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Gdańsk University of Technology

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  • Mechanical analysis of eccentric defected bilayer graphene sheets considering the van der Waals force
    • Shahriar Dastjerdi
    • Mohammad Malikan
    2021 Full text Proceedings of the Institution of Mechanical Engineers Part N-Journal of Nanomaterials Nanoengineering and Nanosystems

    In this article, we have tried to simulate nonlinear bending analysis of a double-layered graphene sheet which contains a geometrical imperfection based on an eccentric hole. The first-order shear deformation theory is considered to obtain the governing equations. Also, the nonlinear von Kármán strain field has been assumed in order to obtain large deformations. Whereas the double-layered graphene sheet has been considered, the effect of van der Waals forces has been taken into account in the analysis. In order to implement the nanoscale impact, the nonlocal elasticity theory has been employed. The solution methodology, which is here based on the semi-analytical polynomial method solving technique presented previously by the authors, has been applied and again its efficiency has been demonstrated due to its highly accurate results. Due to the fact that this research has been done for the first time and there is no validation available, the results of the local single layer sheet are compared with ABAQUS software. The effects of some other parameters on the results have been studied such as the value of eccentricity, van der Waals interaction, and nonlocal parameter.

  • Mechanical Behavior of Bi-Layer and Dispersion Coatings Composed of Several Nanostructures on Ti Substrate
    • Dorota Rogala-Wielgus
    • Beata Majkowska-Marzec
    • Andrzej Zieliński
    • Bartłomiej J. Jankiewicz
    2021 Full text Applied Sciences-Basel

    Three coatings suitable for biomedical applications, including the dispersion coating composed of multi-wall carbon nanotubes (MWCNTs), MWCNTs/TiO2 bi-layer coating, and MWCNTs-Cu dispersion coating, were fabricated by electrophoretic deposition (EPD) on Ti Grade II substrate. Optical microscopy, scanning electron microscopy, energy-dispersive X-ray spectroscopy, and nanoindentation were applied to study topography, chemical, and phase composition, roughness, hardness, Young’s modulus, plastic, and elastic behavior. The results showed that the best mechanical properties in terms of biomedical application were achieved for the MWCNTs coating with titania outer layer. Nevertheless, both the addition of nanocopper and titania improved the mechanical resistance of the base MWCNTs coating. Compared to our previous experiments on Ti13Nb13Zr alloy, a general tendency is observed to form more homogenous coatings on pure metal than on the alloy, in which chemical and phase compositions are more complex.

  • Mechanical Behavior of Bi-Layer and Dispersion Coatings Composed of Several Nanostructures on Ti13Nb13Zr Alloy
    • Dorota Rogala-Wielgus
    • Beata Majkowska-Marzec
    • Andrzej Zieliński
    • Michał Bartmański
    • Bartosz Bartosewicz
    2021 Full text Materials

    Titanium implants are commonly used because of several advantages, but their surface modification is necessary to enhance bioactivity. Recently, their surface coatings were developed to induce local antibacterial properties. The aim of this research was to investigate and compare me-chanical properties of three coatings: multi-wall carbon nanotubes (MWCNTs), bi-layer composed of an inner MWCNTs layer and an outer TiO2 layer, and dispersion coatings comprised of simulta-neously deposited MWCNTs and nanoCu, each electrophoretically deposited on the Ti13Nb13Zr alloy. Optical microscopy, scanning electron microscopy, X-ray electron diffraction spectroscopy, and nanoindentation technique were applied to study topography, chemical composition, hardness, plastic and elastic properties. The results demonstrate that the addition of nanocopper or titanium dioxide to MWCNTs coating increases hardness, lowers Young’s modulus, improves plastic and elastic properties, wear resistance under deflection, and plastic deformation resistance. The results can be attributed to different properties, structure and geometry of applied particles, various dep-osition techniques, and the possible appearance of porous structures. These innovative coatings of simultaneously high strength and elasticity are promising to apply for deposition on long-term ti-tanium implants.

  • Mechanical, durability, depolluting and electrical properties of multifunctional mortars prepared with commercial or waste carbon-based fillers
    • Alessandra Mobili
    • Alberto Belli
    • Chiara Giosuè
    • Mattia Pierpaoli
    • Luca Bastianelli
    • Alida Mazzoli
    • Maria Letizia Ruello
    • Tiziano Bellezze
    • Francesca Tittarelli
    2021 Full text CONSTRUCTION AND BUILDING MATERIALS

    Carbon-based fillers from industrial wastes and commercial ones were compared to improve the properties of lime-based mixes. As commercial fillers, graphene nanoplatelets and activated carbon were used, whereas as industrial wastes a char obtained by the gasification of biomasses and a used foundry sand were chosen. Carbon-based wastes were found to be a good cost-effective alternative to commercial carbon based fillers to increase the compressive strength (of about 25%) and to reduce water capillary absorption (of about 50%) thanks to the paste refinement; to enhance depollution capacity (of about 25%) and increase both electrical conductivity (up to 65%) and electromagnetic shielding effectiveness (of about 6%) of the hardened compounds thanks to the carbon content.

  • Mechanical Performance and Environmental Assessment of Sustainable Concrete Reinforced with Recycled End-of-Life Tyre Fibres
    • Magdalena Pawelska-Mazur
    • Maria Kaszynska
    2021 Full text Materials

    The presented research’s main objective was to develop the solution to the global problem of using steel waste obtained during rubber recovery during the tire recycling. A detailed comparative analysis of mechanical and physical features of the concrete composite with the addition of recycled steel fibres (RSF) in relation to the steel fibre concrete commonly used for industrial floors was conducted. A study was carried out using micro-computed tomography and the scanning electron microscope to determine the fibres’ characteristics, incl. the EDS spectrum. In order to designate the full performance of the physical and mechanical features of the novel composite, a wide range of tests was performed with particular emphasis on the determination of the tensile strength of the composite. This parameter appointed by tensile strength testing for splitting, residual tensile strength test (3-point test), and a wedge splitting test (WST), demonstrated the increase of tensile strength (vs unmodified concrete) by 43%, 30%, and 70% relevantly to the method. The indication of the reinforced composite’s fracture characteristics using the digital image correlation (DIC) method allowed to illustrate the map of deformation of the samples during WST. The novel composite was tested in reference to the circular economy concept and showed 31.3% lower energy consumption and 30.8% lower CO2 emissions than a commonly used fibre concrete.

  • Mechanical Properties and Residual Stress Measurements of Grade IV Titanium and Ti-6Al-4V and Ti-13Nb-13Zr Titanium Alloys after Laser Treatment
    • Magdalena Jażdżewska
    • Dominika Kwidzińska
    • Wiktor Seyda
    • Dariusz Fydrych
    • Andrzej Zieliński
    2021 Full text Materials

    Nowadays, surface engineering focuses on research into materials for medical applications. Titanium and its alloys are prominent, especially Ti-6Al-4V and Ti-13Nb-13Zr. Samples made of pure grade IV titanium and the titanium alloys Ti-6Al-4V and Ti-13Nb-13Zr were modified via laser treatment with laser beam frequency f = 25 Hz and laser beam power P = 1000 W during a laser pulse with duration t = 1 ms. Subsequently, to analyze the properties of the obtained surface layers, the following tests were performed: scanning electron microscopy, chemical and phase composition analysis, wetting angle tests and roughness tests. The assessment of the impact of the laser modification on the internal stresses of the investigated materials was carried out by comparing the values of the stresses of the laser-modified samples to those of the reference samples. The obtained results showed increased values of tensile stresses after laser modification: the highest value was found for the Ti-6Al-4V alloy at 6.7434 GPa and the lowest for pure grade IV titanium at 3.742 GPa. After laser and heat treatment, a reduction in the stress was observed, together with a significant increase in the hardness of the tested materials, with the highest value for Ti-6Al-4V alloy at 27.723 GPa. This can provide better abrasion resistance and lower long-term toxicity, both of which are desirable when using Ti-6Al-4V and Ti-13Nb-13Zr alloys for implant materials.

