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Gdańsk University of Technology

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Publications from the year 2025

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  • Effect of rPET Content and Preform Heating/Cooling Conditions in the Stretch Blow Molding Process on Microcavitation and Solid-State Post-Condensation of vPET-rPET Blend: Part II—Statistical Analysis and Interpretation of Tests
    • Waldemar Karaszewski
    • Paweł Wawrzyniak
    • Marta Safandowska
    • Rafał Idczak
    2025 Materials

    This research explores how varying proportions of virgin polyethylene terephthalate (vPET) and recycled polyethylene terephthalate (rPET) in vPET-rPET blends, combined with preform thermal conditions during the stretch blow molding (SBM) process, influence PET bottles’ microscopic characteristics. Key metrics such as viscosity, density, crystallinity, amorphous phase relaxation, and microcavitation were assessed using response surface methodology (RSM). Statistical analysis, including Analysis of variance (ANOVA) and its power, supported the interpretation of results. The first part of the work details the experimental design and statistical methods. Positron annihilation lifetime spectroscopy (PALS) and amorphous phase density analysis revealed reduced free volume size, a substantial increase in free volume quantity, and a transformation toward ellipsoidal geometries, highlighting significant structural changes in the material. At the same time, the intrinsic viscosity (IV) and PALS studies indicate that the solid-state post-condensation effect (SSPC) is linked with microcavitation through post-condensation product diffusion. The conclusions, which resulted from the microstructure analysis, affected the material’s mechanical strength and were validated by pressure resistance tests of the bottles.

  • Effects of aggregate crushing and strain rate on fracture in compressive concrete with a DEM-based breakage model
    • Michał Nitka
    • Andrzej Tejchman-Konarzewski
    2025 Full text GRANULAR MATTER

    W tym artykule zbadano, w jaki sposób kruche kruszywa wpływają na mezoskopowe zachowanie dynamiczne betonu w warunkach jednoosiowego ściskania. Przeprowadzono obszerne dynamiczne obliczenia dwuwymiarowe (2D), aby zbadać wpływ kruszenia kruszywa i szybkości odkształcania na dynamiczną wytrzymałość betonu i wzory pęknięć. Wykorzystując model pękania oparty na DEM, beton symulowano jako materiał czterofazowy składający się z kruszywa, zaprawy, ITZ i makroporów. Mezostrukturę betonu uzyskano z laboratoryjnych testów mikro-CT. Zbiory kulistych cząstek wykorzystano do imitacji pękania kruszywa o różnych rozmiarach i kształtach, umożliwiając między nimi pękanie wewnątrzziarniste. Zaprawę opisano w kategoriach niełamliwych kul o różnych średnicach. W porównaniu z zaprawą wytrzymałość kruszywa była zawsze większa. Uzyskano jakościową spójność wyników DEM z dostępnymi danymi eksperymentalnymi. Dynamiczna wytrzymałość betonu na ściskanie wzrosła znacząco wraz ze szybkością odkształcania i nieznacznie wraz z wytrzymałością kruszywa. Proces pękania był znacząco zależny od kruszenia kruszywa i szybkości odkształcenia. Liczba zerwanych styków rosła wraz ze wzrostem szybkości odkształcenia i spadkiem wytrzymałości kruszywa.

  • Efficacy of modal curvature damage detection in various pre-damage data assumptions and modal identification techniques
    • Milena Drozdowska
    • Marek Szafrański
    • Anna Szafrańska
    • Agnieszka Tomaszewska
    2025 Full text Bulletin of the Polish Academy of Sciences-Technical Sciences

