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Gdańsk University of Technology

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  • The effect of Fe on chemical stability and oxygen evolution performance of high surface area SrTix-1FexO3-δ mixed ionic-electronic conductors in alkaline media
    • Krystian Lankauf
    • Aleksander Mroziński
    • Patryk Błaszczak
    • Karolina Górnicka
    • Justyna Ignaczak
    • Marcin Łapiński
    • Jakub Karczewski
    • Grzegorz Cempura
    • Piotr Jasiński
    • Sebastian Molin
    2021 Full text INTERNATIONAL JOURNAL OF HYDROGEN ENERGY

    Development of environmentally friendly, high performing oxygen evolution reaction (OER) catalysts is an important research challenge. In this work, iron doped strontium titanates with a general formula SrTi1-xFexO3-δ (x = 0.35, 0.50, 0.70, 0.90, and 1.00) denoted as STFx, were synthesized via a solid state reaction technique and characterized in terms of oxygen evolution reaction electrocatalysis in an alkaline electrolyte (0.1 M KOH). The produced powders were characterized by a high specific surface area (>20 m2 g−1), beneficial for OER. The evaluation of specific activity indicated the following trend of increasing performance: STF35 < STF50 < STF70 < SFO < STF90. The lowest overpotential at 10 mAcm−2 GEO of 410 mV (350 mV at 25 μA cm−2OX) was achieved by STF90 with the corresponding Tafel slope of 60 mV dec−1. The two materials with the highest Fe content (i.e. STF90 and SFO) showed, however, poor chemical stability in alkaline solution demonstrated by the dissolution of Sr. Based on the good electrochemical performance (~460 mV at 10 mA cm−2GEO, ~405 mV at 25 μA cm−2OX) and chemical stability for at least 30 days (no Sr dissolution) of STF50, it can be considered an interesting, working at room temperature OER catalyst based on non-toxic and abundant elements.

  • The Effect of Increasing the Amount of Indium Alloying Material on the Efficiency of Sacrificial Aluminium Anodes
    • Krzysztof Żakowski
    • Juliusz Orlikowski
    • Kazimierz Darowicki
    • Marcin Czekajło
    • Piotr Igliński
    • Kinga Domańska
    2021 Full text Materials

    Al-Zn-In alloys having 4.2% zinc content and various indium content in the range of 0.02–0.2% were tested with respect to the most important electrochemical properties of sacrificial anodes in a cathodic protection, i.e., the current capacity and potential of the operating anode. The distribution of In and Zn in the tested alloys was mapped by means of the EDX technique, which demonstrated that these elements dissolve well in the alloy matrix and are evenly distributed within it. The current capacity of such alloys was determined by means of the method of determining the mass loss during the dissolution by a current of known charge. The results obtained demonstrate that the current capacity of Al-Zn-In alloy decreases with the increase in the In content, which results in an increased consumption of anode material and shorter lifetime of anodes. With 0.02% In content, the capacity amounted to approx. 2500 Ah/kg, whereas the alloy with 0.2% In had as much as 30% lower capacity amounting to approx. 1750 Ah/kg. Microscopic examination for the morphology and surface profile of the samples after their exposure demonstrated that a higher indium content in the alloy results in a more uneven general corrosion pattern during the dissolution of such alloy, and the cavities (pits) appearing on the alloy surface are larger and deeper. As the indium content is increased from 0.02% to 0.05%, the Al-Zn-In alloy potential decreases by about 50 mV to −1100 mV vs. Ag/AgCl electrode, which is advantageous in terms of using this alloy as a sacrificial anode. When the indium content is further increased from 0.05% to 0.2%, the potential of the alloy is no longer changed to a more negative one. The results obtained from all these tests demonstrate that alloys containing up to 0.05% of In additive are practically applicable for cathodic protection.

  • The Effect of Protrusions on the Initiation of Partial Discharges in XLPE High Voltage Cables
    • Mohammad AlShaikh Saleh
    • S. Shady Refaat
    • Marek Olesz
    • Haitham Abu-Rub
    • Jarosław Guziński
    2021 Full text Bulletin of the Polish Academy of Sciences-Technical Sciences

    This paper is focusing on 3D Finite Elements Analysis (FEA) based modelling of protrusions as defects or imperfections in the XLPE high voltage cable. This study is aiming to examine the impact protrusions have on the initiation of partial discharges. Spherical and ellipsoidal protrusions with different sizes at the conductor screen of the high voltage cable is an essential content of this paper. In addition, a spherical gas-filled void is placed inside and outside the protrusions, and a water tree produced from protrusions is under consideration. The partial discharge influence taking place at the protrusions and the stress enhancement factor is determined for all the variations mentioned to quantify the rise in the inception of partial discharges due to the protrusions.

