2023 - Publications Repository - Gdańsk University of Technology

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Publications from the year 2023

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Improved-Efficacy EM-Driven Optimization of Antenna Structures Using Adaptive Design Specifications and Variable-Resolution Models
- Sławomir Kozieł
- Anna Pietrenko-Dąbrowska
2023 IEEE TRANSACTIONS ON ANTENNAS AND PROPAGATION
Optimization-driven parameter tuning is an essential step in the design of antenna systems. Although in many cases it is still conducted through parametric studies, rigorous numerical methods become a necessity if truly optimum designs are sought for, and the problem intricacies (number of variables, multiple goals, constraints) make the interactive approaches insufficient. The two practical considerations of electromagnetic (EM)-driven optimization are reliability and computational cost. Repetitive EM simulations may incur unmanageable expenses, whereas the lack of a decent starting point or objective function multimodality may prevent the numerical procedures (especially the local ones) from identifying satisfactory designs. In pursuit of reliability improvements, a design specification adjustment procedure has been recently proposed that improves the immunity of local search procedures to poor starting points. Therein, the objective function is modified by relocating the design goals (e.g., center frequencies) closer to the actual operating parameters of the antenna at the current design, to make them attainable through local search. The goals are then gradually adjusted and converge to the original targets towards then end of the optimization process. In this paper, we introduce an algorithm for reliable and low-cost antenna tuning that capitalizes on the specification management scheme while embedding it in variable-resolution optimization framework. In our approach, the EM model fidelity is adaptively adjusted based on the misalignment between the actual and target operating conditions, as well as the convergence status of the algorithm. By initiating the search process from the lowest-fidelity model (gradually dialed up to the highest-fidelity one), considerable computational savings of almost sixty percent can be achieved, with respect to the single-fidelity procedure. The speedup is possible without compromising reliability of the optimization process, as demonstrated using three examples of microstrip antennas, designed under different and challenging scenarios.
Improvement of speech intelligibility in the presence of noise interference using the Lombard effect and an automatic noise interference profiling based on deep learning
- Krzysztof Kąkol
2023 Full text
The Lombard effect is a phenomenon that results in speech intelligibility improvement when applied to noise. There are many distinctive features of Lombard speech that were recalled in this dissertation. This work proposes the creation of a system capable of improving speech quality and intelligibility in real-time measured by objective metrics and subjective tests. This system consists of three main components: speech type detection, noise profiling, and an adaptive strategy of selection the modification. The role of the first component is to detect the Lombard speech in the input signal to avoid unnecessary speech modifications when the speech is naturally Lombard in its character. The second module is noise profiling, as the type of noise strongly impacts the selection of the best modification. The last part of the system is the adaptive modification selection component. The selection is made based on the speech signal features, resulting in the most considerable speech quality improvement, measured with objective metrics. To solve the problem posed, machine learning was used in this dissertation – especially deep learning with convolutional neural networks and typical multilayer networks. It was proven that it is possible to create an adaptive system that would improve speech quality in the presence of noise in real-time or near real-time.
Improving carbon dioxide capture in aqueous ammonia solutions by fine SiO2 particles
- Donata Konopacka-Łyskawa
- Temesgen Amibo
- Dominik Dobrzyniewski
- Marcin Łapiński
2023 Full text Chemical and Process Engineering : New Frontiers
Ammonia solutions are considered to be effective solvents for carbon dioxide absorption. Despite the numerous advantages of these solvents, their high volatility is a significant technical and economic problem. Therefore, in this work, silica particles were used as additives to improve CO2 absorption and inhibit NH3 desorption. SiO2 microparticles and colloidal SiO2 particles in the concentration range of 0-0.15 wt.% were used in this study. The most favorable mass transport for CO2 absorption was at the concentration of colloidal particles of 0.05 wt.%. Under these conditions, the enhancement in the number of moles of absorbed CO2 was above 30%. However, in solvents containing 0.01 wt.% SiO2 microparticles, the increase in CO2 absorption was about 20%. At the same time, the addition of SiO2 particles significantly reduced the escape of ammonia from the solution. The best improvement was obtained when colloidal SiO2 particles were added, and then NH3 escape was decreased by about 60%. This unfavorable phenomenon was also inhibited in ammonia solutions containing SiO2 microparticles at a concentration of 0.01 wt.%.
