2024 - Repozytorium publikacji - Politechnika Gdańska

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Strain energy density and entire fracture surface parameters relationship for LCF life prediction of additively manufactured 18Ni300 steel
- Wojciech Macek
- Ricardo Branco
- Joel de Jesus
- José Domingos Costa
- Shun-Peng Zhu
- Reza Masoudi Nejad
- Andrew Gryguć
2024 Pełny tekst INTERNATIONAL JOURNAL OF DAMAGE MECHANICS
In this study, the connection between total strain energy density and fracture surface topography is investigated in additively manufactured maraging steel exposed to low-cycle fatigue loading. The specimens were fabricated using laser beam powder bed fusion (LB-PBF) and examined under fully-reversed strain-controlled setup at strain amplitudes scale from 0.3% to 1.0%. The post-mortem fracture surfaces were explored using a non-contact 3D surface topography measuring system and the entire fracture surface method. The focus is on the relationship between fatigue characteristics, expressed by the total strain energy density, and the fracture surface topography features, represented by areal, volume, and fractal dimension factors. A fatigue life prediction model based on total strain energy density and fracture surface topography parameters is proposed. The presented model shows good accordance with fatigue test results and outperforms other existing models based on the strain energy density. This model can be useful for post-failure analysis of engineering elements under low-cycle fatigue, especially for materials produced by additive manufacturing (AM).
Strain-dependent behaviour of cold recycled material mixtures in cyclic compression tests
- Mariusz Jaczewski
- Andrea Graziani
2024 Pełny tekst MATERIALS AND STRUCTURES
The purpose of the study is to evaluate strain-dependent behaviour of Cold Recycled Material (CRM) mixtures using three frameworks typically applied for Hot Mix Asphalt (HMA): linear viscoelastic (LVE) limits; non-linearity directions; changes in rheological model parameters. To this aim, the complex modulus of three CRM mixtures with different bitumen-to-cement ratio (0.2, 0.6 and 1.8) was measured in cyclic compression mode, at increasing level of axial deformation (from 35 to 195 μstrain) and at three temperatures (4, 20 and 40 °C). CRM mixtures showed strong strain dependent behaviour, which does not fully comply with the LVE hypothesis. LVE limit framework is applicable, but strain limits for CRM are different from HMA. Linearity direction framework does not give unique trend, hence it is not applicable in the same way as it was developed for HMA. The most promising framework for further analysis is the change in rheological model parameters, but it requires high number of performed tests.
Structural phase transitions in multicomponent La0.2Nd0.2Sm0.2Gd0.2RE50.2NbO4 (RE5 = Ho, Y, Tb, Eu, Pr) oxides
- Arkadiusz Dawczak
- Aleksandra Mielewczyk-Gryń
- Maria Gazda
2024 Pełny tekst JOURNAL OF THE AMERICAN CERAMIC SOCIETY
In this work, the influence of compositional complexity on the structural and thermal properties of multicomponent rare-earth ortho-niobates from the La0.2Nd0.2Sm0.2Gd0.2RE50.2NbO4 (RE5 = Ho, Y, Tb, Eu, Pr) series have been investigated. Based on X-ray powder diffraction studies using synchrotron radiation, it was found that all tested materials were pure single-phase compositions and showed stability in the monoclinic I2/c crystal structure at room temperature. High-temperature X-ray powder diffraction studies and dilatometry studies confirmed the presence of a structural phase transition between low- (I2/c ) and high-temperature (I41/a) polymorphs. The structural phase transition temperatures are between 676 °C and 701 °C. Interestingly, despite their compositional complexity, the structural phase transition temperature behaves similarly to conventional ortho-niobates, i.e. it depends on the radius of the A-cation, that is, as the ionic radius increases, the phase transition temperature decreases. The transition has been categorized as a second-order phase transition based on the observed relationship between the Landau order parameter and spontaneous strain. The coexistence of the tetragonal and monoclinic phases has been seen in all compositions around the temperature of the structural phase transition. The presence of two orientation states in the monoclinic structure leads to the so-called spontaneous strain, which consists of longitudinal (u) and shear (v) strain components. The values of these strains at 300 °C range between 2.42 – 2.58·10-2 for longitudinal, 2.98 – 3.04·10-2 for shear, and 5.46 – 5.57·10-2 for scalar spontaneous strain. It was found that the spontaneous strain in each of the materials under test was very little impacted by the variation in the complexity of the A sublattice's composition. In addition, thermal expansion coefficients of both polymorphs were determined, which range from 12.7·10-6 1/K to 13.2·10-6 1/K for the monoclinic structure and 9.7·10-6 1/K to 9.9·10-6 1/K for the tetragonal one.
