This paper presents the results of an experimental study on the operation of a wick-type heat pipe equipped with an innovative induction heating system. This work is a logical continuation of theoretical studies published by the authors in 2025 and aims to verify a mathematical model of thermal processes in the “inductor–magnetic core–heat transfer fluid” system. The design of the tube under study includes a copper housing, a wick based on an AISI 304 stainless steel mesh, and a ferromagnetic core made of AISI 430 steel. Heating was performed using a parallel resonant circuit at a frequency of 28.15 kHz. The aim of the study was to determine the effect of the tilt angle on the thermal efficiency of the tube in the low-temperature range (18–50°C). The architecture of the experimental setup is described, which includes a two-channel thermometer based on an Arduino microcontroller and film thermistors, which ensure high measurement accuracy in the evaporation and condensation zones. A series of experiments yielded sets of temperature curves for tilt angles of 30°, 45°, 60°, and 90°. It was found that in the vertical orientation (90°), the tube exhibits the highest isothermality and the shortest time to reach steady state. A characteristic temperature threshold for phase transition activation was identified in the range of 30–32°C. It has been proven that when the tilt angle is reduced below 30°, thermal efficiency decreases significantly, which is due to the limited capillary potential of the AISI 304 steel wick, which does not ensure sufficient condensate return to the heating zone under conditions of weak gravitational influence. The obtained data allow for the optimization of heat pipe parameters for their application in mobile personal heating systems, particularly in thermal mats, and indicate the need to modernize the wick structure for operation in a horizontal position.
Систему Zr–Ru–Al досліджено за 900 °С методами Х-променевої дифракції та скануючої електронної мікроскопї. Встановлено низку фазових рівноваг в цій системі за вмісту Al ≤ 55 ат. %. Підтверджено існування двох тернарних сполук: ZrRuxAl2-x з гексагональною структурою типу MgZn2 (просторова група (ПГ) P63/mmc): a = 5,2225(5), c = 8.1980(8) Å та кубічної Zr6Ru7+xAl16-x (x=0.58) структурного типу Th6Mn23: a = 12,27655(8) Å. Вздовж ізоконцентрати за 50 ат. % Ru виявлено неперервний твердий розчин на основі бінарних сполук RuAl та ZrRu зі структурою типу CsCl (ПГ Pm3^(-)m).
In this work, polymer nanocomposites films of (PEO-MnO2-SrTiO3) were manufactured using the casting method, where varying percentages of nanoparticles (MnO2-SrTiO3) were mixed at concentrations of 1.7%, 3.4%, and 5.1%, respectively. The morphological and optical properties of (PEO-MnO2-SrTiO3) films were studied. The results showed that by increasing the percentages of MnO2-SrTiO3 the optical properties improved. The results showed that with increasing concentration, the morphology on the surface of PEO-MnO2-SrTiO3 appears homogeneous and more cohesive. The absorption of PEO doped with MnO2-SrTiO3 increased of 75% with wavelength equal to 380 nanometer and 76% with wavelength equal to 680 nanometer, by increasing the content of MnO2-SrTiO3 nanoparticles to reach of 5.1%. The transmittance decreased from 43% to 41%. Absorption coefficient increased from 6453 cm-1 at Eph=4.41 electron volt to reach 8589 cm-1 for MnO2-SrTiO3 nanoparticles content equal to 5.1%. The energy gap for the allowed indirect transitions decreased from 3.7 eV to reach 3.3 eV while content of the nanoparticles increased to reach of 5.%. The energy gap of forbidden indirect transition decreased from 3.7 eV to 3.2 eV while the nanoparticles content of MnO2-SrTiO3 increased to reach of 5.1%. Extinction and refractive indexes, and dielectric constant increased. The optical conductivity increased from 3.1 × 1012 S-1 at the wavelength of 800 nanometer for pure PEO to 1.6 × 1013 S-1 when the addition of nanoparticles equal to 5.1%. Results showed that the PEO-MnO2-SrTiO3 films could be used for transistors application and flexible solar cells, and diodes.
The influence of structural defects in fast neutron-irradiated CdSb to 2 ⸱ 1018 n/cm2 on the state of the crystal surface was studied. It was shown that during storage of irradiated crystals, their surface (layer 60 ÷ 80 μm) increases its conductivity. A model is proposed that explains the influence of irradiation on the state of the crystal surface. The migration energy of interstitial cadmium atoms, the values of diffusion coefficients at different temperatures, and the frequency factor are experimentally determined. Also, the isochronal annealing of radiation defects in neutron-irradiated CdSb crystals was studied in detail.
