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Gdańsk University of Technology

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  • The Influence of Loop Heat Pipe Evaporator Porous Structure Parameters and Charge on Its Effectiveness for Ethanol and Water as Working Fluids
    • Krzysztof Błauciak
    • Paweł Szymański
    • Dariusz Mikielewicz
    2021 Full text Materials

    Abstract: This paper presents the results of experiments carried out on a specially designed experimental rig designed for the study of capillary pressure generated in the Loop Heat Pipe (LHP) evaporator. The commercially available porous structure made of sintered stainless steel constitutes the wick. Three different geometries of the porous wicks were tested, featuring the pore radius of 1, 3 and 7 um. Ethanol and water as two different working fluids were tested at three different evaporator temperatures and three different installation charges. The paper firstly presents distributions of generated pressure in the LHP, indicating that the capillary pressure difference is generated in the porous structure. When installing with a wick that has a pore size of 1 um and water as a working fluid, the pressure difference can reach up to 2.5 kPa at the installation charge of 65 mL. When installing with a wick that has a pore size of 1 um and ethanol as a working fluid, the pressure difference can reach up to 2.1 kPa at the installation charge of 65 mL. The integral characteristics of the LHP were developed, namely, the mass flow rate vs. applied heat flux for both fluids. The results show that water offers larger pressure differences for developing the capillary pressure effect in the installation in comparison to ethanol. Additionally, this research presents the feasibility of manufacturing inexpensive LHPs with filter medium as a wick material and its influence on the LHP’s thermal performance.

  • The Influence of Nanometals, Dispersed in the Electrophoretic Nanohydroxyapatite Coatings on the Ti13Zr13Nb Alloy, on Their Morphology and Mechanical Properties
    • Michał Bartmański
    • Łukasz Pawłowski
    • Aleksandra Mielewczyk-Gryń
    • Gabriel Strugała
    • Krzysztof Rokosz
    • Sofia Gaiaschi
    • Patrick Chapon
    • Steinar Raaen
    • Andrzej Zieliński
    2021 Full text Materials

    In this work, nanohydroxyapatite coatings with nanosilver and nanocopper have been fabricated and studied. The presented results concern coatings with a chemical composition that has never been proposed before. The present research aims to characterize the effects of nanosilver and nanocopper, dispersed in nanohydroxyapatite coatings and deposited on a new, non-toxic Ti13Zr13Nb alloy, on the physical and mechanical properties of coatings. The coatings were obtained by a one-stage electrophoretic process. The surface topography, and the chemical and phase compositions of coatings were examined with scanning electron microscopy, atomic force microscopy, X-ray diffractometry, glow discharge optical emission spectroscopy, and energy-dispersive X-ray spectroscopy. The mechanical properties of coatings were determined by nanoindentation tests, while coatings adhesion was determined by nanoscratch tests. The results demonstrate that copper addition increases the hardness and adhesion. The presence of nanosilver has no significant influence on the adhesion of coatings.

  • The influence of selected strain-based failure criteria on ship structure damage resulting from a collision with an offshore wind turbine monopile
    • Karol Niklas
    • Alicja Bera
    2021 Full text Polish Maritime Research

    Offshore wind farms are developing well all over the world, providing green energy from renewable sources. The evaluation of possible consequences of a collision involves Finite Element computer simulations. The goal of this paper was to analyse the influence of selected strain-based failure criteria on ship damage resulting from a collision with an offshore wind turbine monopile. The case of a collision between an offshore supply vessel and a monopile-type support structure was examined. The results imply that simulation assumptions, especially the failure criteria, are very important. It was found that, using the strain failure criteria according to the minimum values required by the design rules, can lead to an underestimation of the ship damage by as much as 6 times, for the length of the hull plate, and 9 times, for the area of the ship hull opening. Instead, the adjusted formula should be used, taking into account both the FE element size and the shell thickness. The influence of the non-linear representation of the stress-strain curve was also pointed out. Moreover, a significant influence of the selected steel grade on collision damages was found.

  • The influence of the basic conditions of the forced feed of abrasive compound on the roughness of flat ceramic elements after lapping.
    • Adam Barylski
    • Maciej Gniot
    2021 Technologia i Automatyzacja Montażu

    W docieraniu standardowym zawiesina ścierna dostarczana jest do strefy obróbki w sposób ciągły - zalewowo lub kroplowo, co generuje duże straty ścierniwa. W artykule opisano innowacyjny system dozowania i nanoszenia zawiesiny ściernej na powierzchnię żeliwnego docieraka tarczowego, który eliminuje tą wadę. W przeprowadzonych eksperymentach badano wpływ procentowej zawartości ziaren ściernych w nośniku oraz wielkość dawki zawiesiny i lepkości nośnika płynnego na wartości poszczególnych parametrów chropowatości powierzchni docieranych elementów ceramicznych. Docieranie jest jedna z technologii stosowanej w montażu zespołów podczas zastosowania kompensacji technologicznej lb przy indywidualnym dopasowaniu składanych elementów.

  • The influence of the grid density of measurement points on damage detection in an isotropic plate by the use of elastic waves and laser scanning Doppler vibrometry
    • Łukasz Doliński
    • Marek Krawczuk
    • Magdalena Palacz
    • Wiktor Waszkowiak
    • Arkadiusz Żak
    2021 Full text SENSORS

    Damage detection in structural components, especially in mechanical engineering, is an 2 important element of engineering practice. There are many methods of damage detection, in which 3 changes in various parameters caused by the presence of damage are analysed. Recently, methods 4 based on the analysis of changes in dynamic parameters of structures, i.e. frequencies or mode shapes 5 of natural vibrations, as well as changes in propagating elastic waves, have been developed at the 6 highest rate. Diagnostic methods based on the elastic wave propagation phenomenon are becoming 7 more and more popular, therefore it is worth to focus on the improvement of the efficiency of these 8 methods. Hence, a question arises whether it is possible to shorten the required measurement time 9 without affecting the sensitivity of the diagnostic method used. This paper discusses the results 10 of research carried out by the authors in this regard both numerically and experimentally. The 11 numerical analysis has been carried out by the use of the Time-domain Spectral Finite Element 12 Method (TD-SFEM), whereas the experimental part has been based on the measurement performed 13 by 1-D Laser Doppler Scanning Vibrometery (LDSV).

  • The influence of the type of halogen substituent and its position on the molecular conformation, intermolecular interactions and crystal packing for a series of 1-benzoyl-3-(halogenophenyl)thioureas
    • Damian Rosiak
    • Andrzej Okuniewski
    • Jarosław Chojnacki
    2021 Full text Acta Crystallographica Section C-Structural Chemistry

    By the reaction of benzoyl chloride, potassium isothiocyanate and the appropriate halogenoaniline, i.e. 2/3/4-(bromo/iodo)aniline, we have obtained five new 1-benzoyl-3-(halogenophenyl)thioureas, namely, 1-benzoyl-3-(2-bromophenyl)- thiourea and 1-benzoyl-3-(3-bromophenyl)thiourea, C14H11BrN2OS, and 1-benzoyl-3-(2-iodophenyl)thiourea, 1-benzoyl-3-(3-iodophenyl)thiourea and 1-benzoyl-3-(4-iodophenyl)thiourea, C14H11IN2OS. Structural and conformational features of the compounds have been analyzed using X-ray diffraction and theoretical calculations. The novel compounds were characterized by solid-state IR and 1H/13C NMR spectroscopy. The conformations and intermolecular interactions, such as hydrogen bonds, pi–pi and S(6)... pi stacking, and X...O (X = Br or I) , I...S and I...pi, have been examined and rationalized, together with four analogous compounds described previously in the literature. The set of nine compounds was chosen to examine how a change of the halogen atom and its position on the phenyl ring affects the molecular and crystal structures.