  • Mechanical Properties, Microstructure and Surface Quality of Polypropylene Green Composites as a Function of Sunflower Husk Waste Filler Particle Size and Content
    • Mateusz Barczewski
    • Jacek Andrzejewski
    • Radomir Majchrowski
    • Kamil Dobrzycki
    • Krzysztof Formela
    2021 Full text Journal of Renewable Materials

    Agricultural waste is a still untapped source of materials that can, in case of proper utilization, significantly improve the sustainability of polymers and their composites. In this work, polymer composites based on isotactic polypropylene were produced incorporating ground sunflower husk in the amount of 10 wt% and 20 wt%. The work’s main objective is to evaluate how preliminary fractioning of this agricultural waste filler affects the thermomechanical properties, microstructure and surface topology of polypropylene-based injection molded composites. The composites were analyzed for mechanical properties (tensile, impact strength and hardness), thermomechanical properties (Vicat softening point VST, heat deflection temperature HDT, and dynamic thermomechanical analysis DMTA) with reference to morphological changes evaluated using scanning electron microscopy (SEM). The quality of the produced composites was assessed on the basis of the analysis of the surface topology of the injected composites. It has been shown that the larger particle size of used filler has a direct impact on increasing composite stiffness in the room and elevated temperature. Moreover, a relationship was demonstrated between the size of the filler and the deterioration of the tensile strength in the case of composites with a higher content of filler. The results show that the addition of sunflower husk as a particle-shaped waste filler is an effective method to increase sustainability of polypropylene-based green composites with beneficial thermomechanical properties and to reduce the residue of sunflower husk from industrial oil production.

  • Mechanical Properties of Bio-Composites Based on Epoxy Resin and Nanocellulose Fibres
    • Martyna Roszowska-Jarosz
    • Joanna Masiewicz
    • Marcin Kostrzewa
    • Wojciech Kucharczyk
    • Wojciech Żurowski
    • Justyna Kucińska-Lipka
    • Paweł Przybyłek
    2021 Full text Materials

    The aim of our research was to investigate the effect of a small nanocellulose (NC) addition on an improvement of the mechanical properties of epoxy composites. A procedure of chemical extraction from pressed lignin was used to obtain nanocellulose fibers. The presence of nanoparticles in the cellulose pulp was confirmed by FTIR/ATR spectra as well as measurement of nanocellulose particle size using a Zetasizer analyzer. Epoxy composites with NC contents from 0.5% to 1.5% w/w were prepared. The obtained composites were subjected to strength tests, such as impact strength (IS) and resistance to three-point bending with a determination of critical stress intensity factor (Kc). The impact strength of nanocellulose composites doubled in comparison to the unmodified epoxy resin (EP 0). Moreover, Kc was increased by approximately 50% and 70% for the 1.5 and 0.5% w/w NC, respectively. The maximum value of stress at break was achieved at 1% NC concentration in EP and it was 15% higher than that for unmodified epoxy resin. The highest value of destruction energy was characterized by the composition with 0.5% NC and corresponds to the increase of 102% in comparison with EP 0. Based on the analysis of the results it was noted that satisfactory improvement of the mechanical properties of the composite was achieved with a very small addition of nanofiller while other research indicates the need to add much more nanocellulose. It is also expected that this kind of use of raw materials will allow increasing the economic efficiency of the nanocomposite preparation process. Moreover, nanocomposites obtained in this way can be applied as elements of machines or as a modified epoxy matrix for sandwich composites, enabling production of the structure material with reduced weight but improved mechanical properties.

  • Mechanical simulation of artificial gravity in torus-shaped and cylindrical spacecraft
    • Shahriar Dastjerdi
    • Mohammad Malikan
    • Victor Eremeev
    • Bekir Akgöz
    • Ömer Civalek
    2021 Full text ACTA ASTRONAUTICA

    Large deformations and stress analyses in two types of space structures that are intended for people to live in space have been studied in this research. The structure under analysis is assumed to rotate around the central axis to create artificial gravitational acceleration equal to the gravity on the Earth's surface. The analysis is fully dynamic, which is formulated based on the energy method by using the first-order shear deformation shell theory in two systems, cylindrical and torus. Also, the nonlinear von Kármán strain field has been assumed. The obtained set of partial differential equations has been solved using the semi-analytical polynomial solution method (SAPM). The main purpose of this paper is to study the effects of unusual conditions in the space outside the Earth's atmosphere (which is a complete vacuum environment without pressure) on the strength of the analyzed structure. The numerical results of the governing equations have been evaluated using those of other studies and the simulation efficiency performed in this research has been proven. Finally, the effect of important parameters on the numerical results, including the angular velocity of the structure (which causes artificial gravity), the amount of imposed mechanical and hygro-thermal loads, the structure size and material specifications have been investigated in more detail.

  • Mechanism of Li nucleation at graphite anodes and mitigation strategies
    • Chao Peng
    • Arihant Bhandari
    • Jacek Dziedzic
    • John R. Owen
    • Chris-Kriton Skylaris
    • Denis Kramer
    2021 Full text Journal of Materials Chemistry A

    Lithium metal plating is a critical safety issue in Li-ion cells with graphite anodes, and contributes significantly to ageing, drastically limiting the lifetime and inducing capacity loss. Nonetheless, the nucleation mechanism of metallic Li on graphite anodes is still poorly understood. But in-depth understanding is needed to rationally design mitigation measures. In this work, we conducted FirstPrinciples studies to elucidate the Li nucleation mechanism on graphite surfaces. These large-scale density-functional-theory (DFT) calculations indicate that nano-particulate Li forms much more readily than classical nucleation theory predicts. Further, our calculations indicate a crucial role of topological surface states near the zigzag edge, lowering the nucleation barrier by a further 1.32 eV relative to nucleation on the basal plane. Li nucleation, therefore, is likely to initiate at or near the zigzag edges of graphitic particles. Finally, we suggest that chemical doping with a view to reducing the effect of the topological surface states might be a potential mitigation strategy to increase nucleation barriers and reduce the propensity to plate Li near the zigzag edge.

  • Mechanism of recognition of parallel G-quadruplexes by DEAH/RHAU helicase DHX36 explored by molecular dynamics simulations
    • Kazi Hossain
    • Michal Jurkowski
    • Jacek Czub
    • Mateusz Kogut
    2021 Full text Computational and Structural Biotechnology Journal

    Because of high stability and slow unfolding rates of G-quadruplexes (G4), cells have evolved specialized helicases that disrupt these non-canonical DNA and RNA structures in an ATP-dependent manner. One example is DHX36, a DEAH-box helicase, which participates in gene expression and replication by recognizing and unwinding parallel G4s. Here, we studied the molecular basis for the high affinity and specificity of DHX36 for parallel-type G4s using all-atom molecular dynamics simulations. By computing binding free energies, we found that the two main G4-interacting subdomains of DHX36, DSM and OB, separately exhibit high G4 affinity but they act cooperatively to recognize two distinctive features of parallel G4s: the exposed planar face of a guanine tetrad and the unique backbone conformation of a continuous guanine tract, respectively. Our results also show that DSM-mediated interactions are the main contributor to the binding free energy and rely on making extensive van der Waals contacts between the GXXXG motifs and hydrophobic residues of DSM and a flat guanine plane. Accordingly, the sterically more accessible 5′-G-tetrad allows for more favorable van der Waals and hydrophobic interactions which leads to the preferential binding of DSM to the 5′-side. In contrast to DSM, OB binds to G4 mostly through polar interactions by flexibly adapting to the 5′-terminal guanine tract to form a number of strong hydrogen bonds with the backbone phosphate groups. We also identified a third DHX36/G4 interaction site formed by the flexible loop missing in the crystal structure.