Structure versus hydrolytic and thermal stability of bio-based thermoplastic polyurethane elastomers composed of hard and soft building blocks with high content of green carbon
- Ewa Głowińska
- Joanna Smorawska
- Joanna Niesiobędzka
- Janusz Datta
2024 Pełny tekst JOURNAL OF THERMAL ANALYSIS AND CALORIMETRY
Nowadays, sustainability plays a key role in the design and synthesis of new materials. One of the methods for the preparation of green materials is incorporation into their structure the monomers with a high content of green carbon. Therefore, the aim of this work was to investigate the influence of the type and molecular mass of two bio-based polyester polyols and bio-glycol on the properties of aliphatic partially bio-based thermoplastic polyurethane elastomers (bio-TPU). Two series of bio-TPUs materials composed of hard and soft building blocks with high green carbon content were prepared via the two-step method (prepolymer method). Two amorphous bio-based polyester polyols with the molecular mass ~ 2000 (P1) and ~ 3000 (P2) were used. Bio-TPUs were prepared at three different molar ratio of [NCO]/[OH]: 0.9, 0.95, and 1.0. In order to determine the influence of bio-based polyols and the content of hard segments on the properties of bio-TPU, relevant test methods were used. The Fourier transform infrared spectroscopy (FTIR), differential scanning calorimetry (DSC), and thermogravimetry (TG) revealed hydrolytic and thermal stability of bio-TPUs. Viscoelastic behavior, mechanical and physical properties were examined in terms of dynamic mechanical thermal analysis (DMTA), tensile test, hardness, and density. Analysis of the measurement results confirmed the significant influence of the molecular mass of the bio-based polyols and the molar ratio of [NCO]/[OH] on the bio-TPUs properties. Due to good mechanical properties, low density, and thermal stability up to 300 °C, the obtained materials can find many useful applications. This issue is essential in terms of sustainable development and reduction in the CO 2 emissions to the atmosphere.
Studies of the Interaction Dynamics in Albumin-Chondroitin Sulfate Systems by Recurrence Method
- Piotr Bełdowski
- Piotr Weber
- Adam Gadomski
- Piotr Sionkowski
- Natalia Kruszewska
- Krzysztof Domino
2024
The physicochemical basis of lubrication of articular cartilage is still not fully understood. However, the synergy between components of the synovial fluid can be a crucial factor that could explain this phenomenon. This work presents a nonlinear data analysis technique named the recurrence method, applied to the system involving two components of synovial fluid: albumin and chondroitin sulfate (CS) immersed in a water environment. This analysis is performed in order to obtain the ”statistical fingerprint” of the dynamics of the interaction between the molecules and to answer whether the variables are more deterministic or more random. The system simulation has been prepared by molecular docking method followed by molecular dynamics simulations. The already mentioned recurrence method has been applied to the time series of the energy of binding, and the time series of the number of intermolecular hydrogen bonds, as these features describe well binding between the two molecules. In detail, the time delay approach and embedded dimension approach have been applied to extract meaningful records from time series. Then, by means of recurrence plots and entropy approach, we discuss the similarities and differences between the molecular systems consisting of CS-4 and CS-6 molecules. Our main finding is a higher affinity of chondroitin sulfate IV to albumin as compared with chondroitin sulfate VI.