In situ transformation boosts the pseudocapacitance of CuNi-MOF via cooperative orientational and electronic governing
- Xianyu Chu
- Fanling Meng
- Wei Zhang
- Lihua Zhang
- Sebastian Molin
- Piotr Jasiński
- Weitao Zheng
2023 Full text Materials Research Letters
The disordered arrangement and thereof inferior conductivity of 2D MOF sheets seriously hinder their practical application. Herein, we propose in situ transformation strategy to architect vertically oriented bimetallic CuNi-MOF as a self-supporting electrode, leading to a decuple high specific capacitance of 1262 C g-1 in comparison with the pristine Ni-MOF powder of 114 C g-1 at 2 A g-1. DFT calculations reveal that introduction of Cu can modulate the electronic structure of metal centers in the Ni-MOF sheets and optimize electrical conductivity. Our strategy is promising to maximize the utilization of MOF superiorities for optimizing their electrochemical performance.
In vitro and in silico assessment of anti-inflammatory activity of cocoa powders
- Jelena S. Katanić Stanković
- Vanja Todorović
- Jelena Dorović Jovanović
- Zoran Marković
- Sanja Krstić
- Nevena Dabetić
- Sladana Sobajić
- Agnieszka Bartoszek-Pączkowska
- Zoran Maksimovic
- Rudolf Bauer
2023
Plants are considered the major sources of biologically active compounds, which provide unlimited opportunities for their use either as medical treatments or as novel drug formulations. Cocoa powder is frequently used in nutrition and is known to have many benefits thanks to its wide range of biological activities. The presented study was focused on th evaluation of the anti-inflammatory potential of extracts obtained from cocoa powder. In vitro assays were employed to evaluate the level of inhibition of cyclooxygenases-1 and -2 activities (COX-1 and COX-2) by tested extracts. Molecular docking was used for in silico prediction of cyclooxygenase isoforms inhibition by selected cocoa powder constituents. The results showed that all tested extracts exerted much higher potential in inhibiting COX-2 activity and may be considered in use as selective inhibitors of COX-2 enzyme. On the other hand, in silico study shows quercetin and clovamide as the compounds with the highest potential to inhibit both COX-1 and COX-2.
In Vitro and In Vivo Imaging-Based Evaluation of Doxorubicin Anticancer Treatment in Combination with the Herbal Medicine Black Cohosh
- Agata Płoska
- Marcin Woźniak
- Jamila Hedhli
- Christian J. Konopka
- Antonios Skondras
- Sarah Matatov
- Andrew Stawarz
- Sarah Schuh
- Andrzej Czerwinski
- Lawrence W. Dobrucki
- Leszek Kalinowski
- Iwona T. Dobrucki
2023 Full text INTERNATIONAL JOURNAL OF MOLECULAR SCIENCES
As a substitution for hormone replacement therapy, many breast cancer patients use black cohosh (BC) extracts in combination with doxorubicin (DOX)-based chemotherapy. In this study, we evaluated the viability and survival of BC- and DOX-treated MCF-7 cells. A preclinical model of MCF-7 xenografts was used to determine the influence of BC and DOX administration on tumor growth and metabolism. The number of apoptotic cells after incubation with both DOX and BC was significantly increased (~100%) compared to the control. Treatment with DOX altered the potential of MCF-7 cells to form colonies; however, coincubation with BC did not affect this process. In vivo, PET-CT imaging showed that combined treatment of DOX and BC induced a significant reduction in both metabolic activity (29%) and angiogenesis (32%). Both DOX and BC treatments inhibited tumor growth by 20% and 12%, respectively, and combined by 57%, vs. control. We successfully demonstrated that BC increases cytotoxic effects of DOX, resulting in a significant reduction in tumor size. Further studies regarding drug transport and tumor growth biomarkers are necessary to establish the underlying mechanism and potential clinical use of BC in breast cancer patients.