  • The Effect of Surface Treatment with Isocyanate and Aromatic Carbodiimide of Thermally Expanded Vermiculite Used as a Functional Filler for Polylactide-Based Composites
    • Mateusz Barczewski
    • Olga Mysiukiewicz
    • Aleksander Hejna
    • Radosław Biskup
    • Joanna Szulc
    • Sławomir Michałowski
    • Adam Piasecki
    • Arkadiusz Kloziński
    2021 Full text Polymers

    In this work, thermally expanded vermiculite (TE-VMT) was surface modified and used as a filler for composites with a polylactide (PLA) matrix. Modification of vermiculite was realized by simultaneous ball milling with the presence of two PLA chain extenders, aromatic carbodiimide (KI), and 4,4’-methylenebis(phenyl isocyanate) (MDI). In addition to analyzing the particle size of the filler subjected to processing, the efficiency of mechanochemical modification was evaluated by Fourier transform infrared spectroscopy (FTIR) and scanning electron microscopy (SEM). The composites of PLA with three vermiculite types were prepared by melt mixing and subjected to mechanical, thermomechanical, thermal, and structural evaluation. The structure of composites containing a constant amount of the filler (20 wt%) was assessed using FTIR spectroscopy and SEM analysis supplemented by evaluating the final injection-molded samples’ physicochemical properties. Mechanical behavior of the composites was assessed by static tensile test and impact strength hardness measurements. Heat deflection temperature (HDT) test and dynamic thermomechanical analysis (DMTA) were applied to evaluate the influence of the filler addition and its functionalization on thermomechanical properties of PLA-based composites. Thermal properties were assessed by differential scanning calorimetry (DSC), pyrolysis combustion flow calorimetry (PCFC), and thermogravimetric analysis (TGA). The use of filler-reactive chain extenders (CE) made it possible to change the vermiculite structure and obtain an improvement in interfacial adhesion and more favorable filler dispersions in the matrix. This translated into an improvement in impact strength and an increase in thermo-mechanical stability and heat release capacity of composites containing modified vermiculites.

  • The Effect of the Selection of Three-Dimensional Random Numerical Soil Models on Strip Foundation Settlements
    • Kamil Żyliński
    • Karol Winkelmann
    • Jarosław Górski
    2021 Full text Applied Sciences-Basel

    This paper delivers a probabilistic attempt to prove that the selection of a random three-dimensional finite element (FE) model of a subsoil affects the computed settlements. Parametricanalysis of a random soil block is conducted, assuming a variable subsoil Young’s modulus inparticular finite elements. The modulus is represented by a random field or different-sized setsof random variables; in both cases, the same truncated Gaussian model is assumed. Mean valuesand standard deviations of random soil settlement are estimated by a Monte Carlo simulationprocedure. With regard to the adopted FE model, the estimated settlement mean values do notvary significantly, but standard deviations do strongly. Similarities also appear in the diagrams ofrandom field correlation length versus settlement standard deviation and the diagrams displayinga total number of model random variables versus settlement standard deviation. Thus, relevantsingle random variable models represent the random field approach well with regard to settlementparameter estimation. This remark is verified upon a settlement analysis of a three-dimensional FEmodel of a hypothetical strip foundation. Following the preliminary model observations, variousprobabilistic geotechnical analyses may be supported, e.g., continuous footing design, slope stabilityanalysis, and foundation reliability assessment.

  • The Effectiveness of Basic Resuscitation Activities Carried out by Combat Paramedics of the Police, as Exemplified by Polish Counterterrorist Units
    • Waldemar Zubrzycki
    • Jarosław Przyjemczak
    • Beata Świeczko-Żurek
    2021 Full text Internal Security

    The tasks carried out by Police officers are often accompanied by dangerous situations that threaten the life and health of the people involved, the police themselves, and bystanders. It concerns especially counter-terrorism police units whose activities are aimed at terrorists and particularly dangerous criminals, and their course is violent and aggressive. In conjunction with the inability to bring civilian rescue services into the action zone, this results in the need to expand the assault team by including one more specialisation — combat paramedic, having the appropriate knowledge, skills and qualifications, as well as equipment that allows for independent first aid while the operations are underway. A paramedic’s preparation must be versatile, but the key to effective action is the ability to perform basic activities, including cardiopulmonary resuscitation, after the diagnosis of sudden cardiac arrest. The study aims to present the results of research conducted on a fairly unique research sample regarding the effectiveness of indirect heart massage by combat paramedics of police special units and conclusions resulting from empirical research and their comparison with the results of similar studies, in relation to other professional groups. The knowledge and skills acquired during the training quickly become obsolete, requiring systematic consolidation and improvement. Therefore, cyclical repetition of exercises in the area of rescue activities plays a key role in maintaining the required quality of life support. The collected material may be a premise for further research, indicating their potential directions.

