The aim of the work is to study the effect of the 3D printing process on the microstructural and hydrophilic properties of polylactic acid (PLA) samples with various model printing patterns obtained from the black filament PLA by sequentially applying polymer layers using the FDM (fused deposition modeling) method. X-ray phase analysis revealed the partial crystallization of PLA polymer chains in the printed samples, which occurs under thermal and mechanical action on the original amorphous PLA filament during 3D printing to varying degrees, depending on the geometry of the pattern and the morphology of its surface. At the same time, IR spectroscopy data indicate the preservation of all intrastructural chemical bonds of polylactide. Measured at the original installation, the values of the wetting edge angles on the surface of the printed samples are in the range φ = 50–60°, which is significantly less than the right angle. This indicates the hydrophilic properties of the whole sample’s surface. At the same time, the influence of different geometries of model drawings in printed samples was found not only on the morphology of the sample’s surface according to SEM data but also on its wettability.

Nanostructured composite films based on Ag-Si containing silver nanoparticles are used as a material for SERS (Surfaceenhanced Raman spectroscopy) substrates, plasmonic back reflector, nanoplasmonic sensors, nonlinear optics devices, memristor structures, etc. Due to the widespread use of nanocomposite films based on Ag-Si, there is a need to develop simple and affordable methods for their production compatible with semiconductor technology. Therefore, this work is devoted to the production of an Ag80Si20 nanocomposite film with a high silver content (80 at.%) by ion-beam sputtering with simultaneous control of the morphology, structure, phase composition and electrical properties of the manufactured sample. As a result of complex studies using X-ray diffraction, ultra-soft X-ray emission spectroscopy, SEM and AFMmicroscopy, it was found that the film is a nanocomposite material based on silver nanoparticles with an average size of ~15÷30 nm. At the same time, some silver nanoparticles are in direct contact, while some Ag nanoparticles are isolated from each other by a shell of silicon dioxide SiO2 and amorphous silicon a-Si. Such a nanogranulated structure of the Ag80Si20 film causes the presence in the test sample of the effect of switching from a high-resistance state (880 Ohm) to a lowresistance state (~1 Ohm) under the action of a voltage of ~ 0.2 V. As a result of the formation of conductive filaments (CF) of Ag atoms in the dielectric layer between the silver granules

Based on X-ray reflectometry and ultrasoft X-ray spectroscopy data, the opportunity of controlling surface porosity using multi-stage electrochemical etching modes is presented. It is presented how, with an increase in the porosity index of the near-surface layer, the morphology changes and the degree of oxidation of multilayer porous silicon samples increases.

Subject of study. Multilayer samples of porous silicon produced using a variety of electrochemical etching process parameters were studied. Goal of work. An experimental study of production techniques for multilayer porous silicon was conducted, and techniques for fine-tuning the volume and surface properties for use in nanoelectronic devices were developed. Method. The surface morphology was studied by atomic force microscopy and scanning electron microscopy. The surface-layer porosity was studied using X-ray reflectometry. The electron structure of the surface was studied using ultrasoft X-ray emission spectroscopy. The optical properties were determined using photoluminescence spectra. Main results. It was found that stepwise increases in electrochemical anodizing current through a monocrystalline silicon substrate produce multilayer structures in which the layers have different morphologies, surface compositions, and porosity values. Photoluminescence was found to be determined primarily by the composition of the top layer. The effects of gradually increasing the current density while holding the overall etching time constant are also discussed in detail. Practical significance. The research results for the effect of etching mode on porous-silicon morphology and optical properties will be used for the development of nanoelectronic devices based on porous structures. (c) 2025 Optica Publishing Group

Silver(I) oxide is considered as one of the promising materials for photoelectrochemical technologies because it has an optimal band gap, relatively low cost, and a wide variety of production methods. However, its characteristics such as quantum efficiency, morphology, and crystal structure parameters require optimization, which can be achieved by applying the most suitable method for the obtaining of the material. One of the fairly simple methods is the anodic oxidation of silver or its alloys in alkaline media, which allows obtaining oxide phases with a controlled composition and predictable properties by varying the concentration of the alloy components and electrolysis mode. The purpose of this work is to reveal the features of anodic formation and to determine the photoelectrochemical characteristics of silver(I) oxide on silver–palladium alloys in deaerated 0.1 M KOH solution. The regularities of the anodic formation of Ag(I) oxide on alloys of the Ag–Pd-system with the palladium atomic fraction from 0.05 to 0.20 in deaerated 0.1 M KOH solution were studied by non-stationary electrochemical methods of cyclic voltammetry, chronoamperometry with synchronous recording of photocurrent, and photopotential measurements. The phase composition of the alloys (alpha phase) was determined from the results of X-ray diffractometry. Chemical composition was determined by energy dispersive microanalysis. Photoelectrochemical parameters were calculated from the results of the photocurrent and photopotential measurements. It was established that the Ag(I) oxide anodically formed on silver–palladium alloys is characterized by n-type conductivity and the predominance of donor defects. On the alloys with a relatively low palladium concentration (5 and 10 at

