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Politechniki Gdańskiej

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  • Experimental and numerical investigations of ultimate strength of degradated structures
    • Krzysztof Wołoszyk
    2021 Pełny tekst

    The presented work investigates the corrosion influence on the structural behaviour of structural elements. Nine welded large-scale stiffened plates, and 30 standard small specimens have been subjected to the accelerated marine immersed conditions. After corrosion testing, the specimens have been accurately measured in terms of surface characteristics. The coupon specimens were furtherly subjected to tensile loading to develop the mechanical properties conditional on the severity of corrosion degradation. The FE analyses employing the technique of random field modelling were developed and validated against experiments. The stiffened plates were subjected to the compressive loading, and the structural response has been analysed, accounting for initial imperfection, corrosion degradation, welding-induced residual stresses, and material nonlinearity. The numerical models of different accuracy of corrosion degradation models were validated with the experimental results showing that only when non-uniform thickness reduction with subsequent changes in mechanical properties is taken into account, the structural behaviour could be accurately simulated. An analytical formulation allowing for a fast estimation of the structural capacity of corroded stiffened plates and the reliability formulation taking into account the time-dependent development of corrosion degradation has been developed.

  • Experimental and theoretical investigation of conformational states and noncovalent interactions in crystalline sulfonamides with a methoxyphenyl moiety
    • Mateusz Kowalik
    • Jakub Brzeski
    • Małgorzata Gawrońska
    • Katarzyna Kazimierczuk
    • Mariusz Makowski
    2021 CRYSTENGCOMM

    Four sulfonamide derivatives with a methoxyphenyl moiety, namely N-{4-[(2-methoxyphenyl)sulfamoyl] phenyl}acetamide (1a), N-{4-[(3-methoxyphenyl)sulfamoyl]phenyl}acetamide (1b), 4-amino-N-(2- methoxyphenyl)benzenesulfonamide (2a) and 4-amino-N-(3-methoxyphenyl)benzenesulfonamide (2b), have been synthesized and characterized physiochemically by CHNS, MS, FT-IR, 1H NMR, 13C NMR, PXRD and TG methods. Crystal structures were determined by SC-XRD and their conformational and noncovalent interaction properties were examined by both experimental and theoretical (HS, MEPS, NBO, dimerization energy, QTAIM) methods. The conformational flexibility of the bridge connecting two phenyl rings was studied and minimum-energy conformations were theoretically found. The packing architecture and hydrogen bond networks were described by graph set notation. Hirshfeld surface analysis revealed regions of stronger contacts and allowed us to indicate the relative contributions of different noncovalent contacts in the crystal packing. MEPS calculations helped to distinguish the electron rich and electron poor regions and to find the best H-bond donors and acceptors. The use of the QTAIM method enabled us to explain the influence of functional groups and molecular arrangement on the strength of noncovalent interactions in the crystals and overall packing efficiency

  • Experimental and theoretical investigation of the reactivity of [(BDI*)Ti(Cl){η2-P(SiMe3)-PiPr2}] towards selected ketones
    • Aleksandra Ziółkowska
    • Natalia Szynkiewicz
    • Łukasz Ponikiewski
    2021 DALTON TRANSACTIONS

    In this work, we report a new type of reactivity of [(BDI*)Ti(Cl){η2-P(SiMe3)-PiPr2}] (1) towards ketones (BDI* = 2,6-diisopropylphenyl-β-methyldiketiminate ligand). In the reaction of 1 with acetone, cyclopentanone or cyclohexanone, a ketone moiety is inserted into Ti–Pphosphanyl or Ti–Pphosphido bonds to form complexes with a new C–P–P moiety, providing [(BDI*)Ti(Cl){η2-P(SiMe3)-PiPr2-C(Me)2O}] (2a), [(BDI*)Ti(Cl){η2-OC(Me)2P(SiMe3)-PiPr2}] (2b), [(BDI*)Ti(Cl){η2-P(SiMe3)-P(iPr)2-{C(CH2)4}O}] (3a), and [(BDI*)Ti(Cl){η2-P(SiMe3)-P(iPr)2-{C(CH2)5}O}] (4a). Starting complex 1 reacts with cyclohexanone, yielding a monocrystalline complex [{(ArN[double bond, length as m-dash]C(Me)CHC(Me)[double bond, length as m-dash]NAr)C(CH2)5O}Ti(Cl){PiPr2-P(SiMe3)C(CH2)5O}] (4d) with the insertion of two ketone molecules. Interestingly, we found that monoinserted complexes 2a and 3a may be oxidized via a reaction with AgCl, leading to elimination of the –SiMe3 group and oxidation of the titanium atom. This reaction led us to isolate the Ti(IV) complex [(BDI*)Ti(Cl){η2-P-P(iPr)2-{C(CH2)5}O}] (5) in crystalline form. To identify the kinds of products that may be formed and determine which products are the most energetically favoured ones, we conducted a thermodynamic DFT study of 1 towards acetone, cyclopentanone and cyclohexanone. Structures 2a, 2b, 3a, 3e, 4a, 4d, and 5 were characterized by X-ray crystallography, and complex 5 was also identified by NMR spectroscopy.

  • Experimental and theoretical study of a vertical tube in shell storage unit with biodegradable PCM for low temperature thermal energy storage applications
    • Rafał Andrzejczyk
    • Tomasz Kowalczyk
    • Przemysław Kozak
    • Tomasz Muszyński
    2021 Pełny tekst APPLIED THERMAL ENGINEERING

    This article presents the experimental investigations of the coconut oil-based TES module for HVAC applications in the ambient and-sub ambient temperature range. To properly study this problem modular experimental module and test loop were developed. Special attention has been paid to study the physical mechanism of the melting/solidification process for natural substance (coconut oil) which has perspectives to be used in thermal energy storage systems. It has been a highlight that the melting/solidification process is much more complex for non-eutectic mixtures and there are limited analytical models witch could be used to design TES working with such substances. Due to the limit of literature data for thermophysical properties of coconut oil own experimental data has been conducted. The article presents both visual and thermal characteristics of the melting and solidification process. It has been confirmed the strong influence of natural convection phenomena at the melting process. What is more, it has been observed that in the case of coconut oil it is better to talk about appearance melting temperature than melting temperature. The experimental analysis confirmed that appearance melting temperature is a function of radial distance from the heat source. In the case of solidification, the influence of natural convection is reduced quickly due to the increasing domination of the conduction heat transfer mechanism. For the solidification temperature profiles are characteristic of the occurrence of subcooling temperature. The level of temperature drop in sub cooling is a function of radial distance from the heat source. It has been also confirmed that in case of melting as well as solidification process the shape of the phase-change profile seems to form a truncated cone (in case of melting inverted). To validate the engineering approach to vast discrepancies in the literature data own experiment has been evaluated with a simple mathematical model to verify the applicability of the literature data in system behavior prediction. Based on the best-fit approach the parameters thermal resistance of the module R = 1.3 W/K was found. Additionally the latent heat of the coconut oil of 178 kJ/kg with Gaussian distribution for melting in temperature of 25 °C and solidification at 21 °C. The proposed correlation can be easily used to optimize latent thermal energy storage cooperated with the HVAC system.