  • The efficiency of turbomachinery in the zero-and three-dimensional approaches
    • Paweł Ziółkowski
    • Tomasz Kowalczyk
    • Janusz Badur
    • Michel Feidt
    2021 Entropie

    Efficiency of turbomachinery is usually defined using an isentropic process. This approach provides a reliable reference point only when pressure and temperature measurements are available, e.g. at the casing inlet and outlet. In the case of a single stage internal efficiency determination the reference point is difficult. Computational fluid dynamics allows for an exact calculation of values of losses occurring in a turbine stage from turbine blades geometry, clearances, uneven steam distribution and other. Present method is a three-dimensional polytrophic approach based on work comparison of a turbine stage using real and ideal working fluid. The reference state is estimated by iterative simulation of considered geometry using the Eulerian model of compressible fluid. This approach is more convenient and feels natural when using 3D modeling. Moreover, calculations conducted for a control stage indicated differences between results attained using those two approaches less than 0.2%.

  • The Energy of Finance in Refining of Medical Surge Capacity
    • Oleksandr Melnychenko
    2021 Full text ENERGIES

    The availability of resources and their concentration in the place of greatest need, will not allow us to successfully overcome a medical surge without the energy required to activate these resources and activities, and increase their quantities if necessary, that is why the staff and management of healthcare institutions are forced to making ethical crisis decisions about who wins and who loses. This study highlights the versatility of the concept of ‘energy’ by attributing it to money or financial resources, which are highly essential in dealing with surges as the healthcare system adopts the appropriate capacity level. This study considers the means (space, staff, supplies, and specific resources) at the disposal of healthcare institutions for the control of diseases as economic resources to identify ways for enhancing their capacity, especially during periods of medical surges such as that caused by the coronavirus disease (COVID-19). The medical resources are dependent on ‘energy’, albeit not in the strictest sense of the term. The article, thus, points out that while limited resources are the norm in economic theory, a medical surge provides an opportunity to sufficiently extend the resources within the health system capacity through increased funding.

  • The equivariant spectral flow and bifurcation of periodic solutions of Hamiltonian systems
    • Marek Izydorek
    • Joanna Janczewska
    • Nils Waterstraat
    2021 Full text NONLINEAR ANALYSIS-THEORY METHODS & APPLICATIONS

    We define a spectral flow for paths of selfadjoint Fredholm operators that are equivariant under the orthogonal action of a compact Lie group as an element of the representation ring of the latter. This G-equivariant spectral flow shares all common properties of the integer valued classical spectral flow, and it can be non-trivial even if the classical spectral flow vanishes. Our main theorem uses the G-equivariant spectral flow to study bifurcation of periodic solutions for autonomous Hamiltonian systems with symmetries.

  • The evidence for the impact of policy on physical activity outcomes within the school setting: A systematic review
    • Catherine Woods
    • Kevin Volf
    • Liam Kelly
    • Bláthín Casey
    • Peter Gelius
    • Sven Messing
    • Sarah Forberger
    • Jeroen Lakerveld
    • Joanna Żukowska
    • Enrique García Bengoechea
    2021 Full text Journal of Sport and Health Science

    Purpose Despite the well-established health benefits of physical activity (PA) for young people (aged 4–19 years), most do not meet PA guidelines. Policies that support PA in schools may be promising, but their impact on PA behavior is poorly understood. The aim of this systematic review is to ascertain the level and type of evidence reported in the international scientific literature for policies within the school setting that contribute directly or indirectly to increasing PA. Methods This systematic review is compliant with Preferred Reporting Items for Systematic Review and Meta-Analysis guidelines. Six databases were searched using key concepts of policy, school, evaluation, and PA. Following title and abstract screening of 2323 studies, 25 progressed to data synthesis. Methodological quality was assessed using standardized tools, and the strength of the evidence of policy impact was described based on pre-determined codes: positive, negative, inconclusive, or untested statistically. Results Evidence emerged for 9 policy areas that had a direct or indirect effect on PA within the school setting. These were whole school PA policy, physical education, sport/extracurricular PA, classroom-based PA, active breaks, physical environment, shared use agreements, and active school transport and surveillance. The bulk of the evidence was significantly positive (54%), 27% was inconclusive, 9% was significantly negative, and 11% was untested (due to rounding, some numbers add to 99 or 101). Frequency of evidence was highest in the primary setting (41%), 34% in the secondary setting, and 24% in primary/secondary combined school settings. By policy area, frequency of evidence was highest for sport/extracurricular PA (35%), 17% for physical education PA, and 12% for whole school PA policy, with evidence for shared use agreements between schools and local communities rarely reported (2%). Comparing relative strength of evidence, the evidence for shared use agreements, though sparse, was 100% positive, 60% of the evidence for whole school PA policy was positive, 59% of the evidence for sport/extracurricular PA was positive, 57% of the evidence for physical education was positive, and 50% of the evidence for PA in classroom and for active breaks/recess was positive.

