Moscow University Chemistry Bulletin最新文献

Lattice tilings of a plane into polyominoes are constructed for N from 3 to 12, where N is the order of the packing space. A total of 5191 symmetrically independent lattice tilings of the plane with one polyomino in a reduced (primitive) cell are obtained, among which 122 variants belong to the structural class (SC) cm, Z = 2(m), with a rectangular conventional (centered) unit cell. Chain tilings of the plane are derived, for which both the SC and structural subclass (SSC) are identified. The results of the analysis of the lattice tilings of a plane into polyominoes are illustrated with examples of real molecular layers in crystal structures.

A new interpretation is proposed for the dependence of dynamic moduli on the strain amplitude in the course of shear vibrations at a fixed vibration frequency. The interpretation is based on a structural rheological model that includes kinetic equations for the formation and destruction of particles’ aggregates under the action of an oscillating shear flow. The rheological equations, which can be used for the approximation of rheological curves G'(γ₀) and G''(γ₀) in separate sections with different amplitudes of the shear strain, are obtained. The possibilities of the new rheological model are demonstrated through the example of two polymer systems with solid particle-based fillers.

As insecticides, fungicides, heavy metals, and aflatoxins enter the food chain, they cause adverse effects on living organisms and humans. Given that rice is a widely-consumed food in Iran, the present study aimed to investigate the probability of the existence of insecticides, fungicides, heavy metals, and aflatoxins, as well as the nutritional value of rice in Mazandaran province. To this end, four cultivars of rice, namely Tarom, Fajr, Neda, and Shiroodi rice were collected from farms in the region, and after preparation, the concentration of pollutants in rice was measured in different ways in the laboratory. SPSS 25 software was used to analyze data. Based on the findings, the average nutritional value of four cultivars of rice was high in terms of protein (8.575 ± 0.298 g), fiber (less than 1), fat (1.2 g), carbohydrates (81.725 ± 0.512 g), calcium (405.64 ± 0.81 ppm), and B vitamins, where the average of vitamin B1 was 2.775 ± 1.305 g, vitamin B2 was 3.5 ± 1.62 g, vitamin B3 and B6 were less than 0.2, and vitamin B12 was less than 5. Heavy metals (less than 0.1 ppm), arsenic (0.095 ± 0.338 ppm), and cadmium (less than 0.025 ppm) were lower than the standard level. Due to the proximity of heavy metals to the standard, its status was considered critical. The average concentrations of aflatoxins, insecticides, fungicides, and herbicides were standard in different cultivars of rice. Given the nutritional value, the standard level of pollutants, and the health of Iranian rice species, rice consumption is recommended in diets and exports.

We prepared a novel series of 1,3,4-oxadiazole and benzo[d]imidazolecontaining fi fteen new connections to develop potential antimicrobial agents (9a–9o). The structures of this new series were characterized by various spectral techniques like IR, ¹H NMR, ¹³C NMR, LC–MS, and elemental analysis. Using the Broth Dilution method, the hybrids were examined for antimicrobial activity against a variety of bacterial and fungal strains. Compound 9n (MIC = 50 μg/mL) exhibited good activity against gramnegative E. coli and compound 9m (MIC = 50 μg/mL) showed potent activity against P. aeruginosa. While compounds 9c, 9f, 9g and 9m indicated MIC = 250 μg/mL against C. albicans.

The results of studies in which the relationship of the self-organization, physicochemical properties, and bioeffects in dilute aqueous solutions of various biologically active substances sustained under natural and reduced levels of external physical fields (geomagnetic and low-frequency electromagnetic), as well as under exposure to ionizing radiation solutions studied by the complex of physicochemical methods, are considered. The established patterns can be used to create a scientific base related to the clarification of the mechanisms of the negative influence of hypomagnetic conditions on the functioning of living organisms necessary to ensure the normal operation of the ecosystem of spacecraft during flights.

In this paper, we analyze the behavior of low-molecular-weight non-Newtonian fluids (liquid paraffin, silicone oil, and FC70 oil) in which the shear thinning phenomenon is observed at low shear rates. Over a wide range of a high shear rate, the behavior is described, which is similar to the Newtonian behavior in the case when the shear viscosity is practically constant. In terms of the structural rheological model, an explanation is proposed for this type of the Newtonian flow.

The adsorption of cationic and anionic polyelectrolytes (PEs) from aqueous solutions on the polystyrene surface is studied by quartz crystal microbalance (QCM) and contact angle measurements. It is shown that, despite the multilayer nature of adsorption, only a monolayer of PE macromolecules is firmly retained on the polymer surface, and the polystyrene surface is hydrophilized. It is shown that with the complete monolayer filling of the surface, the degree of modification of the polystyrene surface does not depend on the nature of the studied PEs, and the modifying monolayers provide the value of the polystyrene/water interfacial energy, which indicates the potential biocompatibility of the material based on the modified polystyrene.

The expression of PD-L1 protein is quantified in 56 samples of urothelial bladder cancer (BC). PD-L1 expression is detected in all BC samples, while in non-muscle-invasive bladder cancer (NMIBC) this score is 1.5 times higher than in muscle-invasive bladder cancer (MIBC) (p = 0.001). High PD-L1 expression level (≥30%) is observed in 20% of MIBC samples and among NMIBC tumors in 68% of cases, i.e., 3.4 times more often (p = 0.0004). The last fact justifies the prospect of starting therapy with immune checkpoint inhibitors at the onset of the disease for NMIBC.

It is shown that the removal of CO₂ from a gas can be implemented in a disk film absorber using water as an absorbent. The proposed technical solution is focused on solving various decarbonization problems.

In this review, the methods used to study internal rotation in the ground (S₀) and excited (S₁) electronic states in the following series of α,β-unsaturated carbonyl compounds: R₄R₃C = CR₂–COR₁, where R₁ = H, R₁ = F, R₁ = C_I; R₂ = H, R₂ = CH₃, R₂ = F; and R₃ = R₄ = H = CH₃, are compared. Differences in the values of (0-v)-transitions of torsional vibration for s-trans- and s-cis-isomers for some studied compounds are revealed in the methods of analysis of the vibrational structure of the n-π*-transition of high-resolution UV absorption spectra and Fourier-transform IR spectra used in the study of the internal rotation in the (S₀) electronic state. The reasons for such differences are established. It is shown that in the (S₀) state, a more reliable determination of the values of (0-v)-transitions of the torsional vibration of both isomeric forms of molecules is obtained in the method of analysis of the vibrational structure of n-π*-transition of UV absorption spectra. A new assignment for transitions of the torsional vibration of the s-trans isomer of acrolein in the spectrum of the cavity ringdown spectroscopy (CRDS) method in the excited (S₁) state is proposed. It is concluded that the method of analyzing the vibrational structure of the n-π*-transition of high-resolution UV absorption spectra of vapors of the studied compounds is more reliable and accurate when studying the internal rotation in both electronic states.