In vitro enzyme kinetics and NMR-based product elucidation for glutathione S-conjugation of the anticancer unsymmetrical bisacridine C-2028 in liver microsomes and cytosol: major role of glutathione S-transferase M1-1 isoenzyme
- Agnieszka Potęga
- Dominika Rafalska
- Dawid Kazimierczyk
- Michał Kosno
- Aleksandra Pawłowicz
- Witold Andrałojć
- Ewa Paluszkiewicz
- Tomasz Laskowski
2023 Full text MOLECULES
This work is the next step in studying the interplay between C-2028 (anticancer-active unsymmetrical bisacridine developed in our group) and the glutathione S-transferase/glutathione (GST/GSH) system. Here, we analyzed the concentration- and pH-dependent GSH conjugation of C-2028 in rat liver microsomes and cytosol. We also applied three recombinant human GST isoenzymes, which altered expression was found in various tumors. The formation of GSH S-conjugate of C-2028 in liver subfractions followed Michaelis-Menten kinetics. We found that C-2028 was conjugated with GSH preferentially by GSTM1-1, revealing a sigmoidal kinetic model. Using a colorimetric assay (MTT test), we initially assessed the cellular GST/GSH-dependent biotransformation of C-2028 in relation to cytotoxicity against Du-145 human prostate cancer cells in the presence or absence of the modulator of GSH biosynthesis. Pretreatment of cells with buthionine sulfoximine resulted in a cytotoxicity decrease, suggesting a possible GSH-mediated bioactivation process. Altogether, our results confirmed the importance of GSH conjugation in C-2028 metabolism, which humans must consider when planning a treatment strategy. Finally, nuclear magnetic resonance spectroscopy elucidated the structure of the GSH-derived product of C-2028. Hence, synthesizing the compound standard necessary for further advanced biological and bioanalytical investigations will be achievable.
Incorporating installation effects into the probability analysis of controlled modulus columns
- Jakub Konkol
2023 Full text SOILS AND FOUNDATIONS
This technical report presents the probabilistic analysis which integrates the Monte Carlo simulation (MCS) with random field theory to model the load–displacement behavior of Controlled Modulus Columns (CMCs) in overconsolidated Poznań clay. Presented study focuses on the practical aspects of statistical analysis of geotechnical data, numerical model development, and results evaluation. Variability and spatial distribution of geotechnical parameters are based directly on field and lab testing. The inherent variability of soil parameters obtained from geotechnical investigation at the site is similar to the values reported in worldwide datasets for clays. The extensive discussion about incorporation of installation effects into numerical modelling is made. It was found that proper incorporation of installation effects is governed by correct estimation of initial stress level and interface shear strength parameters. The Anisotropic Undrained Shear Strength (AUS) model which captures nonlinear behavior and anisotropy of soil (Krabbenhøft et al., 2019) is a good choice to model overconsolidated clay in intact and interface zones. The application of total stress approach, the AUS model, installation effects, and natural (inherent) variability of soil and interface parameters is sufficient to explain differences in CMC load – displacement behavior observed in the field.
Increasing the conductivity of V2O5-TeO2 glass by crystallization: structure and charge transfer studies
- Piotr Okoczuk
- Natalia Wójcik
- Leon Murawski
- Leszek Wicikowski
- Marcin Łapiński
- Piotr Winiarz
- Barbara Kościelska
2023 Full text JOURNAL OF MATERIALS SCIENCE
In the present paper, V 2 O 5 -TeO 2 glass was prepared by the melt-quenching technique. Crystallization of glass with a vanadium content higher than 35%mol results in an increase in electrical conductivity by a few orders of magnitude and a decrease in activation energy from ~0.40 to ~0.12 eV. In this work, a critical review of existing charge transfer models was presented on the example of V 2 O 5 -TeO 2 glass and glass–ceramics. Schnakenberg’s and Friedman-Triberis’ charge transfer models were found to be applicable to both glass and glass–ceramics. Optical phonon frequencies obtained from Schnakenberg’s model are in agreement with FTIR studies. Values of activation energies obtained from the Schnakenberg model decrease after crystallization. Friedman-Triberis’ model shows an increase in the density of states near the Fermi level from 10 ¹⁹ eV ⁻¹ cm ⁻³ in glass, to 10 ²¹ eV ⁻¹ cm ⁻³ in glass ceramics. Structural studies show that the main crystallizing phase is Te 2 V 2 O 9 which occurs with the V 2 O 5 shell in glasses with compositions 50–50%mol and 45–55%mol. It is concluded that crystallization results in the reduction of vanadium ions in the remaining glass matrix which leads to an increase in the V ⁴⁺ /V ⁵⁺ ratio and therefore, an increase in electrical conductivity.