    The efficacy of modal curvature approach for damage localization is discussed in the paper in the context of input data. Three modal identification methods, i.e., Eigensystem Realization Algorithm (ERA), Natural Excitation Technique with ERA (NExT-ERA) and Covariance Driven Stochastic Subspace Identification (SSI-Cov), and four methods of determining baseline data, i.e., real measurement of the undamaged state, analytical function, Finite Element (FE) model and approximation of current experimental mode shape, are considered. Practical conclusions are formulated based on analysis of two cases. The first is a laboratory beam with a notch and the second is a stone masonry historic lighthouse with modern restoration in its upper part. The analysis shows that NExT-ERA and SSI-Cov in combination with approximation of current mode shape provide high efficacy in damage localization alongside relatively straightforward determination of baseline data. It proves that the construction of advanced FE models of a structure can be replaced with a much simpler method of baseline data acquisition. Furthermore, the research shows the structural mode shapes identified with ERA may not always indicate the presence of damage.

  • Ekspertyz techniczne zabytkowych obiektów budowlanych . Wybrane zagadnienia
    • Maciej Niedostatkiewicz
    2025

    Współczesna tendencja do skracania czasu realizacji prac remontowo- naprawczych obiektów budowlanych będących zabytkami nieruchomymi, przy jednoczesnym ograniczaniu zakresu oraz stopnia szczegółowości dokumentacji projektowej, jak również często realizowane zmiany sposo- bu użytkowania obiektów zabytkowych wymagają zwrócenia szczególnej uwagi na zagadnienie właściwej oceny stanu technicznego tego typu obiek- tów prowadzonej na etapie przygotowywania opracowań o charakterze eksperckim, określanych powszechnie jako ekspertyzy techniczne. W książce omówiono najważniejsze elementy i zagadnienia na które należy zwrócić uwagę podczas realizacji opracowań eksperckich dotyczących zabytków nieruchomych

  • Electrifying the bus network with trolleybus: Analyzing the in motion charging technology
    • Mikołaj Bartłomiejczyk
    • Priscilla Caliandro
    2025 APPLIED ENERGY

    Currently, electric buses are becoming more and more popular, and their number in operation is increasing. The range of electric buses is also increasing and solutions that seem to be working almost without fixed infrastructure are being promised. However, this requires the use of high-capacity batteries, which increases the weight and price of the vehicle and causes high costs of battery replacement during operation. Moreover, if we take into account the growing demand for batteries, limited raw material resources, and the environmental impact of the battery production process, the optimization of battery capacity in vehicles may turn out to be a key issue. In this light, trolleybus becomes a sustainable and economically efficient bus electrification technology, if considered in an international scope and a medium- to long-term approach. The article provides a comprehensive study of challenges and potential solutions related to electric buses, which covers the theoretical analysis, technical aspects and practical applications, thus making a valuable resource for readers interested in sustainable urban transport systems. It presents the trolleybus technology, especially with modern solutions, as a sustainable and economically efficient tool for bus electrification. The article shows that the In Motion Charging (IMC) system reduces the need for high-capacity batteries under 100 kWh, which allows to extend their service life up to 15 years and, consequently, to reduce the number of buses needed for operation. The research was based on real measurement data from the transport system in Gdynia (Poland).

  • Energy landscape and structural transformations of C38 penta-fullerene: The stabilizing role of octagons and insights into penta-octa-penta-fullerene
    • Kinga Warda
    • Szymon Winczewski
    • Julien Guthmuller
    2025 Materials Today Communications

    Theoretical investigations were conducted to study the stability and energy landscape of C38 penta-fullerene, a structure comprising six penta-graphene unit cells. Vibrational analysis at the B3LYP/def2SVP level revealed 18 negative frequencies, indicating the dynamic instability of penta-fullerene. Analyzing the energy profiles for these vibrational modes led to the identification of six energetically favourable isomers, featuring octagons and pentagons. Additionally, ab initio molecular dynamics (AIMD) at 300 K revealed a structure (named popfullerene) resembling the 0-dimensional equivalent of penta-octa-penta-graphene. Subsequent analyses confirmed the dynamic stability of pop-fullerene and op-fullerene, another identified isomer. According to binding energy (Eb) calculations, both isomers exhibit greater stability than penta-fullerene. Moreover, popfullerene, having Eb = -8.52 eV, demonstrates higher thermodynamic stability than C20 but lower stability than C60. AIMD simulations confirmed the thermal stability of pop-fullerene, even at 2000 K. B3LYP/def2QZVP calculations revealed bond lengths in pop-fullerene ranging from 1.37 to 1.51 Å, with one unique triple bond of 1.23 Å. The valence angles span from 60◦ to 146◦, which, as showed by population analysis, is associated with symmetric charge polarization and unique reactivity. By demonstrating the stability of fullerenes composed of pentagons and 3–7–8-carbon rings, this study revises traditional stability criteria, such as the isolated pentagon rule, and opens new avenues in fullerene research.

