This paper presents the results of ellipsometric studies on thin films of organic materials, namely tris-(8hydroxyquinoline)aluminum (Alq), dicyanomethylenepyran (DCM), and its derivatives (DCM-5, DCM-18). These compounds are widely used in organic light-emitting diodes (OLEDs), lasers, and sensors. The thin films of DCM, DCM-5, DCM-18, Alq3:DCM ($10 \mathrm{wt} \%$.DCM), and Alq3:DCM-5 (10 wt. \% DCM-5) were deposited on glass substrates using the thermal vacuum evaporation method. A key goal was to investigate the influence of the deposition angle on the refractive index (n). Films were deposited onto substrates placed perpendicular ($n_{\perp}$) and at an oblique angle of $10^{\circ}\left(n_{\angle}\right)$ to the vapor flux.Ellipsometric measurements (using a He-Ne laser at $\lambda=632.8 \mathrm{~nm}$) revealed that the refractive index could be manipulated by adjusting the deposition angle, consistent with the oblique angle deposition (OAD) technique, which is known to reduce n by creating porous, columnar structures. The difference in refractive indices $\Delta n=\left|n_{\perp}-n_{\angle}\right|$) ranged from $\approx 0.05$ to $\approx 0.18$ for the studied compounds. The lower $\Delta \mathrm{n}$ values compared to literature data for small molecules like pure Alq3 are attributed to the larger molecular size of DCM and its derivatives, which are high-molecular-weight compounds, making ordered, porous growth more challenging. These results are valuable for the optimization and design of high-efficiency OLEDs, where reducing the refractive index of thin-film layers is a known strategy to enhance quantum efficiency.

The time evolution of nanoscale structure formation on the surface of CdI2 crystals grown both from the melt and from the gas phase is investigated. Atomic force microscopy was used to show that, already at the initial stages of exposure to air at room temperature, island-shaped nanostructures form, which subsequently aggregate into nanoclusters as the exposure time increases. Similar nanostructures, including nanopores and nanoclusters, are observed for CdI2 crystals grown from the gas phase after prolonged exposure to air. Photoluminescence spectroscopy indicates that the formed nanoclusters are consistent with the presence of cadmium hydroxide (Cd(OH)2) and cadmium oxide (CdO). The formation of nanostructures determines the time evolution of the low-temperature luminescence spectra of CdI2 crystals. Additional bands with maxima at 1.87 eV and long-wavelength luminescence in the region with a maximum at 1.68 eV appear in the spectral structure. These results highlight the close relationship between surface structural evolution and the time-dependent optical properties of CdI2.

The evolution of structural nanovoids in crystallized (80GeS2-20Ga2S3)100-x(CsCl)x glasses (x = 0, 5, 10, 15) was studied using positron annihilation lifetime spectroscopy. CsCl incorporation affected the defect structure: for x = 5-10 mol%, the second positron lifetime component tau 2 increased from 0.36 to 0.42 ns, while its intensity I2 decreased by similar to 20%, indicating void expansion and agglomeration. At x = 15 mol%, tau 2 decreased and I2 increased, evidencing void fragmentation due to network loosening. These transformations enable tuning of physical, and optical, with potential applications in infrared optical sensors, photonic waveguides, solid-state ionic conductors, and thermo-resistant optical coatings.

Thermosensitive spinel ceramics based on transition-metal oxides are widely applied in temperature sensing, while their functional stability is largely determined by micro- and nanostructural defect organization. In this study, Cu0.4Ni0.4Co0.4Mn1.8O4 ceramics were synthesized from precursor powders of different dispersities to clarify the influence of dispersity on free-volume nanostructuring. X-ray diffraction confirmed the formation of a single-phase cubic spinel structure for all samples, with nearly identical lattice parameters. Scanning electron microscopy revealed pronounced differences in grain morphology and pore architecture, with finer grains and reduced pore sizes observed for micro-modified ceramics. Porosimetry and positron annihilation lifetime spectroscopy demonstrated the presence of intrinsic nanopores with an effective radius of ~0.27 nm, whose distribution depends on powder dispersity. The results show that dispersity mainly affects defect distribution and connectivity rather than crystal structure, providing a route to improve the stability of thermosensitive spinel ceramics.

