In this study, the method of thermal decomposition of iron(III) oleate at different ratios of oleic acid and octadecene-1 was used to obtain iron oxide nanoparticles (IONPs). Transmission electron microscopy (TEM) showed that they all had a spherical shape and a diameter of 8–9 nm, and FT-IR spectroscopy revealed the presence of oleate shells in them, which ensure the stability of the colloidal solutions of these nanoparticles in nonpolar solvents. For all synthesized IONPs, the sizes of the crystalline core formed by iron oxides were determined using X-ray diffraction analysis and magnetometry. The sizes of the oleate protective shells were established by comparison with the TEM data. These values were in agreement with those from the literature.

This paper considers a method for determining the type of electrical conductivity of a previously developed composite transparent conductive coating based on oriented platinum networks embedded in the polymer matrix. Many researchers have recently been grappling with finding electrically conductive transparent coatings for smart devices with touch screens, particularly an alternative to the massively used indium tin oxide (ITO) having some disadvantages, the most serious of which is the lack of coating flexibility. The latter can be overcome by using various metal-polymer composites with high transparency in the optical range and low surface resistance. However, one should be aware that the type of conductivity depends on both the polymer matrix and the metal framework of a composite. This defines its electrical properties. Therefore, it is important to correctly identify and measure the electrical conductivity. The developed method is based on studying the temperature dependence of the surface resistance in the material.

The mechanism of self-assembly by short-chain peptides (oligopeptides) – the process by which their molecules spontaneously form an ordered structure – has received much attention recently. Selfassembling phenylalanine oligopeptides have been of particular interest due to their potential as an effective aid in the design of new functional materials. This paper considers the results of an SPM study on the ability of L-alanyl-L-phenylalanine to self-assemble into a thin film under the action of methanol vapor. The micro- and nanostructures that develop on the surface of amorphous films of this dipeptide were characterized. A method for monitoring the state of the surface of dipeptide films using atomic force spectroscopy was proposed. The results obtained contribute to the development of approaches for the controlled selfassembly of oligopeptides used to produce new biocompatible materials and environmentally friendly micro- and nanodevices that would help solve various problems in the medical, environmental, and energy fields.

A theoretical study of the association of phenyl and ortho-substituted aryl derivatives of lactic acid was carried out. Two variants of hydrogen-bonded associates in the gas phase were calculated: nonclassical, actually found in the crystals, and simulated classical dimers. The energy advantage of classical dimers and the non-equivalence of diastereotopic electron lone pairs at the carbonyl oxygen atom were shown.

Polyscias fruticosa (L.) Harms root extracts were obtained and separated using ultrasound-assisted extraction (UAE) with the preset optimal parameters, such as solvent/solid

(SS) ratio (50/1, mL g^–1), ethanol concentration (40%, v/v), temperature (45 °C), and extraction time (20 min). The best values of the total phenolic content (TPC) and antioxidant capacity (AC) of the extracts under these extraction conditions were 2.13 ± 0.02 mg of gallic acid equivalents (GAE) per gram of dry sample weight (DW) for TPC and 78.13 ± 0.25% for AC. In addition, the structure of the plant material was examined by scanning electron microscopy (SEM): it was revealed that the structure of the residues changed completely as a result of the ultrasound treatment compared to the initial material.

To obtain reliable results in the quantitative determination of rare earth elements (REE) by atomic emission spectroscopy, it is particularly important to take into account the matrix effects of the macrocomponents contained in the analyzed solutions. Analytes obtained by liquid-phase and autoclave opening of geological samples of REE ores and minerals contain significant amounts of strong mineral acids used as reagents and such macrocomponents of the samples as aluminum (aluminosilicates) and phosphorus (phosphates in apatites). Here, we studied the effects of hydrochloric, nitric, sulfuric, and orthophosphoric acids and aluminum on the relative intensity of the ion analytical lines of La, Ce, Nd, Sm, Gd, Tb, Er, and Yb in atomic emission spectroscopy of the microwave-induced plasma (AES MIP). With an increase in the acid concentration from 0 to 1 mol/L, the relative intensity of the spectral lines of all investigated REE decreased monotonically by 10–20%. The depressing effect of aluminum, which is due to a decrease in the degree of ionization of REE atoms, was much stronger and reached 70%. It was shown that the AES MIP method is not inferior to atomic emission spectroscopy of inductively coupled argon plasma in terms of the detection limits of lanthanum, cerium, gadolinium, and erbium.