  • Mechanism of Solute and Thermal Characteristics in a Casson Hybrid Nanofluid Based with Ethylene Glycol Influenced by Soret and Dufour Effects
    • Muhammad Bilal Hafeez
    • Wojciech Sumelka
    • Umar Nazir
    • Ahmad Hijaz
    • Sameh Askar
    2021 Full text ENERGIES

    This article models a system of partial differential equations (PDEs) for the thermal and solute characteristics under gradients (concentration and temperature) in the magnetohydrodynamic flow of Casson liquid in a Darcy porous medium. The modelled problems are highly non-linear with convective boundary conditions. These problems are solved numerically with a finite element approach under a tolerance of 10−8. A numerical algorithm (finite element approach) is provided and a numerical procedure is discussed. Convergence is also observed via 300 elements. Simulations are run to explore the dynamics of flow and the transport of heat and mass under parametric variation. To examine the impact of a temperature gradient on the transport of mass and the role of a concentration gradient on the transport of heat energy, simulations are recorded. Remarkable changes in temperature and concentration are noted when Dufour and Soret numbers are varied

  • Medially positioned plate in first metatarsophalangeal joint arthrodesis
    • Wojciech Witkowski
    • Leszek Kuik
    • Magdalena Rucka
    • Karol Daszkiewicz
    • Angela Andrzejewska
    • Piotr Łuczkiewicz
    2021 Full text PLOS ONE

    Objective The purpose of this study was to biomechanically compare the stability of first metatarsophalangeal (MTP1) joint arthrodesis with dorsally and medially positioned plates. Methods A physical model of the MTP1 joint consists of printed synthetic bones, a titanium locking plate and screws. In the experiments, samples with dorsally and medially positioned plates were subjected to loading of ground load character in a universal testing machine. Force-displacement relations and relative displacements of bones were recorded. The obtained results were used to validate the corresponding finite element models of the MTP1 joint. Nonlinear finite element simulations of the toe-off phase of gait were performed to determine the deformation and stress state in the MTP1 joint for two positions of the plate. Results In numerical simulations, the maximum displacement in the dorsal direction was noticed at the tip of the distal phalanx and was equal to 19.6 mm for the dorsal plate and 9.63 mm for the medial plate for a resultant force of 150 N. Lower relative bone displacements and smaller plastic deformation in the plate were observed in the model with the medial plate. Stress values were also smaller in the medially positioned plate and locking screws compared to fixation with the dorsal plate. Conclusions A medially positioned locking plate provides better stability of the MTP1 joint than a dorsally positioned plate due to greater vertical bending stiffness of the medial plate. Smaller relative bone displacements observed in fixation with the medial plate may be beneficial for the bone healing process. Moreover, lower stress values may decrease the risk of complications associated with hardware failure.

  • Medieval Bourgeois Tenement Houses as an Archetype for Contemporary Architectural and Construction Solutions: The Example of Historic Downtown Gdańsk
    • Antoni Taraszkiewicz
    • Karol Grębowski
    • Karolina Taraszkiewicz
    • Jarosław Przewłócki
    2021 Full text Buildings

    The basic urban tissue of medieval European cities consisted of brick townhouses. In the cities of northern Europe, these tenements were characterised by a block based on an elongated rectangular plan, covered with a gable roof with a ridge oriented perpendicularly to the street. The side walls of the tenement house were common for both neighbours and constituted a basic structural element. The gable façades were not loaded with ceilings, providing freedom in shaping them. The aim of this work is to determine the reasons why this method of shaping tenement houses in historical city centres has survived to the present day, becoming an archetype for contemporary architectural and construction solutions, despite the passage of time, numerous historical events, war damage, changing architectural styles, fashions and building techniques and technologies. The historical centre of Gdańsk has become the research material in this paper, where by means of such methods as historical source material analysis (iconographic), observation (operationalisation of preserved historical objects), comparative analysis of completed contemporary investments, and 3D modelling of structural systems, an attempt has been made to determine the main factors determining contemporary architectural and structural solutions. The reason for the extraordinary durability of this type of construction model can be found in the enormous rationality and efficiency of this solution. It allows for very intensive use of land, easy access of all front elevations to the main communication routes, cheapness of construction resulting from small spans and use of common structural walls for the neighbouring buildings, ease of shaping gable elevations, and fire safety. Aesthetic considerations are probably also important here, although it should be assumed that their significance began to grow only in the second half of the 19th century. However, it seems that the most important factor which made the model of the mediaeval bourgeois tenement house become an archetype for contemporary architectural and construction solutions is the timeless message contained in this model, a specific code allowing it to be unambiguously identified as a form of urban house – a place of safe living and at the same time a visible sign of the rich history of European cities, an element creating their cultural and spatial identity, a component of the living, constantly transforming urban fabric.

  • Membrane separation processes for the extraction and purification of steviol glycosides: an overview
    • Roberto Castro-Muñoz
    • Elsa Díaz-Montes
    • Alfredo Cassano
    • Emilia Gontarek
    2021 CRITICAL REVIEWS IN FOOD SCIENCE AND NUTRITION

    Steviol glycosides (SGs), as natural sweeteners from Stevia rebaudiana, are currently employed for replacing sugar and its derivatives in several food products and formulations. Such compounds play an essential role in human health. Their usage provides a positive effect on preventing diseases related to sugar consumption, including diabetes mellitus, cancer, and lipid metabolism disorders. The traditional extraction of SGs is performed by means of solvent extraction, which limits their application since the removal of residual solvents is a challenging task requiring further downstream purification steps. In addition, the presence of residual solvents negatively affects the quality of such compounds. Today, food technicians are looking for innovative and improved techniques for the extraction, recovery and purification of SGs. Membrane-based technologies, including microfiltration, ultrafiltration, and nanofiltration, have long been proven to be a valid alternative for efficient extraction and purification of several high added-value molecules from natural sources. Such processes and their possible coupling in integrated membrane systems have been successfully involved in recovery protocols of several compounds, such as metabolites, polyphenols, anthocyanins, natural pigments, proteins, from different sources (e.g., agro-food wastes, plant extracts, fruits, fermentation broths, among others). Herein, we aim to review the current progresses and developments about the extraction of SGs with membrane operations. Our attention has been paid to the latest insights in the field. Furthermore, key process parameters influencing the extraction and purification of SGs are also discussed in detail.

  • Mercury in Living Organisms: Sources and Forms of Occurrence, Bioaccumulation, and Determination Methods
    • Piotr Konieczka
    • Małgorzata Rutkowska
    • Małgorzata Misztal-Szkudlińska
    • Piotr Szefer
    2021 Full text

    Mercury (Hg) is a heavy metal with well-known and broadly tested toxicity. Since Hg pollution and its impacts on human health are of global concern, it has become necessary to develop analytical methodologies that will provide tools to obtain reliable analytical information about the levels of Hg in samples, which very often have a complex matrix composition. This chapter summarizes key information on Hg and its chemical forms, sources of its emission to the environment, and the global Hg cycle. In addition, the concepts of bioaccumulation and biomagnification of Hg along the food chain are characterized. This chapter also describes the analytical methods used in the determination of Hg and its compounds.

  • Mesh dependence study for numerical assessment of hydrodynamic characteristics of windsurfing fin
    • Hanna Pruszko
    2021

    The presented research aims to assess the drag coefficient and lift coefficient versus angle of attack curves for windsurfing fin. Special attention in the research was being paid to the evaluation of the stall angle value. The angle of incidence for which the stall occurs was searched, and the sensitivity of the solution for the mesh resolution was studied. The mesh resolution sensitivity analysis was done by systematically decreasing the value of y+, and the influence on the value of stall angle and slopes of the drag and lift curves were checked. The last part of the research compared the experimental results that are part of the current state of the art.

  • Metabolic Profiles of New Unsymmetrical Bisacridine Antitumor Agents in Electrochemical and Enzymatic Noncellular Systems and in Tumor Cells
    • Anna Mieszkowska
    • Anna M. Nowicka
    • Agata Kowalczyk
    • Agnieszka Potęga
    • Monika Pawłowska
    • Michał Kosno
    • Ewa Augustin
    • Zofia Mazerska
    2021 Full text Pharmaceuticals

    New unsymmetrical bisacridines (UAs) demonstrated high activity not only against a set of tumor cell lines but also against human tumor xenografts in nude mice. Representative UA compounds, named C-2028, C-2045 and C-2053, were characterized in respect to their physicochemical properties and the following studies aimed to elucidate the role of metabolic transformations in UAs action. We demonstrated with phase I and phase II enzymes in vitro and in tumors cells that: (i) metabolic products generated by cytochrome P450 (P450), flavin monooxygenase (FMO) and UDP-glucuronosyltransferase (UGT) isoenzymes in noncellular systems retained the compound’s dimeric structures, (ii) the main transformation pathway is the nitro group reduction with P450 isoenzymes and the metabolism to N-oxide derivative with FMO1, (iii), the selected UGT1 isoenzymes participated in the glucuronidation of one compound, C-2045, the hydroxy derivative. Metabolism in tumor cells, HCT-116 and HT-29, of normal and higher UGT1A10 expression, respectively, also resulted in the glucuronidation of only C-2045 and the specific distribution of all compounds between the cell medium and cell extract was demonstrated. Moreover, P4503A4 activity was inhibited by C-2045 and C-2053, whereas C-2028 affected UGT1A and UGT2B action. The above conclusions indicate the optimal strategy for the balance among antitumor therapeutic efficacy and drug resistance in the future antitumor therapy.