  • The fate and contamination of trace metals in soils exposed to a railroad used by Diesel Multiple Units: Assessment of the railroad contribution with multi-tool source tracking
    • Jacek Szmagliński
    • Nicole Nawrot
    • Ksenia Pazdro
    • Jolanta Walkusz-miotk
    • Ewa Wojciechowska
    2021 Full text SCIENCE OF THE TOTAL ENVIRONMENT

    Soil samples from cut slopes from lightly loaded railway lines used by Diesel Multiple Units for 5 years in Gdansk (Poland) were collected and analyzed for trace metals (TMs): Zn, Pb, Cd, Ni, Cr, Cu, and Fe. The main aim was to assess soil enrichment, contamination status, and distribution of TMs relative to the distance from the railway track. Extensive source tracking analyses were performed using cluster analysis (CA) and the Pb isotope ratios approach (206Pb, 207Pb, and 208Pb). Soil samples were affected by Cr, Cu, Pb, and Zn (max values in mg/kg d.w.: 31.1, 145, 80.5, and 115, respectively). The Enrichment Factor showed moderate (Cr, Zn, Pb) to very severe (Cu) enrichment. CA allowed TMs to be divided into two general groups: a) containing Zn, Pb, Cd with slight interaction with Cu; and b) containing Fe and Niwith slight interactionwith Cr. Correlation analyses indicated Cr as an outlying TM delivered from a separate source associated with the specificity of the construction of railroad 248, where alloys containing Cr were used to counteract increasing wear-and-tear of the rails. Pb isotopic ratios in the ranges of 1.16–1.20 (206Pb/207Pb) and 2.05–2.10 (208Pb/206Pb) corresponded to anthropogenic supplementation (coal combustion, road vehicles, and railroad transport) of Pb and Pb-correlated TMs (Zn, Cd, and partly Cu). Despite the research focus on the impact of the railroad contribution, a comparison with other forms of transport indicated that road transport appeared to have a higher contributing factor to TM pollution at the investigated site. This general conclusion againemphasizes the lower environmental footprint exhibited by railway transport in comparison to road transport.

  • The Green Approach to the Synthesis of Bio-Based Thermoplastic Polyurethane Elastomers with Partially Bio-Based Hard Blocks
    • Ewa Głowińska
    • Paulina Kasprzyk
    • Janusz Datta
    2021 Full text Materials

    Bio-based polymeric materials and green routes for their preparation are current issues of many research works. In this work, we used the diisocyanate mixture based on partially bio-based diisocyanate origin and typical petrochemical diisocyanate for the preparation of novel bio-based thermoplastic polyurethane elastomers (bio-TPUs). We studied the influence of the diisocyanate mixture composition on the chemical structure, thermal, thermomechanical, and mechanical properties of obtained bio-TPUs. Diisocyanate mixture and bio-based 1,4-butanediol (as a low molecular chain extender) created bio-based hard blocks (HS). The diisocyanate mixture contained up to 75 wt % of partially bio-based diisocyanate. It is worth mentioning that the structure and amount of HS impact the phase separation, processing, thermal or mechanical properties of polyurethanes. The soft blocks (SS) in the bio-TPU’s materials were built from α,ω-oligo(ethylene-butylene adipate) diol. Hereby, bio-TPUs differed in hard segments content (c.a. 30; 34; 40, and 53%). We found that already increase of bio-based diisocyanate content of the bio-TPU impact the changes in their thermal stability which was measured by TGA. Based on DMTA results we observed changes in the viscoelastic behavior of bio-TPUs. The DSC analysis revealed decreasing in glass transition temperature and melting temperature of hard segments. In general, obtained materials were characterized by good mechanical properties. The results confirmed the validity of undertaken research problem related to obtaining bio-TPUs consist of bio-based hard building blocks. The application of partially bio-based diisocyanate mixtures and bio-based chain extender for bio-TPU synthesis leads to sustainable chemistry. Therefore the total level of “green carbons” increases with the increase of bio-based diisocyanate content in the bio-TPU structure. Obtained results constitute promising data for further works related to the preparation of fully bio-based thermoplastic polyurethane elastomers and development in the field of bio-based polymeric materials

  • The image of the City on social media: A comparative study using “Big Data” and “Small Data” methods in the Tri-City Region in Poland
    • Jianxiang Huang
    • Hanna Obracht-Prondzyńska
    • Dorota Kamrowska-Załuska
    • Yiming Sun
    • Lishuai Li
    2021 Full text LANDSCAPE AND URBAN PLANNING

    “The Image of the City” by Kevin Lynch is a landmark planning theory of lasting influence; its scientific rigor and relevance in the digital age were in dispute. The rise of social media and other digital technologies offers new opportunities to study the perception of urban environments. Questions remain as to whether social media analytics can provide a reliable measure of perceived city images? If yes, what implication does it hold for urban planners? This paper describes a study on the perception of city images using a combination of “big data” and “small data” methods in the Tri-City Region in Poland. The aims were to 1) test the hypothesis whether social media analytics can elicit Lynchian elements of city image in consistency with conventional methods, and 2) develop and evaluate social media-based indicators of Imageability for planning practice. Geo-tagged images and texts were collected from Instagram and Twitter, two popular social media platforms in Poland. Text-Mining, Image Processing, Clustering Analysis, Kernel Density Estimation, and Sentiment Analysis were used. Results were compared with benchmarks constructed from official GIS database, questionnaire responses and sketch maps. “District”, “landmark”, and “path” identified on social media were in good agreements with benchmarks, less so for “edge” and “node”. Two social media-based indicators have influenced the perception of a place: Instagramability, the frequency of a place captured on Instagram, was linked to its perception as an architectural landmark and tourist attraction, while Twitterability, the frequency of a place mentioned on Twitter by name, was linked to its perceived niceness and relevance to everyday life of communities. Methods developed in this study have theoretical and practical implications for urban planners.