In this study, glass systems with chemical composition (40-x)Li2O–10Y2O3–50SiO2:xV2O5 were prepared using melt-quenching method. The XRD patterns of the prepared samples conform to the glassy nature. Optical absorption spectra exhibit two absorption bands at around roughly 630 nm and 1030 nm, identified as the transitions due to 2B2→2B1 and 2B2→2E transitions of [VO]2+ ions. The intensities of these identified peaks are observed to grow with a slightly red shift with the V2O5 content in the glass matrix. The direct and indirect optical band gaps, evaluated using Davis-Mott theory, decreased with increasing V2O5 concentration, while the Urbach energy obtained from the Urbach rule increased. IR spectral analysis revealed that the glass samples exhibit various structural units via., asymmetric and symmetric stretching linkages, , linkages and ; it appeared that the intensity of asymmetric linkages was observed to increase by the expense of symmetric linkages with a gradual increase in the content of V2O5. The optical absorption spectra of the investigated glasses suggest the coexistence of V4+ and V5+ ionic species. The observed evolution of the characteristic vanadyl absorption bands with increasing V2O5 concentration indicates a possible shift in the V4+/V5+ equilibrium within the glass network.
In this study, the efficiency of Gd-doped Ni-Co ferrites for the adsorption-catalytic removal of oxytetracycline (OTC) from aqueous solutions was evaluated. A series of ferrites with the composition Ni0.5Co0.5GdxFe2-xO4 (x=0; 0.01; 0.25; 0.5) were synthesized by the sol-gel autocombustion method, and their catalytic activity was evaluated in the presence of 30 mM H2O2 and under the action of electromagnetic heating (EMH). The Ni0.5Co0.5Gd0.01Fe1.99O4 sample demonstrated the highest OTC degradation efficiency, achieving 100% removal of 25 mg/L OTC in 30 min, with a reaction rate constant of 0.1416 min-1. The Ni0.5Co0.5Gd0.025Fe1.975O4 and Ni0.5Co0.5Gd0.05Fe1.95O4 samples showed significantly lower activity with constants of 0.0446 and 0.0444 min-1, respectively, and the degree of OTC removal decreased to 67-80% depending on the concentration. Electromagnetic field generates heat locally in the catalyst, which accelerates the formation of reactive oxygen species (•OH), increases the reaction rate constant and contributes to the effective destruction of the antibiotic. Excessive Gd doping leads to reduced catalyst efficiency. Increasing the OTC concentration reduces the degradation rate, probably by blocking the active centers of the catalyst. The obtained results demonstrate the promising potential of Ni0.5Co0.5Gd0.01Fe1.99O4 in combination with H2O2 and EMH for the rapid and effective removal of antibiotics from water, which is important for environmental protection.
The nature of the stress-deformed state of the system "dental implant - bone tissue" was determined using three-dimensional computer models that were created in the solid-state parametric modeling program Solid Works 2024 using the finite element method. The actual research was performed using the Simulation package. Using the Solid Works 2024 program, solid-state parametric models were developed, which included a fragment of the jaw bone with a dental implant and orthopedic elements. The study used physical and mechanical parameters of orthopedic elements (crown and abutment), dental implant, cortical and trabecular bone tissue of the jaws. The study of the stress-strain state was carried out under the condition of average strength and density of trabecular bone tissue of the jaws. During the study, conditions were created for the maximum asymmetric application of chewing load force to orthopedic elements and dental implant, which allowed to identify unfavorable conditions for the functioning of the crown - implant - bone tissue system.
The microhardness of ceramics in the AlB12-Al2O3 system was studied across a wide range of component ratios. Dense composite samples were fabricated using hot pressing with nano- and submicron-sized powders of AlB12 and α-Al2O3 synthesized in-house. A nonlinear relationship between hardness and composite composition was identified, suggesting a reinforcing effect due to interfacial surface interactions. A proprietary software tool developed by the authors was employed to compute the multifractal characteristics of microstructures captured via electron microscopy. A correlation was established between the microhardness of the composites and the multifractal parameters of the interfacial structures.