The Au–Bi binary system electrodeposited on the surface of a glassy carbon electrode exhibits catalytic activity during the electrooxidation of phenylephrine, paracetamol, and caffeine that enhances the peak currents and decreases overvoltage in the oxidation of organic compounds. The potential difference between the peaks of oxidation on the modified electrode is 400 mV for phenylephrine and paracetamol and 300 mV for phenylephrine and caffeine, respectively. The possibility of simultaneous voltammetric determination of phenylephrine, paracetamol, and caffeine on the glassy carbon electrode modified by the Au–Bi binary system was established. The calibration curve is linear in the concentration range from 5·10^–6 to 5·10^–3 M. The developed method was tested in the analysis of combined drugs.

Plants of the Lamiaceae family have been used for thousands of years in cooking, as well as phyto- and aromatherapy. Their essential oils are characterized by high antioxidant and other types of biological activities. In our study, the phytochemical profile and quantification of the essential oil components of thyme, marjoram, and sage were analyzed by gas chromatography with mass-spectrometric detection (GC-MSD). The antioxidant properties of the samples were evaluated using total antioxidant parameters (total antioxidant capacity (TAC), ferric reducing power (FRP), antioxidant activity (AOA) towards 2,2-diphenyl-1-picrylhydrazyl (DPPH^•), and total phenolics by Folin–Ciocalteu method). The obtained FRP was 46–321-fold lower than TAC, which is consistent with the contents of phenolics identified in the samples. Terpenes, isopropylmethylphenols, and eugenol turned out to be the major components of all essential oils and determined their TAC and AOA. The Folin–Ciocalteu method was applicable to the thyme essential oil only. Its FRP, which is based on the reaction of phenolic antioxidants with electrogenerated ferricyanide ions, agreed well with the total phenolic contents (329 ± 17 and 334 ± 15 mg of carvacrol per mL, respectively). The thyme essential oil had the highest antioxidant parameters, while sage showed the weakest antioxidant properties. Positive correlations (r = 0.8846–0.9964) of the antioxidant parameters were obtained.

It was shown by the conductometric study that the formation of micelles in the cetyltrimethylammonium bromide (CTAB) – dimethylsulfoxide (DMSO) – water system occurs at higher critical micelle concentrations (CMC) than in the CTAB – water system. The solubilization of nitroxoline in this system upon reaching the CMC was determined by the spectrophotometric method. The Box–Behnken design was used to obtain systems with the highest light absorption of nitroxoline, depending on the CTAB concentration, the acidity of the pH medium, and the proportion of DMSO when searching for the optimal matrix. A sensitive and selective technique suitable for micellar media and spectrophotometric analysis was developed using the response surface methodology for the determination of nitroxoline in medicines.

Novel disulfinyl derivatives based on 3,4-dichloro-2(5H)-furanone, aliphatic dithiols, and monoterpene alcohols were synthesized. Chiral bis-thioethers in the molecules of which the dithiol fragment links two five-membered cycles at C⁴ atoms were obtained in the reactions of 5(S)-(l-menthyloxy)- and 5(S)-(l-bornyloxy)-2(5H)-furanones with ethane-1,2-dithiol and propane-1,3-dithiol in acetone in basic medium. The action of an excess of m-chloroperoxybenzoic acid (2.0–3.2 equiv.) on bis-thioethers led to the formation of the corresponding mono- and disulfoxides bearing l-menthol or l-borneol fragments at the 5th position of the lactone ring. The methods of column chromatography and fractional recrystallization were used for the isolation of individual products. The structure of the synthesized heterocycles was proved by IR and NMR spectroscopy, and their composition was confirmed by high-resolution mass spectrometry. The molecular structure of the three disulfoxides was characterized by X-ray diffraction analysis.

The structure and intramolecular mobility of some derivatives of bis(thio)phosphorylated amides in CCl₄, CD₂Cl₂, and CD₃CN solutions were examined by ¹H and ³¹P NMR spectroscopy. A comparative analysis of the temperature-dependent ¹H and ³¹P NMR spectra of the studied compounds with symmetric and asymmetric substitution at phosphorus atoms was carried out. Various intramolecular processes were identified – rotation around C-N bonds, conformational transformations of molecules, tautomerism, and phosphorylotropic rearrangement with the formation of various conformational forms. It was shown that a dynamic equilibrium of several forms is reached, with the amide (phosphazo-) form having a clear advantage.

Alkylation reactions of α-carboxylate phosphabetaines were carried out and studied to enhance the biological activity of previously synthesized carboxylate phosphabetaines. As a result of these reactions, the original structure was destroyed with the formation of quaternary salts of phosphonium triiodide. The structure and composition were confirmed by a complex of physical research methods, including NMR, IR spectroscopy, and elemental analysis. The bactericidal and antimycotic activity of the synthesized salts was assessed. The compounds showed activity similar to that of commercial drugs. The reactions of complexation of these structures were also investigated. In the reactions with nickel and copper chloride, complexes were isolated and characterized. The structure of the nickel complex was unambiguously confirmed by the data obtained with the help of single-crystal X-ray diffraction analysis.