  • The Impact of Covid-19 on the Performance of Exchange Traded Funds on Developed and Emerging Markets
    • Krystian Zawadzki
    2021 Full text

    In this paper an endeavour was made to evaluate the impact of Covid-19 on the achievement of the investment objectives by selected ETFs in developed and emerging markets. For this purpose, the tracking errors calculated for 18 different ETFs operating on the basis of American, Asian and European stock indexes were analyzed. The time range of the research was selected in such a way as to compare the period before the pandemic(pre-Covid) and the period after the pandemic (post-Covid). The research results show that the outbreak of the coronavirus pandemic has not had a negative impact on the degree of implementation of the investment objective, regardless of the degree of market development. For each of the analyzed markets, the calculated tracking errors were not higher in the post-Covid period as compared to the pre-Covid period. In the vast majority of cases, they were even lower. This means that the management of the ETF has run smoothly in the most turbulent period of the 21st century.

  • The Impact of Decommissioning Cemeteries on the Urban Ecosystem
    • Anna Myślińska
    • Jakub Szczepański
    • Witold Dłubakowski
    2021 Full text Sustainability

    The decommissioning of cemeteries noticeably transforms the urban fabric. The purpose of this article was to determine what impact the decommissioning of cemeteries has on the urban ecosystem. For this purpose, it was necessary to assess the value of cemeteries within the urban ecosystem. Cemeteries are classified as urban green spaces, and their value as preservers of flora and fauna in local ecosystems has been proven. However, numerous decaying bodies in one place could have adverse effects on the environment. In order to assess the impact of transforming cemetery areas for other uses in the context of sustainable city development, it is necessary to define what these other functions might be. This article presents the main reasons for decommissioning cemeteries and links them with subsequent land use. The history of cemetery locations in five major Polish cities was analyzed to determine the extent to which cemeteries were decommissioned. In the two cities with the highest number of decommissioned cemeteries, further research was carried out in order to establish the typical land use of these former cemeteries, whether this usage is related to the size or type of the former cemetery, and whether change in land use is an advantage or a disadvantage for the urban ecosystem.

  • The impact of freeze-thaw processes on a cliff recession rate in the face of temperate zone climate change
    • Halina Kaczmarek
    • Arkadiusz Bartczak
    • Sebastian Tyszkowski
    • Michał Badocha
    • Michał Krzemiński
    2021 CATENA

    Freeze-thaw action is a common type of geomorphological processes eroding cliff faces in the temperate climate zone. In our previous study, we assessed the geomorphological effects of freeze-thaw fluctuations occurring within the cliff of Jeziorsko Reservoir (central Poland). Based on those findings, we have now determined the number of freeze-thaw cycles to assess their historical impact on the studied cliff. We have also traced the directions and the pace of changes in freeze-thaw processes in Poland. The results reveal a gradually decreasing role of freeze-thaw action in the process of the recession of the cliff of Jeziorsko Reservoir throughout its existence. The same is true nearly across Poland, although with some regional variation. Within 1951–2018, the impact of freeze-thaw action declined most significantly in north-western and central Poland, i.e. the area with the smallest annual number of freeze-thaw cycles. Consequently, this is also where the impact of geomorphological results of freeze-thaw cycles will be the least pronounced. It was only in the north-eastern edges of the country, which are under the dominant influence of continental air masses, where no significant changes in the impact of freeze-thaw processes were identified. The obtained results strongly legitimise the conclusion that global warming in the mid-latitude zone of the temperate climate has reduced the role of freeze-thaw processes in the geomorphological transformation of cliffs developed within river banks and lake or water reservoir shores.

  • The Impact of Ground Tire Rubber Oxidation with H2O2 and KMnO4 on the Structure and Performance of Flexible Polyurethane/Ground Tire Rubber Composite Foams
    • Aleksander Hejna
    • Adam Olszewski
    • Łukasz Zedler
    • Paulina Kosmela
    • Krzysztof Formela
    2021 Full text Materials

    The use of waste tires is a very critical issue, considering their environmental and economic implications. One of the simplest and the least harmful methods is conversion of tires into ground tire rubber (GTR), which can be introduced into different polymer matrices as a filler. However, these applications often require proper modifications to provide compatibility with the polymer matrix. In this study, we examined the impact of GTR oxidation with hydrogen peroxide and potassium permanganate on the processing and properties of flexible polyurethane/GTR composite foams. Applied treatments caused oxidation and introduction of hydroxyl groups onto the surface of rubber particles, expressed by the broad range of their hydroxyl numbers. It resulted in noticeable differences in the processing of the polyurethane system and affected the structure of flexible composite foams. Treatment with H2O2 resulted in a 31% rise of apparent density, while the catalytic activity of potassium ions enhanced foaming of system decreased density by 25% and increased the open cell content. Better mechanical performance was noted for H2O2 modifications (even by 100% higher normalized compressive strength), because of the voids in cell walls and incompletely developed structure during polymerization, accelerated by KMnO4 treatment. This paper shows that modification of ground tire rubber is a very promising approach, and when properly performed may be applied to engineer the structure and performance of polyurethane composite foams.