The results of studying the electronic structure of transition-metal oxides TiO2 and MoO2 with a rutile-type crystal structure are presented. The electronic structure is studied theoretically within the framework of the linearized augmented-plane-wave method using the Wien2k software package. The band structure, and the total and partial densities of electronic states are calculated. Based on the filling of energy bands with electrons, an explanation is given for the different types of electrical conductivity of TiO2 and MoO2. The valence band and subvalent states of commercial TiO2 and MoO2 samples in the form of powders at two different excitation energies of 120 and 1486.6 eV are studied using X-ray photoelectron spectroscopy. Based on calculations, the observed features of the structure of the experimentally recorded spectra are interpreted.

Copper oxides combined with other materials, for example, zinc oxide, are considered promising materials for photocatalytic processes of organic impurities’ oxidation or photoelectrochemical water splitting. One of the methods for one-stage production of oxide structures of complex composition is the anodic oxidation of alloys. Evaluation of the photocatalytic or photoelectrochemical activity of the obtained materials is possible using photoelectrochemical parameters: the photocurrent or photopotential generated under illumination. The purpose of the work is to determine the effectiveness of the using of Cu(I) oxides anodically formed in alkaline solution on the Cu–Zn system alloys with zinc concentration of 34 to 50 at

Porous silicon samples with a porosity index of 5% to 80% were obtained in the work by electrochemical etching and their photoluminescence properties were studied as well, Porosity index was calculated according to the data of X-ray reflectometry technique.Composition of the surface was controlled by ultra-soft X-ray spectroscopy and infrared (IR) spectroscopy. Degree of the sample surface oxidation was shown to be increased with the enhancement of porosity enhancement. Two known mechanisms of photoluminescence in porous silicon were detected related with a composition and morphology of its surface. It was found the values of porosity index specifying the dominations of these mechanisms. An increase of porosity index was shown to result in the enhancement of photoluminescence.

Прямой карбидизацией циркониевого проката в атмосфере смеси газообразных аргона и этилена синтезирован компактный образец стехиометрического карбида циркония ZrC заданной формы. Формирование керамики происходит в результате взаимодействия металла с газообразным этиленом и при поглощении углерода, образующегося на реакционной поверхности при пиролизе С 2 Н 6 . Охарактеризована субструктура керамики, дана оценка механических и проводящих свойств ZrC.

The present work is devoted to research on the interaction between carboxymethyl cellulose sodium salt and its derivatives (graft copolymer of carboxymethyl cellulose sodium salt and N,N-dimethyl aminoethyl methacrylate) with cysteine protease (ficin). The interaction was studied by FTIR and by flexible molecular docking, which have shown the conjugates' formation with both matrices. The proteolytic activity assay performed with azocasein demonstrated that the specific activities of all immobilized ficin samples are higher in comparison with those of the native enzyme. This is due to the modulation of the conformation of ficin globule and of the enzyme active site by weak physical interactions involving catalytically valuable amino acids. The results obtained can extend the practical use of ficin in biomedicine and biotechnology.

tangar77@mail.ru Abstract. We present an experimental study of multilayer porous silicon formed by elec-trochemical etching. Special emphasis is placed on effects that arise from a stepwise decrease in the current density while maintaining the total etching time. In order to provide a fully understanding of the morphology of the surface, we used scanning electron and atomic force microscopy. X-ray reflectivity was used to assess the porosity of porous layers. It was found that a stepwise decrease in the current density leads to the formation of a two-layer structure without changing the porosity of the base bottom layer. However, the porosity of the top layer can be varied over a wide range, which directly affects the photoluminescence of the samples. Our results show how the sample production conditions affect the fine tuning of the surface layer morphology of multilayer porous silicon.

In this work, we obtained porous silicon with different porosity by electrochemical etching and studied their photoluminescence. Two well-known photoluminescence mechanisms of porous silicon related to the composition and morphology of the surface have been discovered, and it has been established at what porosity values they prevail. It is shown that an increase in the porosity index leads to an increase in the intensity of photoluminescence.

Porous silicon samples with a porosity index of 5% to 80% were obtained in this work by electrochemical etching, and their photoluminescence properties were also studied. The porosity index was calculated according to the data from X-ray reflectometry. The composition of the surface was controlled by ultra-soft X-ray spectroscopy and infrared (IR) spectroscopy. The degree of the sample surface oxidation increased with the porosity enhancement. Two known mechanisms of photoluminescence in porous silicon were detected that are related to the composition and morphology of its surface. The values of the porosity index specifying the dominations of these mechanisms were determined. Enhancement of photoluminescence was shown to be attributed to an increase in the porosity index.