This study investigates the effect of varying GeS2 and Ga2S3 content on the atomic-deficient structure and free volume in GeS2-Ga2S3 chalcogenide glasses. Glasses with different compositions were examined using positron annihilation spectroscopy. The results show that increasing the GeS2 content leads to changes in the lifetime of the second component of the annihilation spectra, reflecting the redistribution of internal free space and variations in the concentration of free-volume defects. Positron trapping parameters decrease with higher Ge content, while the mean lifetimes remain almost unchanged. These findings highlight the important role of the Ga subsystem in positron capture and demonstrate the influence of composition on the evolution of free volume in chalcogenide glasses.

The electrophysical properties and humidity sensitivity of MgAl2O4 ceramics with varying structural perfection were systematically investigated. Samples sintered at temperatures from 1100 to 1400 °C with different times exhibited distinct microstructural features, including phase composition and pore size distribution, which strongly influenced their humidity-dependent electrical resistance. Ceramics with a near-optimal trimodal pore distribution demonstrated the widest humidity sensitivity range, high linearity, and minimal hysteresis during adsorption–desorption cycles. Prolonged sintering increased electrical resistance and improved linearity but reduced low-humidity sensitivity due to the evolution of pore structure. Degradation tests under prolonged high-humidity conditions showed that structurally optimized MgAl2O4 ceramics maintain or improve their functional characteristics. These results highlight the critical role of microstructure and porosity in governing the moisture-dependent electrical behavior of MgAl2O4 ceramics and provide guidance for designing reliable, high-performance humidity-sensitive dielectric materials.

Accurate air quality forecasting is critical for environmental regulation and safeguarding public health. This study presents an analytical framework which uses a Long Short-Term Memory (LSTM) neural network, enhanced with data imputation via the Expectation–Maximisation (EM) algorithm, as well as standardised pre-processing. The EM procedure reconstructs incomplete monitoring records to ensure a consistent and reliable dataset, while standardisation strengthens model robustness and facilitates efficient training. The LSTM architecture is used to identify temporal patterns in pollutant time series, and its forecasting ability is compared with that of several alternative models. Experimental findings suggest that combining imputation, normalization and deep learning techniques significantly enhances the accuracy of air quality forecasts and improves the overall reliability of the model.

This study presents the technological modification of NiMn2O4–CuMn2O4–MnCo2O4-based spinel ceramics aimed at improving their performance in sensor electronics. Ceramic samples with the nominal composition Cu0.1Ni0.8Co0.2Mn1.9O4 were synthesized using three distinct processing regimes. Their phase composition and structural characteristics were examined through X-ray diffraction analysis. The findings indicate that the formation of secondary transition metal oxide phases in controlled amounts contributes to the suppression of low-temperature, thermally activated defects, thereby enhancing the structural integrity of the primary spinel phase. The impact of NiO-related defects was found to be minimal due to its limited presence. Furthermore, the degradation behavior of ceramics subjected to various sintering conditions was investigated in order to determine the most thermally stable composition suitable for temperature-sensitive sensor elements.

Background. This paper focuses on developing and evaluating a facial recognition system optimized for real-world conditions. A prototype system was implemented, featuring a face detection algorithm, hardware configuration, and integration of OpenCV, Dlib, and Picamera2 libraries, along with pre-trained models for accurate facial landmark detection. Experimental tests were conducted under various conditions, including lighting changes, different angles, and partial occlusions. Materials and Methods. The study aimed to analyze and select an algorithm for face recognition, considering hardware limitations, ensuring high image processing accuracy and speed, and integrating the proposed solution into the compact and energy-efficient Raspberry Pi platform. The subject of the study involved the development of an efficient and energy-saving system for real-time face detection and recognition, ensuring accuracy, reliability, and high performance under constrained computational resources. Results and Discussion. The study presented the main stages of developing a face recognition system and assessed its performance and resilience under real-world operating conditions. This approach substantially reduced processing time and accelerated the identification procedure during subsequent queries, which is crucial for resource-limited platforms like the Raspberry Pi. Additionally, methods for improving system efficiency were explored through algorithmic optimizations and fine-tuning. The results demonstrated the proposed system's high accuracy and operational stability under favorable conditions, such as frontal face orientation relative to the camera, minimal external interference, and a fixed facial position. Conclusion. The study successfully developed a face recognition system optimized for the Raspberry Pi platform, achieving high accuracy and efficiency despite hardware limitations. Integrating a pre-processed feature descriptor database and algorithmic optimization strategies was key in improving system performance. The proposed solution showed strong potential for real-world deployment, particularly in applications where energy efficiency and compactness are critical.