  • Experimental Investigation of Free Convection Heat Transfer from Horizontal Cylinder to Nanofluids
    • Dorota Sawicka
    • Janusz Cieśliński
    • Slawomir Smolen
    2021 Pełny tekst ENERGIES

    The results of free convection heat transfer investigation from a horizontal, uniformly heated tube immersed in a nanofluid are presented. Experiments were performed with five base fluids, i.e., ethylene glycol (EG), distilled water (W) and the mixtures of EG and water with the ratios of 60/40, 50/50, 40/60 by volume, so the Rayleigh (Ra) number range was 3 104 Ra 1.3 106 and the Prandtl (Pr) number varied from 4.4 to 176. Alumina (Al2O3) nanoparticles were tested at the mass concentrations of 0.01, 0.1 and 1%. Enhancement as well as deterioration of heat transfer performance compared to the base fluids were detected depending on the composition of the nanofluid. Based on the experimental results obtained, a correlation equation that describes the dependence of the average Nusselt (Nu) number on the Ra number, Pr number and concentration of nanoparticles is proposed.

  • Experimental investigation of performance and emission characteristics of a miniature gas turbine supplied by blends of kerosene and waste tyre pyrolysis oil
    • Tomasz Suchocki
    • Łukasz Witanowski
    • Piotr Lampart
    • Paweł Kazimierski
    • Katarzyna Januszewicz
    • Bartosz Gawron
    2021 ENERGY

    Fossil fuels are non-renewable sources of energy that could be depleted in the near future, giving rise to amajor energy crisis. Scientists from all over the world are working on new technologies to produce fuelnot only from renewable sources but also from waste. This article is concerned with: (i) waste tyremanagement by means of the pyrolysis process, (ii) investigation of physico-chemical parameters ofwaste tyre pyrolysis oil (TPO), and (iii) investigation of performance and emission characteristics of aminiature GTM-140 turbine engine supplied by blends of kerosene and waste tyre pyrolysis oil. Thefinalaim of the research is to determine the influence of the applied blend composition (between 10 and 50%of TPO in the blends) on the performance and emission parameters of a small gas turbine. Turbine inletand outlet temperatures, fuelflow, static thrust, thrust specific fuel consumption (TSFC) and emissionsindex of NOx, CO, SO2are measured in a wide range of turbine load. The differences are the largest for thehighest rotational speeds, where the temperatures, TSFC and emissions of NOxespecially tend to increasewith the increasing fraction of pyrolytic oil in the blends, as compared to those of kerosene. However,emissions of SO2are lower for the all blends in the entire range of load.

  • Experimental Research of an Axial Piston Pump with Displaced Swash Plate Axis of Rotation
    • Paweł Załuski
    2021

    The article describes the influence of displacement of the swash plate rotation axis on the efficiency of axial piston pumps. The dead space volume was defined as the volume of the working chamber in the extreme position of the piston at the end of the pumping phase and its variability was determined as a function of the position of the axis of rotation of the swash plate and the swing angle of swash plate. The influence of swash plate rotation axis displacement on leaks between piston and cylinder was determined. It has been proven that displacement of the swash plate rotation axis reduces the dead space volume and leaks, thus improving the volumetric efficiency visible at small swash plate swing angles. The results of a comparative study of the volumetric and total efficiency of a modified design of a pump that allows the rotation axis to be repositioned are presented. The efficiency curves for the swash plate rotation axis crossing the shaft rotation axis and for the displaced swash plate axis of rotation are compared. The article also presents the author’s construction of an axial piston pump with displaced swash plate rotation axis with a follow-up mechanism of capacity change controlled by a stepper motor. The diagram and view of the test stand are shown, as well as the results of tests of volumetric and hydromechanical pump efficiency.

  • Experimental research of the effect of face milling strategy on the flatness deviations
    • Michał Dobrzyński
    • Daniel Chuchała
    • Kazimierz Orłowski
    • Mateusz Kaczmarczyk
    2021 Pełny tekst MATERIALS AND MANUFACTURING PROCESSES

    In this paper the dependencies between face milling strategy of EN AW6082-T6 aluminum alloy samples, with difference thicknesses (6, 8, and 12 mm) and two cold rolling directions, and flatness deviations were presented. Three strategies of milling included different proportions of material removed from both sides of the plates. This approach allowed to control the proportions of residual surface stresses on both sides of the specimens, which were created by the cold rolling process. The face milling strategy involving the symmetrical removal of material from both sides of the sample resulted in the best results of flatness deviations. This strategy was most effective for both rolling directions. It has been observed that the use of an appropriate face milling strategy is particularly important for thin sheets (6 mm thick). In the case of thicker plates (12 mm thick), the selected strategy has less impact on the final values of flatness deviations.

  • Experimental Study of the Resistance to Influence of Aggressive Liquids on Lightweight Concrete
    • Marzena Kurpińska
    • Elżbieta Haustein
    2021 Pełny tekst Materials

    In light of the scientific research, the corrosion of concrete structures is one of the main problems that may reduce their durability due to the negative impact of the natural environment. The paper analyzes the influence of the type of component on the selected properties of lightweight concrete subjected to the influence of aggressive liquids. Four concrete mixes were prepared with a granular aggregate made of foamed glass (GEGA) and aggregate made of sintered fly ash (GAA) with the use of a mineral additive: silica fly ash. The prepared lightweight concrete after one year was exposed for 60 days to the following environments: strong acid—HCl, 1% and 2% concentration, weak acid—CH3COOH, 1% and 2% concentration, and an aqueous salt solution of Na2SO4 , 1% and 2% concentration. Then, the compressive strength was tested, and the microstructure analysis of the ready-made lightweight concrete (LWC) was performed. The degree of penetration of aggressive solutions into the cracks of the samples was assessed by means of applying 1% phenolphthalein solution. Changes in the weight of lightweight concrete samples after the test period were estimated. The obtained test results indicate that the decrease in the durability of lightweight concrete can be classified as a long-term process. Concrete with GEGA and GAA showed high resistance to aggressive environments. Moreover, the environment containing chlorides turned out to be the most aggressive, while the environment containing sulfates proved to be the least aggressive. The higher the concentration of the destructive factor was, the faster the corrosion process went. This has been proven by measuring the pH using phenolphthalein and carrying out microscopic examination. Concretes containing aggregates made of foamed glass and sintered fly ash are suitable for use both in traditional construction and in facilities exposed to an aggressive environment (e.g., in the chemical industry and at gas stations.