Study of Nanohydroxyapatite Coatings Prepared by the Electrophoretic Deposition Method at Various Voltage and Time Parameters
- Klaudia Malisz
- Beata Świeczko-Żurek
- Jean Marc Olive
- Grzegorz Gajowiec
- Gilles Pecastaings
- Aleksandra Laska
- Alina Sionkowska
2024 Pełny tekst Materials
The aim of the work is to compare the properties of nanohydroxyapatite coatings obtained using the electrophoretic deposition method (EDP) at 10 V, 20 V, and 30 V, and with deposit times of 2 and 5 min. The primary sedimentation was used to minimize the risk of the formation of particle agglomerates on the sample surface. Evaluation of the coating was performed by using a Scanning Electron Microscope (SEM), Energy-Dispersive Spectroscopy (EDS), Atomic Force Microscopy (AFM), optical profilometer, drop shape analyzer, and a nanoscratch tester. All of the coatings are homogeneous without any agglomerates. When low voltage (10 V) was used, the coatings were uniform and continuous regardless of the deposition time. The increase in voltage resulted in the formation of cracks in the coatings. The wettability test shows the hydrophilic behavior of the coatings and the mean contact angle values are in the range of 20–37° . The coatings showed excellent adhesion to the substrate. The application of a maximum force of 400 mN did not cause delamination in most coatings. It is concluded that the optimal coating for orthopedic implants (such as hip joint implants, knee joint implants or facial elements) is obtained at 10 V and 5 min because of its homogeneity, and a contact angle that promotes osseointegration and great adhesion to the substrate.
Study on extraction and characterization of anchote (Coccinia abyssinica) starch and reinforced enset (Ensete ventricosum) fiber for the production of reinforced bioplastic film
- Samuel Latebo Majamo
- Temesgen Amibo
2024 Pełny tekst Heliyon
Population expansion is causing an increase in dependence on plastic materials. The worst aspects of conventional plastics were their inability to biodegrade, their poor capacity to transmit water vapor, and their production of greenhouse gases. Usages of bioplastics are necessary for the advancement of a green economy and environment in order to eradicate these drawbacks of traditional plastics. In this study, reinforced bioplastic film was produced from anchote (Coccinia Abyssinica) starch and enset (Ensete Ventricosum) fiber. Starch from anchote was extracted and its properties were characterized via adequate techniques. The maximum carbohydrate content (86.26 ± 0.25%w/w) of anchote starch indicates that it is suitable feedstock for plastic film production. In addition, extracted starch was characterized by SEM, FTIR, TGA and XRD. The reinforcing material enset fiber was extracted and characterized by FTIR and XRD. The results of both feedstock materials exhibited the good characteristics and viability for bioplastic film pro- duction. Enset fiber loadings used were 0 %, 4 %, 8 %, 12 % and 16 % w/w in starch basis. Tensile strength, elongation, thickness, moisture content, transparency, solubility and density of pro- duced bioplastic were determined. Tensile force grew and elongation reduced as fiber loading rose up to 8 %. The tensile strength gradually declined with increasing fiber loading. Additionally, the created bioplastic film’s groups of functions and chemical bonds were examined. In com- parison to unreinforced plastic film, the results showed that the reinforced bioplastic film used in this study was an excellent and effective product.
Study on the wear characteristics of a 3D printed tool in flat lapping of Al2O3 ceramic materials
- Mariusz Deja
- Dawid Zieliński
- Sisay Workineh Agebo
2024 Pełny tekst WEAR
Widespread and popular use of ceramic products in various industry sectors necessitates the search for methods of their efficient processing. Lapping technology, which enables obtaining high dimensional and shape accuracy and high surface flatness, is one of the basic methods of finishing hard and brittle technical ceramics with a porous structure. This study analyzed the characteristics and wear value of an SLS-printed abrasive tool intended for single-sided lapping of Al2O3 technical ceramics. As earlier research demonstrated, introduction of a 3D printed lapping plate by selective laser sintering (SLS), leads to a significant development in the field of precision machining technology. This method showed not only efficient machining performance on oxide technical materials, but was also characterized by relatively low abrasive wear. Straightness errors were evaluated with the use of a least-squares method (LSQ) and minimum zone method based on control line rotation scheme (CLRS). The proposed model proved the experimental results by identifying a similar location of a higher contact density on the lapping tool, where this location is expected to be the one for bigger wear. Surface topography of the lapping tool depends on the tool wear intensity and as a consequence on its shape error. An SLS-printed lapping plate, by obtaining good technological effects, revealed its potential ability in machining hard and brittle technical ceramics.