This work investigates the morphology and fractal characteristics of silver and gold films obtained by thermal evaporation at pre-percolation thicknesses. They contain both metallic and insulating (void) phases, making them metal-dielectric composites. The fractal dimensions were evaluated using two approaches: the box-counting method (Hausdorff dimension) and correlation function analysis (correlation dimension). The dependence of the fractal parameters on the films’ mass thickness was established. It was shown that values of correlation dimension are smaller than the Hausdorff dimension for both Ag and Au films, consistent with the theoretical framework of multifractal analysis. The results confirm the multifractal nature of ultrathin metallic films and highlight the significant influence of morphology on their optical and plasmonic properties. The results confirm the multifractal nature of ultrathin metallic films and highlight the significant influence of morphology on their plasmonic properties.

Background. WebAssembly (Wasm) is a fundamental component for high-performance web applications, valued for strategic integration, not simple JavaScript replacement. Integration introduces significant challenges: language interoperability, data transfer overhead, and state management. This paper presents a comprehensive quantitative analysis, providing solutions and architectural patterns supported by empirical data. Materials and Methods. The study comprised two parts. Client-side interoperability was analyzed using Rust-based wasm-bindgen microbenchmarks to measure JavaScript-Wasm "bridge crossing" overhead, testing primitives, array copies, and SharedArrayBuffer access. Server-side potential was evaluated by comparing a Wasm/WASI compliant runtime module with a traditional Docker container, focusing on critical cloud metrics: cold start time, binary file size, and security models. Results and Discussion. Interoperability costs vary significantly. Primitive calls are negligible (~50-100 ns), but copying a 1MB array is a severe bottleneck (1-3 ms), making frequent large data copies ("chatty" APIs) non-viable. SharedArrayBuffer overhead is minimal (~15 ns). Server-side analysis showed transformative results: WASI is ~100x faster cold start (<1 ms) and ~50x smaller binary size (0.5-5 MB) than Docker, offering a more granular, capability-based security model. Benchmarks confirm Rust+Wasm achieves up to 8.7x performance gains. We discuss "Wasm as a Pure Function" vs. "Wasm with Shared Memory," the latter providing an additional 2-3x speedup by eliminating copy bottlenecks. Conclusion. Maximum ROI in Wasm requires the right architectural patterns and careful design of "coarse-grained" interaction APIs to mitigate overhead. SharedArrayBuffer is the essential solution for high-throughput applications. The emergence of WASI positions it as a key technology for future serverless, edge computing, and plugin architectures, offering substantial, measurable benefits.

Organic donor-acceptor molecules such as dicyanomethylene-pyran (DCM) and its derivatives exhibit strong charge transfer and solvatochromic behavior, making them promising for optoelectronic applications. This study investigates polarized photoluminescence of DCM, DCM-5, and DCM-18 thin films deposited by thermal vacuum evaporation on glass at normal and 10 degrees oblique angles. Emission spectra (550-800 nm) showed red shifts for DCM and DCM-5 under oblique deposition, while DCM-18 exhibited minimal change. Polarized emission revealed intensity differences between parallel and crossed polarizers, with higher linear polarization for obliquely deposited films, indicating orientation-dependent optical properties.

The thermal characteristics of refractory nanocomposites embedded with single-walled carbon nanotubes (SWCNTs) were systematically examined utilizing a novel automated analytical approach. This method effectively accentuates the variations in thermal behavior of nanocomposites prepared with different processing parameters, specifically under controlled temperature gradients and applied thermal loads. Such insights are critical for optimizing these materials for integration into sensor technologies and applications demanding superior fire resistance. Experimental results revealed that nanocomposites subjected to a nanotube dispersion duration of two hours exhibited a maximum temperature differential of 55 °C, whereas samples processed with a one-hour dispersion time demonstrated a peak differential of 50 °C. Comparative evaluation of the heat transfer kinetics indicates that prolonging the dispersion time by an additional hour enhances the material’s fire resistance by approximately 15%.