  • The Influence of Tool Shape and Process Parameters on the Mechanical Properties of AW-3004 Aluminium Alloy Friction Stir Welded Joints
    • Anna Janeczek
    • Jacek Tomków
    • Dariusz Fydrych
    2021 Full text Materials

    The purpose of the following study was to compare the effect of the shape of a tool onthe joint and to obtain the values of Friction Stir Welding (FSW) parameters that provide the bestpossible joint quality. The material used was an aluminium alloy, EN AW-3004 (AlMn1Mg1). To theauthors’ best knowledge, no investigations of this alloy during FSW have been presented earlier. Fivebutt joints were made with a self-developed, cylindrical, and tapered threaded tool with a rotationalspeed of 475 rpm. In order to compare the welding parameters, two more joints with a rotationalspeed of 475 rpm and seven joints with a welding speed of 300 mm/min with the use of a cylindricalthreaded pin were performed. This involved a visual inspection as well as a tensile strength test ofthe welded joints. It was observed that the value of the material outflow for the joints made withthe cylindrical threaded pin was higher than it was for the joints made with the tapered threadedpin. However, welding defects in the form of voids appeared in the joints made with the taperedthreaded tool. The use of the cylindrical tool resulted in higher values for about 37% of mechanicalproperties compared with the highest result for the tapered threaded joint. As far as the parameterswere concerned, it was concluded that most of the specimens were properly joined for a rotationalspeed of 475 rpm. In the joints made with a welding speed of 300 mm/min, the material was notstirred properly. The best joint quality was given for a rotational speed of 475 rpm as well as a varietyof welding speed values between 150 and 475 mm/min.

  • The Influence of Water and Mineral Oil on Pressure Losses in Hydraulic Motor
    • Paweł Śliwiński
    • Piotr Patrosz
    2021

    In this paper, pressure losses in hydraulic motor supplied with water and mineral oil (two liquids that have significantly different viscosity and lubricating properties) are described and compared. The experimental tests were conducted using a hydraulic satellite motor that is dedicated to working with different liquids, including water. The methodology of measuring the pressure drop in internal channels of this motor is also described. The known mathematical formulas describing the pressure losses in the internal channels are presented also. Experimental studies have shown that a high flow rate in the motor causes the pressure losses in the motor supplied with water to be several percent greater than the pressure losses in the motor supplied with oil. However, low flow rates cause the pressure losses in the motor supplied with water to be about ten percent lower than the pressure losses in the motor supplied with oil. Furthermore, when the volume of the working chamber nears the minimum, additional pressure increase caused by compression of liquid occurs in this chamber.

  • The Interaction of Heptakis (2,6-di-O-Methyl)-β-Cyclodextrin with Mianserin Hydrochloride and Its Influence on the Drug Toxicity
    • Sylwia Belica-Pacha
    • Magdalena Małecka
    • Mateusz Daśko
    • Katarzyna Miłowska
    • Maria Bryszewska
    • Grażyna Budryn
    • Joanna Oracz
    • Bartłomiej Pałecz
    2021 Full text INTERNATIONAL JOURNAL OF MOLECULAR SCIENCES

    One tetracyclic antidepressant, mianserin hydrochloride (MIA), has quite significant side effects on a patients’ health. Cyclodextrins, which are most commonly used to reduce the undesirable features of contained drugs within their hydrophobic interior, also have the potential to alter the toxic behavior of the drug. The present paper contains investigations and the characteristics of interaction mechanisms for MIA and the heptakis (2,6-di-O-methyl)-β-cyclodextrin (DM-β-CD) system, and evaluated the effects of the complexation on MIA cytotoxicity. In order to assess whether there was an interaction between MIA and DM-β-CD molecules, isothermal titration calorimetry (ITC) have been chosen. Electrospray ionization mass spectrometry (ESI-MS) helped to establish the complex stoichiometry, and circular dichroism spectroscopy was used to describe the process of complex formation. In order to make a wider interpretative perspective, the molecular docking results have been performed. The viability of Chinese hamster cells were investigated in the presence of DM-β-CD and its complexes with MIA in order to estimate the cytotoxicity of the drug and the conjugate with the chosen cyclodextrin. The viability of B14 cells treated with MIA+DM-β-CD is lower (the toxicity is higher) than with MIA alone, and no protective effects have been observed for complexes of MIA with DM-β-CD in any ratio.

  • The interaction of the pulsed laser irradiation with titania nanotubes - Theoretical studies on the thermal effect
    • Piotr Kupracz
    • Katarzyna Grochowska
    • Jakub Wawrzyniak
    • Katarzyna Siuzdak
    2021 INTERNATIONAL JOURNAL OF THERMAL SCIENCES

    This paper reports temperature dispersion simulations of titania nanotubes irradiated by the 355 nm, pulsed, nanosecond laser. The modelling with the use of Finite Elements Method concerns titania nanotubes of the length and the wall thickness in the range of 0.5–2 μm and 5–20 nm, respectively. The uniqueness of the morphology was preserved by ensuring the wall thickness variation along the height of the tube, which was determined by an exponential equation. The easily adapted model of optical transition under the heat treatment in vacuum was successfully introduced. According to the obtained results, the change in titania nanotube shape and formation of the doping centres during laser annealing are crucial to accurately reproduce the temperature distribution along the nanotubes. The temperature profiles suggest that treatment with a fluence of 25 mJ cm−2 at 355 nm wavelength may lead to the re-solidification of the nanotubes surface only, if their wall is thinner than 15 nm. Such simulations are reported for the first time and are important for the understanding of thermal transport in nanomaterials with highly ordered, tubular architecture.

  • The Issue of Shading Photovoltaic Installation Caused by Dust Accumulation on the Glass Surface
    • Małgorzata Rudnicka
    • Ewa Klugmann-Radziemska
    2021 Full text Ecological Chemistry and Engineering S - Chemia i Inżynieria Ekologiczna S

    The issue of accumulation of dust and other pollutants on the surface of photovoltaic modules was thoroughly analysed over the years. One of the first surveys in this field of knowledge linked pollutant accumulation on the module surface with transmittance loss of its glass covering, which leads to lessened amount of solar radiation reaching solar cells. First stage of this accumulation process is linear transparency loss, and second stage - molecule agglomeration and settlement some grains on the already existing layer of dust. Additionally, the pace of working parameters reduction for photovoltaic installation is influenced by the type of dust itself. Molecules with smaller grains cover the surface much more densely, therefore limiting the amount of light passing though the top glass layer far more than molecules with bigger grains. The aim of the carried out study was to find the relationship between dust surface density and change in electrical parameters. Such approach makes it possible to compare electrical and physical parameters of different photovoltaic modules. Additionally, glass coverage itself was noted to have a significant impact on the overall decrease in working parameters of PV modules.

  • The law of the Iterated Logarithm for random interval homeomorphisms
    • Klaudiusz Czudek
    • Tomasz Szarek
    • Hanna Wojewódka-Ściążko
    2021 Full text ISRAEL JOURNAL OF MATHEMATICS

    A proof of the law of the iterated logarithm for random homeomorphisms of the interval is given.

  • The Many Faces of Enterococcus spp.—Commensal, Probiotic and Opportunistic Pathogen
    • Beata Krawczyk
    • Paweł Wityk
    • Mirosława Gałęcka
    • Michał Michalik
    2021 Full text Microorganisms

    Enterococcus spp. are Gram-positive, facultative, anaerobic cocci, which are found in the intestinal flora and, less frequently, in the vagina or mouth. Enterococcus faecalis and Enterococcus faecium are the most common species found in humans. As commensals, enterococci colonize the digestive system and participate in the modulation of the immune system in humans and animals. For many years reference enterococcal strains have been used as probiotic food additives or have been recommended as supplements for the treatment of intestinal dysbiosis and other conditions. The use of Enterococcus strains as probiotics has recently become controversial due to the ease of acquiring different virulence factors and resistance to various classes of antibiotics. Enterococci are also seen as opportunistic pathogens. This problem is especially relevant in hospital environments, where enterococcal outbreaks often occur. Their ability to translocate from the gastro-intestinal tract to various tissues and organs as well as their virulence and antibiotic resistance are risk factors that hinder eradication. Due to numerous reports on the plasticity of the enterococcal genome and the acquisition of pathogenic microbial features, we ask ourselves, how far is this commensal genus from acquiring pathogenicity? This paper discusses both the beneficial properties of these micro-organisms and the risk factors related to their evolution towards pathogenicity.

