges of 100 ↔ 850, 100 ↔ 900, 100 ↔ 1000°C without delay and 100 ↔ 800, 100 ↔ 900, 100 ↔ 1000, 100 ↔ 1100, 500 ↔ 1000, 500 ↔ 1050°C with delay at the maximum temperature from 2 to 15 min were considered. The performed tests of specimens with corrosion damages of different intensity have shown a significant influence of the corrosion layer and separate delay time at the maximum cycle temperature on the thermal fatigue resistance of materials. A method for taking into account the effect of corrosion damage on thermal fatigue resistance has been developed using a four-term deformation criterion of thermal fatigue failure by taking into account the linear dependence of the criterion parameters on the thickness of the corrosion layer. The proposed method was initially tested on two heat-resistant alloys KhN56KVMTYuB and VZhM4-VI with varying degrees of corrosion damage.

The purpose of the presented work is an in-depth study of the processes of defect formation and energy distribution during the impact interaction of a composite material with a fragile body. Ice balls imitating hail particles acted as a fragile indenter. A specialized laboratory setup for ballistic testing was developed and constructed at Novosibirsk State Technical University. This experimental system is equipped with a gas gun capable of accelerating projectiles to speeds of up to 200 m/sec, enabling precise simulation of impact conditions. Spherical projectiles with a diameter of 35 mm were fabricated using silicone molds to ensure high geometric accuracy. Composite panels made from the carbon-epoxy system Toray T800-24K/UD were selected as test materials due to their widespread application in various industries. Real-world testing, involving impacts of hail-like particles with a diameter of 35 mm on the panels, demonstrated that damage begins to form at impactor velocities starting from 130 m/sec. Experimental results, including detailed visual inspection of panel surfaces and ultrasonic analysis of internal structures, allowed the identification and classification of observed damage. The results of ultrasonic testing showed that in most cases, the destruction began from the center of the impact and spread to the adjacent areas. The data obtained were presented in detailed tables and graphs illustrating the relationship between the kinetic energy of the impact and the degree of damage to the composite material. These findings provide critical insights for further analysis and optimization of composite structures used in practical applications.

Hardness measurement of metallic materials at its high levels is usually performed using Rockwell (HRC) or Vickers (HV) methods. The purpose of this study is to investigate the correlation between Rockwell and Vickers hardness values. Analysis of technique gives the following general formula: HV = (A/(B – HRC))². This formula describes well the high hardness region at A = 4400 MPa^1/2 and B = 110. Comparison with the tables of ASTM A370-20 and ASTM E140-12b standards yields A = 4700 MPa^1/2 and B = 117. In both cases the formulae tend to the borders of the scatter band of available data. The relative middle of the scatter band corresponds to A = 4500 MPa^1/2 and B = 113. The difference between the three relationships increases with increasing hardness and reaches four units at the level of 70 HRC. This means that numeric values of the A and B coefficients are to be determined more specifically for separate groups of materials. Obtained results can be used for improvement of the technique of determination of hardness of metallic materials and for comparison of the values of hardness determined by different methods.