  • Metabolomic and antioxidant properties of different varieties and origins of Dragon fruit
    • Nabil Ali Al-Mekhlafi
    • Ahmed Mediani
    • Nor Hadiani Ismail
    • Faridah Abas
    • Tomasz Dymerski
    • Martyna Lubinska-Szczygeł
    • Suchada Vearasilp
    • Shela Gorinstein
    2021 MICROCHEMICAL JOURNAL

    Dragon fruit has appealed much concern from consumers as a novelty fruit with potent nutritional and medicinal benefits. Dragon fruit quality warrants comprehensive evaluation, based on the contents of pigments and health- promoting natural compounds in different varieties. This study was aimed to evaluate the differences among dragon fruit varieties extracted with methanol–water (CD3OD-D2O) and methanol (CD3OD) by proton nuclear magnetic resonance ( 1 H NMR)-based metabolomics approach. The variation features of the metabolite profiles were studied between varieties and origins of dragon fruit, considering the differences in principal component analysis (PCA). The hierarchical clustering analysis (HCA) based on score values of PCA model was also per- formed to analyze the distance between samples based on metabolites contents. The results of 1 H NMR spectra showed that the CD3OD-D2O extracts quantitatively differ from CD3OD ones. In dragon fruit extracts, 36 me- tabolites were identified. The results demonstrated that the methanol and methanol/water extracted similar compounds with higher intensity in methanol. The metabolic differences among varieties were also shown for CD3OD extracts by comparing both Pareto and UV scaling methods. The big size red fleshed dragon fruit (samples 2 and 3), growing in Israel were clustered similar to that growing in Thailand with the abundance of phenolic compounds. Glucose and fructose were more prominent in the yellow and white fleshed fruit (samples 4 and 5) growing in Israel. To support the obtained results two dimensional 1 H–1 H J-resolved and UHPLC-MS measure- ments were carried out. This research gain novel insights into the field as the first NMR metabolites finger- printing of the major dragon fruit varieties. The correlations between DPPH, CUPRAC, antioxidant and metabolomic properties were also evaluated. The chemical markers associated with varieties of dragon fruit quality and their appearances were identified and can be utilized for the basis of authentication purpose of this fruit.

  • Metal (Mo, W, Ti) Carbide Catalysts: Synthesis and Application as Alternative Catalysts for Dry Reforming of Hydrocarbons—A Review
    • Natalia Czaplicka
    • Andrzej Rogala
    • Izabela Wysocka
    2021 Full text INTERNATIONAL JOURNAL OF MOLECULAR SCIENCES

    Dry reforming of hydrocarbons (DRH) is a pro-environmental method for syngas production. It owes its pro-environmental character to the use of carbon dioxide, which is one of the main greenhouse gases. Currently used nickel catalysts on oxide supports suffer from rapid deactivation due to sintering of active metal particles or the deposition of carbon deposits blocking the flow of gases through the reaction tube. In this view, new alternative catalysts are highly sought after. Transition metal carbides (TMCs) can potentially replace traditional nickel catalysts due to their stability and activity in DR processes. The catalytic activity of carbides results from the synthesis-dependent structural properties of carbides. In this respect, this review presents the most important methods of titanium, molybdenum, and tungsten carbide synthesis and the influence of their properties on activity in catalyzing the reaction of methane with carbon dioxide.

  • Metal–Organic Frameworks (MOFs) for Cancer Therapy
    • Mohammad Saeb
    • Navid Rabiee
    • Masoud Mozafari
    • Francis Verpoort
    • Leonid G. Voskressensky
    • Rafael Luque
    2021 Full text Materials

    MOFs exhibit inherent extraordinary features for diverse applications ranging from catalysis, storage, and optics to chemosensory and biomedical science and technology. Several procedures including solvothermal, hydrothermal, mechanochemical, electrochemical, and ultrasound techniques have been used to synthesize MOFs with tailored features. A continued attempt has also been directed towards functionalizing MOFs via “post-synthetic modification” mainly by changing linkers (by altering the type, length, functionality, and charge of the linkers) or node components within the MOF framework. Additionally, efforts are aimed towards manipulating the size and morphology of crystallite domains in the MOFs, which are aimed at enlarging their applications window. Today’s knowledge of artificial intelligence and machine learning has opened new pathways to elaborate multiple nanoporous complex MOFs and nano-MOFs (NMOFs) for advanced theranostic, clinical, imaging, and diagnostic purposes. Successful accumulation of a photosensitizer in cancerous cells was a significant step in cancer therapy. The application of MOFs as advanced materials and systems for cancer therapy is the main scope beyond this perspective. Some challenging aspects and promising features in MOF-based cancer diagnosis and cancer therapy have also been discussed.

  • Metals and metal-binding ligands in wine: Analytical challenges in identification.
    • Magdalena Fabjanowicz
    • Justyna Płotka-Wasylka
    2021 TRENDS IN FOOD SCIENCE & TECHNOLOGY

    Background Due to important role of metals in the vinification process as well as their impact on the human health, their content in this alcoholic beverage has been extensively studied by many researchers. It is already known that speciation of metals determines their toxicity and bioavailability as well as influences their activity. Understanding the chemistry and knowing the structures of metal complexes could have relevant influence on more effective approaches for prevention of some diseases including cancer. Thus, monitoring and studying the metal complexation process, structures of metal complexes present in wine, as well as their stability, is crucial. Scope and approach In this review the main developments in the metal complex identification in wine samples are described. The study emphasizes metal complexes with two ligand groups such as polyphenols and organic acids as a group of compounds well known for their health-beneficial nature. Key findings and conclusions Complexity of the wine matrix related with the presence of numerous organic compounds makes the examination of wine in the context of metal complexes identification a highly challenging task. Metals and metal complexes are present in low concentrations, which can potentially cause interferences during an analytical process. Currently, the most promising technique that can be used for metal complex identification is ESI-MS coupled with separation technique such as liquid chromatography.

  • Metamaterial-Based Sub-Microwave Electromagnetic Field Energy Harvesting System
    • Mikołaj Nowak
    2021 Full text ENERGIES

    This paper presents the comprehensive analysis of the sub-microwave, radio frequency band resonant metastructures’ electromagnetic properties with a particular emphasis on the possibility of their application in energy harvesting systems. Selected structures based on representative topologies of metamaterials have been implemented in the simulation environment. The models have been analyzed and their substitute average electromagnetic parameters (absorption, reflection, transmission and homogenized permeability coefficients) have been determined. On the basis of simulation research, prototypes of electromagnetic field two-dimensional absorbers have been manufactured and verified experimentally in the proposed test system. The absorber has been implemented as a component of the low-cost energy harvesting system with a high-frequency rectifier and a voltage multiplier, obtaining usable DC energy from the electromagnetic field in certain frequency bands. The energy efficiency of the system has been determined and the potential application in energy harvesting technology has been assessed.

  • Method for the correlation coefficient estimation of the bottom echo signal in the shallow water application using interferometric echo sounder
    • Piotr Grall
    • Jacek Marszal
    2021 Full text Vibrations in Physical Systems

    The article presents a new method for the assessment of bottom echo correlation coefficient in the presence of multiple echoes. Bottom correlation coefficient is a parameter that characterizes spatial properties of echo signal. Large variability of the bottom shape or properties (for example caused by the presence of bottom objects) and the presence of the acoustic shadow strongly influence the value of the correlation coefficient. There is a problem, however, in the proper determination of correlation coefficient of the bottom echo when more than one echo is present. In the shallow water application, the echoes coming to the hydroacoustic array from various directions influence the measured value of the correlation coefficient. The method proposed by the authors challenges this issue by applying a subarray processing based on the initial depth estimation. The article presents the preliminary research results and describes the limitations of the proposed method.