  • The Matter of Decision-Making Control Over Operation Processes of Marine Power Plant Systems with the Use of their Models in the form of Semi-Markov Decision-Making Processes
    • Jerzy Girtler
    • Jacek Rudnicki
    2021 Full text Polish Maritime Research

    The article presents the possibility to control the real operation process of an arbitrary device installed in the marine power plant based on the four-state semi-Markov process, being the model of the process, which describes the transition process of operational states of the device and the transition process of its technical states. All these states are precisely defined for the ship main engine (SG). A hypothesis is proposed which justifies the use of this model to examine real state transitions in marine power plant device operation processes. The article shows the possibility to make operating decisions ensuring a rational course of the device operation process when the proposed model of this process and the dynamic programming method based on the Bellman’s principle of optimality are applied. The optimisation criterion adopted when making operating decisions is the expected profit to be gained as a result of functioning of the device in the time interval , being the sum of the expected profit gained in interval and to be gained in interval.

  • The microbial community, its biochemical potential, and the antimicrobial resistance of Enterococcus spp. in Arctic lakes under natural and anthropogenic impact (West Spitsbergen)
    • Agnieszka Kalinowska
    • Katarzyna Jankowska
    • Sylwia Fudala-Książek
    • Mattia Pierpaoli
    • Aneta Łuczkiewicz
    2021 Full text SCIENCE OF THE TOTAL ENVIRONMENT

    The sustainable management of small human communities in the Arctic is challenging. In this study, both a water supply system (Lake 1) under the natural impact of a bird-nesting area, and a wastewater receiver (Lake 2) were analysed in the vicinity of the Polish Polar Station on West Spitsbergen. Microbial community composition, abundance and activity were assessed in samples of the treated wastewater, lake water and sediments using next-generation sequencing and direct microscope counts. Special attention was given to the faecal indicator, Enterococcus spp., whose occurrence and antimicrobial resistance were tested in water and wastewater samples. The results indicate that Lake 1, at a tundra stream discharge (L-TS) and at a water supply point (L-WS) were dominated by three phyla: Proteobacteria (57–58%) Bacteroidetes (27–29%) and Actinobacteria (9–10%) showing similar microbial composition up to the genus level. This suggests that nutrient-rich runoff from the bird colony was retained by surrounding tundra vegetation and reached Lake 1 at L-TS to a limited extent. Lake 2, being the wastewater recipient (WW-R), mirrors to some extent the core phyla of treated wastewater (WW-E), but in different shares. This suggests the possible washout of wastewater-related bacteria with activated sludge flocs, which was also supported by the microscopic observations. Compared to Lake 1, in WW-R an increase in all tested parameters was noted: total prokaryotic cell number, average cell volume, prokaryotic biomass and live cell percentage. The presence of Enterococcus spp. antibiotic resistance patterns highlights the importance of human associated microbiome and resistome dissemination via wastewater discharge. Additionally, it can be expected that temperature-related biochemical processes (e.g. nutrient cycling) may be accelerated by the ongoing climate change. Thus, proper wastewater treatment requires locally adapted solutions in increasingly visited and inhabited polar regions. Additionally, microbial community discharged to the environment with the treated wastewater, requires critical attention.

  • The Modernist Centre of Gdynia. Management Plan for the Nominated Property for the Years 2022-2027. Attachment to: Nomination Dossier on the inscription on the UNESCO World Heritage List of a part of Gdynia City Centre, Poland
    • Robert Hirsch
    • Celina Łozowska
    • Anna Orchowska-Smolińska
    • Katarzyna Piotrowska
    • Maria Sołtysik
    2021

    The Management Plan is a document that helps in managing the Nominated Property and follows the Operational Guidelines for the Implementation of the Convention. The Plan is intended as a management tool to ensure the protection and maintenance of the Outstanding Universal Value (OUV) and the features that determine the integrity and authenticity of the place.

  • The non-invasive evaluation of heart function in patients with an acute myocardial infarction: The role of impedance cardiography
    • Łukasz Lewicki
    • Maria Fijałkowska
    • Maciej Karwowski
    • Konrad Siebert
    • Grzegorz Redlarski
    • Aleksander Pałkowski
    • Radosław Targoński
    • Janusz Siebert
    2021 Full text Cardiology Journal

    Background: The purpose of this study was to analyze hemodynamic changes in patients treated with percutaneous coronary intervention (PCI) at an early stage of acute myocardial infarction (AMI) and at one-month follow-up. Methods: Patients with AMI (n = 27) who underwent PCI were analyzed using impedance cardiography (ICG). ICG data were collected continuously (beat by beat) during the whole PCI procedure and thereafter at every 60 s for the next 24 h. Blood pressure was taken every 10 min and stored for analysis. Additionally the following parameters were measured: cardiac index (CI), stroke volume index (SVi), left cardiac work index (LCWi), contractility index (CTi), ventricular ejection time (VET), systemic vascular resistance index (SVRi), thoracic fluid content index (TFCi) and heart rate (HR). Results: In the first 24 h after PCI all the contractility parameters including CI, SVi, LCWi, CTi and VET significantly decreased, whereas HR, SVRi and TFCi increased compared to baseline. All of the parameters examined got normalized at one month. The CI, SVi, LCWi, CTi, SVRi did not significantly differ from baseline, however the HR and VET were significantly lower compared to first day after PCI. Conclusions: 1. Cardiac performance deteriorates early after PCI and normalizes after one month in patients with an AMI. 2. ICG is useful for hemodynamic monitoring of AMI patients during and after invasive therapy.

  • The Opening of Central and Eastern European Countries to Free Trade: A Critical Assessment
    • Marta Kuc-Czarnecka
    • Andrea Saltelli,
    • Magdalena Olczyk
    • Erik, S. Reinert
    2021 Full text Structural Change and Economic Dynamics

    Three decades after the fall of the Berlin wall and one and a half decades after the Big Bang enlargement of the European Union (2004-2007), we revisit contrasting narratives about the benefit of both free trade and the EU enlargement for Central and Eastern European (CEE) countries. We distinguish old, pre-2004 EU countries from CEE countries that joined the EU in 2004-2007, as well as from the CEE countries that have not become part of the EU, in particular Belarus, Moldova, and Ukraine. Our analysis looks at two temporal windows: one from 1991 – the demise of the Eastern European free trade zone (COMECON) – to today, and the second zooming on the period following the enlargement process of 2004-2007. Our analysis points to an unfavourable turn of events for CEE countries, which appear to have experienced significant losses in their process of rapid integration in the world and EU economies. We are comparing these events in Central and Eastern Europe with the patterns of de-industrialisation and migration that took place in Latin America after a similar free trade shock starting in the 1970s.

  • The Optical Coherence Tomography and Raman Spectroscopy for Sensing of the Bone Demineralization Process
    • Maciej Jerzy Głowacki
    • Aleksandra Kamińska
    • Marcin Gnyba
    • Jerzy Pluciński
    • Marcin Strąkowski
    2021 Full text SENSORS

    The presented research was intended to seek new optical methods to investigate the demineralization process of bones. Optical examination of the bone condition could facilitate clinical trials and improve the safety of patients. The authors used a set of complementary methods: polarization-sensitive optical coherence tomography (PS-OCT) and Raman spectroscopy. Chicken bone samples were used in this research. To stimulate in laboratory conditions the process of demineralization and gradual removal of the hydroxyapatite, the test samples of bones were placed into 10% acetic acid. Measurements were carried out in two series. The first one took two weeks with data acquired every day. In the second series, the measurements were made during one day at an hourly interval (after 1, 2, 3, 5, 7, 10, and 24 h). The relation between the content of hydroxyapatite and images recorded using OCT was analyzed and discussed. Moreover, the polarization properties of the bones, including retardation angles of the bones, were evaluated. Raman measurement confirmed the disappearance of the hydroxyapatite and the speed of this process. This work presents the results of the preliminary study on the possibility of measuring changes in bone mineralization by means of the proposed methods and confirms their potential for practical use in the future.