Ferrites are ferrimagnetic iron-oxide–based materials whose magnetic and functional properties are governed by cation distribution, defects, and microstructure, all of which are strongly affected by synthesis. This review focuses on spinel copper ferrite (CuFe2O4) nanoparticles, emphasizing how synthesis-controlled structure determines multifunctional performance. Particular attention is given to the coexistence and stabilization of tetragonal and cubic CuFe2O4 phases, the role of Jahn–Teller distortion of Cu2+, and the influence of oxygen nonstoichiometry, cation redistribution, and surface disorder in the nanoscale regime. The most widely used chemical routes – co-precipitation, hydrothermal/solvothermal synthesis, and sol–gel (including autocombustion) – are discussed with respect to their ability to control phase purity, crystallinity, particle size, morphology, and defect chemistry. The structure–property framework is then linked to key application domains covered in this work: visible-light-driven photocatalytic degradation of dyes, adsorption-based removal of pollutants, photocatalytic hydrogen evolution, electromagnetic interference shielding/microwave attenuation, and functional sensing platforms. Finally, practical limitations are summarized, including reproducibility of cation/defect states, phase stability, performance degradation, and regeneration, highlighting the need for standardized evaluation protocols and rational materials design for scalable, reusable CuFe2O4-based technologies.
It was demonstrated within a simple theoretical model that the size dispersion of the colloidal quantum dots ensemble influence essentially on the absorption coefficient of the photodiodes on their base, and therefore is to be taken into consideration within the description of the operation of modern photodetectors for the Infra-Red range. The increase of dispersion of the nanoparticles ensemble in the photodetector leads to essential decrease of the absorption coefficient at the frequency, which corresponds the absorption in the nanoparticles of the mean size. The typical dependence of the absorption coefficient on frequency includes the sharp increase at the frequencies, close to the intrinsic absorption edge of the quantum dot, followed then by the decrease according to formula , where the denominator includes the gap value in the bulk material, and later – the further increase due to transitions including the upper energy levels of the nanoparticle.
B4C–TiB2 ceramic materials were prepared by spark plasma sintering of powder mixtures B4C+TiB2 (12 wt.%) in an argon atmosphere at 1900°C and a uniaxial pressure of 70 MPa. X-ray powder diffraction was used for the phase analysis and to refine the crystal structures of the individual phases. The influence of homogenization of the initial powders (using ball milling) on the mechanical properties of the ceramics was studied. Vickers hardness values of 38.8 GPa (without ball milling) and 41.1 GPa (ball-milled starting powders) for B4C–TiB2 composites were reached and the relative density of the samples exceeded 99 %.
The structural, electrokinetic, energetic, and magnetic properties of the semiconductor solid solution Zr1-xAlxNiSn, obtained by doping the half-Heusler phase n-ZrNiSn with Al atoms by substituting Zr atoms in the 4a position, were investigated. It was established that Al atoms can occupy different crystallographic positions, causing complex transformations of the crystal and electronic structures. It was shown that in Zr1-xAlxNiSn, х = 0–0.02, the increase in the unit cell parameter a(x) is due to the preferential substitution of the Ni atoms present (rNi = 0.125 nm) in the 4a position by Al atoms (rAl = 0.143 nm) generating defects and energy states of an acceptor nature. The decrease in the parameter a(x) for Zr1-xAlxNiSn, 0.02 < x ≤ 0.04, is caused by the replacement of larger Zr atoms (rZr = 0.160 nm, 4d25s2) with smaller Al atoms, which also generates defects and energy states of an acceptor nature. At concentrations of Zr1-xAlxNiSn, x > 0.04, Al atoms are mainly localized in tetrahedral voids of the structure, generating defects and energy states of a donor nature. The ratio of the concentrations of the generated energy states of Zr1-xAlxNiSn determines the position of the Fermi level εF. The performed studies allowed us to identify the mechanisms of electrical conductivity to determine the conditions for the synthesis of thermoelectric materials Zr1-xAlxNiSn with the maximum efficiency of converting thermal energy into electrical energy.