Increasing the Utilization of dc-link Voltage of a Five-Leg VSI Based on Rotor Angle Control of Dual Induction Motors
- Dmytro Kondratenko
- Arkadiusz Lewicki
- Charles Odeh
2023 Full text
This paper introduces an increased utilization of the dc-link voltage of a five-leg voltage source inverter (VSI) based on the rotor flux angle control technique for dual induction motors, IM. The main purpose is to utilize additional abilities provided by a multi-motor drive system in limited operating conditions. Generally, a multi-motor drive system is widely used in electric vehicles (EVs), traction systems and in several industrial applications. A dual IM drive system is investigated in this paper, where field-oriented control (FOC) scheme and space vector pulse-width modulation (SVPWM) technique are used for the drives control. Therein, additional rotor angle control is implemented to increase the maximum modulation index. The proposed control technique allows the control of two independent three-phase IM. Under limited conditions, both motors can achieve high modulation index values and decreased losses as well. Simulation studies and results carried out in PLECS software package show the effectiveness and feasibility of the proposed control strategy. Experimental results presented proved the idea of the proposed solution.
Indole-Acrylonitrile Derivatives as Potential Antitumor and Antimicrobial Agents—Synthesis, In Vitro and In Silico Studies
- Anita Kornicka
- Karol Gzella
- Katarzyna Garbacz
- Małgorzata Jarosiewicz
- Maria Gdaniec
- Joanna Fedorowicz
- Lukasz Balewski
- Jakub Kokoszka
- Anna Ordyszewska
2023 Full text Pharmaceuticals
A series of 2-(1H-indol-2-yl)-3-acrylonitrile derivatives, 2a–x, 3, 4a–b, 5a–d, 6a–b, and 7, were synthesized as potential antitumor and antimicrobial agents. The structures of the prepared compounds were evaluated based on elemental analysis, IR, 1H- and 13NMR, as well as MS spectra. X-ray crystal analysis of the representative 2-(1H-indol-2-yl)-3-acrylonitrile 2l showed that the acrylonitrile double bond was Z-configured. All compounds were screened at the National Cancer Institute (USA) for their activities against a panel of approximately 60 human tumor cell lines and the relationship between structure and in vitro antitumor activity is discussed. Compounds of interest 2l and 5a–d showed significant growth inhibition potency against various tumor cell lines with the mean midpoint GI50 values of all tests in the range of 0.38-7.91 mM. The prominent compound with remarkable activity (GI50 = 0.0244-5.06 mM) and high potency (TGI = 0.0866-0.938 mM) against some cell lines of leukemia (HL-60(TB)), non-small cell lung cancer (NCI-H522), colon cancer (COLO 205), CNS cancer (SF-539, SNB-75), ovarian cancer ((OVCAR-3), renal cancer (A498, RXF 393), and breast cancer (MDA-MB-468) was 3-[4-(dimethylamino)phenyl]-2-(1-methyl-1H-indol-2-yl)acrylonitrile (5c). Moreover, the selected 2-(1H-indol-2-yl)-3-acrylonitriles 2a–c and 2e–x were evaluated for their antibacterial and antifungal activities against Gram-positive and Gram-negative pathogens as well as Candida albicans. Among them, 2-(1H-indol-2-yl)-3-(1H-pyrrol-2-yl)acrylonitrile (2x) showed the most potent antimicrobial activity and therefore it can be considered as a lead structure for further development of antimicrobial agents. Finally, molecular docking studies as well as drug-likeness and ADME profile prediction were carried out.