Study the impact of design method preference on the usefulness of concrete and on CO2 emissions
- Salem Abdelgader
- Marzena Kurpińska
- Hakim S. Abdelgader
- Farzam Omidi Moaf
- Mugahed Amran
2024 International Journal of Building Pathology and Adaptation
Purpose – The research investigates the impact of concrete design methods on performance, emphasizing environmental sustainability. The study compares the modified Bolomey method and Abrams’ law in designing concretes. Significant differences in cement consumption and subsequent CO2 emissions are revealed. The research advocates for a comprehensive life cycle assessment, considering factors like compressive strength, carbonation resistance, CO2 emissions, and cost. The analysis underscores the importance of evaluating concrete not solely based on strength but also environmental impact. The study concludes that a multicriteria approach, considering the entire life cycle, is essential for sustainable concrete design, addressing durability, environmental concerns, and economic factors. Design/methodology/approach – The study employed a comprehensive design and methodology approach, involving the formulation and testing of 20 mixed concretes with strengths ranging from 25 MPa to 45 MPa. Two distinct design methods, the modified Bolomey method (three equations method) and Abrams’ law, were utilized to calculate concrete compositions. Laboratory experiments were conducted to validate the computational models, and subsequent analyses focused on assessing differences in cement consumption, compressive strength, CO2 emissions, and concrete resistance to carbonation. The research adopted a multidisciplinary perspective, integrating theoretical analysis, laboratory testing, and life cycle assessment to evaluate concrete performance and sustainability.
Stymulacyjna funkcja podatku dochodowego
- Piotr Kasprzak
2024
W opracowaniu podjęto próbę opisania i usystematyzowania wiedzy na temat systemu ulg i zwolnień podatkowych stosowanych w Polsce. Autor przedstawia m.in. historię i ewolucję systemu podatkowego w Polsce, począwszy od roku 1989, tłumacząc przy tym rolę państwa. Omówione zostały też trendy i kierunki rozwoju podatków dochodowych. W książce znajdują się informacje na temat istoty i funkcji podatków, ze szczególnym uwzględnieniem stymulacyjnej funkcji podatków. W pracy omówiono również teorię dotyczącą podatków dochodowych od osób fizycznych i prawnych. Autor wymienia i objaśnia stosowane w praktyce ulgi i zwolnienia w podatku dochodowym dla osób fizycznych i prawnych. W opracowaniu przedstawiono analizę pojęć systemu gospodarczego, podatku dochodowego, preferencji podatkowych. Przeprowadzono także analizę sposobów stymulacji zachowań przedsiębiorców w kontekście mechanizmów makroekonomicznych, w tym automatycznych stabilizatorów koniunktury w postaci ulg i zwolnień. Niniejsza książka jest kolejną pozycją, która powstała na podstawie rozprawy doktorskiej autora. Tym razem skupiono się jednak na teoretycznej stronie systemu preferencji podatkowych w systemie gospodarczym.
Subjective quality evaluation of 8- and 10-bit MP4-coded video sequences from Netflix
- Przemysław Falkowski-Gilski
- Tadeus Uhl
- Parameshachari Bidare Divakarachari
2024 Zeszyty Naukowe Akademii Morskiej w Szczecinie
Recently, many researchers have been intensively conducting quality of service (QoS), quality of experience (QoE), and user experience (UX) studies in the field of video analysis. This paper is intended to make a new, complementary contribution to this field. Currently, streaming platforms are key products in relation to delivering video content online. Most often, they include the MP4 video format, which is most widely utilized among audio-visual codecs. This study involves a group of 38 individuals, aged between 21–35 years old, in a laboratory consisting of 20 iMacs with 4K retina display. The presented signal sequences included content sourced from the Netflix Chimera repository, with 8- and 10-bit depth, available in different resolutions of 270p, 432p, 720p, and 1080p. Tests included a subjective quality evaluation in a 5-step mean opinion score (MOS) scale, focused on the UX aspect. According to the obtained results, content with the lowest and highest resolutions is optimal in 8-bit depth, while movies with intermediate resolutions are better in 10-bit depth. For 8-bit content, the main problem is pixelation, whereas, in the case of 10-bit samples, the main issue is color noise, particularly in the case of the lowest resolution. Many viewers indicated that 10-bit encoding offered lower quality. Moreover, 8-bit movies caused a lower quality of the gradient, presumably due to the smaller range of the available color. However, 8-bit movies in the same situation generate visible stripes on static images in the background, causing a lower quality of the gradient, which is probably due to the smaller range of available colors. The results of the performed experiments may be of particular interest to content creators and distributors, particularly network and cable operators, as well as wireless and wired providers.