  • Enhanced electrochemical capacitance of TiO2 nanotubes/MoSe2 composite obtained by hydrothermal route
    • Mariusz Szkoda
    • Anna Ilnicka
    2025 APPLIED SURFACE SCIENCE

    This study presents the hydrothermal synthesis of a novel TiO2 nanotubes/MoSe2 nanocomposite and investigates its enhanced electrochemical capacitance properties. The composite material was fabricated through a hydrothermal method, embedding MoSe2 onto TiO2 nanotubes. The resulting composite, termed Ti/TiO2/MoSe2, exhibited significantly improved electrochemical capacitance compared to TiO2 nanotubes alone. The synthesized composite was comprehensively characterized using solid-state physics techniques, including scanning electron microscopy (SEM), transmission electron microscopy (TEM), Raman spectroscopy, X-ray diffraction (XRD), and X-ray photoelectron spectroscopy (XPS). These analyses provided detailed insights into the structural and chemical composition of the TiO2/MoSe2 nanocomposite. The investigation revealed that the TiO2/MoSe2 nanocomposite displayed superior electrochemical performance, as determined by various electrochemical methods. Notably, the composite exhibited a capacitance approximately 10 times higher than that of pristine TiO2 nanotubes. These findings underscore the significant enhancement in energy storage capabilities achieved through the hydrothermal synthesis of TiO2/MoSe2. The observed enhancement in capacitance positions the TiO2/MoSe2 nanocomposite as a promising candidate for high-performance energy storage applications.

  • Enhanced electrochemical performance of sulfur-doped laser-induced graphene supercapacitors: Synergistic effects of doping and plasmochemical surface modification
    • Samaneh Shahsavarifar
    • Paweł Jakóbczyk
    • Anna Wcisło
    • Jacek Ryl
    • Robert Bogdanowicz
    2025 APPLIED SURFACE SCIENCE

    This work introduces a novel, scalable methodology for rapidly fabricating sulfur-doped laser-induced graphene with enhanced porosity and wetting characteristics, targeting advanced supercapacitor applications. An infrared laser scribing technique was employed to create a three-dimensional porous graphene network, with in-situ sulfur doping achieved through physical evaporation using powder precursor. A second-pass laser process ensured uniform sulfur integration and optimized graphene structure. Sulfur incorporation facilitated the formation of a hierarchical porous network, significantly improving hydrophilicity and surface chemistry. This modification enhanced ion transport and charge storage mechanisms through synergistic double-layer and pseudo-capacitance effects. Physicochemical characterization revealed a dramatically increased ID/IG ratio post-sulfur doping and plasma treatment, indicating increased crystal plane defects and promising capacitive properties. Systematic optimization of sulfur loading, synthesis temperature, and electrolyte composition yielded remarkable electrochemical performance. The optimized S-doped electrodes achieved a high areal capacitance of 30.18 mF/cm² at 0.08 mA/cm² using a PVA/H₂SO₄ gel electrolyte. Notably, the developed supercapacitors demonstrated mechanical flexibility, maintaining 84.7% of their initial capacitance after 5000 cycles, highlighting the potential for scalable, flexible energy storage technologies.

