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This study investigates the influence of prolonged electrolysis on the electrochemical performance and surface characteristics of NiFe-modified compressed graphite electrodes used in alkaline water electrolysis. The electrochemical experiment was conducted over a two-week period at a constant temperature of 60 °C. The electrodes were evaluated for changes in surface morphology and composition using scanning electron microscopy (SEM), energy-dispersive X-ray spectroscopy (EDS), and X-ray diffraction (XRD). The results demonstrated stable electrochemical performance with minimal current variation. However, significant structural changes occurred, including the formation of new microstructures on the cathode and the emergence of KHCO3 (potassium bicarbonate) compound on both electrodes. Crystallographic analysis revealed an increase in crystallite size and tensile lattice strain on the cathode, while the anode exhibited compressive lattice strains and a reduction in crystallite size. These findings suggest that the observed changes were driven by electrochemical annealing processes, contributing to material redistribution and surface modifications during prolonged electrolysis. This study provides insight into optimizing NiFe-based catalysts for enhanced durability and efficiency in water splitting technologies.

This paper investigates the evolution of the outer surface geometry of Invisalign®—clear orthodontic aligners—caused by degradation triggered by wearing. The obtained results served to confirm whether or not the aligners could continue to be used once their wear time in the therapeutic procedure had ended, taking both their geometric and mechanical features into account. The measurements were performed using atomic force microscopy which allowed the mapping of nanomechanical properties. The obtained images were then processed to determine statistical and functional surface geometry parameters in accordance with relevant ISO standards. The results revealed that the unrepeatability of the manufacturing process causes the surface shape parameters of new aligners to be irregular; however, these features become gradually consistent for worn samples. On the other hand, properly used aligners may change in two ways: the outer layer flattens and its thickness decreases, and at the same time the Young’s modulus of the material decreases. It follows that the degradation processes may be caused by tribological phenomena (abrasion of contact surfaces) and/or biochemical phenomena (biofilm growth, decomposition of the material under the influence of enzymes in the oral cavity).

Abstract Previous research has shown that the endosperm microstructure and physical properties of grain have significance in grain processing and in the development of processing machines. The aim of our study was to analyze the endosperm microstructure, physical, thermal properties, and specific milling energy of organic spelt (Triticum aestivum ssp. spelta) grain and flour. Image analysis combined with fractal analysis was used to describe the microstructural differences of the endosperm of spelt grain. The endosperm morphology of spelt kernels was monofractal, isotropic, and complex. A higher proportion of Type-A starch granules resulted in an increased proportion of voids and interphase boundaries in the endosperm. Changes in the fractal dimension were correlated with kernel hardness, specific milling energy, the particle size distribution of flour, and the starch damage rate. Spelt cultivars varied in size and shape of the kernels. Kernel hardness was a property that differentiated specific milling energy, particle size distribution of flour, and starch damage rate. Fractal analysis may be considered as a useful tool for evaluating milling processes in the future.

In this work the effect of preliminary curing on mechanical, physicochemical and tribological properties of SLA (Stereolithography Appearance) manufactured samples is presented. Three preliminary curing times of 5, 10 and 15 s were selected for SLA manufacturing. The materials’ friction, hardness and capacitance values were determined by ball cratering, Brinell method and electrochemical impedance spectroscopy, respectively. The obtained results showed that the mechanical property values changed most significantly after 10 s of preliminary curing, but friction wear and electrochemical capacitance showed greatest change for samples cured for 15 s. This effect may be explained by the domination of elongation of molecular chains in the first 10 seconds of preliminary curing and the gradual increase of branching processes during the next 15 s.

This paper presents the results of diagnostic examinations conducted on the coils of super-heaters made of 10CrMo9‒10 steel that were operated in industrial conditions at 480°C for 130 thousand hours. The tube was exposed in a coal-fired boiler. The chemical and phase composition of the oxide/deposit layers formed on both sides of the tube walls (outside – flue-gas side and inside – steam side) and their sequence was examined using optical microscopy, scanning electron microscopy with electron backscatter diffraction and energy-dispersive X-ray spectroscopy, and X-ray diffraction. The changes in the mechanical properties caused by corrosion and aging processes were concluded from the hardness measurements. In addition, the nature of cracks in the oxide layers caused by pressing a Vickers indenter was determined. The results of these examinations have shown a high degradation of steel on the flue-gas inflow side and identified the main corrosion products and mechanisms.