  • Experimental tuning of AuAg nanoalloy plasmon resonances assisted by machine learning method
    • Robert Kozioł
    • Marcin Łapiński
    • Paweł Syty
    • Wojciech Sadowski
    • Józef Sienkiewicz
    • Bartosz Nurek
    • Valentin Maraloiu
    • Barbara Kościelska
    2021 Pełny tekst APPLIED SURFACE SCIENCE

    Plasmonic nanostructures based on AuAg nanoalloys were fabricated by thermal annealing of metallic films in an argon atmosphere. The nanoalloys were chosen because they can extend the wavelength range in which plasmon resonance occurs and thus allow the design of plasmonic platforms with the desired parameters. The influence of initial fabrication parameters and experimental conditions on the formation of nanostructures was investigated. For the surface morphology studies, chemical composition analysis and nanograin structure, Scanning Electron Microscopy (SEM), X-Ray Photoelectron Spectroscopy (XPS), Energy Dispersive X-Ray Spectroscopy (EDS) and High-Resolution Transmission Electron Microscopy (HR TEM) measurements were performed. The position of the resonance band was successfully tuned in the 100 nm range. The EDS together with the XPS analysis confirmed the formation of an alloy with the aspect ratio of individual metals in a single nanoisland similar to the ratio of the thicknesses of the initially sputtered layers. The experimental research was complemented by the neural network model, which enables the calculation of the absorbance peak depending on the thickness of Au and Ag layers and the annealing time. The proposed model of machine learning makes it possible to fine-tune the desired position of the plasmon resonance.

  • Explicit Size-Reduction of Circularly Polarized Antennas through Constrained Optimization with Penalty Factor Adjustment
    • Marzieh Mahrokh
    • Michał Kozieł
    2021 Pełny tekst IEEE Access

    Modern communication systems of high data capacity incorporate circular polarization (CP) as the preferred antenna radiation field configuration. In many applications, integration of the system circuitry with antennas imposes size limitations on CP radiators, which makes their development process a challenging endeavor. This can be mitigated by means of simulation-driven design, specifically, constrained numerical optimization. Majority of the performance-related constraints are expensive to evaluate, i.e. require full-wave electromagnetic (EM) analysis of the system. Their practical handling can be realized using a penalty function approach, where the primary objective (antenna size reduction) is complemented by contributions proportional to properly quantified constraint violations. The coefficients determining the contribution of the penalty terms are normally set up using designer’s experience, which is unlikely to render their optimum values in terms of the achievable miniaturization rates as well as constraint satisfaction. This letter proposes a procedure for automated penalty factor adjustment in the course of the optimization process. Our methodology seeks for the most suitable coefficient levels based on the detected constraint violations and feasibility status of the design. It is validated using two CP antenna structures. The results demonstrate a possibility of a precise constraint control as well as superior miniaturization rates as compared to the manual penalty term setup.

  • Exploring DAD and ADD Methods for Dealing with Urban Heat Island Effect
    • Julia Kurek
    • Justyna Martyniuk-Pęczek
    2021 Pełny tekst Sustainability

    The Urban Heat Island (UHI) effect in the context of climate change and temperature fluctuations is an increasing challenge for contemporary cities. Numerous activities focus on mitigation and adaptation to the UHI effect using both appropriately selected design strategies and technological solutions. However, not all of these technologies support the postulates of ecological and low-carbon cities. Their design, implementation, and operation process sometimes causes conflicts or misunderstandings among designers, industry engineers, and residents. The aim of the research was to examine the relationship between UHI effect mitigation, adaptation, and energy efficiency strategies. A further goal was to build a matrix of synergistic elements and conflicts for respective actors and stakeholders, and an analysis of the elitist DAD (Decide-Announce-Defend) method and participatory ADD (Announce-Discuss-Decide) or EDD (Engage-Deliberate-Decide) in dealing with the UHI effect. The literature review and case study analysis methods were applied. In the study, the strategies of five chosen European capitals (Berlin, London, Paris, Vienna, and Warsaw) experiencing a UHI problem were analyzed. As result, a matrix of the most common goal differences of respective stakeholders in dealing with the UHI effect was developed. One of the main conclusions is the necessity of undergoing synergic collaboration between actors that are not cooperating yet, combined with risk analysis and appropriate education at different levels for a successful and socially equal mitigation and adaptation to the UHI effect.

  • Exploring multi-step glucose oxidation kinetics at GOx-functionalized nanotextured gold surfaces with differential impedimetric technique
    • Wiktoria Lipińska
    • Jacek Ryl
    • Paweł Ślepski
    • Katarzyna Siuzdak
    • Katarzyna Grochowska
    2021 Pełny tekst MEASUREMENT

    For a few past years, we can observe the enormous growth of investigations related to ultrasensitive electrochemical sensors capable of reliable determination of important body parameters and analytes. Utilized procedures rely on standard electrochemical methods, demanding electrode polarization, and information about the initial characteristics of the working electrode. More and more complex electrode materials are characterized however their electrochemical response is not fully understood or defined, affecting data reproducibility. Herein, we propose a novel protocol utilizing dynamic electrochemical impedance spectroscopy in galvanostatic mode (g-DEIS) to verify the sensor performance. The protocol was applied to study the response of Ti-Au nanotextured electrode depending on glucose concentration changes. The g-DEIS allowed to monitor complex mechanism occurring at the electrode/electrolyte interface with the continuously dosed glucose through electric parameters derivatives in analyte content. Our studies revealed a visible increase in electrode electric heterogeneity above 1.9 mM of glucose and gold nanoparticles’ oxidation above 3.8 mM, both influencing electrode kinetics. The results were confirmed using supporting cyclic voltammetry and x-ray photoelectron spectroscopy studies. The proposed protocol’s unique features could significantly spread further application of targetable biosensors for real-time diagnostics.

  • Exploring the Institutional and Bottom-Up Actions for Urban Air Quality Improvement: Case Studies in Antwerp and Gdańsk
    • Joanna Badach
    • Małgorzata Dymnicka
    • Jarosław Załęcki
    • Maciej Brosz
    • Dimitri Voordeckers
    • Maarten Van Acker
    2021 Pełny tekst Sustainability

    The article presents the results of qualitative studies concerning the presence of air quality management in the process of urban planning and in the public discourse in Antwerp, Belgium, and Gdańsk, Poland. We focused on the way urban planners, environmental experts, and stakeholders perceive the problem of air pollution, especially with respect to urban development policy, and whether they consider it one of the major factors determining the quality of the urban built environment. The analysis was empirically based on free, partially structured interviews with experts. With that aim, we referred to certain assumptions of the multidimensional concept of environmental protection and integrated urban planning, highlighting the knowledge gained through interview analysis, literature review, and comparative case study research. The approach brings to light the difference between the perceived and measured air quality and to what extent it is affected by the spatial conditions. The research reveals how the range of perceptions of air pollution is embedded in several sociological, urban planning, and cultural perspectives and how these perceptions differ between the different profiles of the stakeholders and experts.