  • Enhanced sorption of inhibitory compounds from fermentation broth using a MOF@pseudo-DES composite
    • Zhila Honarmandrad
    • Seyed Soroush Mousavi Khadem
    • Karolina Kucharska
    • Massoud Kaykhaii
    • Justyna Łuczak
    • Jacek Gębicki
    2025 Full text JOURNAL OF MOLECULAR LIQUIDS

    The increase in biorefinery processes underscores the need for effective biofuel generation; nevertheless, inhibitors such as hydroquinone (HQ), 5-hydroxymethylfurfural (HMF), furfural (FF), and vanillin (VAN) resulting from biomass degradation impede microbial growth and process efficiency. Herein, a deep eutectic solvent (DES)-like substance was in-situ generated on the surface of NH2-UiO-66 via a post-synthetic coating process using an amine-functionalized UiO-66 MOF and choline chloride (ChCl). ChCl, selected for its low cost and non-toxic properties as a hydrogen bond acceptor, enabled the formation of the thin layer of pseudo-DES on NH2-UiO-66 under solvent-free, thermal conditions, resulting in the composite material NH2-UiO-66@ pseudo-DES. The Zr6O4(OH)4 nodes and NH2 groups in NH2-UiO-66 are capable of forming robust hydrogen bonds with ChCl, enhancing the stability and functionality of the pseudo-DES coating. Various parameters influencing the removal efficiency, including pH, adsorbent amount, initial inhibitor concentration, and vortex time, were systematically investigated and optimized. Under the optimal conditions, the removal efficiency of HQ, HMF, FF, and VAN was 62.08%, 56.09%, 45.29%, and 83.46% respectively, for a synthetic sample. These values for real samples after hydrolysis and prior to fermentation were exceeded 51.73%, 53.21%, 42.69%, and 37.59%, for HQ, HMF, FF, and VAN, respectively. Inhibitor removal is driven by hydrogen bonding, electrostatic interactions, van der Waals forces, and π-π stacking with the inhibitors. This method demonstrates effective reusability for inhibitor removal up to four cycles. This groundbreaking research is the first of its kind to employ a MOF in conjunction with a pseudo-DES for this purpose; the results are simple, very effective, environmentally friendly, quick to react, and highly selective, making it ideal for biomass hydrolysis purification.

  • Enhancing Internal Cooling Channel Design in Inconel 718 Turbine Blades via Laser Powder Bed Fusion: A Comprehensive Review of Surface Topography Enhancements
    • Cho-pei Jiang
    • Masrurotin Masrurotin
    • Alvian Toto Wibisono
    • Wojciech Macek
    • Maziar Ramezani
    2025 International Journal of Precision Engineering and Manufacturing

    Inconel 718, a widely utilized Ni-based superalloy in the aerospace industry, is renowned for its exceptional mechanical properties, high-temperature corrosion resistance, and thermal stability, making it an ideal material for turbine blades operating under extreme conditions of up to 2200 °C and high-pressure. Traditional single crystal casting, the prevalent manufacturing method for turbine blades, poses inflexibility challenges. Laser Powder Bed Fusion Additive Manufacturing (LPBF-AM) emerges as a disruptive alternative, providing flexibility and intricate design possibilities. However, LPBF-fabricated turbine blades face challenges, notably low thermal stability due to the polycrystalline microstructure. To address this, implementing an internal cooling channel to the turbine blade geometry can overcome this challenge. The flow of cooling fluid inside the cooling channel absorbs the heat of turbine, and maintains the turbine at low-temperature. The performance of internal cooling channel can be improved by implementing controllable surface texture to provide the heat sink mechanism. Nowadays, the LPBF has opportunity to fabricate the complex geometry of turbine blade with surface-textured internal cooling channel. This review delves into the specific requirements for the next generation of turbine blades featuring surface-textured internal cooling channels. It covers considerations such as geometric design, LPBF parameters, metallurgical aspects of processing Inconel 718, and quality testing encompassing material properties and geometric accuracy. Additionally, the review outlines existing challenges and research prospects in LPBF of Inconel 718 for advancing turbine blade components. In conclusion, the review inspires further development in high-performance Inconel 718 turbine blades, emphasizing advancements in surface textures and internal cooling channels via LPBF.

