National Academy of Sciences of Belarus

Influenza A virus hemagglutinin (HA) is a major virus antigen. No cryo-electron microscopy or X-ray data can be obtained for the HA intraviral (cytoplasmic) domain (CT) post-translationally modified with long fatty acid residues bound to three highly conserved cysteines. We recently proposed a model of HA CT of Influenza A/H1N1 virus possessing an antiparallel beta structure based on the experimental secondary structure analysis of four 14–15 amino acid long synthetic peptides, corresponding to the HA CT sequence, with free or acetaminomethylated cysteines. To dispel doubts about possible non-specific “amyloid-like” aggregation of those synthetic peptides in phosphate buffer solution, we have determined the order of oligomers based on blue native gel electrophoresis, membrane filtration, fluorescence spectroscopy and molecular modeling approaches. We have found that unmodified peptides form only low molecular weight oligomers, while modified peptides form both oligomers of low order similar to those found for unmodified peptides and high order conglomerates, which however are not of beta-amyloid-like fold. This study confirms that the beta structure previously detected by circular dichroism spectroscopy analysis is more likely the result of intrinsic propensity of the HA CT amino acid sequence than the consequence of aggregation. The structures of low order oligomers of the synthetic peptides were used for in silico experiments on modeling of HA CT interactions with matrix protein M1 at physiological and acidic pH levels and revealed two different areas of binding. Finally, tripeptides capable of blocking interactions between HA CT and M1 were proposed.

It is common knowledge that the O2 evolution reaction (OER) is a crucial half-reaction in the electrolysis of water. However, it is currently difficult to create inexpensive OER electrode materials in a way that is efficient, simple, and environmentally friendly. In this research, metal oxy-hydroxides with numerous oxygen defects (M-OOHv) are created at surface of Cu foam (CF) using a unique, straightforward electro-oxidation reconstitution (ER) process. Different spectroscopic and microscopy methods are used to analyse the electrode characteristics of Al2Cu-MOF@M-OOHv-ER/CF; electrochemical measurements display a lower overpotential (η) of 366 mV @ 10 mA cm-2 and a Tafel slope of 95.2 mV dec-1 in 1.0 M KOH. X-Ray diffraction (XRD), scanning electron microscopy (SEM), and Raman studies confirm the phase transition of the metal-organic framework (MOF) to the M-OOH, which acts as the active site to boost the OER activity. Through spectroscopic and microscopic investigations, it is determined that the efficiency of bimetallic electrode materials and oxygen vacancies in the M-OOHv have an impact on the electron power density. The manufactured electrode material additionally showed good durability for 50 hours. As a result, the newly developed Al2Cu-MOF@M-OOHv-ER/CF nanomaterial has greater potential for both electrolysis of water and other energy storage equipment.

Adsorption natural gas (ANG) is a technology in which natural gas is stored on the surface of porous materials at relatively low pressures, which are promising candidates for adsorption of natural gas. Adsorbent materials with a large surface area and porous structure plays a significant role in the ANG technology, which holds promise in increasing the storage density for natural gas while decreasing the operating pressure. Here, we demonstrate a facile synthetic method for rational construction of a sodium alginate (SA)/ZIF-8 composite carbon aerogel (AZSCA) by incorporating ZIF-8 particles into SA aerogel through a directional freeze-drying method followed by the carbonization process. The structure characterization shows that AZSCA has a hierarchical porous structure, in which the micropores originated from MOF while the mesopores are derived from the three-dimensional network of the aerogel. The experimental results show that AZSCA achieved high methane adsorption of 181 cm3·g-1 at 65 bar and 298 K, along with higher isosteric heat of adsorption (Qst) throughout the adsorption range. Thus, the combination of MOF powders with aerogel can find potential applications in other gas adsorption.

The analysis of the ring rolling machine capabilities in providing increased accuracy of ring blanks is performed. The necessity of operator’s participation in controlling the ring rolling machine to achieve the required accuracy even with full automation of the ring blanks manufacturing process is noted. The necessity of controlling the process of cooling of circular blanks after the circular rolling machine to ensure increased accuracy of the circular blanks has been noted. To eliminate the ovality of low rigidity ring blanks after the circular rolling mill it is proposed to use the technology of their controlled cooling and stabilization. The sequence of thermal strain control of the ring blanks during cooling to preserve the achieved accuracy of the “hot” ring after the ring rolling on the “cold” ring after cooling has been developed. The proposed recommendations are intended for the development of technological support for automated ring rolling complex at OJSC “BELAZ”.