Sub‐Nanometer‐Scale Cu9S5 Enables Efficiently Electrochemical Nitrate Reduction to Ammonia
- Chao Feng
- Hanyang Wu
- Jiaxin Shao
- Qihua Huo
- Afaq Hassan
- Hengpan Yang
- Qi Hu
- Chuanxin He
2024 Advanced Energy Materials
The sub-nanometer is a key feature size in materials science. Unlike single-atom and nanomaterials, size effects and inter-component cooperative actions in sub-nanomaterials will effective on its performance is more significant. Here, 0.95 nm ordered arrangement Cu9S5 sub-nanowires (Cu9S5 SNWs) are synthesized through the co-assembly effect of inorganic nuclei (Cu9S5) and clusters (phosphotungstic acid-PTA), achieving a significant increase in the specific surface area of the sample and ≈100% atomic exposure rate, which is the key to its high catalytic activity. PTA clusters not only act as a “charge transfer station” to accelerate the inter-component electron transfer process, but also facilitate the dissociation of water and provide more hydrogen protons, thus dramatically facilitating the electrocatalytic process. The experimental results show that the Cu9S5 SNWs exhibited excellent nitrate reduction reaction (NO3−RR) properties. The Faraday efficiency (FE) of NO3−RR is 90.4% at the optimum potential −0.3 VRHE (reversible hydrogen electrode) and the ammonia production is as high as 0.37 mmol h−1 cm−2, which is superior to most reported electrocatalysts. In addition, the Zn-NO3− liquid-flow battery devices assembled using Cu9S5 SNWs as electrode materials show excellent application results. This work provides a reference for the design of highly efficient sub-nanoscale NO3−RR electrocatalysts.
Substrate Integrated Waveguide-Based Frequency-Tunable Self-Octaplexing Antenna
- Nrusingha Pradhan
- Sławomir Kozieł
- Karthikeyan Subramanian
2024 AEU-INTERNATIONAL JOURNAL OF ELECTRONICS AND COMMUNICATIONS
This communication presents the first-ever substrate integrated waveguide (SIW)-based frequency-tunable self-octaplexing antenna (SOA) for wireless communication. The structure is arranged by implementing eight distinct patches with planar 50-ohm feedlines at the top of the SIW cavity, which realize eight distinct resonant frequencies. Independent tuning of each resonant frequency is achieved by incorporating appropriately allocated pockets in the antenna substrate, which can be filled with solid dielectrics of dierent permittivity. The obtained tuning range is broad, from 4.76 GHz to 9.82 GHz, with the capability of tuning each port individually. Furthermore, the port isolation (for all ports) that is better than 20.5 dB. The proposed antenna has a realized gain of 3.91, 3.2, 4.05, 4.14, 3.8, 3.37, 3.55 and 3.28 dBi when using Rogers RT-6010 for pocket filling. Furthermore, the antenna provides stable radiation characteristics with precise tuning. The proposed device is suitable for various applications, including multi-standard wireless communications, due to its small size, wide tuning range, consistent radiation patterns, and comparable isolation levels.