  • Exposure to Bisphenol A Analogs and the Thyroid Function and Volume in Women of Reproductive Age—Cross-Sectional Study
    • Justyna Milczarek-Banach
    • Dominik Rachoń
    • Tomasz Bednarczuk
    • Katarzyna Myśliwiec-Czajka
    • Andrzej Wasik
    • Piotr Miśkiewicz
    2021 Pełny tekst Frontiers in Endocrinology

    Bisphenols (BPs) are commonly known plastifiers that are widely used in industry. The knowledge about the impact of BPs on thyroid function is scarce. Proper thyroid functioning is especially important for women of reproductive age, as hypothyroidism affects fertility, pregnancy outcomes and the offspring. There are no studies analyzing the influence of BPs on thyroid function and volume in non-pregnant young women. The aim of this cross-sectional study was to evaluate the relationship between bisphenol A and its 10 analogs (BPS, BPC, BPE, BPF, BPG, BPM, BPP, BPZ, BPFL, and BPBP) on thyroid function and volume in women of reproductive age. Inclusion criteria were: female sex, age 18–40 years. Exclusion criteria were history of any thyroid disease, pharmacotherapy influencing thyroid function, pregnancy or puerperium, and diagnosis of autoimmune thyroid disease during this study. Venous blood was drawn for measurement of thyrotropin (TSH), free thyroxine, thyroid peroxidase antibodies, thyroglobulin antibodies, BPs. Urine samples were analyzed for: ioduria and BPs. Ultrasound examination of thyroid gland was performed. One hundred eighty participants were included into the study. A negative correlation was found between urine BPC and the thyroid volume (R = −0.258; p = 0.0005). Patients with detected urine BPC presented smaller thyroid glands than those with not-detected urine BPC (p = 0.0008). A positive correlation was found between TSH and urine BPC (R = 0.228; p = 0.002). Patients with detected urine BPC presented higher concentrations of TSH versus those with not- detected urine BPC (p = 0.003). There were no relationships between any of serum BPs as well as the other urine BPs and thyroid function and its volume. The only BP that demonstrated the relationship between thyroid function and its volume was BPC, probably because of its chemical structure that most resembles thyroxine. Exposure to this BP may result in the development of hypothyroidism that could have a negative impact on pregnancy and the offspring.

  • Extended Newmark method to assess stability of slope under bidirectional seismic loading
    • Aleksandra Korzec
    • Robert Jankowski
    2021 SOIL DYNAMICS AND EARTHQUAKE ENGINEERING

    The paper concerns the dynamic behavior of a simple slope model subjected to simultaneous horizontal and vertical excitations. The proposed method is based on Newmark’s sliding block concept, however, four new features are introduced. The most important assumption is that the normal component of dynamic excitations affects the resisting force both before and after the initiation of the relative slope motion, making it time-dependent. The proposed formula and solution method is validated by experiments conducted on the shaking table and the bidirectional oscillatory device. The block displacement and acceleration time-histories are measured and analyzed. Experiments results conducted for bidirectional cyclic motion showed that the influence of vertical acceleration on the stability of the slope can be both negligible and significant (up to 57%). The numerical tests results, performed for thirty-five European seismic records, showed the underestimation of permanent displacement can reach up to 19% if the vertical excitation is neglected.

  • Extending the Frequency Limit of Microstrip-Coupled CSRR Using Asymmetry
    • Abhishek Kumar Abhishek
    • Adam Lamęcki
    • Roberto Gómez-García
    • Michał Mrozowski
    2021 IEEE TRANSACTIONS ON MICROWAVE THEORY AND TECHNIQUES

    Abstract— This article explains the frequency limitation in designing microstrip circuits based on a complementary split-ring resonator (CSRR) and reports a novel technique for increasing its operating frequency, which makes the CSRR suitable for high-frequency applications. This study helps in synthesizing the dimensions of symmetric CSRR (SCSRR) and asymmetric CSRR (ACSRR) circuits, which shows the applicability of the proposed technique in designing mm-wave circuits. It is observed that the upper frequency limit of the microstrip-coupled SCSRR is mainly due to weak electric coupling. The weak coupling implicates radiation loss in the structure, and the frequency at which the SCSRR has maximum loss due to radiation is found to be much less than the cutoff frequency of the higher order mode of the microstrip line, thus effectively limiting the operating frequency range of the circuit. In this article, the type of coupling and associated electrical parameters, e.g., reflected power, transmitted power, radiated power, losses, quality factor, voltage standing wave ratio, and gain, are investigated in detail. The allowable bandwidth of the fundamental mode of the microstrip line can be utilized to design CSRR with improved coupling. It is found that the ACSRR enhances the coupling coefficient using the cross-coupling effect. At higher frequencies, where the electric coupling is becoming too weak for the SCSRR, it is possible to design a magnetically coupled ACSRR of the same dimensions as the SCSRR. Finally, the design profile for both the SCSRR and ACSRR is studied in detail, and the radiating condition is discussed as a function of the height and dielectric constant of the substrate. For practical-verification purposes, two circuit prototypes are fabricated on a 1.5-mm-thick Rogers RT5880 substrate, and the measured results are found to be in good agreement with the proposition. It is found that, for a given microwave substrate, the maximum allowable resonating frequency of the ACSRR structure is nearly twice that of the SCSRR structure.

  • Fabrication of toughened plastic using styrene butadiene rubber-poly (methyl methacrylate) interpenetrating polymer networks
    • J. James
    • G.v. Thomas
    • D Rouxel
    • Michał Strankowski
    • N. Kalarikkal
    • Sabu Thomas
    2021 Materials Today Chemistry

    A standard set of interpenetrating polymeric networks (IPNs) has been contrived using an elastomerstyrene butadiene rubber and a thermoplastic poly (methyl methacrylate) through sequential polymerization protocol. This low-cost material can be hopefully engaged as a toughened plastic with cocontinuous morphology. Different morphological protocols including Raman imaging are effectively utilized to envisage the effect of blend ratio in IPN fabrication. The different mechanical properties of IPNs revealed that the cross-linking in phases have their own impact. Thermogravimetric analysis is used as an efficient tool to prove the extra thermal stability of IPNs. Of seven different composites theoretical models, the Davies model showed better fit to the experimental data. The etiquette of characterization adopted in this work including mechanical, morphological, and thermal protocols and their correlation with theoretical predictions can definitely be act as a platform for the synthesis of low-cost toughened plastic.