  • The Impact of Thermal Stresses on Volume Resistivity: Performance Comparison between TR-XLPE and XLPE Cables
    • Jasem Mohammed
    • Shady S. Refaat
    • Haitham Abu-Rub
    • Marek Olesz
    • Jarosław Guziński
    2021

    Most failures in electric power cables are attributed to the development of water trees inside the insulating materials. Thus, the development and utilization of Tree Retardant Cross-Linked Polyethylene (TR-XLPE) based cables have recently been given great attention to overcome the treeing issues. TR-XLPE cables use low-density polyethylene compounds suppressing the formation of water trees while retaining excellent electrical, physical, and processing attributes. This paper investigates and analyzes the impact of thermal stress on a 33kV three-core power cable with TR-XLPE and XLPE insulations in the presence of different types, shapes and sizes of voids. The results have been obtained after 500 hours of the accelerated aging test. The obtained results confirm the superiority of TR-XLPE over XLPE cables in terms of retaining higher volume resistivity. Results obtained from simulations conclude that TR-XLPE insulated cable retains 6% more dielectric strength when compared to XLPE insulated cable.

  • The Influence of a Photovoltaic Micro-Installation on the Low-Frequency Parameters of Electricity at PCC and Its Impact on the Thermal Characteristics of Selected Devices
    • Stanisław Galla
    • Mirosław Włas
    2021 Full text ENERGIES

    This manuscript illustrates the measurement results of parameters describing the quality of energy at the PCC (point of common coupling) of a photovoltaic micro-installation that can significantly affect devices in the same power grid. The analyses reflecting heating of selected devices used in domestic installations, which were performed in an isolated laboratory environment, are also indicated. The conducted study aimed at checking the thermal characteristics of the chosen equipment, i.e., AC/DC power supply, LED and fluorescent light sources, a step-down transformer at synergistically higher voltage harmonics and constant component in the network voltage. The tests were carried out at the disturbance levels recorded at the site of the photovoltaic micro-installation. The conducted tests aimed at indicating the presence of an increased level of synergetic disturbances in the vicinity of micro-photovoltaic installations. Based on the research, recommendations were made for photovoltaic micro-installations.

  • The Influence of Antitumor Unsymmetrical Bisacridines on 3D Cancer Spheroids Growth and Viability
    • Jolanta Kulesza
    • Monika Pawłowska
    • Ewa Augustin
    2021 Full text MOLECULES

    The culture of 3D spheroids is a promising tool in drug development and testing. Recently, we synthesized a new group of compounds, unsymmetrical bisacridines (UAs), which exhibit high cytotoxicity against various human cell lines and antitumor potency against several xenografts. Here, we describe the ability of four UAs—C-2028, C-2041, C-2045, and C-2053—to influence the growth of HCT116 and H460 spheres and the viability of HCT116 cells in 3D culture compared with that in 2D standard monolayer culture. Spheroids were generated using ultra-low-attachment plates. The morphology and diameters of the obtained spheroids and those treated with UAs were observed and measured under the microscope. The viability of cells exposed to UAs at different concentrations and for different incubation times in 2D and 3D cultures was assessed using 7-AAD staining. All UAs managed to significantly inhibit the growth of HCT116 and H460 spheroids. C-2045 and C-2053 caused the death of the largest population of HCT116 spheroid cells. Although C-2041 seemed to be the most effective in the 2D monolayer experiments, in 3D conditions, it turned out to be the weakest compound. The 3D spheroid culture seems to be a suitable method to examine the efficiency of new antitumor compounds, such as unsymmetrical bisacridines.

  • The influence of atmospheric circulation on the occurrence of dry and wet periods in Central Poland in 1954–2018
    • Andrzej Araźny
    • Arkadiusz Bartczak
    • Rafał Maszewski
    • Michał Krzemiński
    2021 Full text THEORETICAL AND APPLIED CLIMATOLOGY

    This work presents the influence of atmospheric circulation on the occurrence of dry and wet periods in the central Polish region of Kujawy. The material on which the authors relied encompassed monthly totals of precipitation obtained from 10 weather stations in the period 1954–2018. Both dry and wet periods have been identified on the basis of monthly values of the Standardised Precipitation Index (SPI). Additionally, the calendar of circulation types over Central Poland was used to determine the atmospheric circulation indices: western (W), southern (S) and cyclonicity (C). The analyses have indicated that the region concerned experiences low precipitation totals in comparison with the rest of Poland. According to the circulation indices W, S and C, for Central Poland, the air mass advection from the West prevails over that from the East. Moreover, a slightly more frequent inflow of air from the South than from the North has been observed. The frequency of anticyclonic situations is higher than that of the cyclonic types in this part of Europe. Drought spells occurred in the study area at a clear dominance of anticyclonic circulation, with the inflow of air mostly from the North and with increased westerly circulation. On the other hand, the occurrence of wet periods was mainly influenced by cyclonic circulation during the advection of the masses from the South and West. Dry and wet periods accounted for 28% and 27% of the study period, respectively.