  • The Physicochemical and Antibacterial Properties of Chitosan-Based Materials Modified with Phenolic Acids Irradiated by UVC Light
    • Beata Kaczmarek-Szczepańska
    • Marcin Wekwejt
    • Olha Mazur
    • Lidia Zasada
    • Anna Pałubicka
    • Ewa Olewnik‐Kruszkowska
    2021 Full text INTERNATIONAL JOURNAL OF MOLECULAR SCIENCES

    This paper concerns the physicochemical properties of chitosan/phenolic acid thin films irradiated by ultraviolet radiation with wavelengths between 200 and 290 nm (UVC) light. We investigated the preparation and characterization of thin films based on chitosan (CTS) with tannic (TA), caffeic (CA) and ferulic acid (FA) addition as potential food‐packaging materials. Such materials were then exposed to the UVC light (254 nm) for 1 and 2 h to perform the sterilization process. Different properties of thin films before and after irradiation were determined by various methods such as Fourier transform infrared spectroscopy (FTIR), scanning electron microscopy (SEM), atomic force microscopy (AFM), differential scanning calorimeter (DSC), mechanical properties and by the surface free energy determination. Moreover, the antimicrobial activity of the films and their potential to reduce the risk of contamination was assessed. The results showed that the phenolic acid improving properties of chitosan‐based films, short UVC radiation may be used as sterilization method for those films, and also that the addition of ferulic acid obtains effective antimicrobial activity, which have great benefit for food packing applications.

  • The Polish adaptation of the Burnout Assessment Tool (BAT-PL) by W. Schaufeli et al.
    • Beata Basińska
    • Ewa Gruszczyńska
    • Wilmar B. Schaufeli
    2021 Full text Psychiatria Polska

    Aim. The study aimed to present the Polish version of the Burnout Assessment Tool (BAT-PL) by Schaufeli et al. and to assess its validity and reliability. The tool measures the core symptoms of burnout (BAT-C): exhaustion, mental distance, cognitive and emotional impairment, and its secondary symptoms (BAT-S): psychosomatic complaints and psychological distress. Method. The participants were 255 nursing staff members. The construct validity was assessed with a one-point job satisfaction scale, the Utrecht Work Engagement Scale (UWES-3) by Schaufeli et al. and the Job-related Affective Well-being Scale (JAWS) by van Katwyk et al. Results. The results of the confirmatory factor analysis supported an assumed bi-factor structure. This applies to both BAT-C as the four core symptoms and a general factor (metatrait) representing burnout and BAT-S as a set of two secondary symptoms and a general factor. Both scales were strongly correlated with one another and differed from other measures of jobrelated well-being (job satisfaction, work engagement and negative emotions). The values of Cronbach’s alpha and composite reliability indicated BAT-PL as a reliable measurement tool. Conclusions. BAT-PL by Schaufeli et al. has good psychometric characteristics to be used in research on burnout and further validated in clinical practice.

  • The potential of web awareness as a determinant of dually defined customer value
    • Wiesława Caputa
    • Izabela Krawczyk-Sokolowska
    • Agata Pierścieniak
    2021 TECHNOLOGICAL FORECASTING AND SOCIAL CHANGE

    In the conditions of increasing demand barrier, the enterprise’s basic capital is customers. From an enterprise point of view, this means the need to create a dual perceived and defined customer value which remains related to market value (income and development potential) and customer resource value (reference, information and cooperative potential). The progressing digitisation process transfers business processes, and thus relationships, into virtual space. We identify customers consumers’ behaviour in virtual space and the goals they connect with participation in relational networks. We believe that the use of the potential of the virtual space in which the customer moves is determined by the awareness of the potential of the web, which is related to its readiness and ability to use it. This factor determining customer value (customer equity) exerts and will exert a significant impact on the process of creating value for the customer in the future, strengthening its position as a partner in the process of creating value.

  • The Prospects of Retail Payment Developments in the Metaverse
    • Oleksandr Melnychenko
    2021 Full text Virtual Economics

    In the age of technological development, rapid technological progress, and the metaverse development in which humans interact with each other and with the environment using virtual real-world metaphors, payment systems may also need to be re-considered. The study aims to find an answer to the question of what should be retail payments in the metaverse and to begin interdisciplinary discussions about their implementation in this environment. The author reviews the literature which shows that i) socio-economic relations are being implemented in the metaverse, but they still require the money to participate in the exchange relationships, as well as to support such a system; ii) it is impossible to abandon all forms of physical exchange, which is the basis of modern society; iii) the metaverse is an environment usually of anonymous users, who do not have the right to make significant purchases without their identification; iv) accounting of transactions remains the basis of payments in the metaverse as well

  • The protective properties of graphene oxide coatings functionalized with phosphorus atoms.
    • Karolina Grajewska
    • Marek Lieder
    2021

    Recently, electrophoretically deposited graphene oxide coatings are commonly applied as an anti-corrosion layer. However, improper adjustment of electrophoretic deposition (EPD) parameters as well as the hydrophilic nature of graphene oxide contribute to the formation of defects in the coatings and the increase in the wetting properties, respectively, and thus lead to a reduction of protective properties. The growth of wetting performance can be eliminated by a modification of graphene oxide with other chemical compounds. Phosphorus functionalized graphene oxide (P-rGO) coatings as anti-corrosion layers have not been reported yet. As a result of hydrothermal treatment in the presence of orthophosphoric acid, P-rGO samples were obtained. The formation of phosphorus precursors of coatings was confirmed by numerous structural studies. FTIR spectra indicated two peaks, which can be assigned to P-C and P-O bonds. The foreign atoms were introduced into graphene oxide structure in the content of 5%, which was proved based on XPS analysis. The stable and uniform suspension of precursors of coatings allows the production of coatings on the copper substrate by EPD. The uniform and hydrophobic surface of coatings enhanced the anti-corrosion performance compared to nonmodified graphene oxide coatings.

  • The Reactivity of the Imine Bond within Polynuclear Nickel(II) Complexes
    • Magdalena Siedzielnik
    • Dimitrios A. Pantazis
    • Jakub Bruniecki
    • Kinga Kaniewska-Laskowska
    • Anna Dołęga
    2021 Full text Crystals

    Three novel Ni complexes with the Schiff base ligand 2-methoxy-6-(E-2-pyridyliminomethyl)-phenol (L1) are described. In comparison with the similar 2-(pyridine-2-ylimino-methyl)phenol (pymp), the mode of coordination of L1 is altered due to the presence of methoxy substituent introducing the sterical hindrance. During the synthesis of the complexes, partial hydrolysis of the ligand was observed. Since such immediate hydrolysis of L1 was not detected during the reactions of Zn(II) and Cu(II) salts with L1, the DFT calculated structures of a series of similar Zn, Cu, Ni, and Co complexes with L1 are compared to account for the phenomenon

  • THE RISE OF FISCAL OPACITY IN POLAND IN THE ERA OF THE COVID-19 PANDEMIC
    • Maria Jastrzębska
    2021

    Research background: The quality of information provided by the fiscal authorities and the correct flow of this information between them and the society are very important especially in times of crisis, when there is an imbalance in public finances and an increasing public debt. Ensuring fiscal transparency (transparency of public finances) reduces fiscal risk and corruption and supports public acceptance of fiscal reforms. Purpose of the article: The aim of the article is to assess the transparency of public finances in Poland in the era of COVID-19 pandemic. Changes in the system of public finances, which cause an increase in the opacity of public finances, were analysed. It also recommends necessary actions to be taken in order to increase transparency of public finances. Research methods: Qualitative analysis, deductive and inductive reasoning were used. Findings and added value: Poland lacks a transparent message about public finances with a particular focus on the state budget, which would allow citizens to control the government's fiscal policy actions. In 2020, a number of solutions were introduced, which meant that a significant part of public expenditure is made outside the control of the parliament. In addition, a significant source of their financing is the issue of debt securities issued by the State Treasury, or guaranteed by the State Treasury. It is difficult to reliably assess the condition of public finances due to differences in the methodology of calculating the level of public sector deficit and debt in terms of national and EU legal regulations.