— Compact stoichiometric zirconium carbide (ZrC) with a tailored shape has been synthesized by direct carburization of rolled zirconium metal in an atmosphere of an argon + ethylene gas mixture. Ceramics have been produced by reacting zirconium metal with ethylene gas, through absorption of the carbon released on the reaction surface as a result of C 2 H 6 pyrolysis. We have characterized the microstructure of the ceramics and assessed the mechanical and conductive properties of the synthesized ZrC.

We describe a sequence of structural transformations characterizing high-temperature nitridation of zirconium–niobium alloys containing 0.1–10 wt % niobium. High-temperature saturation of solid solutions of niobium in zirconium with nitrogen is accompanied by decomposition of the Zr〈Nb〉 solid solution and the formation of Zr1 – хNbхN–(ZrN1 – n/β-solid solution of Zr in Nb)–Zr1 – хNbхN composite structures. During nitridation of the heterostructures, zirconium nitride reacts with β-niobium, which is the final step of the nitridation of the parent Zr〈Nb〉 solid solution. Characteristically, the ceramics thus prepared have near-surface porosity reproducing the surface porosity of the as-rolled material.

Owing to exceptionally high selectivity, membranes based on palladium alloys are widely used for obtaining high-purity hydrogen. An important issue for providing high hydrogen permeability of the membranes is to form the required phase composition. The structural organization of the solid solutions consisting of Cu–36.4 at .% Pd and Cu–50 at .% Pd were studied by X-ray diffraction (XRD), electron diffraction (ED), high-resolution transmission electron microscopy (HRTEM) and energy dispersive X-ray spectroscopy (EDXS). It was found that the former composition can be ordered in the temperature range of 300–400 °C and in the heating (up to 800 °C)–cooling cycle. In the presence of excess Cu atoms (27.2%), this structure can be represented by CsCl type structural units (β-phase) and distributed body center cubic (BCC) copper structural units in the corresponding concentration dose. The formation of a single crystal ordered phase within the mosaic blocks of the disordered phase was established. Experimental evidence was obtained for the separation of the α-phase solid solution in the elemental composition; the very low rate of ordering inherent in this system was attributed to this effect. The hydrogen permeability of a foil of the equiatomic composition was described.

Liposomes provide high biocompatibility with the cells of the human body due to the prevalence of membrane lipids in their composition. They can be used as an effective tool for targeted delivery of drugs against diseases of different etiology. Interactions between liposomes and target cells can be different, i.e., adsorption on the cell surface, endocytosis, and fusion of liposomes with cell membranes. The incorporation of magnetic nanoparticles into liposomes for active control using an external magnetic field makes it possible to enhance the efficiency and rate of drug release. To create magnetically controlled liposomes, we have chosen nanostructured magnetite created in our laboratory. We used nanoparticles with a diameter of 4.23 ± 1.19 nm. The surface of synthesized magnetite nanoparticles was covered with molecules of cetyltrimethylammonium bromide (CTAB), followed by inclusion into phosphatidylcholine-based liposomes. The quantitative analysis of magneto-sensitive nanoparticles embedded in the lipid bilayer was carried out by spectral methods and transmission electron microscopy. This study has shown that modification of nanostructured magnetite with CTAB increases the efficiency of the incorporation of magnetite nanoparticles into the lipid bilayer by 31.6%.

A controlled change in the composition and electronic structure of porous silicon nanoparticles by variation the drying conditions is proposed. Two types of nanopowders were obtained from mechanically milled porous silicon films with subsequent air- or freeze-drying processing. Obtained nanoparticles surface morphology and structure were investigated. Silicon atoms local surrounding specificity and electronic structure probing of studied powders were performed with the use of synchrotron ultrasoft X-ray absorption near edge structure spectroscopy technique. Noticeable changes in surface composition and structure are observed. The air-dried porous silicon nanoparticles were characterized by the presence of a thick surface oxide layer, while the presence of unoxidized silicon atoms at a depth of less than 3 nm was demonstrated for the lyophilized ones.

Zr–Nb–N nitride ceramics have been prepared via nitridation of rolled Zr–Nb solid solutions at temperatures of 1700, 1900, and 2400°C. We have determined the phase composition of the as-rolled alloys and the composition of the heterostructures and compact nitride obtained. Interaction of solid solutions of niobium in zirconium (0.1–10 wt % Nb) with nitrogen at temperatures below and above the peritectic reaction temperature has been shown to occur in two steps. In the first step, the solid solution decomposes to give zirconium nitride and metallic niobium embedded in its bulk: Zr〈Nb〉 + N2 → ZrN1 – х + β-Nb. In the second step, the metallic niobium reacts with nitrogen: ZrN1 – х/β-Nb + N2 → (Zr,Nb)N. The resulting niobium nitride dissolves in the ZrN, reducing the lattice parameter of the zirconium nitride.