Substrate Integrated Waveguide-Based Ultra-Compact Self-Heptaplexing Antenna for IoT Connectivity
- Nrusingha Pradhan
- Sławomir Kozieł
- Karthikeyan Subramanian
2024 AEU-INTERNATIONAL JOURNAL OF ELECTRONICS AND COMMUNICATIONS
This paper introduces an innovative design of a substrate-integrated waveguide (SIW)-based self-heptaplexing antenna (SHA). The proposed structure is implemented using a combination of circular and rectangular HM-SIW cavities. Furthermore, the antenna contains seven individual patches on top of the SIW cavity to operate at seven distinct frequencies. The microstrip feeding technique has been used to activate seven distinct ports. All patches are excited through 50-ohm feedlines. The antenna operation is elucidated using an equivalent LC model. To demonstrate its operating principles a self-heptaplexing antenna has been designed to work at 2.45, 3, 3.58, 4, 4.45, 5.2, and 5.88 GHz. The measured realized gain of the proposed antenna at the respective bands is 3.2, 3.85, 3.1, 3.245, 4, 2.98, and 4.5 dBi. The isolation exceeds 20 dB over the entire working bands. The EM-simulated and measured characteristics are in good agreement. Although the suggested antenna has been designed for seven ports and lower frequencies, it has a relatively compact size of 0.28 2g. The major advantages of the proposed self-heptaplexing antenna include excellent isolation, an ultra-compact design, and good radiation characteristics. The proposed antenna offers a high degree of flexibility. It allows for independent frequency tuning, which makes it suitable for IoT, wireless communication systems, and diverse sub-6 GHz band applications.
Superconductivity–Electron Count Relationship in Heusler Phases─the Case of LiPd2Si
- Karolina Górnicka
- Xin Gui
- Juan Chamorro
- Tyrel McQueen
- Robert J. Cava
- Tomasz Klimczuk
- Michał Winiarski
2024 Pełny tekst CHEMISTRY OF MATERIALS
We report superconductivity in the full Heusler compound LiPd2Si (space group Fm3̅m, No. 225) at a critical temperature of Tc = 1.3 K and a normalized heat capacity jump at Tc, ΔC/γTc = 1.1. The low-temperature isothermal magnetization curves imply type-I superconductivity, as previously observed in LiPd2Ge. We show, based on density functional theory calculations and using the molecular orbital theory approach, that while LiPd2Si and LiPd2Ge share the Pd cubic cage motif that is found in most of the reported Heusler superconductors, they show distinctive features in the electronic structure. This is due to the fact that Li occupies the site which, in other compounds, is filled with an early transition metal or a rare-earth metal. Thus, while a simple valence electron count–property relationship is useful in predicting and tuning Heusler materials, inclusion of the symmetry of interacting frontier orbitals is also necessary for the best understanding.
Support Materials of Organic and Inorganic Origin as Platforms for Horseradish Peroxidase Immobilization: Comparison Study for High Stability and Activity Recovery
- Muhammad Bilal
- Oliwia Degorska
- Daria Szada
- Agnieszka Rybarczyk
- Agata Zdarta
- Michał Kaplon
- Jakub Zdarta
- Teofil Jesionowski
2024 Pełny tekst MOLECULES
In the presented study, a variety of hybrid and single nanomaterials of various origins were tested as novel platforms for horseradish peroxidase immobilization. A thorough characterization was performed to establish the suitability of the support materials for immobilization, as well as the activity and stability retention of the biocatalysts, which were analyzed and discussed. The physicochemical characterization of the obtained systems proved successful enzyme deposition on all the presented materials. The immobilization of horseradish peroxidase on all the tested supports occurred with an efficiency above 70%. However, for multi-walled carbon nanotubes and hybrids made of chitosan, magnetic nanoparticles, and selenium ions, it reached up to 90%. For these materials, the immobilization yield exceeded 80%, resulting in high amounts of immobilized enzymes. The produced system showed the same optimal pH and temperature conditions as free enzymes; however, over a wider range of conditions, the immobilized enzymes showed activity of over 50%. Finally, a reusability study and storage stability tests showed that horseradish peroxidase immobilized on a hybrid made of chitosan, magnetic nanoparticles, and selenium ions retained around 80% of its initial activity after 10 repeated catalytic cycles and after 20 days of storage. Of all the tested materials, the most favorable for immobilization was the above-mentioned chitosan-based hybrid material. The selenium additive present in the discussed material gives it supplementary properties that increase the immobilization yield of the enzyme and improve enzyme stability. The obtained results confirm the applicability of these nanomaterials as useful platforms for enzyme immobilization in the contemplation of the structural stability of an enzyme and the high catalytic activity of fabricated biocatalysts.