  • THE ROLE OF INFERENCE IN MOBILE MEDICAL APPLICATION DESIGN
    • Tomasz Kocejko
    2021

    In the early 21st century, artificial intelligence began to be used to process medical information. However, before this happened, predictive models used in healthcare could only consider a limited number of variables, and only in properly structured and organised medical data. Today, advanced tools based on machine learning techniques - which, using artificial neural networks, can explore extremely complex relationships - and deep learning technologies effectively support the user in performing parts of healthcare tasks, often resulting in better results that cannot be achieved by humans. AI systems are designed to cope with the complex data generated within modern healthcare. Although deep learning algorithms proved to provide reliable results on variety of data types most common algorithms performs best when applied on images. Therefor in this chapter, the step-by-step process of building the medical application that utilizes the neural network model for image based diagnosis is presented

  • THE ROLE OF THE STATE IN TAXATION. POLISH TAX POLICY AFTER 2015
    • Piotr Kasprzak
    2021

    This article is an attempt to present and evaluate tax policy Polish of the years 2015-2020, i.e. the period which resulted in formulating the new government. These time was a period of tax reforms, the introduction of new taxes and public tributes, as well as new mechanisms to control tax collection. Moreover, the policies introduced also concern changes in the level of fiscalism and tax redistribution. The research methods adopted in the paper include, in particular, the evaluation and analysis of secondary statistics, legal acts, literature review and specialized industry reports analyses.

  • The room above the porte cochere of the Kwidzyn castle in the times of Pomesanian chapter
    • Aleksander Piwek
    • Tomasz Jażdżewski
    2021 Full text Architectus

    Artykuł przedstawia historię budowlaną pomieszczenia nad przejazdem bramnym w skrzydle północnym zamku w Kwidzynie w czasach kapituły pomezańskiej. Prezentowane ustalenia uzyskano na podstawie wyników badań architektonicznych, stratygraficznych oraz analizy materiałów archiwalnych, które przeprowadzono w 2017 roku. Według nich pomieszczenie powstało w pierwszym etapie wznoszenia zamku. W kolejnych wiekach podlegało architektonicznym zmianom odpowiadającym nowym potrzebom mieszkańców zamku. Zachowane ślady świadczą, że od XIV do XVI wieku pełniło ono kilka następujących po sobie funkcji, dotąd nie w pełni rozpoznanych i umotywowanych: strażnicy, kancelarii bądź izby sądowej, a nawet kaplicy. Znaczną część wiedzy o nich zawarto w rozwarstwieniu ścian i rekonstrukcjach historycznych przekształceń z okresu średniowiecza. W późniejszych czasach wnętrze uniknęło znacznych zniszczeń i do dziś stanowi cenne źródło wiedzy o historii zamku.

  • The Self-employment of Women in Azerbaijan
    • Krystyna Gomółka
    2021 Full text STUDIA EUROPEJSKIE

    Azerbaijan has a population of more than 10 million, of which women accounted for 50% in 2020. At the same time, 93% of Azerbaijan’s citizens describe themselves as Muslims. Since the beginning of independence, Azerbaijan has been a secular state by virtue of Article 48 of the Constitution, which guarantees the freedom of worship, choice, or non-practice of religion and the freedom of expression of one’s own views on religion. This article aims to assess the changes in the self-employment of women in Azerbaijan through a deductive analysis of data and observation of changes in the structure of resources based on generally available macroeconomic data. This study focuses on the situation of women on the Azerbaijani labour market over the two decades of the 21st century. The numbers of economically active women, including those in employment and the unemployed, and economically inactive women are specifi ed. Further, the government’s legal and fi nancial policy in respect of women’s self-employment is analysed. The author determines what percentage of companies were set up by women and in which sectors and locations.

  • The share of investments in gold and oil using the example of selected European stock exchanges– A comparative analysis
    • Marcin Potrykus
    2021 Full text Cogent Economics & Finance

    In this article, optimal investment portfolios with minimal risk and maximum efficiency were calculated. The portfolios were designated for ten selected European stock exchanges, based on the listings of the twenty largest companies in each of those markets. All calculations were made based on company shares only, company shares and investments in gold, shares of companies and investments in crude oil as well as shares of companies and investments in gold and crude oil. The research hypothesis tested in the study is: The share of alternative investments in the investment portfolio does not depend on the stock exchange, but it differs depending on the length of the estimation window used. The study showed that for most exchanges there were statistically significant differences for the distribution of the determined weight for alternative investments. However, it was noted that the longer the estimation window, the greater the number of exchanges with no differences in the distributions of that weight. In addition, for portfolios with minimal risk, there were larger differences between the designated weights of alternative investments than for the same portfolios, which were determined based on maximizing efficiency. It was also found that the longer the estimation window, the higher the efficiency of the designated portfolios. Moreover, the investment in gold had an average weight, in four-element portfolios with a minimum risk, greater than 60%. Oil investment in the same portfolios had an average weight of 28%.

  • The Staged Combustion of Meat-and-Bone Meal:The Characteristics of Conversion Sub-processes and Large-Scale Process Outputs
    • Marcin Kantorek
    • Krzysztof Jesionek
    • Sylwia Polesek-Karczewska
    • Paweł Ziółkowski
    • Janusz Badur
    2021

    t Organic waste has been playing an increasingly important role in the energy market as those that may support the economies in pursuing towards decarbonization by increasing the share of renewables in the overall energy balance. In this group of alternative fuels, meat-and-bone meals being a post-production waste of the steadily developing meat industry, constitute a considerable proportion. Though they are rich in minerals, their direct use as natural fertilizer has been restricted to eliminate the spread of potential pathogens. This has focused the worldwide interest on thermal utilization of this type of fuel. Still, there are relatively few units dedicated to deal with large streams of meals. To provide their safe destruction, the conversion process must ensure specific conditions regarding the temperature and residence time. Therefore, most technologies developed to date involve the fluidized bed combustion. By virtue of nature and the variety of physicochemical properties of animal meals, the in-depth analyses of a raw material and its thermal behaviour need to be carried out on the way to develop the efficient and low-emission conversion technology. The concept of the said staged combustion of animal meal has therefore been supported by extensive studies, including the investigation of specific issues related to the process stages, such as drying, devolatilization, gas and char combustion. The developed technology appears to respond to the challenges encountered in the conversion of waste organics, providing the possibility to utilize fuels with a moisture content of up to 90%wt, while keeping the acceptable emission levels (NOx, CO, SO2 and HCl). The 12 MW operating pilot-scale plant tested while supplied with meat-and-bone meal has exhibited high efficiency, 88.4–84.8% depending on a facility load, offering a complete fuel combustion resulting in a flue gas being free from flammable gas compounds, and the ashes with low percentages of combustibles.