The paper presents the results of a physicochemical study of mixed fuel thermal decomposition products using an integrated approach that combines X-ray fluorescence (XRF) analysis and gas chromatography-mass spectrometry (GC-MS). The relevance of the research is determined by the need to develop reliable criteria for identifying the composition of fuel raw materials for environmental monitoring and fire-technical forensics. The aim of the work was to identify specific mineral and organic markers in soot and ash to establish the nature of the combusted materials. State-of-the-art instrumentation was employed for the analysis, ensuring high precision in quantifying the elemental composition and identifying volatile organic compounds. The study established that the mineral phase of combustion products reflects the presence of anthropogenic contaminants in the fuel. Specifically, in samples containing municipal solid waste and polymers, significant concentrations of zinc and lead were detected in conjunction with sulphur, resulting from the degradation of inorganic pigments and stabilisers. GC-MS analysis enabled the identification of biomass decomposition markers, such as levoglucosan and methoxyphenols, and the detection of dibutyl phthalate and heavy polycyclic aromatic hydrocarbons (PAHs), indicating deep chemical transformations of synthetic chains in the high-temperature zone. The investigation of interfacial interactions confirmed the complex nature of organic compound stabilisation by the mineral matrix. It was found that ash components act as adsorption centres for heavy aliphatic hydrocarbons and siloxanes, preventing their complete thermal decomposition. The intensity ratios of PAH peaks with varying degrees of condensation indicate the catalytic role of metal oxides in secondary aromatisation processes. The obtained results confirm that the proposed physicochemical approach is an effective tool for diagnosing the composition of combusted raw materials, enabling the detection of illicit use of harmful additives and establishing the sources of anthropogenic impact on the environment.
We investigate the influence of nonmagnetic impurities and pair-breaking effects on the magnetic properties of tunnel superconducting junctions at temperatures close to the critical one. We show that as the transparency of the dielectric layer increases, the current-phase relation (CPR) strongly deviates from the classical sinusoidal form. An analytical expression for the magnetic field dependence of the critical current is derived, which is valid for an arbitrary impurity concentration. We analyze the role of the electron mean free path (impurity concentration) in the formation of the diffraction pattern. It is demonstrated that an increase in the barrier transparency and a change in the junction purity parameter lead to pronounced CPR anharmonicity. This anharmonicity results in a significant suppression of the side lobes in the magnetic diffraction pattern of the supercurrent. Asymptotic analysis confirms that in the limit of low barrier transparency, the diffraction pattern reduces to the classical Fraunhofer distribution.
The concept and hardware and software tools for automated measurement of thermoelectric parameters of semiconductor energy converters have been developed. The system is built on the basis of advanced vacuum methods of direct measurements using a modern element base, high-precision analog-to-digital converters, which, in combination with software methods for processing the obtained experimental data, made it possible to increase the measurement accuracy. A precision software-controlled current stabilizer has been developed, which allows measuring the electrical characteristics of thermoelectric energy converters in a wide range of loads from units of microamperes to several amperes. The possibility of automated diagnostics and determination of operational parameters of semiconductor thermoelectric energy conversion modules, in particular thin-film ones, has been implemented, which makes it possible to reject defective modules and in general significantly increases the reliability of thermoelectric generators. Experimental studies of a series of generator thermoelectric samples with known characteristics have been carried out and the effectiveness of the developed tools has been shown using the described methods for analyzing experimental data.
The present work investigated the electrochemical properties of activated carbon material/conductive additive composites as electrodes for electrochemical capacitors in an aqueous electrolyte. The influence of the type of conductive additive on the specific capacitance characteristics of the obtained activated carbon material has been established. The activated carbon material (ACM) was obtained by thermochemical activation of plant-based raw material using potassium hydroxide. The influence of the type of conductive additive on the electrochemical properties of the activated carbon material was studied by means of electrochemical impedance spectroscopy, cyclic voltammetry, and galvanostatic charge/discharge measurements. The study demonstrated that the choice of conductive additive significantly affects the performance of electrochemical capacitors, particularly the specific capacitance of the electrode material and its stability during cycling. Among the tested conductive additives, Super-P carbon black proved to be the most promising, as its combination with the activated carbon material provides optimal electrochemical characteristics. The resulting composite exhibits the highest specific capacitance (~100-120 F/g), stable performance at high charge-discharge rates, and a significant reduction in internal resistance, which is crucial for enhancing the energy and power efficiency of electrochemical capacitors.