  • The Influence of Cement Type on Early Properties of Cold In-Place Recycled Mixtures
    • Bohdan Dołżycki
    • Mariusz Jaczewski
    • Cezary Szydłowski
    2021 Full text

    Cold in-place recycling is a commonly used maintenance treatment in rehabilitation of low and medium volume roads in Poland. Typically, two types of binding agents are used—cement and bituminous emulsion (or foamed bitumen).Due to the harsh Polish climate with many freeze/thaw cycles and frequent occurrence of saturated conditions, the used amounts of cement are higher than those commonly used in warmer parts of Europe. While there is usually only one type of bituminous emulsion dedicated for cold recycling on the market, there are numerous types of cements, which differ in chemical composition and properties. The conducted research presents possible development of cold recycled mixture properties over curing time, taking into account the type of cement used. Two types of cement were tested in laboratory investigation—common Portland CEM I 32.5 R cement and Portland-fly ash CEM II 32.5 B-V cement with longer setting time. Cold recycled mixtures were designed with the same composition and amount of binding agents, but differed in the type of cement used. For both mixtures, indirect tensile strength and modulus were tested after 7, 28 and 90 days of curing in laboratory conditions. The laboratory tests confirmed lower values of strength and modulus for the fly ash cement after 7 and 28 days in comparison to the typical cement, but after 90 days the properties of both tested mixtures presented similar values. If the overall predicted fatigue life and long-term mechanical properties are the same, the use of slow-setting cementsmay result in reduction of reflective cracking on the surface of the pavement. In the case of low and medium volume roads, where there is no need for fast paving of the asphalt layers and more time may be allowed for the cold-recycled mixture to achieve the required initial strength, slow-setting cements should be considered as a viable treatment for reduction of the risk of reflective cracking.

  • The influence of climate change on the life insurance in the EU: A panel data approach
    • Oleksandr Melnychenko
    • Tetyana Kalna-Dubinyuk
    • Olha Vovchak
    • Tetiana Girchenko
    2021 Full text E3S Web of Conferences

    The financial sector, as one of the most sensitive economic sectors, is alert to all trends and changes in the environment. The aim of the article is to study the impact of climate change on the life insurance market using panel data from 28 countries of the European Union (EU) for the last 9 years. This study is based on a panel model, where the amount of premiums under life insurance contracts is defined as a function of the fundamental factor of climate change - greenhouse gas emissions. According to empirical findings, an increase in greenhouse gas emissions per thousand tons leads to an increase in the amount of life insurance premiums by 0.1786 million euros. It has also been found that an increase in greenhouse gas emissions per thousand tons leads to an increase in deaths in the European Union by 1.0442 people, and these consequences are statistically significant. In general, our results suggest that the life insurance market as well as the nonlife insurance market is dependent on climate change. The empirical results of this study provide valuable insight into how greenhouse gas emissions affect mortality in the European Union.

  • The Influence of Co-Fermentation of Agri-Food Waste with Primary Sludge on Biogas Production and Composition of the Liquid Fraction of Digestate
    • Anna Wilińska-Lisowska
    • Monika Ossowska
    • Krzysztof Czerwionka
    2021 Full text ENERGIES

    Energy self-sufficiency is a current trend in wastewater treatment plants. This effect can be achieved by increasing the production of electricity from biogas and by reducing energy consumption for technological processes. One idea, in line with the circular economy concept, is the use of waste rich in organic matter as co-substrates for the fermentation process. The aim of this study was to determine the effect of waste co-fermentation on biogas production and nitrogen concentration in the reject water. A co-fermentation process with flotate or flotate and vegetables increased biogas production compared to primary sludge by 162 and 180%, respectively. During the tests, there was no inhibition of the fermentation process. Hydrolysis of organic compounds contained in flotate and vegetables resulted in a significant increase in ammonium nitrogen (by 80–100%) and dissolved organic nitrogen concentration (by 170–180%). The biogas and methane production rate as well as the ammonium and total nitrogen release rate were calculated. An energy balance was made, which took into account the variable amount of electric energy production depending on the efficiency of the cogeneration systems and energy consumption for supplying oxygen necessary to remove nitrogen contained in the reject water. A positive energy balance was obtained for all analyses.