  • The Toolbox of Methods for Multidirectional Characterization of Dietary Nucleic Acids; Verification for Raw and Processed Food Products
    • Joanna Cieślewicz
    • Zuzanna Koziara
    • Wiktoria Ćwiklińska
    • Agnieszka Bartoszek-Pączkowska
    2021 Full text Food Analytical Methods

    Currently, the nutritional value of food is associated mainly with components such as proteins, carbohydrates, and lipids. However, another important macromolecules present in many foods are dietary nucleic acids (dietNA), i.e., DNA as well as both coding and non-coding RNAs. In the context of food chemistry and nutrition, dietNA are nowadays vastly neglected. In consequence, there are no dedicated methodologies to characterize dietNA. In this study, using raw or processed meat and plant products as model foodstuffs, we developed a toolbox of methods borrowed from other fields (histology, toxicology, molecular biology) that enable the initial characterization of dietNA as a necessary step on the way to systematic evaluation of their nutritional role. The proposed set of methods embraces (i) paraffin embedding of food samples and their staining to visualize the distribution and variety of dietNA in situ; (ii) comet assay to assess integrity of nuclear DNA with possible detection of DNA damage; (iii) dietNA isolation with and without RNAse digestion to determine the content of both DNA and RNA; (iv) electrophoretic separation of isolates to profile dietNA fragments. Such a combined methodological approach revealed clear differences between dietNA derived from raw and processed food products. We believe that the presented set of methods will encourage the broader research on dietNA to understand their role as a nutritionally relevant food component.

  • The Touristification of Italian Historic City Centres: The Lesson for Central Europe about the Airbnb Eruption
    • Łukasz Bugalski
    2021

    The unparalleled scale of the recent growth in tourism – the rise of the number of temporary visitors – could not have emerged without the impact on other socio‑economic aspects, namely, a change on the part of the destinations. Especially historic city centres are vulnerable to such an impact that could be manifested through diverse transformations of public space usage, housing market economics, availability of services, employment market, cultural heritage management, and everyday life of ordinary residents. Those processes may be indicated as the so‑called “touristification” – the kind of gentrification caused by the uncontrollable growth of the tourism economy. Therefore, together with the latest eruption of the short‑term rental market, identified with the foundation of the peer‑to‑peer Airbnb platform, those processes seem to accelerate and lead to the state of saturation known as “overtourism.” And as such, the ongoing touristification should be positioned in the very centre of urban tourism studies – the intersection of tourism studies and wider understand urban studies – becoming a fundamental issue for the future of the globe.

  • The unstable thermoelectric effect in non-stoichiometric Cu2Se during the non-equilibrium phase transition
    • Bartosz Trawiński
    • Marcin Łapiński
    • Bogusław Kusz
    2021 Full text JOURNAL OF MATERIALS SCIENCE

    The superionic α ↔ β phase transition in Cu1.96Se thermoelectric material is investigated by means of thermal analysis (DSC) and measurements of Seebeck coefficient and electrical conductivity. Results of the DSC measurements with 1–10 K/min heating and cooling rates show that the material is close to the equilibrium phase composition during the transformation. However, the kinetic limitation of the process exists, which is indicated by supercooling. At the beginning of the β → α transition, the most significant kinetic delay was attributed to the nucleation of the α phase. During the phase transformation, the Seebeck coefficient was lower than in a stabilised material (measured with 0.1 K/min heating/cooling rate). During cooling, a decrease from 130 μV/K (in a stabilised measurement) to 7 μV/K (5 K/min cooling rate) was observed. The deviation from the expected values of the Seebeck coefficient was correlated with the difference between the actual and equilibrium phase compositions.

  • The usage of the openBIM idea in architectural design on the example of Blender and BlenderBIM add-on
    • Michał Malewczyk
    2021 Full text Architectus

    The aim of the article is the research about the method and advancement of the openBIM idea implementation, clearly defined by the buildingSMART organization. The conducted analysis are limited to the Blender program and the BlenderBIM add-on and has been embedded in the context of the work of an architect and other IT solutions. The article presents four aspects of the openBIM concept implementation. The first approach relates to process of data exchanging between different computer applications using the open IFC standard. Another two focus on the method of creating and coding the three-dimensional geometry itself, through the prism of cooperation between various entities and further editing possibilities. The last aspect deals with the extension of the openBIM concept by combining it with the open-source idea. The author bases his considerations on the existing, analyzed scientific material, as well as on his own experience in the everyday of a designer and a teacher.

  • The Use of Cluster Analysis to Evaluate the Impact of COVID-19 Pandemic on Daily Water Demand Patterns
    • Paulina Dzimińska
    • Stanisław Drzewiecki
    • Marek Ruman
    • Klaudia Kosek
    • Karol Mikołajewski
    • Paweł Licznar
    2021 Full text Sustainability

    Proper determination of unitary water demand and diurnal distribution of water consumption (water consumption histogram) provides the basis for designing, dimensioning, and all analyses of water supply networks. It is important in the case of mathematical modelling of flows in the water supply network, particularly during the determination of nodal water demands in the context of Extended Period Simulation (EPS). Considering the above, the analysis of hourly water consumption in selected apartment buildings was performed to verify the justification of the application of grouping by means of k-means clustering. The article presents a detailed description of the adopted methodology, as well as the obtained results in the form of synthetic distributions of hourly water consumption, and the effect of the COVID-19 pandemic on their change.

  • The use of thermal imaging camera to estimate velocity profiles based on temperature distribution in a free convection boundary layer
    • Michał Ryms
    • Krzysztof Tesch
    • Witold Lewandowski
    2021 INTERNATIONAL JOURNAL OF HEAT AND MASS TRANSFER

    This work describes an attempt to assess whether the temperature field from a thermal imaging camera can be converted into a velocity field with an accuracy sufficient for qualitative conducting or describing the phenomenon, i.e. when the Navier-Stokes, Fourier-Kirchhoff and continuity equations are mutually coupled. The consequence of this link between temperature fields and velocity is the possibility to formulate the hypothesis that knowledge of the temperature field value is theoretically synonymous with knowledge of the velocity field value. To examine this statement, both experimental and computational research were carried out. The experimental study involved determining the air temperature field by means of a thermal imaging camera in the vicinity of a vertical isothermal plate during free convection heat transfer. The calculation procedure leading from raw data obtained with an IR camera to the velocities has been presented. The calculation results were validated by comparing them with the results of experimental tests carried out under the same conditions. In addition, a comparative analysis using numerical calculations has also been carried out. Satisfactory compliance with current studies has been achieved in both cases.

  • Theoretical Encapsulation of Fluorouracil (5-FU) Anti-Cancer Chemotherapy Drug into Carbon Nanotubes (CNT) and Boron Nitride Nanotubes (BNNT)
    • Maryam Zarghami Dehaghani
    • Farrokh Yousefi
    • S. Mohammad Sajadi
    • Muhammad Tajammal Munir
    • Otman Abida
    • Sajjad Habibzadeh
    • Amin Hamed Mashhadzadeh
    • Navid Rabiee
    • Ebrahim Mostafavi
    • Mohammad Saeb
    2021 Full text MOLECULES

    Introduction: Chemotherapy with anti-cancer drugs is considered the most common approach for killing cancer cells in the human body. However, some barriers such as toxicity and side effects would limit its usage. In this regard, nano-based drug delivery systems have emerged as cost-effective and efficient for sustained and targeted drug delivery. Nanotubes such as carbon nanotubes (CNT) and boron nitride nanotubes (BNNT) are promising nanocarriers that provide the cargo with a large inner volume for encapsulation. However, understanding the insertion process of the anti-cancer drugs into the nanotubes and demonstrating drug-nanotube interactions starts with theoretical analysis. Methods: First, interactions parameters of the atoms of 5-FU were quantified from the DREIDING force field. Second, the storage capacity of BNNT (8,8) was simulated to count the number of drugs 5-FU encapsulated inside the cavity of the nanotubes. In terms of the encapsulation process of the one drug 5-FU into nanotubes, it was clarified that the drug 5-FU was more rapidly adsorbed into the cavity of the BNNT compared with the CNT due to the higher van der Waals (vdW) interaction energy between the drug and the BNNT. Results: The obtained values of free energy confirmed that the encapsulation process of the drug inside the CNT and BNNT occurred spontaneously with the free energies of −14 and −25 kcal·mol−1, respectively. Discussion: However, the lower value of the free energy in the system containing the BNNT unraveled more stability of the encapsulated drug inside the cavity of the BNNT comparing the system having CNT. The encapsulation of Fluorouracil (5-FU) anti-cancer chemotherapy drug (commercial name: Adrucil®) into CNT (8,8) and BNNT (8,8) with the length of 20 Å in an aqueous solution was discussed herein applying molecular dynamics (MD) simulation.