  • Methodology for determining the elemental composition, as well as energy and ignition properties of the low-sulfur marine fuels
    • Zbigniew Korczewski
    2021 Full text Combustion Engines

    The key metrological issue of substance and energy balance in research engines is the precise determination of the elemental composition of the applied fuel and its net calorific value. This makes it possible to calculate the amount of heat brought with the fuel into the combustion chamber, as well as the amount and gas composition of the exhaust. However, to fully assess the energy quality of the fuel used, its ignition properties should also be estimated. They determine the combustion kinetics and, consequently, the course of gas pressure alterations and heat release in the cylinder, which have a direct impact on the indicated power and thermal efficiency of the engine. This article presents the methodology for carrying out this type of laboratory tests and their representative results concerning six different low-sulfur marine fuels used to feed marine engines at present. The considerations focus mainly on measurement technology, as well as the measuring apparatus applied today. Additionally some existing metrological difficulties that might be met were shortly described. The laboratory tests in question stand for the first stage of the program of testing a new kind of low-sulfur marine fuels in real operating conditions of a diesel engine, which was carried out at the Department of Ship Power Plants of the Gdańsk University of Technology.

  • Methodology for the Correction of the Spatial Orientation Angles of the Unmanned Aerial Vehicle Using Real Time GNSS, a Shoreline Image and an Electronic Navigational Chart
    • Krzysztof Naus
    • Piotr Szymak
    • Paweł Piskur
    • Maciej Niedziela
    • Aleksander Nowak
    • Pawel Piskur
    2021 Full text ENERGIES

    Undoubtedly, Low-Altitude Unmanned Aerial Vehicles (UAVs) are becoming more common in marine applications. Equipped with a Global Navigation Satellite System (GNSS) Real-Time Kinematic (RTK) receiver for highly accurate positioning, they perform camera and Light Detection and Ranging (LiDAR) measurements. Unfortunately, these measurements may still be subject to large errors-mainly due to the inaccuracy of measurement of the optical axis of the camera or LiDAR sensor. Usually, UAVs use a small and light Inertial Navigation System (INS) with an angle measurement error of up to 0.5 deg. (RMSE). The methodology for spatial orientation angle correction presented in the article allows the reduction of this error even to the level of 0.01 deg. (RMSE). It can be successfully used in coastal and port waters. To determine the corrections, only the Electronic Navigational Chart (ENC) and an image of the coastline are needed.

  • Methodology of Selecting the Optimal Receptor to Create an Electrochemical Immunosensor for Equine Arteritis Virus Protein Detection
    • Mateusz Brodowski
    • Marcin Kowalski
    • Wioleta Białobrzeska
    • Katarzyna Pałka
    • Rafał Walkusz
    • Justyna Roguszczak
    • Tomasz Łęga
    • Marta Sosnowska
    • Małgorzata Biedulska
    • Joanna Kreczko Kurzawa
    • Ewelina Bięga
    • Joanna Wysocka
    • Marta Lisowska
    • Katarzyna Niedźwiedzka
    • Tomasz Lipiński
    • Sabina Żołędowska
    • Dawid Nidzworski
    2021 Full text Chemosensors

    The study reports a methodology of selecting the optimal receptor to create an electrochemical immunosensor for equine arteritis virus (EAV) protein detection. The detection was based on antigen recognition by antibodies immobilized on gold electrodes. Modification steps were controlled by electrochemical impedance spectroscopy and cyclic voltammetry measurements. In order to obtain the impedance immunosensor with the best parameters, seven different receptors complementary to equine arteritis virus protein were used. In order to make the selection, a rapid screening test was carried out to check the sensor’s response to blank, extremely low and high concentrations of target EAV protein, and negative sample: M protein from Streptococcus equi and glycoprotein G from Equid alphaherpesvirus 1. F6 10G receptor showed the best performance.

  • Methods of Determining Pressure Drop in Internal Channels of a Hydraulic Motor
    • Paweł Śliwiński
    • Piotr Patrosz
    2021 Full text ENERGIES

    In this paper, new methods for determining the pressure drop in internal channels of a hydraulic motor are proposed and described. Mathematical models of pressure losses in internal channels have also been described. Experimental tests of the satellite motor were carried out according to one of the proposed methods. The tests were carried out for two liquids, i.e., water and mineral oil. Experimental studies have shown that at a high flow rate in the motor supplied with water the pressure losses are a dozen or so percent greater than in the motor supplied with oil. However, at low flow rates is the inverse, that is, the pressure losses in the motor supplied with water are about ten percent lower than in the motor supplied with oil. The CFD calculation of the pressure drop in the internal channel of the motor was also conducted. It was assumed that holes in the commutation unit plate are placed face to face and that the liquid did not cause changes in the working chambers’ volume. In this way, it has been proven that those simplified assumptions can have up to a 50% difference in relation to the experimental tests.

  • Metoda doboru współczynników sztywności podpór mocujących podczas frezowania wielkogabarytowych przedmiotów podatnych z wykorzystaniem sterowania optymalnego w układzie semiaktywnym
    • Krzysztof Kaliński
    • Marek Galewski
    • Michał Mazur
    • Natalia Stawicka-Morawska
    2021

    W pracy zaproponowano nową metodę doboru w trybie on-line współczynników sztywności zamocowania wielkogabarytowego przedmiotu obrabianego do stołu frezarki, bazującą na koncepcji sterowania optymalnego przy energetycznym wskaźniku jakości w układzie we współrzędnych hybrydowych. Jednak znane z poprzednich opracowań autorskich równanie dynamiki wielowymiarowego układu sterowanego sprowadza się w tym przypadku do postaci, gdzie składowymi wektora sygnałów sterujących są chwilowe zmiany wartości współczynników sztywności podpór mocujących przedmiot. Wyznaczone w trybie on-line wartości współczynników sztywności, na bazie symulacji modelu obliczeniowego układu hybrydowego procesu frezowania, można następnie przybliżyć do tych wynikających z uprzedniego cechowania podpór. W proponowanej metodzie wykorzystano ponadto technikę sprzężenia modalnego, oraz zmodyfikowany energetyczny wskaźnik jakości (ZEWJ) uwzględniający energię pochodzącą od przyspieszeń drgań.

  • Metody bezpośrednie wykrywania przyczyn biokorozji
    • Edyta Malinowska-Pańczyk
    2021

    W rozdziale omówiono teoretyczne podstawy oznaczania najważniejszych grup drobnoustrojów powodujących biokorozję

  • METODY IDENTYFIKACJI STANÓW NIEZDATNOŚCI EKSPLOATACYJNEJ ŁOŻYSK TOCZNYCH W OKRĘTOWYCH UKŁADACH NAPĘDOWYCH Z WYKORZYSTANIEM METODY IMPULSÓW UDAROWYCH
    • Konrad Marszałkowski
    2021 Full text Journal of Polish CIMEEAC

    Rozpatrując okrętowe zespoły napędowe z punktu widzenia transmisji energii mechanicznej największym zagrożeniem dla ich niezawodności jest utrata stabilności układu mechanicznego, co zazwyczaj objawia się zwiększeniem amplitudy drgań mechanicznych. Zwiększeniu tych drgań towarzyszy wzrost amplitudy okresowo zmiennych naprężeń wewnętrznych co jest prostą i nieuniknioną drogą do uszkodzenia znajdujących się w tym układzie łożysk. W artykule przybliżono istotę metody impulsu udarowego służącej do diagnostyki łożysk tocznych jako alternatywę do szeroko stosowanej diagnostyki drganiowej.

  • Metrisability of managing of stream-systemic processes
    • Radosław Drozd
    • Jan Piwnik
    2021 Full text Organizacja i Zarządzanie : kwartalnik naukowy

    To achieve the planned goal, in order to properly describe the manufacturing system management, six process stream functions were introduced. Non-dimensional flows of these functions in time can be empirically defined during the manufacturing process. They are interpreted as non-dimensional expenses. Maximum values for these functions in properly-managed processes equal one. Also, a global management function was introduced, being a sum of areas of circle sections delineated by functions of the streams and their respective weights. Stream weights in the manufacturing process signify the processes’ roles and importance in the system. The paper also provides a vector representation of a manufacturing process as a sum of stream vectors with their associated weights.