Surface finite viscoelasticity and surface anti-plane waves
- Victor Eremeev
2024 Pełny tekst INTERNATIONAL JOURNAL OF ENGINEERING SCIENCE
We introduce the surface viscoelasticity under finite deformations. The theory is straightforward generalization of the Gurtin–Murdoch model to materials with fading memory. Surface viscoelasticity may reflect some surface related creep/stress relaxation phenomena observed at small scales. Discussed model could also describe thin inelastic coatings or thin interfacial layers. The constitutive equations for surface stresses are proposed. As an example we discuss propagation shear (anti-plane) waves in media with surface stresses taking into account viscoelastic effects. Here we analysed surface waves in an elastic half-space with viscoelastic coatings. Dispersion relations were derived.
Surprising Radiolytic Stability of 8‑Thiomethyladenine in an Aqueous Solution
- Magdalena Datta
- Adrian Szczyrba
- Magdalena Zdrowowicz
- Dariusz Wyrzykowski
- Olga Ciupak
- Sebastian Demkowicz
- Farhad Izadi
- Stephan Denifl
- Janusz Rak
2024 Pełny tekst JOURNAL OF PHYSICAL CHEMISTRY B
8-Thiomethyladenine (ASCH3), a potentially radiosensitizing modified nucleobase, has been synthesized in a reaction between 8-thioadenine and methyl iodide. Despite favorable dissociative electron attachment (DEA) characteristics, the radiolysis of an aqueous solution of ASCH3 with a dose of X-ray amounting to as much as 300 Gy leads to no effects. Nevertheless, crossed electron-molecule beam experiments in the gas phase on ASCH3 confirm the theoretical findings regarding the stability of its radical anion, namely, the most abundant reaction channel is related to the dissociation of the S-CH3 bond in the respective anion. Furthermore, electroninduced degradation of ASCH3 has been observed in aprotic acetonitrile, which is strong evidence for the involvement of proton transfer (PT) in stabilizing the radical anion in an aqueous solution. These findings demonstrate that PT in water can be the main player in deciding the radiosensitizing properties of modified nucleobases/nucleosides.
Survey of ICT students' views on self-assessment of professional preparation after remote study
- Marta Szczerska
- Michał Tomczak
- Paweł Ziemiański
- Katarzyna Wajszczyk
2024 Edukacja Ustawiczna Dorosłych
The contemporary post-pandemic reality is characterised by an undisputable shift toward remote education and work. The aim of this article is to identify the assessment of ICT evaluation of different forms of study, including desktop, remote and hybrid forms; to find out their preferences towards different forms of education and work, and to determine their sense of self-efficacy in terms of professional tasks undertaken after remote education. A survey method was used and the research sample was based on purposive sampling. The results indicate that, although a hybrid environment is preferred in both educational and professional contexts, the challenge remains to optimise this format in order to improve the quality of education. Nevertheless, the surveyed students feel self-efficacious in their professional activities after remote education.
Suspension and process parameters selection for electrophoretic deposition of Mn–Co spinel coating on steel interconnects
- Omid Ekhlasiosgouei
- Federico Smeacetto
- Sebastian Molin
2024 INTERNATIONAL JOURNAL OF HYDROGEN ENERGY
Metallic interconnect coatings, consisting of MnCo2O4 spinel, were effectively applied to Crofer 22 APU using the electrophoretic deposition (EPD) method in both H2O: ethanol and pure ethanol solvents. The primary goal of this method was to prevent chromium migration, minimize evaporation, and control the oxidation rate. The study aimed to assess the quality, adhesion, and thickness of the Mn–Co coating, with the objective of achieving a consistent and uniform layer. The results indicated a preference for pure ethanol solvent over H2O: ethanol (40:60 %Vol) for Mn–Co particles. Furthermore, the agglomeration of Mn–Co particles was notably lower (approximately 7 times) in ethanol compared to H2O: ethanol. The morphology and surface roughness of the sintered Mn–Co coating on the alloy were examined using scanning electron microscopy (SEM) and confocal laser scanning microscopy (CLSM). A uniform and dense coating was successfully attained using pure ethanol solvent at a solid concentration of 10 g/L, with 0.5 g/L of iodine serving as a disperser. The deposition process, carried out at a voltage of 30V for 20 s, resulted in a coating with a thickness of 7.4 ± 0.3 μm and a surface roughness of 0.75 ± 0.5 μm.