INDUSTRIAL HERITAGE IN “SACRIFICE ZONES”. THE POTENTIAL OF BOCAMINA I & II THERMOELECTRIC IN CORONEL, CHILE
- Karolina Krośnicka
- Miguel Angel Delso Páez
2023 Full text Przestrzeń Ekonomia Społeczeństwo
This work aims to present the recovery potential of the Chilean Sacrifice Zones, urban areas affected by high amounts of pollution caused by industrial activities. It centers in the case of “Bocamina I & II”, two Thermoelectric based in the city of Coronel, southern Chile. A settlement historically related to the mining processes. These plants operated for decades supplying the national energy grid and are seen as both symbols of progress and detriment. As part of the government Energy Transition Plan, they were recently closed for more sustainable energy sources and though the decision is seen as a national milestone, not much has been said regarding the buildings themselves. This research contextualizes the case of study, elaborates on how its future use and perception could help mitigate the negative impact on its surroundings and how the case can be extrapolated to similar cases internationally. For this, the work focuses on the plant’s infrastructure, their relation to the immediate context of Coronel and importance to Chilean industrial history on two approaches: Analyzing the alternative of their classification as National Monuments by the Chilean National Monuments Council, and by the Adaptive reuse approach, internationally seen as a sustainable strategy for abandoned buildings. Different arguments and examples are presented with the purpose of providing an understanding of the potential of Industrial Heritage reclamation, and how it could change the perception of the Sacrifice Zones through community involvement, urban planning, collaborative design and identity empowerment.
Industry-level analysis of COVID-19’s impact in emerging markets – evidence from Pakistan
- Muhammad Mushafiq
2023 International Journal of Emerging Markets
Purpose – The main purpose of this study is to evaluate COVID-19’s impact on the emerging stock markets. Design/methodology/approach – To evaluate the influence of COVID-19, this study uses a novel method of event study methodology to measure the impact of COVID-19 on emerging stock markets. The research’s sample includes a total of 79 firms from 26 industries that are included in the KSE-100 Index from the Pakistan Stock Exchange. Three events were studied: (1) Announcement of the first case, (2) Start of lockdown and (3) End of lockdown. Findings – This study establishes the findings that industries in the Pakistan Stock Exchange were overall negatively affected by the COVID-19. Commercial banks, Insurance, Real Estate and Textile were badly affected by the COVID-19. However, the Pharmaceutical, Refinery and Food and Personal Care Products industries had shown a positive response. Practical implications – This study could bring in a new and useful insight into the literature on the impact of COVID-19 on the emerging stock markets. The results of this study provide insight to the investors in the emerging stock markets of the industries that are likely to show responses either negative or positive to news of regional or global outbreaks, lockdowns and end of lockdowns. Originality/value – The work on COVID-19 has been mostly limited to the developed markets and the emerging markets have been overlooked. This study is a potential gateway to future works regarding pandemics in emerging markets.
Indywidualna wystawa "Tylko ból jest mój" (1.12.2023 - 18.04.2024)
- Edyta Urwanowicz
2023
Ekspozycja przygotowana przez kobiety – o kobietach. O tym, jak wyglądał ich Sybir i jak one go zapamiętały. Będzie pobudzać do refleksji nad pytaniami: Co znaczyło być kobietą na Sybirze? Jakie trudności spadały na kobiety, które znalazły się w sytuacji granicznej? Wreszcie – czy kobiecie doświadczonej przez przemoc pozostaje tylko ból?