  • Metrisable assessment of the course of stream‑systemic processes in vector form in industry 4.0
    • Radosław Drozd
    • Radosław Wolniak
    2021 Full text Quality and Quantity

    The goal of this paper is to present an innovative conception how to use metrisable vector structure of a manufacturing process, based on quantitative relations between the activity of input streams, features of the product, and effect of losses; all of which are excellent practical solution for Industry 4.0, and in turn intelligent factories. This solution can be a usefull way in the process of building sustainable organization. A vector representation of manufacturing processes was formulated, one which is based in system engineering. Three manufacturing system state vectors were proposed. These are: input stream vector ϕ ⃗, product features vector ( P) ⃗ which is also referred to as quality vector, and losses vector ( S) ⃗. Scalar, vector, and mixed products of these vectors may form constitutive equations of manufacturing processes. The relations between the vectors ϕ ⃗, ( P) ⃗ ,( S) ⃗ provide a possibility for a metrisable, complex analysis and assessment of a contemporary manufacturing process. The paper shows practical methods for defining the size of the vector values within the process. The demonstrated vector description of stream-systemic processes can also be applied to non-material manufacturing.

  • Mg2+ Doping Effects on the Structural and Dielectric Properties of CaCu3Ti4O12 Ceramics Obtained by Mechanochemical Synthesis
    • Piotr Dulian
    • Wojciech Bąk
    • Mateusz Piz
    • Barbara Garbarz-Glos
    • Olena V. Sachuk
    • Krystyna Wieczorek-Ciurowa
    • Agata Lisińska-Czekaj
    • Dionizy Czekaj
    2021 Full text Materials

    In this study, ceramic CaCu3Ti4O12 (CCTO) and CaCu3−xMgxTi4O12 solid solutions in which 0.1 ≤ x ≤ 0.5 were prepared by the mechanochemical method, realized by a high‐energy ball milling technique. The effects of the Mg2+ ion concentration and sintering time on the dielectric response in the prepared ceramics were investigated and discussed. It was demonstrated that, by the use of a sufficiently high energy of mechanochemical treatment, it is possible to produce a crystalline product after only 2 h of milling the mixture of the oxide substrates. Both the addition of magnesium ions and the longer sintering time of the mechanochemically‐produced ceramics cause excessive grain growth and significantly affect the dielectric properties of the materials. The X‐ray diffraction (XRD) analysis showed that all of the as‐prepared solid solutions, CaCu3−xMgxTi4O12 (0.0 ≤ x ≤ 0.5), regardless of the sintering time, exhibit a cubic perovskite single phase. The dielectric study showed two major contributions associated with the grains and the grain boundaries. The analysis of the electric modules of these ceramics confirmed the occurrence of Maxwell–Wagner type relaxation, which is dependent on the temperature.

  • MgPd2Sb : A Mg-based Heusler-type superconductor
    • Michał Winiarski
    • Gabriel Kuderowicz
    • Karolina Górnicka
    • Leszek Litzbarski
    • Kamila Stolecka
    • Bartlomiej Wiendlocha
    • R.j. Cava
    • Tomasz Klimczuk
    2021 Full text PHYSICAL REVIEW B

    We report the synthesis and physical properties of a full Heusler compound, MgPd2Sb, which we found toshow superconductivity belowTc=2.2K. MgPd2Sb was obtained by a two-step solid-state reaction methodand its purity and cubic crystal structure [Fm-3m,a=6.4523(1) Å] were confirmed by powder x-ray diffrac-tion. Normal and superconducting states were studied by electrical resistivity, magnetic susceptibility, andheat capacity measurements. The results show that MgPd2Sb is a type-II, weak coupling superconductor(λe-p=0.53). The observed pressure dependence ofTc(Tc/p≈–0.23 K/GPa) is one of the strongest reportedfor a superconducting Heusler compound. The electronic structure, phonons, and electron-phonon coupling inMgPd2Sb were theoretically investigated. The obtained results are in agreement with the experiment, confirmingthe electron-phonon coupling mechanism of superconductivity. We compare the superconducting parameters tothose of all reported Heusler-type superconductors.

  • Miasto w kontekście uchwał krajobrazowych
    • Magdalena Rembeza
    2021 Zawód: Architekt

    Krajobraz miejski jest zjawiskiem wizualnym, które oddaje charakter przestrzeni, a także określa jej tożsamość. Niestety, zagraża mu jednak powszechny chaos, przekładający się na negatywny wizerunek miasta. Za jedną z jego najistotniejszych przyczyn uznaje się ogromną liczbę reklam umieszczanych dowolnie w przestrzeni publicznej. Mimo że informacja wizualna stanowi nieodłączny element współczesnego miasta, istnieje głęboka potrzeba regulacji tych interwencji. Wraz z wejściem w życie ustawy gminy uzyskały kompetencje do wprowadzenia uchwały będącej aktem prawa miejscowego w sprawie lokalizacji reklam, obiektów małej architektury oraz ogrodzeń. Jednym z pierwszych miast, które zdecydowało się na sporządzenie i uchwalenie takiego dokumentu była Łódź. Za jej przykładem poszły inne, wśród których szczególnym przypadkiem jest Gdańsk.

  • Microbial and chemical quality assessment of the small rivers entering the South Baltic. Part I: Case study on the watercourses in the Baltic Sea catchment area
    • Emilia Bączkowska
    • Agnieszka Kalinowska
    • Oskar Ronda
    • Katarzyna Jankowska
    • Rafał Bray
    • Bartosz Płóciennik
    • Żaneta Polkowska
    2021 Full text Archives of Environmental Protection

    The area of the Coastal Landscape Park (CLP) due to its location is extremely attractive touristic area. In the summer season, a significant increase in population density is observed, which influences surface water quality. Large numbers of tourists generate an increased amount of municipal wastewater, being treated in local treatment plants and discharged into rivers and streams. The paper presents preliminary research from summer 2016 on three watercourses ending in the Baltic Sea: Piaśnica, Karwianka and Czarna Wda rivers. It is a part of a long-term project conducted in CLP to assess surface waters quality. The scope of research included measurements of in situ parameters (temperature, conductivity, pH, dissolved oxygen). Chemical Oxygen Demand was determined using a spectrophotometer. Ion chromatography was used to determine ions concentrations (including biogenic compounds). Sanitary state of watercourses was assessed based on fecal coliforms abundance, which number was determined by the cultivation method. The determination of microbiological parameters such as: prokaryotic cell abundance expressed as total cells number (TCN), prokaryotic cell biovolume expressed as average cell volume (ACV), the prokaryotic biomass (PB) and prokaryotic cell morphotype diversity was determined using epifluorescence microscopy method. Results showed that water quality of Piaśnica and Czarna Wda rivers were affected by discharged treated wastewater. In the case of Karwianka River, the main pollution source could be surface runoff from fields and unregulated sewage management in this area. The conducted research confirmed the urgent need for better protection of this area to conserve both its ecosystem and value for tourism.

  • Micro-modelling of shear localization during quasi-static confined granular flow in silos using DEM
    • Aleksander Grabowski
    • Michał Nitka
    • Andrzej Tejchman-Konarzewski
    2021 COMPUTERS AND GEOTECHNICS

    The paper deals with the quasi-static confined flow of cohesionless sand in a plane strain model silo with parallel walls and a slowly movable bottom. Numerical modelling was carried out by the discrete element method (DEM) using spheres with contact moments to approximately capture a non-uniform shape of sand particles. Different initial void ratios of sand and silo wall roughness grades were employed. Regular triangular grooves (asperities) with the same inclination and a different height were used to describe the varying wall surface topography. The emphasis was on the formation and evolution of both wall and internal shear zones during sand flow. DEM simulation outcomes were compared with corresponding model experiments and theoretical solutions. In addition, the particle displacements, particle rotations, normal contact forces, void ratios and wall stresses were evaluated. The numerical findings enhance the understanding of shear localization at the grain level during confined flow in silos and its strong impact on the magnitude, distribution and oscillation of wall stresses.

  • Microsphere structure application for supercapacitor in situ temperature monitoring
    • Paulina Listewnik
    • Mikhael Bechelany
    • Małgorzata Szczerska
    2021 Full text SMART MATERIALS & STRUCTURES

    Constant, real-time temperature monitoring of the supercapacitors for efficient energy usage is in high demand and seems to be crucial for further development of those elements. A fiber-optic sensor can be an effective optoelectronic device dedicated for in-situ temperature monitoring of supercapacitors. In this work, the application of the fiber-optic microstrucutre with thin zinc oxide (ZnO) coating fabricated in the atomic layer deposition process applied as a temperature sensor is reported. Such a structure was integrated with supercapacitors and used for the temperature measurements. Described sensors are built with the utility of the standard optical telecommunication fibers. The inner temperature of the supercapacitor was investigated in the range extending from 30 °C to 90 °C with a resolution equal to 5 °C. The sensitivity of temperature measurement is about 109.6 nW °C−1. The fitting of the sensor was achieved with a correlation coefficient R2 = 0.97.