  • Evaluation of overstrength-based interaction checks for columns in steel moment frames
    • Tomasz Falborski
    • Greta Murtas
    • Ahmed Elkady
    • Dimitrios Lignos
    • Amit Kanvinde
    2025 JOURNAL OF CONSTRUCTIONAL STEEL RESEARCH

    Current design guidelines in the United States require a check for only column axial force under overstrength seismic loads for capacity-designed steel moment frames. A study is presented to examine the implications of this guidance, which disregards the column interaction check (including both axial force and moment) under overstrength seismic loads. A set of thirteen steel moment frames are designed using multiple rules that apply and disregard overstrength, drift, and cross-sectional compactness checks in various combinations. The frames are subjected to a suite of simulations including linear elastic, nonlinear static pushover, nonlinear response history, and continuum finite element simulations that are able to represent a range of physical behavior modes in the columns including interactive nonlinear geometric instabilities that could trigger loss of the load carrying capacity of the member. The simulations indicate no significant distinction between the seismic performance of steel moment resisting frames designed as per current code-based provisions (i.e., disregarding the column interaction check for overstrength seismic loads), and those designed with the use of the interaction check, with each providing acceptable response without failure. The simulations also indicate that design checks for drift and cross-sectional compactness play a significant role ensuring acceptable response, providing additional margin of safety beyond the member strength checks.

  • Evaluation of Selected Modulation Techniques in Underwater Multipath Channel
    • Agnieszka Czapiewska
    • Andrzej Łuksza
    • Ryszard Studański
    • Łukasz Wojewódka
    • Andrzej Żak
    2025 IEEE Access

    There is a growing interest in the use of Autonomous Underwater Vehicles (AUVs) and Underwater Sensor Networks (USNs) for scientific, military, and industrial applications, leading to the development of wireless underwater communications. However, the channel for Underwater Acoustic (UWA) communications is challenging compared to the radio wave propagation in the air. Especially in shallow waters, where the channel has strong multipath effects. The difficulties are even greater when the communicating objects are in motion. Nevertheless, it is worth to analyze if solutions known from radio communication systems are applicable for underwater hydroacoustic purposes. In this paper, a comparison is made between two well-known modulation techniques used in radio communication: the widely used BPSK (Binary Phase Shift Keying) modulation and CSS (Chirp Spread Spectrum) technique used in LoRa (Long Range communication) system. The modulation techniques mentioned are compared with MBFSK (Multiple Binary Frequency Shift Keying) modulation used in underwater wireless communication systems, which is said to be very resistant to the multipath effect. In MBFSK, the value of the bit determines the value of the frequency on which the power is transmitted. The paper presents simulation results as well as results of measurements in the towing tank of the CTO (Maritime Advanced Research Centre). The comparison of simulation and real measurements leads to worrying conclusions, as they differ considerably.

  • Evaluation of the Variability of Vibration Measurement Results in Rolling Bearing Quality Control
    • Paweł Zmarzły
    • Mateusz Wrzochal
    • Stanisław Adamczak
    2025 Applied Sciences-Basel

    The final result of rolling bearing quality control is influenced by many factors that are not always taken into account. If non-conforming products leave the factory, then the reliability of equipment containing rolling bearings is significantly weakened. The paper presents an analysis of the reasons for the variability of vibration measurement results in rolling bearing quality control. The paper describes the organisation of rolling bearing acceptance inspection on the production line and its place in the rolling bearing production process. The study evaluates the influence of the measuring device and the location of the sensor on the result of the rolling bearing vibration monitoring process. The problem of repeatability and reproducibility of rolling bearing vibration measurement was also investigated. On the basis of the obtained results, conclusions were drawn regarding the improvement of the quality control process of rolling bearings in production plants.