  • The Influence of Drying Temperature on Color Change of Hornbeam and Maple Wood Used as Surface and Inner Layers of Wood Composites
    • Ivan Klement
    • Peter Vilkovský
    • Tatiana Vilkovská
    • Kazimierz Orłowski
    • Jacek Barański
    • Daniel Chuchała
    • Aleksandra Suchta
    2021 Full text Applied Sciences-Basel

    The thermal treatment of wood changes its structure due to the degradation of wood polymers (cellulose, hemicellulose and lignin), so the physical properties of wood are either improved or degraded. Color changes apply not only to natural wood, but also to such wood composites for which some amount of glue is used in their construction (e.g., plywood, blockboard or laminboard). This article is focused on the analysis of hornbeam and field maple wood color changes influenced by drying temperature. Two types of drying modes were used: hot-air mode where the temperature of the drying environment was 60 C, and high-temperature mode with a drying temperature of 120 C. The drying mode was divided into two phases depending on the moisture content of the wood. The compared woods had similar values of color coordinates at the beginning of drying. During hot-air drying, the largest changes in color coordinates occurred during the first 24 h. The total color difference between the color at the end and the beginning of drying was 7.3 for hornbeam and 11.1 for maple. The overall color difference between the compared woods was minimal. During high-temperature drying (120 C), the color changes of the dried woods were more pronounced. In the case of maple wood, there was a very significant change in color and the value of DE* was twice as high as for hornbeam. The total color difference between the color at the end and at the beginning of drying was 8.7 for hornbeam and 18.9 for maple.

  • The Influence of External Additional Loading on the Muscle Activity and Ground Reaction Forces during Gait
    • Bartłomiej Zagrodny
    • Michał Ludwicki
    • Wiktoria Wojnicz
    2021 Full text Applied Bionics and Biomechanics

    Asymmetrical external loading acting on the usculoskeletal system is generally considered unhealthy. Despite this knowledge, carrying loads in an asymmetrical manner like carrying on one shoulder, with one hand, or on the strap across the torso is a common practice. This study is aimed at presenting the effects of the mentioned load carrying methods on muscle activity assessed by using thermal field and ground reaction forces. Infrared thermography and pedobarographic force platform (ground reaction force/pressure measurement) were used in this study. Experimental results point out an increased load-dependent asymmetry of temperature distribution on the chosen areas of torso and the influence of external loading on ground reaction forces. Results point out that wearing an asymmetrical load should be avoided and are showing which type of carrying the external load is potentially less and the most harmful.

  • The Influence of External Load on the Performance of Microbial Fuel Cells
    • Szymon Potrykus
    • León-Fernández Fernando Luis
    • Janusz Nieznański
    • Dariusz Karkosiński
    • Francisco-Jesus Fernandez-Morales
    2021 Full text ENERGIES

    In this work, the effect of the external load on the current and power generation, as well as on the pollutant removal by microbial fuel cells (MFCs), has been studied by step-wise modifying the external load. The load changes included a direct scan, in which the external resistance was increased from 120 Ω to 3300 Ω, and a subsequent reverse scan, in which the external resistance was decreased back to 120 Ω. The reduction in the current, experienced when increasing the external resistance, was maintained even in the reverse scan when the external resistance was step-wise decreased. Regarding the power exerted, when the external resistance was increased below the value of the internal resistance, an enhancement in the power exerted was observed. However, when operating near the value of the internal resistance, a stable power exerted of about 1.6 µW was reached. These current and power responses can be explained by the change in population distribution, which shifts to a more fermentative than electrogenic culture, as was confirmed by the population analyses. Regarding the pollutant removal, the effluent chemical oxygen demand (COD) decreased when the external resistance increased up to the internal resistance value. However, the effluent COD increased when the external resistance was higher than the internal resistance. This behavior was maintained in the reverse scan, which confirmed the modification in the microbial population of the MFC.

  • The influence of intermolecular correlations on the infrared spectrum of liquid dimethyl sulfoxide
    • Maciej Śmiechowski
    2021 Full text SPECTROCHIMICA ACTA PART A-MOLECULAR AND BIOMOLECULAR SPECTROSCOPY

    Dimethyl sulfoxide (DMSO) is routinely applied as an excellent, water-miscible solvent and chemical reagent. Some of the most important data concerning its liquid structure were obtained using infrared (IR) spectroscopy. However, the actual extent of intermolecular correlations that connect the isolated monomer spectrum to the IR response of the bulk liquid is poorly studied thus far. Using ab initio molecular dynamics (AIMD) simulations, IR spectra of liquid DMSO are obtained here from first principles and further analyzed using an array of sophisticated spectral decomposition techniques. The calculated spectra when unfolded in space reveal non-trivial spatial correlations underlying the IR response of liquid DMSO. It is unequivocally demonstrated that some of the fundamental vibrations visible in the intramolecular limit are effectively suppressed by the solvation environment due to symmetry reasons and thus disappear in the bulk limit, escaping experimental detection. Overall, DMSO as an aprotic solvent with dominant dipole–dipole interactions displays strong intermolecular correlations that contribute significantly to the IR spectra, on par with the situation observed in strongly associated liquids, such as water.

  • 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.