  • Microstructural Design of Ba0.5La0.5Co0.5Fe0.5O3 Perovskite Ceramics
    • Daria Gierszewska
    • Iga Szpunar
    • Francis Oseko
    • Joanna Pośpiech
    • Małgorzata Nadolska
    • Martyna Pieragowska
    • Karolina Reniecka
    • Kinga Waniek
    • Karol Leszczyński
    • Aleksandra Mielewczyk-Gryń
    • Maria Gazda
    • Sebastian Wachowski
    2021 Full text Materials

    Ba0.5La0.5Co0.5Fe0.5O3 was synthesized in the solid-state reaction route. The influence of ball milling parameters (such as milling media size, angular velocity, and time), pelletizing pressure, and annealing parameters on the microstructure was studied. The grain size distribution and density or specific surface area changes were investigated in each approach while the individual parameters were changed. The evaluation of BLCF synthesis parameters enables tailoring the microstructure to various applications. It was observed that with lowering the size of milling balls and increasing the angular velocity the material will be porous and thus more appropriate as electrode material in proton ceramic fuel cell or electrolyzer. An increase of time, balls diameter, and/or angular velocity of milling enables one to densify the material in case of membrane application in, e.g., as a gas sensor. The significant influence on densification has also annealing temperature increase. Applying 1200 C during annealing leads to dense material, while at 1100 C shows visible porosity of the product. In this work, we present the results of the BLCF synthesis parameters change allowing the selection of appropriate parameter values depending on the further application as PCCs.

  • Microstructure and mechanical properties of laser surface-treated Ti13nb13zr alloy with MWCNTs coatings
    • Beata Majkowska-Marzec
    • Joanna Sypniewska
    2021 Full text Advances in Materials Science

    Laser surface modification of titanium alloys is one of the main methods of improving the properties of titanium alloys used in implantology. This study investigates the microstructural morphology of a laser-modified surface layer on a Ti13Nb13Zr alloy with and without a carbon nanotube coating deposited by electrophoretic deposition. Laser modification was performed for samples with and without carbon nanotube coating for two different laser powers of 800 W and 900 W and for different scan rates: 3 mm/s or 6 mm/s at 25 Hz, and the pulse duration was 2.25 ms or 3.25 ms. A scanning electron microscope SEM was used to evaluate the surface structure of the modified samples. To observe the heat-affected zones of the individual samples, metallographic samples were taken and observed under an optical microscope. Surface wettability tests were performed using a goniometer. A surface roughness test using a profilograph and a nanoindentation test by NanoTest™ Vantage was also performed. Observations of the microstructure allowed to state that for higher laser powers the surfaces of the samples are more homogeneous without defects, while for lower laser powers the path of the laser beam is clearer and more regular. Examination of the microstructure of the cross-sections indicated that the samples on which the carbon nanotube coating was deposited are characterized by a wider heat affected zone, and for the samples modified at 800 W and a feed rate of 3 mm/s the widest heat affected zone is observed. The wettability tests revealed that all the samples exhibit hydrophilic surfaces and the samples with deposited carbon nanotube coating increase it further. Surface roughness testing showed a significant increase in Ra for the laser-modified samples, and the presence of carbon nanotubes further increased this value. Nanoindentation studies showed that the laser modification and the presence of carbon coating improved the mechanical properties of the samples due to their strength.

  • Microstructure and Properties of Electroless Ni-P/Si3N4 Nanocomposite Coatings Deposited on the AW-7075 Aluminum Alloy
    • Kazimierz Czapczyk
    • Paweł Zawadzki
    • Natalia Wierzbicka
    • Rafał Talar
    2021 Full text Materials

    The article presents the results of mechanical and tribological tests of Ni-P/Si3N4 nanocomposite coatings deposited on the AW-7075 aluminum alloy using the chemical reduction method. The influence of the chemical composition on the Vickers microhardness determined by the DSI method was examined. The nanocomposite layers were made of Si3N4 silicon nitride in a polydisperse powder with a particle size ranging from 20 to 25 nm. The influence of the content of the dispersion layer material on the adhesion to the substrate was analyzed. The abrasive wear was tested and determined in the reciprocating motion using the “ball-on-flat” method. The surface topography was examined by the contact method with the use of a profilometer. Based on the obtained test results, it was found that the Ni-P/Si3N4 layers produced in the bath with the Si3N4 nanoparticle content in the amount of 2 g/dm3 are more resistant to wear and show greater adhesion than the Ni-P/Si3N4 layers deposited in the bath with 5 g/dm3 of the dispersion phase. NiP/Si3N4 layers provide protection against abrasive wear under various loads and environmental conditions.

  • Międzynarodowy Projekt "Walizka". Galeria R+ Akademia Sztuki w Szczecinie
    • Dominika Krechowicz
    2021

    Projekt "Walizka", koncepcja: prof. dr hab. Zbigniew Szot Uniwersytet Artystyczny w Poznaniu, Wydział Malarstwa i Rysunku. W projekcie wzięło udział 23 artystów z Polski oraz z Czech, Niemiec, Gruzji I Japonii. Koncepcja projektu dotyczy szeroko pojętego tematu podróży. W obecnych czasach zagrożenia COVID-19 słowo „podróż” zaczyna nabierać zupełnie innego znaczenia. Żyjąc i tworząc w izolacji od wielu miesięcy, została stworzona wspólnie autonomiczna kolekcja prac, dedykowanych tylko tej walizce, która teraz jest wysyłana w podróż. Prace i walizka stanowią nierozłączną całość. Koncepcją projektu jest zaprezentowanie prac w wybranych miejscach oraz pozostawienie swojego znaku na wieku walizki. Wystawa została zaprezentowana w terminie 17-28.05.2021 w Galerii R+ w Akademii Sztuki w Szczecinie. Adres: plac Orła Białego 2, 70-562 Szczecin kurator wystawy: prof.dr hab.Zbigniew Szot

  • Międzynarodowy Projekt Walizka. Wystawa w Galerii Feininger. Trzebiatów
    • Dominika Krechowicz
    2021

    Projekt "Walizka", koncepcja: prof. dr hab. Zbigniew Szot Uniwersytet Artystyczny w Poznaniu, Wydział Malarstwa i Rysunku. W projekcie wzięło udział 23 artystów z Polski oraz z Czech, Niemiec, Gruzji I Japonii. Koncepcja projektu dotyczy szeroko pojętego tematu podróży. W obecnych czasach zagrożenia COVID-19 słowo „podróż” zaczyna nabierać zupełnie innego znaczenia. Żyjąc i tworząc w izolacji od wielu miesięcy, została stworzona wspólnie autonomiczna kolekcja prac, dedykowanych tylko tej walizce, która teraz jest wysyłana w podróż. Prace i walizka stanowią nierozłączną całość. Koncepcją projektu jest zaprezentowanie prac w wybranych miejscach oraz pozostawienie swojego znaku na wieku walizki. Wystawa została zaprezentowana w terminie 3 - 28 lipca 2021 w Galerii Feininger, w Trzebiatowskim Ośrodku Kultury w Trzebiatowie kurator wystawy: prof.dr hab.Zbigniew Szot

  • Migration of container terminals as their natural process of evolution: Case study of Gdańsk and Gdynia ports
    • Karolina Krośnicka
    2021 Full text Journal of Transport Geography

    The paper proposes a theoretical model of container terminals and container port development, based on the life cycle theory, threshold theory and catastrophe theory, and in references to Kuznets' swings (interpreted as waves of infrastructural investments), and Kondratiev long economic waves. The aim of this model is to explain the development process of a container terminal and a port within one technological generation, as well as in intergenerational configuration, and relate it to the migration process of container terminals in the scale of a port-city urban area. Then, the applicability of this model was checked in the case of the container ports in Gdynia and Gdańsk (Poland). The analysed evolution process of ports of Gdynia and Gdańsk conforms with the proposed theoretical model, proving that the migration of container terminals within these ports is a part of their natural process of evolution, being a consequence of their threshold development and location splitting. Considering the physical location of development investments within the container ports of Gdańsk and Gdynia, it was noticed that there are two basic directions of migration of container terminals. One is the migration of the port's main container activity (core terminal or terminals), being a result of a generational change taking place after overcoming the maturity point. The second type of migration is connected with dispersion of port development investments in the increasingly distant port hinterland, caused by the need of the life extension of terminals within one technological generation. In an analogy to the processes of development of living organisms, we can treat the migration of terminal outsourced functions as a “vegetative” increase, being an attempt to extend the life of the terminal, while the migration of the core terminal within the port area (erecting a new generation terminal) can be treated as “generative” growth.