The article considers etch pits that appear in metals and alloys during metallographic etching as an artifact. The optical contrasting tools capabilities, such as dark field, polarized light, and differential interference contrast in detecting etch pits, are demonstrated.

It is shown that, like conventional diffuse fluorescence spectra and despite the complex mechanism of formation of the excited state, the chemi- and bioluminescence spectra contain information about the frequency of the purely electronic (vertical) transition of the emitting molecules and the degree of homogeneity of their ensemble. As in the case of ordinary diffuse luminescence spectra, the frequency of a purely electronic transition is shifted significantly toward the short wavelength side (by almost the half-width of the band) from the maximum of the fluorescence spectrum. An example of the separation of the overlapping spectra using the position of a short-wavelength purely electronic transition is presented.

Nanostructured thin films on a silicon substrate were obtained by high-frequency pulse-periodic (f ~ 8–10 kHz) action of a laser with wavelength λ = 1.064 μm and power density q = 36 MW/cm2 on Y0.1Sr0.9CoO3–x ceramics in a vacuum chamber at pressure p = 2∙10–2 mm Hg. Their morphology was studied using atomic force microscopy. Features of their transmission spectra in the visible and near- and mid-IR regions were revealed. The electrophysical properties of the Y0.1Sr0.9CoO3–x structures were analyzed.

The present paper reviews the uncertainties and errors in complex dosimetry systems that were developed to estimate individual doses in different post-Chernobyl (Chornobyl) radiation epidemiology studies among the general population and the cleanup workers. These uncertainties and errors are associated with (i) instrumental radiation measurements of humans and environmental samples, (ii) inherent uncertainties arising from the stochastic random variability of the parameters used in exposure assessment and from a lack of knowledge about the true values of the parameters, and (iii) human factor uncertainties due to poor memory recall resulting in incomplete, inaccurate, or missing responses during personal interview with study subjects conducted long after exposure. Relative measurement errors of 131I thyroid activity associated with devices for measuring radioactivity in the thyroid reached up to 0.86 (coefficient of variation). The inherent uncertainty in estimates of individual doses varied between different studies and exposure pathways (GSD from 1.2 to 15 for model-based doses and from 1.3 to 5.1 for measurement-based doses). The human factor uncertainties can cause individual doses to be underestimated or overestimated by an average of 10 times for model-based doses and 2 times for measurement-based doses calculated for the general population and up to 3 times for doses calculated for cleanup workers. The sources of errors and uncertainties, especially the human factor uncertainties, should be carefully considered in dose assessment for radiation epidemiological studies, with particular attention to studies involving persons without instrumental radiation measurements.

The results of study of the characteristics of new varieties of fruits, root crops, berries, and vegetables that can move in the fluid flow are obtained. Their interaction with the friction surfaces of trays made of various building materials has been studied. The friction coefficients of rolling and sliding of fruits and vegetables on the wetted surfaces of open channels and trays have been established. They can be used in hydraulic calculations when determining the main parameters of a hydraulic transport installation.

A simple, fast, sensitive method for the determination of preservatives (methyl parahydroxybenzoate, propyl parahydroxybenzoate) in the finished dosage form of sodium oxybutyrate syrup based on the simultaneous determination of preservatives using high performance liquid chromatography (HPLC) is proposed. The HPLC method was validated. The correlation coefficient of the linearity of the technique was 0.999 in the application range of 80–120 % of the normalized value. The calibration graph is linear in the region of 0.495–0.990 mg/ml of methyl 4-hydroxybenzoate and 0.165–0.330 mg/ml of propyl 4-hydroxybenzoate. It has been established that the analytical characteristics of the test procedure (selectivity, linearity, correctness, repeatability, reproducibility) satisfy the selected acceptance criteria.

Effect of water content and storage conditions on the activity of carbon fiber supported palladium-copper-iron containing catalyst was studied. Physical-chemical properties of catalytic system were examined by means of XRD, XPS, SEM and GCh. The optimal water content in the catalyst, which ensures the most effective air purification both at low (0,03 vol.%) and high (0,5 vol.%) CO concentrations in the air and high humidity (70 %) of gas mixture, was determined. Activity loss of the catalytic system after storage under air conditions (1 month) was attributed to the accumulation of the excess amount of water in the catalyst and reorganization of its the active phase – decrease in the palladium content in the near-surface layer and segregation of the Сu2Cl(OH)3 atacamite phase. Catalyst drying in air at 110 оС leads to its complete reactivation. Hermetically sealed freshly as-prepared and dried at 50 оС after experiment samples retain the initial catalytic activity during long-term (more than a year) storage.