  • Theoretical investigation of the structural insights of the interactions of γ-Fe2O3 nanoparticle with (EMIM TFSI) ionic liquid
    • Adam Sieradzan
    • Cezary Czaplewski
    • Aleksandra Bielicka-Gieldon
    • Maciej Bobrowski
    • Artur Gieldon
    2021 JOURNAL OF MOLECULAR LIQUIDS

    One of the possible applications of ionic liquids is to produce electricity from heat. The iron oxide nanoparticle is a potent electrical particle, which is expected to improve the heat’s efficiency to electricity conversion, however, it is prone to aggregation and sedimentation, which hamper its application. One of the methods to enhance the nanoparticle’s solubility and electrical properties is the use of a stabilizing component in the production and application process. In this research, we studied, how the nanoparticle affects the properties of the 1-Ethyl-3-methylimidazolium bis(trifluoromethylsulfonyl)imide (EMIM TFSI) ionic liquid. The citric acid was used as a nanoparticle stabilizing agent and led to decrease of the diffusion coefficient of the ionic liquid’s components. Our results indicated, that with the addition of the citric acid, strong solvation sphere around nanoparticle was formed. The presence of nanoparticles significantly reduced the diffusion of ionic liquid components. Finally, the citric acid was found to be the strongest nanoparticle binding component of the studied system, and therefore it was able to stabilize the nanoparticle in solution.

  • Therapeutic Potential of Multifunctional Derivatives of Cholinesterase Inhibitors
    • Maja Przybyłowska
    • Krystyna Dzierzbicka
    • Szyman Kowalski
    • Klaudia Chmielewska
    • Iwona Inkielewicz-Stępniak
    2021 Full text Current Neuropharmacology

    The aim of this work is review of tacrine analogues from the last three years, which were not included in the latest review work, donepezil and galantamine hybrids from 2015 and rivastigmine derivatives from 2014. In this account we summarize the efforts toward the development and characterization of non-toxic inhibitors of cholinesterases based on mentioned drugs with various interesting additional properties such as antioxidant, decreasing beta-amyloid plaque aggregation, nitric oxide production, pro-inflammatory cytokines release, monoamine oxidase-B activity, cytotoxicity and oxidative stress in vitro and in animal model that classify these hybrids as potential multifunctional therapeutic agents for Alzheimer's disease. Moreover, herein, we have described the cholinergic hypothesis, mechanisms of neurodegeneration and current pharmacotherapy of Alzheimer's disease which is based on the restoration of cholinergic function through blocking enzymes that break down acetylcholine.

  • Thermal and Hydrodynamic Phenomena in the Stagnation Zone — Impact of the Inlet Turbulence Characteristics on the Numerical Analyses
    • Tomasz Kura
    • Jan Wajs
    • Elzbieta Fornalik-Wajs
    • Sasa Kenjeres
    • Sebastian Gurgul
    2021 Full text ENERGIES

    One of the methods of heat transfer enhancement is utilization of the turbulent impinging jets, which were recently applied, for example, in the heat exchangers. Their positive impact on the heat transfer performance was proven, but many questions related to the origin of this impact are still unanswered. In general, the wall-jet interaction and the near-wall turbulence are supposed to be its main reason, but their accurate numerical analysis is still very challenging. The authors’ aim was to construct the numerical model which can represent the real phenomena with good or very good accuracy. Starting with an analysis of single jet and obtaining the agreement with experimental data, it will be possible to extend the model towards the whole minijets heat exchanger. The OpenFOAM software, Bracknell, UK was used for that purpose, with our own implementation of the ζ-f turbulence model. The most difficult area to model is the stagnation region, where the thermal effects are the most intensive and, at the same time, strongly affected by the conditions in the pipe/nozzle/orifice of various size (conventional, mini, micro), from which the jet is injected. In the following article, summary of authors’ findings, regarding significance of the velocity profile and turbulence intensity at the jet place of discharge are presented. In addition, qualitative analysis of the heat transfer enhancement is included, in relation to the inlet conditions. In the stagnation point, Nusselt number differences reached the 10%, while, in general, its discrepancy in relation to inlet conditions was up to 23%.

  • Thermal and Mechanical Behavior of Elastomers Incorporated with Thermoregulating Microcapsules
    • Janusz Datta
    • Patrycja Trzebiatowska,
    • Ana M. Borreguero
    • Irene Izarra
    • Ignacio Garrido
    • Angel Serrano
    • Juan F. Rodríguez
    • Manuel Carmona
    2021 Full text Applied Sciences

    Polyurethane (PU) is one of the principal polymers in the global plastic market thanks to its versatility and continuous improvement. In this work, PU elastomeric materials having thermoregulating properties through the incorporation of microcapsules (mSD-(LDPE·EVA-RT27)) from low-density polyethylene and vinyl acetate containing paraffin®RT27 as PCM were produced. Elastomers were synthesized while varying the molar ratio [NCO]/[OH] between 1.05 and 1.1 and the microcapsule (MC) content from 0.0 to 20.0 wt.%. The successful synthesis of the PUs was confirmed by IR analyses. All the synthesized elastomers presented a structure formed by a net of spherical microparticles and with a minimum particle size for those with 10 wt.% MC. The density and tensile strength decreased with the MC content, probably due to worse distribution into the matrix. Elastomer E-1.05 exhibited better structural and stability properties for MC contents up to 15 wt.%, whereas E-1.1, containing 20 wt.% MC, revealed mechanical and thermal synergy effects, demonstrating good structural stability and the largest latent heat. Hence, elastomers having a large latent heat (8.7 J/g) can be produced by using a molar ratio [NCO]/[OH] of 1.1 and containing 20 wt.% mSD-(LDPE·EVA-RT27).

  • Thermal and technological aspects of double face grinding of C45 carbon steel
    • Mariusz Deja
    • Linus Lichtschlag
    • Eckart Uhlmann
    2021 Full text Journal of Manufacturing Processes

    In grinding, the contact zone temperature is a decisive factor influencing the achievable surface quality and the grinding tool wear. In contrast to other grinding processes, only few information regarding double face grinding with planetary kinematics when processing steel is known up to date. Since the successive substitution of in-dustrial double-sided lapping processes by double-sided grinding, it has become necessary to the conducted research in order to provide deeper understanding of the process and factors that influence it. To determine the workpiece temperature during grinding of C45 components, silicon temperature sensors were integrated into the workpiece holders and technological investigations were carried out. The influences and interactions of the mean cutting speed, cooling lubricant flow rate and cutting ability of the grinding wheels on the resulting workpiece temperature were analysed. Subsequently, modelling enabled an empirical estimation of the resulting workpiece temperature for processes in the investigated test area. With regard to the design and optimization of processes for machining plane-parallel workpiece surfaces, this model is a helpful tool for avoiding thermally induced workpiece damage and reduction of tool wear. Furthermore, the method can be used to conduct further ex-aminations on the grinding process and to reduce the amount of cooling lubricant used, to improve life cycle assessment.