Influence of Actual Curing Conditions on Mechanical Properties of Concrete in Bridge Superstructures
- Jakub Krząkała
- Piotr Łaziński
- Michael Gerges
- Łukasz Pyrzowski
- Grzegorz Grządziela
2023 Full text Materials
This article presents the research on the mechanical characteristics of concrete in the construction of three concrete bridges. A system of recording the internal temperature of concrete and automatic control of laboratory ovens was used for specimen curing. This allowed the specimens to be cured under conditions similar to those occurring in the structure. Before the construction, reference blocks were used to define similar curing conditions. Maximum setting temperatures ranged from 47.6 _C to 62.0 _C and had a favorable effect on the properties of the concrete at an early age. For concretes with the use of CEM I cement, after 3 days of curing, the strength obtained was up to 8.2 MPa (23%) higher than that for specimens cured under standard conditions. The modulus of elasticity was higher up to 4.9 GPa (21%). For concrete with the use of CEM III cement, these differences were 26.9 MPa (174%) and 10.3 GPa (64%), respectively. After 7 days of curing, the results were close to each other and after 14, 28, and 56 days, higher values were obtained for specimens cured under standard conditions. The value of the modulus of elasticity of concrete was determined using the direct method according to Eurocode and the standard A method. A test load of the bridge was carried out to verify the modulus values obtained from laboratory tests. The highest consistency (99%) between the theoretical deflections and those measured in the test load was achieved when using the stabilized modulus values obtained on specimens cured under structure conditions in the FEM model. The research confirms the necessity of determining the mechanical characteristics of concrete with taking into account the curing conditions of concrete in the structure. A procedure for determining the mechanical properties of concrete for the correct construction of a bridge is proposed. These results can also be used in the development of a digital twin for bridge management.
Influence of Added Water Mass on Ship Structure Vibration Parameters in Virtual and Real Conditions
- Do Van Doan
- Lech Murawski
- Adam Szeleziński
- Tomasz Muchowski
- Marcin Kluczyk
- Adam Muc
- Krzysztof Jasiński
- Marek Chodnicki
2023 Full text Scientific Journal of Gdynia Maritime University
Modelling of ship structures in a virtual environment is now standard practice. Unfortunately, many engineers forget to consideri the influence of added water on the frequency values and the amplitude of natural vibrations. The article presents the effect of water damping on the frequency values of the individual natural vibration modes. The tests were carried out in two stages. First, the mentioned values were determined using FEM and then the values obtained in this way were compared with the parameters measured during laboratory tests. For the needs of laboratory measurements, structural elements made of ship steel in one of the Polish shipyards were used. All welds of the test objects have been verified in terms of their correctness. Irregularities in the execution of welded joints could result in a measurement error that is difficult to identify. As a result of the tests, the percentage differences in the frequency of occurrence of natural vibrations of individual modes were determined according to added water mass considerations. Importantly, the research concerned a real structural element of the hull, and the results obtained confirm the need to take into account the mass of accompanying water during the hull's FEM analysis. A number of more detailed research results were obtained, the most important of which is the fact that the finite element method is a valuable method for assessing the dynamics of wetted structures: the error in determining the vibration frequency did not exceed 5% for basic modes. The method of modelling the tested structures was almost equally important: the discrepancy of the results reached 4% depending on the modelling method. When designing marine SHM systems, it is essential to consider the effect of added water mass, since the frequency variations of a damaged structure, in relation to an undamaged one, are of the same order as the effect of added water.
Influence of algorithmic management practices on workplace well-being – evidence from European organisations
- Hanna Kinowska
- Łukasz Sienkiewicz
2023 Full text Information Technology & People
Purpose Existing literature on algorithmic management practices –defined as autonomous data-driven decision making in people's management by adoption of self-learning algorithms and artificial intelligence – suggests complex relationships with employees' well-being in the workplace. While the use of algorithms can have positive impacts on people-related decisions, they may also adversely influence job autonomy, perceived justice and – as a result – workplace well-being. Literature review revealed a significant gap in empirical research on the nature and direction of these relationships. Therefore the purpose of this paper is to analyse how algorithmic management practices directly influence workplace well-being, as well as investigating its relationships with job autonomy and total rewards practices. Design/methodology/approach Conceptual model of relationships between algorithmic management practices, job autonomy, total rewards and workplace well-being has been formulated on the basis of literature review. Proposed model has been empirically verified through confirmatory analysis by means of structural equation modelling (SEM CFA) on a sample of 21,869 European organisations, using data collected by Eurofound and Cedefop in 2019, with the focus of investigating the direct and indirect influence of algorithmic management practices on workplace well-being. Findings This research confirmed a moderate, direct impact of application of algorithmic management practices on workplace well-being. More importantly the authors found out that this approach has an indirect influence, through negative impact on job autonomy and total rewards practices. The authors observed significant variation in the level of influence depending on the size of the organisation, with the decreasing impacts of algorithmic management on well-being and job autonomy for larger entities.