The process of potassium sulfate crystallization from aqueous solutions in the presence of organic modifiers containing phosphonic, phosphate, sulfonic, sulfate and carboxyl functional groups has been studied. It is shown that the introduction of organic substances has an inhibitory effect on the formation of potassium sulfate crystals. Modifiers containing sulfonic, sulfate and phosphonic functional groups have the greatest inhibitory effect. The effectiveness of modifiers containing carboxyl groups is significantly lower. The formation of stable supersaturated solutions of potassium sulfate is achieved by introducing organic modifiers in an amount of 0.25 – 0.50%.

For the first time, a method has been developed for the synthesis of aromatic imides of citraconopimaric acid by the interaction of primary aromatic amines (aniline, p-toluidine) and citraconopimaric acid in p-xylene at reflux. New aliphatic imides have been synthesized by the reaction of citraconopimaric acid and primary aliphatic amines (octyl-, octadecylamine) in a melt at 125–150°C. For the first time, the synthesis of citraconopimaric acid imidoamides was developed by treating citraconopimaric acid N-octylimide with thionyl chloride and subsequent reaction of the resulting acid chloride with primary aromatic amines (aniline, p-bromoaniline). A method has been developed for the synthesis of aliphatic imides of the rosin-citraconic adduct (in the form of technical products) by its interaction with primary aliphatic amines (octyl- and octadecylamine) at 180–200°C for 8–12 hours. Together with Belarusian state technological university, the relationship between the structure of imides of rosin-citraconic adducts as modifiers of unfilled and filled industrial rubber compounds was studied, and the obtained additives were found to improve the technological properties of compositions while maintaining, and in some cases improving physical and mechanical parameters (increasing the resistance of compositions to thermal aging, bond strength of the cord with rubber, etc.).

The influence of the conditions of mechanical activation of a mixture of Cu–12 wt. % Sn with different content of the modifier Cu 9 Al 4 on the structural-phase composition and morphology of the formed composites was studied by the methods of X-ray diffraction analysis, optical and electron microscopy. With the mechanochemical introduction of 10 wt. % of the modifying additive into the matrix of mechanosynthesized tin bronze, the product mainly forms a ternary solid solution of aluminum and tin in copper, Al 0.05 Cu 0.9 Sn 0.05 . In the case of 20 wt. % of the modifying additive, the product contains a solid solution of tin in copper Cu 0.9 Sn 0.1 and an intermetallic compound Cu 9 Al 4 . Studies of the mechanical and tribotechnical characteristics of the material obtained by sintering under pressure showed that the intensity of wear of bronze of the mechanochemically synthesized powder Cu–12 wt. % Sn is slightly less than that of industrial bronze BrTPh10-1, the friction coefficient f decreases by a factor of 1.4, and the range of its values is quite wide f = 0.7–0.9. Modification of mechanically synthesized Cu–12 wt. % Sn bronze with the Cu 9 Al 4 intermetallic compound makes it possible to reduce wear by a factor of 1.4–1.8 and significantly reduces the friction coefficient (by a factor of 2). A stable value of f = 0.5 is achieved for the MA composition Cu–12 wt. % Sn + 20 wt. % Cu 9 Al 4 . The introduction of an intermetallic compound increases the microhardness of the alloys by a factor of 1.6–2.0 (up to Hμ = 2730 MPa) relative to the bronze alloy BrTPh10-1and mechanically synthesized bronze.

The problem of improving the WRF numerical weather model performance for the territory of Belarus by assimilating the Earth remote sensing data is considered. It is shown that for the winter period, the use of satellite data of high spatial resolution, including on the structure of land use , albedo, leaf index and photosynthetically active radiation absorbed by the underlying surface can reduce a root-mean-square error of the short-term forecast (up to 48 h) of the air surface temperature by 0.53–1.11 °С. For the summer period, on the basis of numerical experiments the optimal correction factor for the land surface albedo was estimated. This made it possible to reduce a root-mean-square error of temperature forecast at the meteorological stations of Belarus for the lead time of +12, +24, +36, and +48 h by an average of 0.30 °С, 0.10 °С, 0.15 °С, and 0.16 °С, respectively.