This study investigates the role of cationic and anionic subsystems in nanostructure formation on CdI2 crystals by analyzing CdBr2 and PbI2 surfaces using atomic force microscopy (AFM). After 1 d, CdBr2 developed triangular nanopores and island-shaped clusters. By day three, two nanostructure types emerged: small (200-600 nm) and large (similar to 2 mu m) clusters. After seven days, nanopores increased, and nanowires formed via cluster aggregation, likely due to moisture-induced dissolution. CdBr2 exhibited faster nanostructure formation than CdI2 due to Br-'s higher reactivity. PbI2 surfaces remained smooth, showing atomic steps and quasi-periodic structures (similar to 1.3 mu m period).

Organic fluorescent dyes based on the 4H-pyran core have gained considerable attention due to their wide-ranging applications in optoelectronic devices. Among these, DCM (4-(dicyanomethylene)-2-methyl-6-(p-dimethylamino-styryl)-4H-pyran) is a well-known red-emitting dye, extensively used in OLEDs and laser systems due to its strong intramolecular charge transfer (ICT) characteristics. However, DCM and its derivatives often suffer from significant aggregation and fluorescence quenching in the solid state, limiting their performance in thin-film applications. Here we show that thin films of DCM and its derivatives (DCM-5, DCM-17, and DCM-18) exhibit polarized photoluminescence (PL) when deposited on glass substrates at normal incidence and at a 10° tilt angle using thermal vacuum evaporation. Our results demonstrate that the degree of linear polarization (ρ) of the PL varies depending on the specific derivative and the deposition geometry, with maximum values of ρ = 0.14 for DCM-5 at a 10° tilt angle. This behavior indicates a subtle but detectable degree of molecular alignment induced by the oblique angle deposition method. The observed variations in polarization and emission properties are explained by differences in molecular structure, aggregation tendencies, and film morphology. Notably, DCM-17, which exhibited the lowest polarization degree, is proposed to possess a more disordered or amorphous structure, preventing efficient molecular alignment. Our findings highlight the potential of oblique angle deposition for tailoring the photophysical properties of DCM-based films, providing insights into the design of polarized light-emitting materials. This study contributes to the understanding of structure–property relationships in organic thin films, offering a pathway for optimizing the performance of DCM-based materials in polarized light applications, such as OLEDs, optical sensors, and display technologies.

Magnesium aluminate spinel (MgAl2O4) ceramics are promising for sensor applications due to their stability and tunable microstructural properties. Yet, the influence of sintering conditions on defect evolution and porosity remains insufficiently clarified. In this study, MgAl2O4 ceramics were sintered at 1400 °C for 2, 5, and 9 hours and analyzed using X-ray diffraction, scanning electron microscopy, mercury intrusion porosimetry, and positron annihilation lifetime spectroscopy. The materials exhibited a two-phase composition and heterogeneous microstructure of grains, grain boundaries, and interconnected pores. Longer sintering promoted gradual transformation of free-volume defects, while the total nanopore concentration remained nearly constant with a reduction in their average size. These results reveal a complex relationship between sintering duration, porosity, and defect evolution. The findings provide valuable insights into tailoring the microstructure of MgAl2O4 ceramics, supporting their further optimization for advanced humidity sensor technologies.

The surface topology and fractal dimension of ultrathin silver and gold films have been investigated utilizing atomic force microscopy. These films were formed at the early stages of metal deposition through thermal evaporation and have pre-percolation thicknesses. They contain both metallic and insulating (void) phases, making them metal–dielectric composites. We identified the main parameters of the microstructure, such as the size of the metallic particles and surface roughness, as well as the dependence of these parameters on the film thickness and substrate parameters. Approaches to processing data, including correlation analysis, were employed. An analysis of dependencies and an explanation of their appearance were conducted. The discussion also addressed the limitations of using atomic force microscopy for studying ultrathin metal films. We determined the various types of fractal dimensions, considering the film topology for two- as well as three-dimensional objects. Depending on the actual dimensions of the phase boundary for silver films, a maximum was found. Different approaches to determining the fractal dimensions in 3Ds case show a similar dependence, but different values.