This paper presents the results of the multi-aspect surface characterization of X39Cr13 steel samples subjected to technological processes specific to medical instrumentation, such as heat and thermochemical treatment, as well as sterilization, which are implemented in corrosion resistance measurements. The application of numerical methods of fractal analysis to averaged profiles obtained from SEM images resulted in double-log plots of structure function, from which the determination of the fractal parameters of interest was possible. The discussion was focused on the fractal dimension D, which governs relative height variations upon scaling in length, and corner frequency fc, which separates the scaling behavior of different-order structures (particles and their aggregates). The obtained results show that the heat treatment leaves behind a granular structure of steel (D2 = 2.43; fc2 = 1.97 nm), whereas corrosion tests reveal the appearance of pits (D1 = 2.17; fc1 = 0.303 nm; D2 = 2.59; fc2 = 4.76 nm). In turn, the ion nitriding improves the resistance of steel X39Cr13 to local corrosion. The fractal analysis also shows that the structure of the nitrided layer differs insignificantly from that of the untreated material, seen only as a shortening of the radius of the self-similarity area by a factor of two (fc2 = 1 nm).

The paper presents the results of studies conducted with the use of stationary and time-resolved fluorescence spectroscopy for the new derivative 2-Hydroxy-N-(2-phenylethyl)benzamide (SAL-3) in aqueous solutions with various concentrations of hydrogen ions as well as in solvent mixtures (i.e. media with changing polarity/polarizability). For the compound selected for the study placed in aqueous solutions with varying concentrations of hydrogen ions, the fluorescence emission spectra revealed a single emission band within most of the pH range, however, at low pH (pH

Background: Atomic force microscopy imaging was used to study the structural topography of enamel crystals in healthy and affected enamel. The correlation of topographic images with nanomechanical properties allows for the assessment of morphology and properties at the micro- and nano-meter level in three dimensions simultaneously. Methods: A total of 60 premolars were treated like teeth during orthodontic bonding and debonding procedures. Every stage was observed in AFM. Surface roughness, image surface area difference, mean Young’s modulus, and mean adhesion force (the force of attraction between the scanning blade and the surface averaged over the image) were determined for the following areas: the central part of the surface, responsible for load transmission; the top of the surface, subject to the most abrasive wear; the lower part of the surface, responsible for the transport of fluids. Results: The highest roughness occurred on the etched surface—average 63 nm, followed by the intact enamel—8.3 nm, cleaned enamel—7.0 nm, and the resin-coated surface—5.4 nm. Conclusion: Etching increases enamel roughness and reduces hardness. Resin reduces roughness of the etched surface and increases hardness. The intact enamel has the highest hardness. The enamel smoothness is greater after polishing than in the intact enamel.

The knowledge about high-temperature corrosion of steels operating at elevated temperatures is important due to the durability of power equipment. The paper demonstrated the fractal analysis of oxide layers formed on 10CrMo9-10 steel under the operating temperature of 545 °C for 200 000 h employed in the power industry. The studies were carried out on elements taken from the inner and outer surface of the tube wall on the outlet both on the fire and counter-fire side of the tube wall surface. Thorough examinations of the oxide layer comprised microscopic examinations using scanning electron microscopy and atomic force microscopy. The fractal geometry of oxidized surfaces was characterized by providing the fractal dimension D. Using the methods of numerical analysis of the surface, the texture anisotropy ratio S _tr was also determined. The corner frequency τ and grain size d _g were also determined. The obtained results of performed fractal analysis showed that the studied surface on the tube wall outside was more developed as compared with the inside. In addition it was shown that directly on the flue gas inflow side (the fire side) the oxides/deposits layer was built of densely arranged spherical deposits, which formed an unfavourable barrier between the component (tube) and the atmosphere surrounding it.

The paper describes application of catastrophe theory for analysis of trends of real estate prices inPoznan. It turns out that the evolution of the real estate market is comprised of two main processes: long-term evolution in the area of a non-degenerate stability and discontinuous, rapid changes in the area of a degenerate stability. In the macro scale, the construction and developing branch contributes largely to the Gross Domestic Product affecting overall economic environment. In the micro scale, however, the knowledge about future price trends may help to decide whether or not to buy or sell the house property.

The thin film coatings composed of: undoped ZnO film, ZnO doped with Al, ZnO doped with Cu, and ZnO simultaneously doped with Al and Cu (co-doping) were separately deposited on quartz substrates using RF sputtering method with different targets. The advanced fractal features, crystalline structure and optical properties of sputtered samples were investigated by atomic force microscopy (AFM), X‐ray diffraction (XRD) and UV–vis spectroscopy. Microstructural studies revealed homogeneously granular structure of ZnO layer and axially oriented granular structure of AZO thin film.The transmission spectra of undoped, mono-doped and co-doped ZnO thin films were measured revealing relatively large transmittance of more than 80 % for un-doped and co-doped samples and less than that value for mono-doped thin films in both visible and infrared regions. CAZO thin film was found the most transparent thin film in the visible area being a prerequisite for good TCO. Analysis of absorption coefficients demonstrated that excitonic effects are invisible in mono-doped and co-doped samples. Also, PL spectra show that in these samples there are very high densities of free carriers and presence of impurities, which is important for conductivity of thin films as well as their optical applications. The optical band gap of ZnO thin films decreases by Cu doping from 3.12 eV to 3.09 eV and increases by Al doping to 4.30 eV, but remains exactly between those values in terms of co-doped sample (3.75 eV).