ZAP-70 (Zeta-chain-Associated Protein kinase 70) is a key kinase in the regulation of the adaptive immune response. Zap-70 acts by binding its SH2-domains to the T-cell-associated CD3ζ protein, thus transmitting a T-cell activation signal induced by the interaction of Major Histocompatibility Complex with T-cell Receptor. It has been established that for ZAP-70 kinase activation, the phosphorylation of Tyr315, Tyr319, and Tyr493 is required, however the mechanisms are unclear. In the present study, we use the tools of structural modeling to elucidate the ZAP-70 activation mechanisms.

Adsorbents based on binary lithium-manganese oxides with the spinel structure of Li1.33Mn1.67O4 were synthesized by using solid-phase, sol-gel, and hydrothermal methods. The effect of the synthesis methods and calcination temperature on the crystal structure, phase composition, textural characteristics, and morphology of prepared adsorbents was established. It was found that the samples obtained by solid-phase and sol-gel methods and calcined at 600 °C were single-phase (Li1.33Mn1.67O4) while the Mn2O3 trace phase was also obtained only in hydrothermal synthesis. The increase in the average crystallite size and the decrease in the specific surface and the total volume of pores were observed during temperature rise in the range from 400 to 800 °C. The samples prepared by sol-gel and hydrothermal methods after at 600 °C calcination had the highest adsorption efficiency of Li+ ions.

An important problem of modern clinical biomechanics is to identify complex movement markers that make it possible to evaluate complex motor adaptive reactions regardless of age, gender, and anthropometric deviations. The purpose of the present study was to develop a method for analysis of human motor adaptive reactions based on calculating specific biomechanical markers obtained by performing diverse kinematic tests. The study involved 90 volunteers with a right-leading kinematic side at an age of 18.8 [16.8/20.8] years, with a height of 171.8 [179.2/164.8] cm, a body weight of 65.3 [76.6/58.5] kg, and the ratio of men and women – 5 : 4. During the study, all participants underwent biomechanical analysis using the TESLASUIT remote motion capture suit and performing diverse kinematic tests. In the course of the study, a new method for analyzing human motor adaptive reactions was developed. It is based on calculating specific time markers of the active phase, average angular deviation markers, and inertial kinematic markers. All markers are calculated after each kinematic tests “frontal stability”, “sagittal stability”, “spatial orientation”, and “stimulus identification”. Our survey revealed that specific (p < 0.001) markers of the first test are the time indicators of the active phase, the markers of the second and fourth tests are associated with the average angular deviation parameters, and the specific indicators of the third test can be the inertial kinematics of thighs, legs, and feet.

An algorithm to detect moving objects captured by a moving video camera is presented. The algorithm is based on detection of motion on video frames taken by a moving video camera, as well as on finding and analyzing the trajectories of moving objects. A feature of the algorithm is detection on frames of connected areas (clusters) of possible object motion. Then moving points on the detected clusters are found, and those points trajectories are built with help of the optical flow. The trajectories are used as features of moving objects. Only smooth trajectories are exploited for detection of moving objects, and the remaining ones are removed from consideration. An object is considered as moving on the current frame if it contains ends of a sufficient number of trajectories of moving points found on previous frames. The presented algorithm has a low computational complexity, which allows it to be used in real or near real time on small computers that have only a few processors of the ARM architecture without powerful parallel computing tools such as GPUs or neural network processors NPU.

Increasing incidence, difficulties in early diagnosis, and a high mortality rate in liver cancer (LC) determine the relevance of studying the mechanisms of its development. The aim of the work is to evaluate the expression of high molecular weight glycoproteins MUC-1, MUC-13 in liver cancer. The object of study is LC tissue samples of 65 patients from the archives and 34 blood serum samples from patients with morphologically confirmed LC. The age of subjects was 26– 97 years. The level of antibodies to MUC-1 and MUC-13 was studied by ELISA. The reference value ranges of MUC-1 (0.250 ± 0.10 ng/ml) and MUC-13 (0.321 ± 0.13 ng/ml) in the blood serum of healthy individuals were established. The concentration of antibodies to MUC-1 and MUC-13 in the blood serum in RP was significantly higher than that in practically healthy individuals. The concentration of MUC-1 and MUC-13 in the LC tumor tissue was higher than that in the blood serum of apparently healthy individuals and LC patients. With a confirmed LC diagnosis, the level of antibodies to MUC-1 in the blood serum, which exceeds 0.373 ng/ml, and the level of antibodies to MUC-13, which is more than 0.939 ng/ml, may indicate a high risk of a tumor process.