  • Exergy analysis and thermodynamic optimization of a bioenergy with carbon capture and storage gas power plant using Monte Carlo simulation of sewage sludge composition
    • Kamil Stasiak
    • Ivar Ståle Ertesvåg
    • Paweł Ziółkowski
    • Dariusz Mikielewicz
    2025 APPLIED THERMAL ENGINEERING

    An exergy analysis is performed on the negative CO2 emission gas power plant (nCO2PP), which integrates the fuel preparation, power generation and carbon capture process sections. The cycle is modeled in Aspen Plus coupled with REFPROP, combining deterministic and Monte Carlo stochastic approaches, the latter being a novelty in this work. In all cases studied, the simulations maintain the complex thermodynamic relationships. Exergy losses with areas of potential improvement are identified, while Monte Carlo simulation in Python generates sewage sludge composition, improving cycle realism. In the deterministic approach, the exergies are calculated for a single sewage sludge composition under ambient air conditions with relative humidity of 40 %, 50 % (base case) and 60 % and CO2 air concentration of 375 ppm, 417 ppm (base case) and 1000 ppm, representing a worst case scenario of CO2 increase until the year 2100. For the deterministic base case nCO2PP, the largest exergy losses are observed in the wet combustion chamber (127 kW, 62 % efficiency), gasification process (43 kW, 89 % efficiency), and water condensation in the gas scrubber (43 kW, 87 % efficiency), while the nCO2PP exergy efficiency, related to the chemical exergy of the sewage sludge, is 33.3 %. Sensitivity analysis on turbine vacuum and spray-ejector condenser suction pressure results in an increase of the nCO2PP efficiency by 0.3 % to 33.6 %. Monte Carlo results are incorporated into the Aspen Plus model after the base case optimization. These yield in a range of nCO2PP exergy efficiencies from 33.6 % to 39.7 % with a mean of 37.5 %.

  • Experimental and Theoretical Study on Electron Interactions with Acetic Acid Molecules
    • Natalia Tańska
    • Kuba Wójcik
    • Thiago Corrêa Freitas
    • Márcio H F Bettega
    • Czesław Szmytkowski
    • Paweł Możejko
    2025 JOURNAL OF PHYSICAL CHEMISTRY A

    The absolute total cross section for electron collisions with acetic acid has been measured using an electrostatic electron spectrometerand linear transmission method for collision energies ranging from 0.4 to 300eV. Elastic electron scattering from acetic acid within a low-energy range has also been studied theoretically using the Schwinger multichannel and R-matrix methods, in the static-exchange and static-exchange plus polarization levels of approximation for energies up to 15 eV. The absolute total and the integralelastic cross sections display a π* shape resonance at around 1.7 eV and abroad structure spanned between 4 and 10 eV, which can be associated with a superposition of overlapping σ* resonances. We compared the obtained results with data available in the literature regarding the interaction ofelectrons with acetic acid. The results of electron collisions with acetic acid,methyl formate, and formic acid are also compared and discussed.

  • Experimental evidence of the excited-state mixing in the blue emitter for organic light-emitting diodes
    • Vladyslav Ievtukhov
    • Michał Mońka
    • Olga Ciupak
    • Irena Bylińska
    • Piotr Bojarski
    • Karol Krzymiński
    • Illia E. Serdiuk
    2025 Journal of Materials Chemistry C