  • Thermal Buckling Analysis of Circular Bilayer Graphene sheets Resting on an Elastic Matrix Based on Nonlocal Continuum Mechanics
    • M. Ahmad Pour
    • M. E. Golmakani
    • Mohammad Malikan
    2021 Full text Journal of Applied and Computational Mechanics

    In this article, the thermal buckling behavior of orthotropic circular bilayer graphene sheets embedded in the Winkler–Pasternak elastic medium is scrutinized. Using the nonlocal elasticity theory, the bilayer graphene sheets are modeled as a nonlocal double–layered plate that contains small scale effects and van der Waals (vdW) interaction forces. The vdW interaction forces between the layers are simulated as a set of linear springs using the Lennard–Jones potential model. Using the principle of virtual work, the set of equilibrium equations are obtained based on the first-order shear deformation theory (FSDT) and nonlocal differential constitutive relation of Eringen. Differential quadrature method (DQM) is employed to solve the governing equations for simply-supported and clamped boundary conditions. Finally, the effects of the small scale parameter, vdW forces, aspect ratio, elastic foundation, and boundary conditions are considered in detail.

  • Thermal utilization of meat-and-bone meal using the rotary kiln pyrolyzer and the fluidized bed boiler – The performance of pilot-scale installation
    • Marcin Kantorek
    • Krzysztof Jesionek
    • Sylwia Polesek-Karczewska
    • Paweł Ziółkowski
    • Michał Stajnke
    • Janusz Badur
    2021 Full text RENEWABLE ENERGY

    Thermal utilization of meat-and-bone meal (MBM) is subject to stringent regulations that are meant to provide elimination of any potential pathogens. Incineration as well as other possible routes for thermal conversion of MBM are still at the research state. The universal technology was developed that allows to combust various types of waste organic materials, including animal waste, municipal solid waste and sludge, mixed at any ratio with different types of biomass. It provides the possibility to utilize the wasteand- biomass fuel blends of up to 90%wt of moisture content, while maintaining the allowable pollutant emissions and soil contamination. This regards mainly NOx, SO2, HCl and VOC. Contrary to the typical large scale grate boilers used for waste burning, the developed operating pilot-scale plant with a capacity of 12 MW offers the complete combustion of MBM, resulting in a flue gas which is proved to be free of flammable gaseous components and sooty particles in slag and fly ash. The thermal decomposition and combustion of waste using this technology ensures thermal conversion of chemical energy contained in waste and biomass. The efficiency of the prototype installation varied between 84.8 and 88.4% depending on the facility load.

  • Thermodynamic Analysis of Negative CO2 Emission Power Plant Using Aspen Plus, Aspen Hysys, and Ebsilon Software
    • Paweł Ziółkowski
    • Paweł Madejski
    • Milad Amiri
    • Tomasz Kuś
    • Kamil Stasiak
    • Navaneethan Subramanian
    • Halina Pawlak-kruczek
    • Janusz Badur
    • Łukasz Niedźwiecki
    • Dariusz Mikielewicz
    2021 Full text ENERGIES

    Abstract: The article presents results of thermodynamic analysis using a zero-dimensional mathematical models of a negative CO2 emission power plant. The developed cycle of a negative CO2 emission power plant allows the production of electricity using gasified sewage sludge as a main fuel. The negative emission can be achieved by the use this type of fuel which is already a “zeroemissive” energy source. Together with carbon capture installation, there is a possibility to decrease CO2 emission below the “zero” level. Developed models of a novel gas cycle which use selected codes allow the prediction of basic parameters of thermodynamic cycles such as output power, efficiency, combustion composition, exhaust temperature, etc. The paper presents results of thermodynamic analysis of two novel cycles, called PDF0 and PFD1, by using different thermodynamic codes. A comparison of results obtained by three different codes offered the chance to verify results because the experimental data are currently not available. The comparison of predictions between three different software in the literature is something new, according to studies made by authors. For gross efficiency (54.74%, 55.18%, and 52.00%), there is a similar relationship for turbine power output (155.9 kW, 157.19 kW, and 148.16 kW). Additionally, the chemical energy rate of the fuel is taken into account, which ultimately results in higher efficiencies for flue gases with increased steam production. A similar trend is assessed for increased CO2 in the flue gas. The developed precise models are particularly important for a carbon capture and storage (CCS) energy system, where relatively new devices mutually cooperate and their thermodynamic parameters affect those devices. Proposed software employs extended a gas–steam turbine cycle to determine the effect of cycle into environment. First of all, it should be stated that there is a slight influence of the software used on the results obtained, but the basic tendencies are the same, which makes it possible to analyze various types of thermodynamic cycles. Secondly, the possibility of a negative CO2 emission power plant and the positive environmental impact of the proposed solution has been demonstrated, which is also a novelty in the area of thermodynamic cycles

  • Thermodynamic Studies of Interactions between Sertraline Hydrochloride and Randomly Methylated β-Cyclodextrin Molecules Supported by Circular Dichroism Spectroscopy and Molecular Docking Results
    • Sylwia Belica-Pacha
    • Mateusz Daśko
    • Vyacheslav Buko
    • Ilya Zavodnik
    • Katarzyna Miłowska
    • Maria Bryszewska
    2021 Full text INTERNATIONAL JOURNAL OF MOLECULAR SCIENCES

    The interaction between sertraline hydrochloride (SRT) and randomly methylated β-cyclodextrin (RM β CD) molecules have been investigated at 298.15 K under atmospheric pressure. The method used—Isothermal Titration Calorimetry (ITC) enabled to determine values of the thermodynamic functions like the enthalpy (DH), the entropy (DS) and the Gibbs free energy (DG) of binding for the examined system. Moreover, the stoichiometry coefficient of binding (n) and binding/association constant (K) value have been calculated from the experimental results. The obtained outcome was compared with the data from the literature for other non-ionic βCD derivatives interacting with SRT and the enthalpy-entropy compensation were observed and interpreted. Furthermore, the connection of RM β CD with SRT was characterized by circular dichroism spectroscopy (CD) and complexes of βCD derivatives with SRT were characterized through the computational studies with the use of molecular docking (MD).

  • THERMOMECHANICAL PERFORMANCE OF FLEXIBLE POLYURETHANE FOAMS AS A FUNCTION OF THE ISOCYANATE INDEX
    • Aleksander Hejna
    • Paulina Kosmela
    • Adam Olszewski
    • Łukasz Zedler
    • Krzysztof Formela
    2021

    Polyurethane foams are very versatile materials applied in different branches of industry. Their popularity is attributed, among others, to the flexibility in engineering their mechanical performance by the adjustment of their formulations. One of the most crucial factors is the isocyanate index, determining the ratio between the free hydroxyl and isocyanate groups present in the polyurethane system. By the change of this ratio, the mechanical properties of foams may be adjusted. In the presented paper, we presented the isocyanate index's influence during foams’ preparation on their thermomechanical performance analyzed by the dynamic mechanical analysis.

  • Thermo-Mechanical Simulation of Underwater Friction Stir Welding of Low Carbon Steel
    • Shabbir Memon
    • Jacek Tomków
    • Hesamoddin Aghajani Derazkola
    2021 Full text Materials

    This article investigates the flow of materials and weld formation during underwater friction stir welding (UFSW) of low carbon steel. A thermo-mechanical model is used to understand the relation between frictional heat phenomena during the welding and weld properties. To better understand the effects of the water environment, the simulation and experimental results were compared with the sample prepared by the traditional friction stir welding (FSW) method. Simulation results from surface heat diffusion indicate a smaller preheated area in front of the FSW tool declined the total generated heat in the UFSWed case compared to the FSWed sample. The simulation results revealed that the strain rate of steel in the stir zone (SZ) of the FSWed joint is higher than in the UFSWed case. The microstructure of the welded sample shows that SZ’s microstructure at the UFSWed case is more refined than the FSWed case due to the higher cooling rate of the water environment. Due to obtained results, the maximum temperatures of FSWed and UFSWed cases were 1228 °C and 1008 °C. Meanwhile, the simulation results show 1200 °C and 970 °C for conventional and underwater FSW samples, respectively. The maximum material velocity in SZ predicted 0.40 m/s and 0.32 m/s for FSW and underwater FSWed samples. The better condition in the UFSW case caused the ultimate tensile strength of welded sample to increase ~20% compared to the FSW joint.