This study shows the preparation of chromium oxide (Cr2O3) nanoparticles (NPs) by pulsed laser ablation in liquid (PLAL), a simple and cost-effective method for producing high-purity nanomaterials. The structural properties of chromium oxide were examined using X-ray diffraction (XRD) and the results showed that the formation of pure eskolaite-phase Cr2O3 with a rhombohedral crystal structure and SEM analysis revealed lower laser energies (300–400 mJ) tends to produce smaller, well-dispersed particles, as the energy is sufficient for ablation but not excessive to cause extensive particle fusion, while higher laser energies (500–600 mJ) result in larger particles with increased aggregation, likely due to higher thermal input, enhanced diffusion, and re-nucleation of NPs in the liquid medium while, Optical analysis revealed a slight band gap increase with higher laser energy, attributed to the Burstein-Moss shift, where the Fermi level moves into the conduction band, altering electronic transitions. The nanoparticles demonstrated pronounced antibacterial activity against Klebsiella pneumoniae, Escherichia coli, and Staphylococcus epidermidis. Conversely, their antimicrobial effect was notably diminished against Candida albicans and Staphylococcus aureus, suggesting a differential interaction between the Cr2O3 NPs and the cellular structures of these microorganisms. This variation in antimicrobial activity underscores the potential of Cr2O3 NPs in targeted antibacterial applications.
The photopolymerization of acrylated epoxidized soybean oil (AESO) and vanillin dimethacrylate (VDM) with a photoinitiator (2,2-dimethoxy-2-phenylacetophenone) (DMPA) is studied by using electron paramagnetic resonance (EPR) and near-infrared (NIR) spectroscopy methods. A correlation between a concentration of free radicals deduced from EPR spectra and double bond conversion peak area deduced from NIR spectra as a function of UV-irradiation time for the investigated polymer composite is detected. The observed correlation is agreed well with the prediction of photopolymerization and photodegradation phenomena within a complex systems theory approach.
The paper presents the results of study of physical properties of synthesised by melt quenching and thermally annealed (As2S3)1-xAgx (0.04 ≤ x ≤ 0.40) alloys depending on the silver content. Temperature dependences of the electric conductivity of the alloys under study measured in the 293 to 413 K range in the direct and alternate current (DC and AC) modes showed that the dominating mechanism is thermally activated charge-carrier hopping mediated by delocalised states in the tails close to the energy bandgap boundaries and localised states close to the Fermi level. Thermal activation energy for the alloy ionic conductivity estimated from the Arrhenius plots increases with silver content. For bulk (As2S3)1-xAgx samples with x = 0.30 and 0.40 AC electric conductivity studies revealed the presence of two components in the charge transfer mechanism due to specific features of their inhomogeneous structure. The effect of the increasing Ag content in the (As2S3)1-xAgx alloys on the optical absorption edge, energy bandgap, and refractive index dispersion in the visible and infrared ranges is studied. For thermally annealed alloys with high Ag content the optical bandgap shrinks and the refractive index increases.
In present study, Metal Inert Gas (MIG) welding with ER309L austenitic filler wire was used to weld API X70 and SS 401 steel. This particular joint is mainly used in oil and gas plants where stainless steel need to be connected to the high strength low alloy carbon steel pipelines. MIG welding process is cost effective in these industrial fabrication and maintenance applications as it has high deposition rates and productivity. The investigation focuses on the influence of two distinct heat input levels-HI-1 (0.814 kJ/mm) and HI-2 (0.573 kJ/mm) on the weldment’s microstructure, mechanical performance, and corrosion resistance in simulated seawater and sodium thiosulphate environments. Microstructural examination revealed that the lower heat input (HI-2) produced coarser grains and reduced martensite-austenite (MA) constituent formation in the fusion zone, resulting in improved toughness. Conversely, the higher heat input (HI-1) led to finer grains but increased brittleness. In the heat-affected zone (HAZ), API X70 exhibited grain coarsening-induced softening, while SS 401 demonstrated sensitization and MA phase development, negatively affecting corrosion resistance. Corrosion assessments indicated superior performance of SS 401 over API X70, with minimal weight loss (0.75 mm/year) in seawater due to its protective chromium-rich passive film. However, the dissimilar welded joints, particularly those produced with HI-1-showed significant corrosion degradation (2.1 mm/year in thiosulphate solution), primarily due to microstructural inhomogeneity and galvanic coupling. Mechanical testing results showed that HI-2 welds offered enhanced impact toughness (196 J in the fusion zone) compared to HI-1 (154 J), although the API X70 HAZ under HI-2 exhibited decreased toughness (120 J) likely due to thermal softening. Hardness measurements revealed maximum values near the fusion boundary (~380 HV in HI-1 samples), with noticeable softening in the HAZ regions. These findings suggest that optimizing heat input is critical for balancing mechanical integrity and corrosion resistance in dissimilar metal joints.