Influence of CeO2 and TiO2 Particles on Physicochemical Properties of Composite Nickel Coatings Electrodeposited at Ambient Temperature
- Iryna Makarava
- Mohammadamin Esmaeili
- Dmitry Kharitonov
- Leonardo Pelcastre
- Jacek Ryl
- Mohammad Reza Bilestan
- Esa Vuorinen
- Eveliina Repo
2023 Full text Materials
The Ni-TiO2 and Ni-CeO2 composite coatings with varying hydrophilic/hydrophobic characteristics were fabricated by the electrodeposition method from a tartrate electrolyte at ambient temperature. To meet the requirements of tight regulation by the European Chemicals Agency classifying H3BO3 as a substance of very high concern, Rochelle salt was utilized as a buffer solution instead. The novelty of this study was to implement a simple one-step galvanostatic electrodeposition from the low-temperature electrolyte based on a greener buffer compared to traditionally used, aiming to obtain new types of soft-matrix Ni, Ni-CeO2, and Ni-TiO2 coatings onto steel or copper substrates. The surface characteristics of electrodeposited nickel composites were evaluated by SEM, EDS, surface contact angle measurements, and XPS. Physiochemical properties of pure Ni, Ni-CeO2, and Ni-TiO2 composites, namely, wear resistance, microhardness, microroughness, and photocatalytic activity, were studied. Potentiodynamic polarization, EIS, and ICP-MS analyses were employed to study the long-term corrosion behavior of coatings in a 0.5 M NaCl solution. Superior photocatalytic degradation of methylene blue, 96.2% after 6 h of illumination, was achieved in the case of Ni-TiO2 composite, while no substantial change in the photocatalytic behavior of the Ni-CeO2 compared to pure Ni was observed. Both composites demonstrated higher hardness and wear resistance than pure Ni. This study investigates the feasibility of utilizing TiO2 as a photocatalytic hydrophilicity promoter in the fabrication of composite coatings for various applications.
Influence of controlled crystallization and SrF2 content on the structure and properties of Eu3+ doped phosphate glasses
- Michał Maciejewski
- Karolina Milewska
- Anna Synak
- Wojciech Sadowski
- Barbara Kościelska
2023 JOURNAL OF NON-CRYSTALLINE SOLIDS
New phosphate glasses and glass-ceramics P2O5–Bi2O3–K2O–Nb2O5-SrF2 doped with Eu were synthesized and studied in this work. The influence of the SrF2 content (0–15 mol%) and the parameters of the heat treatment on their structural and optical properties were investigated. For the above purpose, the structural characterization by FTIR spectroscopy and XRD measurements was carried out, which showed a significant effect of SrF2 on the obtained crystal phases and the structure of the glass matrix. The results of combined DSC/DTA techniques enabled the determination of thermal properties and complemented the investigated crystallization characteristics of the glasses. Based on the measurements of the luminescence properties and the decay curves, it was confirmed that the Eu3+ ions were partially incorporated into the crystallites embedded in the glass matrix, which resulted in a significant enhancement of the luminescence. The conducted research confirms that the presented materials are a promising candidate for resistant phosphors in visible LEDs.
Influence of cyclic frozen and defrost on mechanical properties of polytetrafluoroethylene (PTFE)-coated woven fabrics
- Andrzej Ambroziak
- Paweł Kłosowski
2023 Full text Archives of Civil Engineering
This research aims to determine the influence of the cyclic process of freezing and defrosting on the mechanical properties of the chosen glass fibres and PTFE-coated woven fabrics. The specimens were subjected to freezing at about −20 °C for 4 h and thawing by full immersion into the water at about +20 °C for 4 h. The fabric samples after 25 and 50 frozen cycles were air-dried at room temperature for one week and then subjected to uniaxial tensile tests. The same tests have been performed on a reference group of specimens, which were not exposed to temperature change. The authors determined the tensile strength, and longitudinal stiffnesses resulting from performed tests. Although the investigated coated woven fabrics expressed a reduction in the tensile strength in water soaking conditions, the performed frozen cycles don't show a significant decrease in strength under uniaxial tensile tests.