  • Face with Mask Detection in Thermal Images Using Deep Neural Networks
    • Natalia Głowacka
    • Jacek Rumiński
    2021 Pełny tekst SENSORS

    As the interest in facial detection grows, especially during a pandemic, solutions are sought that will be effective and bring more benefits. This is the case with the use of thermal imaging, which is resistant to environmental factors and makes it possible, for example, to determine the temperature based on the detected face, which brings new perspectives and opportunities to use such an approach for health control purposes. The goal of this work is to analyze the effectiveness of deep-learning-based face detection algorithms applied to thermal images, especially for faces covered by virus protective face masks. As part of this work, a set of thermal images was prepared containing over 7900 images of faces with and without masks. Selected raw data preprocessing methods were also investigated to analyze their influence on the face detection results. It was shown that the use of transfer learning based on features learned from visible light images results in mAP greater than 82% for half of the investigated models. The best model turned out to be the one based on Yolov3 model (mean average precision—mAP, was at least 99.3%, while the precision was at least 66.1%). Inference time of the models selected for evaluation on a small and cheap platform allows them to be used for many applications, especially in apps that promote public health.

  • Facet effect of TiO2 nanostructures from TiOF2 and their photocatalytic activity
    • Marta Kowalkińska
    • Szymon Dudziak
    • Jakub Karczewski
    • Jacek Ryl
    • Grzegorz Trykowski
    • Anna Zielińska-Jurek
    2021 Pełny tekst CHEMICAL ENGINEERING JOURNAL

    In this study, special attention is focused on the design of TiO2 morphology and microstructure in the two-step preparation procedure using TiOF2 as a precursor to study their photodegradation mineralization efficiency. Firstly, TiOF2 was synthesized by a simple solvothermal method using titanium(IV) tetrafluoride, which was further used as a precursor in preparation of anatase 2D nanosheets, octahedral, decahedral, and rectangular prisms shape structures. The as-obtained nanostructures were characterized by X-ray diffraction (XRD), scanning electron microscopy (SEM), Brunauer-Emmett-Teller surface area analysis (BET), X-ray photoelectron spectroscopy (XPS), UV–vis diffuse reflectance spectroscopy and photoluminescence spectroscopy. It was assumed that TiOF2 could be applied as a useful precursor for the preparation of nanostructured TiO2 with defined morphology. Simple controlling of the reaction environment, together with the stabilizing effect of the introduced substrates, resulted in the formation of TiO2 particles with different morphologies and consequently exposed crystal facets. The presence of {001}, {101} and {100} facets influence on their photocatalytic activity but mostly on their mineralization efficiency and the pathway of phenol degradation. From the obtained series, the TiO2 octahedra exposing {101} facets exhibited the highest photoactivity and mineralization efficiency under UV–Vis light irradiation, which decreases as the other facets appear and become more exposed. The obtained results were compared with a computational study on the ∙OH and ∙O2– attack on the phenyl ring. Overall results showed that the surface effects of the photocatalyst could be an influencing factor in both mineralization efficiency and photodegradation products formation.

  • Fast and reliable knowledge-based design closure of antennas by means of iterative prediction-correction scheme
    • Sławomir Kozieł
    • Anna Pietrenko-Dąbrowska
    2021 Pełny tekst ENGINEERING COMPUTATIONS

    A novel framework for expedited antenna optimization with an iterative prediction-correction scheme is proposed. The methodology is comprehensively validated using three real-world antenna structures: narrow-band, dual-band and wideband, optimized under various design scenarios. The keystone of the proposed approach is to reuse designs pre-optimized for various sets of performance specifications and to encode them into metamodels that render good initial designs, as well as an initial estimate of the antenna response sensitivities. Subsequent design refinement is realized using an iterative prediction-correction loop accommodating the discrepancies between the actual and target design specifications. The presented framework is capable of yielding optimized antenna designs at the cost of just a few full-wave electromagnetic simulations. The practical importance of the iterative correction procedure has been corroborated by benchmarking against gradient-only refinement. It has been found that the incorporation of problem-specific knowledge into the optimization framework greatly facilitates parameter adjustment and improves its reliability. The proposed approach can be a viable tool for antenna optimization whenever a certain number of previously obtained designs are available or the designer finds the initial effort of their gathering justifiable by intended re-use of the procedure. The future work will incorporate response features technology for improving the accuracy of the initial approximation of antenna response sensitivities. The proposed optimization framework has been proved to be a viable tool for cost-efficient and reliable antenna optimization. To the knowledge, this approach to antenna optimization goes beyond the capabilities of available methods, especially in terms of efficient utilization of the existing knowledge, thus enabling reliable parameter tuning over broad ranges of both operating conditions and material parameters of the structure of interest.

  • Fast Approximate String Search for Wikification
    • Szymon Olewniczak
    • Julian Szymański
    2021 Pełny tekst

    The paper presents a novel method for fast approximate string search based on neural distance metrics embeddings. Our research is focused primarily on applying the proposed method for entity retrieval in the Wikification process, which is similar to edit distance-based similarity search on the typical dictionary. The proposed method has been compared with symmetric delete spelling correction algorithm and proven to be more efficient for longer stings and higher distance values, which is a typical case in the Wikification task.

  • Fast Design Closure of Compact Microwave Components by Means of Feature-Based Metamodels
    • Anna Pietrenko-Dąbrowska
    • Sławomir Kozieł
    2021 Pełny tekst Electronics

    Precise tuning of geometry parameters is an important consideration in the design of modern microwave passive components. It is mandatory due to limitations of theoretical design methods unable to quantify certain phenomena that are important for the operation and performance of the devices (e.g., strong cross-coupling effects in miniaturized layouts). Consequently, the initial designs obtained using analytical or equivalent network models require further adjustment. For reliability reasons, it has to be conducted using electromagnetic (EM) simulation tools, which entails considerable computational expenses whenever conventional numerical optimization algorithms are employed. Accelerating EM-driven design procedures is therefore highly desirable. This work discusses a surrogate-based algorithm for fast design closure and dimension scaling of miniaturized microwave passives. Our approach involves a small database of previously obtained designs as well as two metamodels, an inverse one, employed to yield a high-quality initial design, and the forward surrogate that provides predictions of the system sensitivities. The second model is constructed at the level of response features, which enables a more accurate gradient estimation and leads to improved reliability and a faster convergence of the optimization process. The presented technique is validated using two compact microstrip couplers and benchmarked against the state-of-the-art warm-start optimization frameworks.

  • Fast Fading Influence on the Deep Learning-Based LOS and NLOS Identificationin Wireless Body Area Networks
    • Krzysztof Cwalina
    • Alicja Olejniczak
    • Olga Błaszkiewicz
    • Piotr Rajchowski
    • Jarosław Sadowski
    2021

    In the article, the fast fading influence on the proposed DL (Deep Learning) approach for LOS (Line-of-Sight) and NLOS (Non-Line-of-Sight) conditions identification in Wireless Body Area Networks is investigated. The research was conducted on the basis of the off-body communication measurements using the developed mobile measurement stand, in an indoor environment for both static and dynamic scenarios. The measurements involved five different people with diverse body parameters. The proposed DL approach allows identifying the LOS and NLOS conditions with efficiency over 99% for selected scenarios, which include the fast fading component.