    High hopes have been placed on organic emitters, which are supposed to solve the problem of low stability of blue OLEDs. A peculiar phenomenon of thermally activated delayed fluorescence (TADF), which brought such emitters to the range of the top-studied materials for organic optoelectronics within the last decade, remains poorly understood. Here, we report the results of comprehensive photophysical studies of one of the most successful candidates for blue TADF OLEDs, the TMCz-BO emitter (9-(5,9-dioxa-13b-boranaphtho[3,2,1-de]anthracen-7-yl)-1,3,6,8-tetramethyl-9H-carbazole) characterised by outstanding triplet-harvesting properties. One of the main aims of this work is to understand the reason for these unique properties. Steady-state and time-resolved spectroscopic investigations in media of various polarity, viscosity, and temperature reveal that at least five excited states of different characters and multiplicity are responsible for the emissive and spin–flip transitions in the TMCz-BO molecular systems. First of all, in contrast to typical donor–acceptor TADF emitters, the S1 state of TMCz-BO does not have a pure charge-transfer character but shows a considerable contribution of the locally-excited state of the acceptor fragment, which provides a fast radiative rate. The T1 state is a superposition of two locally excited and one charge-transfer states, providing reasonable spin–orbit coupling. Regarding the TADF mechanism in various media, reverse intersystem crossing follows the T1 - S1 model, considering the excited-state mixing, a notion introduced here to explain the triple and dual nature of the respective states. Such a mixing is dynamic in low-viscosity solutions due to low barriers for molecular vibrations. In films with a host matrix, a static excited-state mixing occurs, assisted by the low-amplitude vibrations within the local energetic minimum of the emitting species. The high efficiency of the excited-state mixing in TMCz-BO is explained by the rigid structure of its donor and acceptor fragments and their limited but still active mutual rotations. This provides negligible structural differences between various electronic states, enabling low reorganisation energies favourable for radiative and spin–flip processes while maintaining vibrational activation of spin–orbit coupling. Despite a lower reverse intersystem crossing rate in media of high viscosity, TMCz-BO shows rare near-UV TADF in films with the non-polar host.

  • Expert system against machine learning approaches as a virtual sensor for ventricular arrhythmia risk level estimation
    • Sebastián García-Galán
    • Jose A. Cabrera-Rodriguez
    • Francisco Javier Maldonado-Carrascosa
    • Nicolás Ruiz-Reyes
    • Małgorzata Szczerska
    • Pedro Vera-Candeas
    • Francisco D. Gonzalez-Martinez
    • Francisco J. Canadas-Quesada
    • Alfonso J. Cruz-Lendinez
    2025 Biomedical Signal Processing and Control

    Recent advancements in machine learning have opened new avenues for preventing fatal ventricular arrhythmia by accurately measuring and analyzing QT intervals. This paper presents virtual sensor based on an expert system designed to prevent the risk of fatal ventricular arrhythmias associated with QT-prolonging treatments. The expert system categorizes patients into three risk levels based on their electrocardiogram-derived QT intervals and other clinical data, such as age or sex, facilitating informed decision-making and reducing the workload for healthcare professionals. Expert systems, known for their effectiveness in classifications with limited data, are particularly advantageous in this context. They not only achieve better standard metrics but also offer interpretability that other machine learning models lack. The proposed system’s performance has been rigorously compared against various machine learning algorithms, demonstrating superior efficiency as evidenced by confusion matrices, standard classification metrics, and receiver operation point curves. With an accuracy of 96.5%, the expert system proves to be the best option among the models evaluated, optimizing patient care and treatment outcomes by enabling more frequent and precise electrocardiogram assessments.

  • Exploration of Behavioral Patterns and Cognitive Biases among Stock Market Investors
    • Maciej Tkacz
    • Celina Olszak
    • Jozef Zurada
    • Paweł Weichbroth
    2025 Full text

    This study aims to explore behavioral patterns and cognitive biases among stock market investors. By analyzing investor behavior through a stock market simulator, the research seeks to understand the impact of cognitive biases on investment decisions. The methodology encompasses a detailed analysis of transaction data to identify prevalent patterns and biases. Findings suggest that biases such as overconfidence, representativeness heuristic, gambler’s fallacy, and herd mentality significantly influence investor behavior.

