M. A. Lazov

Objectives. To develop and validate a methodology for determining inorganic iodine in Laminariae thalli L., corresponding to the norms of the State Pharmacopoeia of the Russian Federation, 15th edition (SPh 15). The methodology needs to be valid and suitable for the quality control of pharmaceutical raw materials in factory laboratories.Methods. Cathode inversion voltammetry was used as an instrumental method for determining inorganic iodine using a graphite electrode capable of sorbing electroactive ion associates of surfactant–iodine.Results. When compared with the titrimetric technique recommended by SPh 15, the proposed technique is more selective, sensitive and less time-consuming. The efficiency and metrological characteristics of the technique were confirmed by validation in accordance with the requirements of SPh 15.Conclusion. The paper presents a new method for determining the gross content of inorganic iodine in Laminariae thalli L. This technique can be used not only in scientific research, but also in the routine quality control of medicinal plant raw materials in control and analytical laboratories engaged in pharmaceutical quality control.

Objectives. Chalcogenides of transition elements with low oxidation states, as well as their substituted derivatives, remain a poorly studied class of chemical compounds. Rhenium disulfide has many distinctive features and great application potential as a new twodimensional semiconductor. This is due to its unusual structure and unique anisotropic properties. The presence of weak interlayer bonding and a unique distorted octahedral (1T) structure suggests the possibility of creating new phases on its basis. The aim of this work is to obtain and study phases in systems Re(IV)S₂–Ti(IV)S₂, Re(IV)S₂–Mo(IV)S₂, and Re(IV)S₂–W(IV)S₂.Methods. The samples were obtained by high-temperature solid-phase ampoule synthesis in a vacuum. The study was carried out using X-ray phase analysis and X-ray photoelectron spectroscopy.Results. The regions of existence of solid solutions, intercalates and two-phase regions in the resulting systems were established.Diffraction patterns were obtained for the new phases and the crystal lattice parameters were calculated. Based on data relating to the binding energies of core electrons with the nucleus, the study showed the valence states of the elements after synthesis. The study also confirmed that all phases obtained as a result of synthesis contain transition elements in the oxidation state (IV).Conclusions. Intercalated solid solutions are formed in areas rich in rhenium, while in areas close to titanium and molybdenum disulfides, intercalated phases are attained. In the ReS₂–WS₂ system there is a region of solid solutions, including 30, 50, and 70 mol % rhenium disulfide. Their structure is a polymorphic modification of the structure of the original components. The presence of rhenium, molybdenum, and tungsten in these phases in the oxidation state (+IV) was confirmed. The data obtained on phase formation in dichalcogenide systems can be practically used in the creation of materials with unique electronic, magnetic, and optical properties with a wide range of applications.

Objectives. The main aim of this review is to summarize the existing knowledge on the use of X-ray photoelectron spectroscopy (XPS) for the characterization of nanoparticles and nanomaterials.Results. XPS or electron spectroscopy for chemical analysis can provide information on the qualitative and quantitative composition, valence states of the elements of the samples under study, the chemical composition of the surface and interfaces that determine the properties of nanoparticles and nanostructured materials. The review describes the role of several different methods for the characterization of nanomaterials, highlights their advantages and limitations, and the possibilities of an effective combination. The main characteristics of XPS are described. Various examples of its use for the analysis of nanoparticles and nanomaterials are given in conjunction with additional methods to obtain complementary information about the object under study.Conclusions. XPS provides depth information comparable to the size of nanoparticles (up to 10 nm depth from the surface) and does not cause significant damage to the samples. Two disadvantages of XPS analysis are sample preparation requiring a dry solid form without contaminations and data interpretation. XPS provides information not only on the chemical identity, but also on the dielectric properties of nanomaterials, recording their charging/discharging behavior. Chemical information from the surface of nanoparticles analyzed by XPS can be used to estimate the thickness of nanoparticle coatings. XPS has a high selectivity, since the resolution of the method makes it possible to distinguish a characteristic set of lines in the photoelectron spectrum at kinetic energies determined by the photon energy and the corresponding binding energies in elements. The intensity of the lines depends on the concentration of the respective element. Obtaining a sufficiently complete picture of the properties of nanomaterials requires the use of a group of complementary instrumental methods of analysis.

A number of metal sulfide catalysts were synthesized by hydrogen treatment of nickel, cobalt, copper, and iron sulfates supported on γ-Al₂O₃ (with a metal content of 5% and 10%). The resultant materials catalyze the decarbonylation of stearic acid to the corresponding higher olefins in the presence of hydrogen. The yield of target products decreases in the following order: Ni, Co > Cu > Fe. In the nickel and cobalt catalysts, X-ray diffraction (XRD) analysis identified interplanar distances (d-spacings) attributable to Ni₃S₂ and Co₉S₈. Such sulfides are likely responsible for their performance in decarbonylation. Hydrogen pretreatment time was found to be a factor that affects the activity of nickel and cobalt catalysts. XPS examination showed a decline in the sulfide sulfur to metal atomic ratio with an extension of hydrogen treatment time. The optimal time was found to range from 1 to 3 h.

Objectives. This paper presents data on the development and study of the structural properties of iron-doped crystalline silicon (nc-Si/SiO_x/Fe) nanoparticles obtained using the plasma-chemical method for application in magnetic resonance imaging diagnostics and treatment of oncological diseases. This work aimed to use a variety of analytical methods to study the structural properties of nc-Si/SiOx/Fe and their colloidal stabilization with citrate anions for in vivo applications.Methods. Silicon nanoparticles obtained via the plasma-chemical synthesis method were characterized by laser spark emission spectroscopy, atomic emission spectroscopy, Fouriertransform infrared spectroscopy, and X-ray photoelectron spectroscopy. The hydrodynamic diameter of the nanoparticles was estimated using dynamic light scattering. The toxicity of the nanoparticles was investigated using a colorimetric MTT test for the cell metabolic activity. Elemental iron with different Fe/Si atomic ratios was added to the feedstock during loading.Results. The particles were shown to have a large silicon core covered by a relatively thin layer of intermediate oxides (interface) and an amorphous oxide shell, which is silicon oxide with different oxidation states SiO_x (0 ≤ x ≤ 2). The samples had an iron content of 0.8–1.8 at %. Colloidal solutions of the nanoparticles stabilized by citrate anions were obtained and characterized. According to the analysis of the cytotoxicity of the modified nanosilicon particles using monoclonal K562 human erythroleukemia cells, no toxicity was found for cells in culture at particle concentrations of up to 5 µg/mL.Conclusions. Since the obtained modified particles are nontoxic, they can be used in in vivo theranostic applications.