  • Fatal N-Ethylhexedrone Intoxication
    • Ewa Domagalska
    • Laura Banaszkiewicz
    • Mateusz Woźniak
    • Marzena Kata
    • Beata Szpiech
    • Michał Kaliszan
    2021 Pełny tekst JOURNAL OF ANALYTICAL TOXICOLOGY

    N-Ethylhexedrone [2-(ethyloamino)-1-phenylhexan-1-one; α-ethylaminohexanophenone; NEH] is one of the most recent synthetic cathinones that appeared on the illegal market in late 2015. The majority of information concerning the model of consumption of NEH and its impact on the body originates only from self-reports from grey literature websites and drug forums. There are only limited data associated with the concentrations of NEH in blood samples available in the literature. This article presents a case of fatal NEH intoxication and a method for the determination of this substance in whole blood. A 21-year-old man without any diagnosed diseases was admitted to the hospital due to disorientation, aggression and finally loss of consciousness. Hyperthermia (>41°C), tachycardia (>160 beats per minute), tachypnoe (20 breaths per minute), blood pressure (110/60 mmHg) and acute kidney failure were diagnosed. After a few hours of hospitalization, the patient died. A plastic bag with a white powder was found in his underwear. Analysis of the powder by another laboratory revealed cocaine hydrochloride; however, no cocaine or its metabolites were found in the biological material upon testing in our laboratory. Therefore, re-analysis of the powder was performed, and NEH was identified. Liquid-liquid extraction followed by LC-MS-MS analysis were used for the determination of NEH in blood. The validation parameters were as follows: calibration range 1-250 ng/mL, accuracy 106.5-109.9%, precision 3.5-6.3%, recovery 90.1-96.9%, LOD 0.07 ng/mL and LOQ 1 ng/mL. NEH was quantified in the blood at a concentration of 145 ng/mL. Additionally, amphetamine at low concentrations and THC-COOH were detected. Our study provided information on the possible lethal concentration and toxidrome that clinicians can observe for NEH-intoxicated patients and can be helpful during the preparation of toxicology analysis reports for a court of law for proper data.

  • Fatigue Performance of Double-Layered Asphalt Concrete Beams Reinforced with New Type of Geocomposites
    • Piotr Jaskuła
    • Dawid Ryś
    • Marcin Stienss
    • Cezary Szydłowski
    • Michał Gołos
    • Jacek Kawalec
    2021 Pełny tekst Materials

    The reinforcement of asphalt layers with geosynthetics has been used for several decades, but proper evaluation of the influence of these materials on pavement fatigue life is still a challenging task. The presented study investigates a novel approach to the reinforcement of asphalt layers using a new type of geogrid composite, in which square or hexagonal polypropylene stiff monolithic paving grid with integral junctions is bonded to polypropylene non-woven paving fabric. The laboratory fatigue tests were performed on large asphalt concrete beams reinforced with the new type of geocomposite. Unreinforced samples were used as reference. Test results were analysed in several aspects, including the standardised approach based on stiffness reduction, but also using energy dissipation. The effect of reinforcement on pavement fatigue life was also estimated. Based on the obtained final results of fatigue life calculations, it can be concluded that the evaluated geogrid composites have an evident positive effect on pavement performance and have a significant potential to extend the overall pavement life, especially in the case of hexagonal grid.

  • Female entrepreneurship in Kazakhstan
    • Krystyna Gomółka
    2021

    Women constitute the majority of the Kazakh population and, even though they live almost 10 years longer than men on average, they are far less economically active. Less than half of the female population take up employment. Women’s wages are often as much as 30% lower than men’s. The subjective reasons for undertaking economic activity as mentioned by women included: independence from the husband, low earnings of the husband and wish to help the family, lower pay compared to men’s, and opportunities in business. Wishing to encourage women to undertake economic activity, the government of Kazakhstan adopted the Act on gender equality, followed by a programme of intensified efforts for SME development. Women’s entrepreneurship was supported by funds made available as part of financial programmes aimed at women, the most important of which is known as DAMU. In 2009 companies with female managers accounted for 5.17% and in 2019 for 43.26% of all SMEs. The majority of the businesses established by women were in the services, retail and wholesale sectors. Car and motorcycle repair enterprises and other services employed the largest number of workers. The largest number of companies were established in two cities: Almaty and Nur-Sultan. The businesses owned by women were mostly one-person companies.

  • Feminidad online:¿ ni feminista ni auténtica?
    • David Duenas Cid
    • Estefanía Jiménez
    • Cilia Willem
    2021

    Mucho se ha escrito sobre internet y sus múltiples y diversos impactos sobre la vida de las personas, la economía, la política o cualquier otro ámbito de la sociedad. Evidentemente, lo relacionado con los modos de expresar las relaciones de género en entornos digitales no ha quedado al margen de esta espiral analítica. De hecho, ha generado una abundante literatura que cubre múltiples subtemas, incluyendo aspectos tan diversos como la sexualización, la violencia de género en las redes sociales, la renovación de las formas del feminismo digital, las diferentes formas de adopción de tecnología según el género o la expresión de roles de género en el mundo gamer. (...).

  • Ferrofluids based analytical extractions and evaluation of their greenness
    • Muhammad Sajid
    • Kaja Kalinowska
    • Justyna Płotka-Wasylka
    2021 JOURNAL OF MOLECULAR LIQUIDS

    Ferrofluids are stable dispersions of magnetic nanoparticles in a carrier liquid. They have attracted considerable attention in analytical extractions as they combine fluid-like properties with magnetic character, providing magnetic control over the extraction process. The synthesis of ferrofluids is very straightforward, and it generally involves the preparation of magnetic nanoparticles, their coating, and then mixing in a suitable carrier solvent. This review provides an overview of the synthesis of ferrofluids and some considerations that should be taken into account when synthesizing ferrofluids for analytical extractions. This review also provides insights into the role of coating/composite materials and carrier liquids and how they can contribute toward the extraction of analytes. The applications of ferrofluids-based microextractions have been covered briefly. Finally, the green index of ferrofluids-based analytical methodologies has been evaluated using Eco-Scale, GAPI, and AGREE metrics. The factors that can induce further greenness in such methods have been critically appraised.

  • Fiber-optic sensors based on microspheres with nanocoatings (Zastosowanie mikrosfer optycznych z cienkowarstwowymi pokryciami w czujnikach światłowodowych)
    • Paulina Listewnik
    2021 Pełny tekst

    Temperature is one of the most important physical quantities. Temperature measurements are used in every field of life, especially electronics, electrical engineering, energy-related fields, including energy source and storage devices. The goal of this dissertation is to design and optimize the microsphere-based fiber-optic sensors construction for measurement of the sensor surrounding medium temperature, including selection of the optical microsphere optimal geometrical parameters and selection of the parameters of the ZnO (zinc oxide) coatings deposited by Atomic Layer Deposition (ALD) method. A comprehensive state of the art about the significance of temperature measurements and measurement methods was performed as well. In the dissertation, the fabrication and the characterization of the designed sensors are described. Experimental results of the measurements validating a proper operation of the sensors are presented. Applications of the microsphere-based fiber-optic sensors, firstly as a device for in situ monitoring of the temperature of the supercapacitors and secondly for investigation of the optical and thermal properties of the few-layer black phosphorus coating was proposed.