  • Mild poikilocapnic hypoxia increases very low frequency haemoglobin oxygenation oscillations in prefrontal cortex
    • Agnieszka Gruszecka
    • Monika Waskow
    • Marta A. Malkiewicz
    • J Neary
    • Jyotpal Singh
    • Taylor Teckchandani
    • Gregory Kratzig
    • Magdalena Wszedybyl-Winklewska
    • Andrzej F. Frydrychowski
    • Jacek Rumiński
    • Natalia Głowacka
    • Piotr Lass
    • Pawel Winklewski
    • Marcin Gruszecki
    2021 Full text BIOLOGICAL RESEARCH

    Background: The aim of the study was to investigate the effect of mild cerebral hypoxia on haemoglobin oxygenation(HbO2), cerebrospinal fluid dynamics and cardiovascular physiology. To achieve this goal, four signals were recorded simultaneously: blood pressure, heart rate / electrocardiogram, HbO2 from right hemisphere and changes of subarachnoid space (SAS) width from left hemisphere. Signals were registered from 30 healthy, young participants (2 females and 28 males, body mass index = 24.5 ± 2.3 kg/m2, age 30.8 ± 13.4 years). Results: We analysed the recorded signals using wavelet transform and phase coherence. We demonstrated for the first time that in healthy subjects exposed to mild poikilokapnic hypoxia there were increases in very low frequency HbO2 oscillations (< 0.052 Hz) in prefrontal cortex. Additionally, SAS fluctuation diminished in the whole frequency range which could be explained by brain oedema. Conclusions: Consequently the study provides insight into mechanisms governing brain response to a mild hypoxic challenge. Our study supports the notion that HbO2 and SAS width monitoring might be beneficial for patients with acute lung disease.

  • Mild X-linked Alport syndrome due to the COL4A5 G624D variant originating in the Middle Ages is predominant in Central/East Europe and causes kidney failure in midlife
    • Aleksandra M. Żurowska
    • Olga Bielska
    • Patrycja Daca-Roszak
    • Maciej Jankowski
    • Maria Szczepańska
    • Dagmara Roszkowska-Bjanid
    • Elżbieta Kuźma-Mroczkowska
    • Małgorzata Pańczyk-Tomaszewska
    • Anna Moczulska
    • Dorota Drożdż
    • Despina Hadjipanagi
    • Constantinos Deltas
    • Danuta Ostalska-Nowicka
    • Alina Rabiega
    • Janina Taraszkiewicz
    • Katarzyna Taranta-Janusz
    • Anna Wieczorkiewicz-Plaza
    • Katarzyna Jobs
    • Judyta Mews
    • Kinga Musiał
    • Anna Jakubowska
    • Hanna Nosek
    • Anna E. Jander
    • Constantina Koutsofti
    • Anna Stanisławska-Sachadyn
    • Dominka Kuleszo
    • Ewa Ziętkiewicz
    • Beata S. Lipska-Ziętkiewicz
    2021 Full text KIDNEY INTERNATIONAL

    A study of 269 children enrolled into a National Registry for children with persistent glomerular hematuria identified 131 individuals with genetically confirmed X-linked Alport Syndrome. A single variant c.1871G>A p.Gly624Asp (G624D) in COL4A5 was predominant and accounted for 39% of Xlinked Alport Syndrome in unrelated Polish families (44 of 113). To evaluate its origins, the genetic variation in a 2.79 Mb segment encompassing the COL4A5 locus on chromosome X was assessed. All G624D alleles were found on the same rare haplotype background, indicating a founder effect dating back to the 12-13th century. The phenotypic data of 131 children with X-linked Alport Syndrome and their 195 affected adult relatives revealed that the G624D variant was associated with a significantly milder clinical course in comparison to other pathogenic COL4A5 variants. Furthermore the clinical course of this genetically uniform cohort was milder than that observed in individuals with other COL4A5 missense mutations. In spite of the benign clinical manifestation throughout childhood and early adulthood, the G624D variant confers significant risk for both kidney failure and deafness in males, albeit 20-30 years later than that observed in individuals with other COL4A5 pathogenic variants (50% cumulative risk of starting dialysis at 54 years (95% confidence interval: 50-62) v. 26 years (95% confidence interval: 22-30)). Thus, males with G624D are candidates for existing and emerging therapies for Alport Syndrome.

  • Mini-Cave Automatic Virtual Environment Application in Security, Safety, and Defence Studies
    • Małgorzata Gawlik-Kobylińska
    • Paweł Maciejewski
    • Jacek Lebiedź
    2021

    The aim of the article is to analyse the use of mini-Cave Automatic Virtual Reality Environment (mini-CAVE) in academic studies on security, safety, and defence. The literature review based on Web of Science database and the case study of the War Studies University research activities indicated the mini-CAVE can be used in two areas as a research infrastructure and as a didactic tool. It can be concluded that due to the development of virtual reality worlds, the application of the mini-CAVE supports research and didactics activities, specifically in creating 3D scenarios for teaching concepts and processes, and simulating situations related to saving life and health.

  • Minichannel and minigap classification criteria based on the aspect ratio of the minigeometry: A numerical study
    • Paweł Dąbrowski
    • Ritunesh Kumar
    2021 Full text INTERNATIONAL COMMUNICATIONS IN HEAT AND MASS TRANSFER

    A detailed numerical investigation has been carried out to analyze the diabatic flow distribution and velocity profile in 18 minigeometries with various aspect ratios for V-type and I-type flow configurations (for 36 cases) assuming ethanol as a working fluid. The aim of the study is to distinguish the value of the aspect ratio for which the flow in minigeometry starts to be two-dimensional (minigap). Cases with a constant Reynolds number of 4167 (variable mass flow rate) were compared. The normalized velocity profiles over the normalized width of the minigeometry acquired from the simulation have been compared with the theoretically calculated profiles based on the one-seventh power-law and turbulent flow theory. The results show that the one-seventh power-law velocity profiles are not consistent with the profiles simulated at an aspect ratio greater than 7. A new correlation for normalized velocity profile incorporating aspect ratio of the minigeometry for minigaps has been proposed. The conclusions are independent of the geometry depth, working fluid, and flow configuration.

  • Minimizing Greenhouse Gas Emissions From Ships Using a Pareto Multi-Objective Optimization Approach
    • Zygfryd Domachowski
    2021 Full text Polish Maritime Research

    To confront climate change, decarbonization strategies must change the global economy. According to statements made as part of the European Green Deal, maritime transport should also become drastically less polluting. As a result, the price of transport must reflect the impact it has on the environment and on health. In such a framework, the purpose of this paper is to suggest a novel method for minimizing emissions from ships, based on so-called Pareto multi-objective optimization. For a given voyage by a ship, the problem is to minimize emissions on the one hand and minimize fuel consumption or passage time on the other. Minimizing emissions is considered as the preferred objective. Therefore, the objective of minimizing fuel consumption or passage time needs to be reformulated as a constraint. Solving such a problem consists of finding most favourable path and speed for the ship and satisfying the optimization criteria. Relatively new systems such as hybrid diesel–electric systems have the potential to offer significant emissions benefits. A hybrid power supply utilizes the maximum efficiency of the direct mechanical drive and the flexibility of a combination of combustion power from the prime mover and stored power from energy storage from an electrical supply, at part load and overload. A new report by the American Bureau of Shipping suggests that maritime transport is likely to meet the International Maritime Organization’s target by 2030, solely by using current technology and operational measures. However, this would not be enough to attain the target of reducing CO2 emissions by 2050 by at least 50% compared to 2008. New technologies and operational methods must be applied.