  • Fatigue Damage Evolution in SS316L Produced by Powder Bed Fusion in Different Orientations with Reused Powder Feedstock
    • Mateusz Kopec
    • U. Gunputh
    • G. Williams
    • Wojciech Macek
    • Zbigniew Kowalewski
    • Paul Wood
    2025 Full text EXPERIMENTAL MECHANICS

    Background Metal Laser Powder Bed Fusion Melting (LPBF-M) is considered economically viable and environmentally sustainable because of the possibility of reusing the residual powder feedstock leftover in the build chamber after a part build is completed. There is however limited information on the fatigue damage development of LPBF-M samples made from reused feedstock. Objective In this paper, the stainless steel 316 L (SS316L) powder feedstock was examined and characterised after 25 reuses, following which the fatigue damage development of material samples made from the reused powder was assessed. Methods The suitability of the powder to LPBF-M technology was evaluated by microstructural observations and measurements of Hall flow, apparent and tapped density as well as Carr’s Index and Hausner ratio. LPBF-M bar samples in three build orientations (Z – vertical, XY – horizontal, ZX – 45° from the build plate) were built for fatigue testing. They were then subjected to fatigue testing under load control using full tension and compression cyclic loading and stress asymmetry coefficient equal to -1 in the range of stress amplitude from ± 300 MPa to ± 500 MPa. Results Samples made from reused powder (25 times) in the LPBF-M process exhibited similar fatigue performance to fresh unused powder although a lower ductility for vertical samples was observed during tensile testing. Printing in horizontal (XY) and diagonal (ZX) directions, with reused powder, improved the service life of the SS316L alloy in comparison to the vertical (Z). Conclusions Over the 25 reuses of the powder feedstock there was no measurable difference in the flowability between the fresh (Hall Flow: 21.4 s/50 g) and reused powder (Hall Flow: 20.6 s/50 g). This confirms a uniform and stable powder feeding process during LPBF-M for both fresh and reused powder. The analysis of fatigue damage parameter, D, concluded cyclic plasticity and ratcheting to be the main mechanism of damage.

  • FeS-based nanocomposites: A promising approach for sustainable environmental remediation – Focus on adsorption and photocatalysis – A review
    • Aqsa Nawaz
    • Aman Khalid
    • Wajeeha Qayyum
    • Rabia Bibi
    • Muhammad Azam Qamar
    • Muhammad Zahid
    • Ahmad Farhan
    • Manoj P Rayaroth
    • Łukasz Cichocki
    • Grzegorz Boczkaj
    2025 JOURNAL OF ENVIRONMENTAL MANAGEMENT

    Population expansion, industrialization, urban development, and climate changes increased the water crisis in terms of drinking water availability. Among the various nanomaterials for nanoremediation towards water treatment, FeS-based nanocomposites have emerged as promising candidates in the adsorptive and photocatalytic removal of contaminants. This paper, therefore, evaluates the potential of FeS-based nanocomposites for environmental applications, more specifically the combined use of adsorption and photocatalysis. Pyrite and mackinawite structures outcompeted the other FeS configurations due to their large surface areas, numerous active sites, and enhanced conductivity, factors that enhance the adsorption and photovoltaic processes. To improve photocatalytic performance FeS requires modification with additional materials. Various fabrication strategies (including hydrothermal method, co-precipitation, electrochemical anodization, electrospinning, impregnation, green synthesis, mechanochemical approach/ball milling) of FeS-based composites and their efficacy and the mechanisms for removing organic and inorganic pollutants are reviewed in this paper. The structural characteristics of FeS scaffolds play a crucial role in the effective removal of heavy metals, such as Hg and Cr ions, primarily through ion exchange and surface complexation. Organic pollutants such as methylene blue and tetracycline were effectively degraded by advanced oxidation processes (AOPs). A large scale applications of FeS include industrial wastewater treatment, groundwater remediation towards trichloroethylene and other organic solvents removal, municipal wastewater, oil spills cleanup, pre-treatment for seawater desalination. Current challenges relate to catalysts stability, their removal after treatment stage, recycling, metals leaching and up-scaling as well as high effectiveness in real case-scenario and costs optimization. In summary, this review will help to advance research in the field of environmental remediation using FeS-based nanocomposites.