  • Financial Markets and Bankruptcy Systems: Is there a Relationship?
    • Sylwia Morawska
    • Michał Łukowski
    • Kamil Gemra
    • Waldemar Rogowski
    • Przemysław Banasik
    • Błażej Prusak
    2021 Pełny tekst European Research Studies Journal

    Purpose: Filling the cognitive gap in the theory of ex-post transaction costs, i.e., at the stage of enforcing market transactions by examining the relationship between friendliness/severity of the bankruptcy and restructuring law towards debtors, the level of development of financial markets, the effectiveness of the judicial system and the rate of debt recovery. Design/Methodology/Approach: In the research, the following methods were used: literature review, cluster, and panel analysis. Findings: Based on the research, the existence of a statistical relationship was proven between the effectiveness of bankruptcy systems (measured by the recovery rate) and factors characterizing the level of development of the financial market as well as the severity of bankruptcy law towards debtors and the effectiveness of the judicial system. Practical Implications: Research shows that the development of the financial market, and the debt market, in particular, forces countries to put more emphasis on the effectiveness of judicial systems and to create more stringent bankruptcy laws for debtors (more creditor-friendly). Originality/value: This is the first study of its type. In the next stage of the research, the authors want to additionally include such variables as the type of the legal system (statutory law vs. common law) and its origin, the form of organization of the financial market, and at the same time, the banking system model (the Anglo-Saxon and continental models), the effectiveness of conducted restructuring measures, the level of development of countries.

  • Finansowanie zadań oświatowych jednostek samorządu terytorialnego
    • Alicja Sekuła
    • Joanna Nucińska,
    2021

    Celem monografii jest przedstawienie, analiza i ocena procesu organizacji i finansowania zadań oświatowych w Polsce. W ujęciu szczegółowym w książce skupiono się opisie zasad organizacji i finansowania zadań oświatowych z punktu widzenia samorządu terytorialnego, w tym także zasad finansowania i przekazywania środków publicznych w formie dotacji placówkom prowadzonym przez podmioty inne niż jednostki samorządu terytorialnego. W efekcie wskazano zalety procesu, a także jego mankamenty wraz z możliwościami ich likwidacji bądź minimalizacji wpływu na proces kształcenia uczniów i wychowanków. Zakres przestrzenny przedstawionych w książce badań i analiz obejmuje cały kraj. Na zakres podmiotowy składają się wszystkie jednostki samorządu terytorialnego, tj. stopnia gminnego, powiatowego i wojewódzkiego. Zakres czasowy pracy, co do zasady, obejmuje lata 2012-2019 (część empiryczna). W niektórych przypadkach, zwłaszcza w odniesieniu do zagadnień prawnych, analizy przekraczają podstawowe ramy czasowe. Opis zmian w systemie oświaty i systemie jej finansowania przedstawiono od roku 1990, aby wyeksponować ich mnogość, nietrwałość i niestabilność, jednocześnie nakreślając tło rozwiązań funkcjonujących w badanym okresie. Prowadzone rozważania nawiązują także do aktualnego stanu prawnego. Adekwatnie do obranego celu sporządzono strukturę obejmującą pięć rozdziałów poprzedzonych wstępem i zwieńczonych zakończeniem.

  • Finite element analysis on failure of reinforced concrete corner in sewage tank under opening bending moment
    • Ireneusz Marzec
    • Jerzy Bobiński
    • Andrzej Tejchman-Konarzewski
    • Jakub Schönnagel
    2021 ENGINEERING STRUCTURES

    W artykule omówiono mechanizm uszkodzenia żelbetowego zbiornika ściekowego w narożniku ściany, który uległ uszkodzeniu podczas próby wypełnienia na skutek nadmiernych przemieszczeń poziomych ścian pod wpływem otwierającego momentu zginającego. Aby wyjaśnić przyczyny awarii, przeprowadzono kompleksowe obliczenia metodą elementów skończonych (MES) żelbetowego zbiornika w warunkach odkształcenia płaskiego. Beton zamodelowano za pomocą sprzężonego modelu konstytutywnego sprężysto-plastycznego z degradacją sztywności. Model został wzbogacony w reżimie osłabienia o charakterystyczną długość mikrostruktury, aby zapewnić obiektywne wyniki siatki. Analizy MES przeprowadzono dla różnych układów zbrojenia na zginanie w narożniku. Skoncentrowano się na ewolucji lokalizacji odkształcenia i wytrzymałości narożników. Omówiono przyczyny awarii zbiornika. Wyniki FE wykazały dużą wrażliwość nośności narożnika ściany zbiornika i lokalizacji odkształcenia na układ zbrojenia na zginanie. Ponadto przeprowadzono analizę numeryczną dwóch eksperymentów laboratoryjnych dotyczących żelbetowych narożników poddanych działaniu otwierających momentów zginających.

  • Finite-difference time-domain analyses of active cloaking for electrically-large objects
    • Tomasz Stefański
    • Konstantinos Baskourelos
    • Kosmas L. Tsakmakidis
    2021 Pełny tekst OPTICS EXPRESS

    Invisibility cloaking devices constitute a unique and potentially disruptive technology, but only if they can work over broad bandwidths for electrically-large objects. So far, the only known scheme that allows for broadband scattering cancellation from an electrically-large object is based on an active implementation where electric and magnetic sources are deployed over a surface surrounding the object, but whose ‘switching on’ and other characteristics need to be known (determined) a priori, before the incident wave hits the surface. However, until now, the performance (and potentially surprising) characteristics of these devices have not been thoroughly analysed computationally, ideally directly in the time domain, owing mainly to numerical accuracy issues and the computational overhead associated with simulations of electrically-large objects. Here, on the basis of a finite-difference time-domain (FDTD) method that is combined with a perfect (for FDTD’s discretized space) implementation of the total-field/scattered-field (TFSF) interface, we present detailed, time- and frequency-domain analyses of the performance and characteristics of active cloaking devices. The proposed technique guarantees the isolation between scattered- and total-field regions at the numerical noise level (around −300 dB), thereby also allowing for accurate evaluations of the scattering levels from imperfect (non-ideal) active cloaks. Our results reveal several key features, not pointed out previously, such as the suppression of scattering at certain frequencies even for imperfect (time-delayed) sources on the surface of the active cloak, the broadband suppression of back-scattering even for imperfect sources and insufficiently long predetermination times, but also the sensitivity of the scheme on the accurate switching on of the active sources and on the predetermination times if broadband scattering suppression from all angles is required for the electrically-large object.

  • FinTech oraz rynek zastosowań technologii blockchain w polskich małych i średnich przedsiębiorstwach
    • Adam Marszk
    • Krzysztof Piech
    2021

    Książka jubileuszowa wydana z okazji 50-lecia pracy zawodowej prof. Piotra Dominiaka. Pierwsza część tytułu niniejszej książki - Ekonomia, kultura, wartości - nawiązuje do nazwy cyklicznej, międzynarodowej konferencji, którą prof. Dominiak współorganizował. Te trzy pojęcia wyznaczają szeroki zakres jego zainteresowań naukowych. Druga część tytułu - trzy oblicza roztropności - określa styl pracy jubilata. I według tego klucza podzielona jest zawartość książki. Jej autorami są naukowcy - przyjaciele, współpracownicy i uczniowie prof. Piotra Dominiaka.

  • First deep eutectic solvent-based (DES) stationary phase for gas chromatography and future perspectives for DES application in separation techniques
    • Malwina Momotko
    • Justyna Łuczak
    • Andrzej Przyjazny
    • Grzegorz Boczkaj
    2021 Pełny tekst JOURNAL OF CHROMATOGRAPHY A

    The paper presents the first application of deep eutectic solvents (DES) as stationary phases for gas chromatography. DES obtained by mixing tetrabutylammonium chloride (TBAC) as a hydrogen bond acceptor (HBA) with heptadecanoic acid being a hydrogen bond donor (HBD) in a mole ratio of HBA:HBD equal to 1:2 was characterized by its ability to separate volatile organic compounds (VOCs). The Rohrschneider – McReynolds constants determined reveal that the synthesized DES is a stationary phase of medium polarity. A detailed retention characteristic was determined for a number of groups of chemical compounds, including aromatic hydrocarbons, alcohols, ketones, sulfides and thiophene derivatives. The synthesized DES was found to have a high selectivity towards alcohols. At the same time, the investigated stationary phase was found to have specific interactions with some analytes. For example, a stronger retention was observed for 1-hexanol and 1-heptanol compared to other alcohols. Retention times of these two alcohols are longer by 191% and 300%, respectively, relative to the expected value based on their boiling point. Such an increased retention is caused by a synergistic effect of various kinds of interactions – the possibility of formation of hydrogen bonds between the DES and the hydroxyl group of alcohols and hydrophobic interactions of alkyl chains of the DES with the alkyl chain of alcohols. The ability to modify properties of DESs by replacement of HBA or HBD with a different chemical compound or by dissolving in DES macromolecular substances makes the proposed stationary phase highly flexible. In addition to using the developed DES in chromatographic techniques, the retention data collected indicate the possibility of its application to other separation techniques, i.e. extractive distillation.

  • First evaluation of wastewater discharge influence on marine water contamination in the vicinity of Arctowski Station (Maritime Antarctica)
    • Małgorzata Szopińska
    • Aneta Łuczkiewicz
    • Katarzyna Jankowska
    • Sylwia Fudala-Książek
    • Joanna Potapowicz
    • Agnieszka Kalinowska
    • Robert Józef Bialik
    • Stanisław Chmiel
    • Żaneta Polkowska
    2021 Pełny tekst SCIENCE OF THE TOTAL ENVIRONMENT

    In Antarctica,waste is generatedmainly during scientific research programmes and related logistics. In this study, the impact ofwastewater on the western shore of Admiralty Baywas investigated during austral summer in 2017 and 2019. A range of physicochemical parameters and the presence of selected trace metals, formaldehyde and different groups of surfactants were determined in wastewater coming from Arctowski Station and in nearby coastal waters. The presence of selected trace metals (e.g., Cr: 2.7–4.4 μg/L; Zn: 15.2–37.3 μg/L; and Ni: 0.9–23.3 μg/L) and the sums of cationic (0.3–1.5mg/L), anionic (3.1–1.7 mg/L), and non-ionic (0.6–2.4mg/L) surfactants in wastewater indicated the potential influence of anthropogenic factors on sea water. The determined surfactants are found in many hygiene products that end up in the waste water tank after human use and, if untreated, can be released into surface waters with discharge. In addition, the levels of some trace metals indicate that they cannot come only from natural sources, but are the result of human activity. The reported data show disturbances in the marine environment caused by non-treatedwastewater discharge, e.g. by comparing the obtained results from the values of the no observed effect concentrations (NOECs) on selected Antarctic bioindicators, and provide information for the implementation of proper wastewater treatment at any Antarctic station in the future.

  • Fiscal decentralization in the European Countries: a cluster analysis approach
    • Alicja Sekuła
    • Kamila Adamowicz
    2021 Pełny tekst

    The scope of public authority depend on many factors. One of them is a declaration, usually expressed in the constitution of a given country (Sferlea, 2014, Libman, 2010, Nehmelman, Vetzo, 2016) of the application of the decentralisation principle in the performance of public tasks. Despite this declaration, the structure of the public sector and the tasks carried out at different levels in particular countries are not identical. This also applies to the countries of the European Union, although some issues related to legal order are regulated by treaties. This fact became a premise for undertaking the research presented in this article. Its aim was to compare the extent of fiscal decentralisation in EU countries, creation groups of states with similar levels of decentralization and then identify the characteristics of countries where the level is similar. Data obtained from Eurostat were subjected to statistical analysis – non-hierarchical grouping. For this purpose, the cluster analysis module of the R software was used. Analyse was made for the years 2013-2019 for 27 European countries. United Kingdom was excluded due to not available data in Eurostat for year 2019. Based on clustering, the following conclusions were drawn: the level of decentralization in the EU increases with the size of the country. Small states are centralized. Due to the second tier of government, federal countries are characterized by a small degree of decentralization, regardless of their size. The highest level of decentralization is in the Nordic countries, in Denmark so large that it formed a separate cluster.

  • Flexomagnetic response of buckled piezomagnetic composite nanoplates
    • Mohammad Malikan
    • Victor Eremeev
    2021 Pełny tekst COMPOSITE STRUCTURES

    In this paper, the equation governing the buckling of a magnetic composite plate under the influence of an in-plane one-dimensional magnetic field, assuming the concept of flexomagnetic and considering the resulting flexural force and moment, is investigated for the first time by different analytical boundary conditions. To determine the equation governing the stability of the plate, the nonlocal strain gradient theory has been used by taking into account the classical plate theory. The axial magnetic force, which is originated from the magnetic field, is investigated. After extracting the governing differential equation, the critical buckling load is obtained for different support conditions. The effect of nonlocal parameter, sheet aspect ratio and the effect of one-dimensional magnetic field on critical load are discussed. It was earned that if the nanoplate is rectangular so that the value of aspect ratio is less than one, the flexomagnetic response will be more noticeable.

  • Flood Classification in a Natural Wetland for Early Spring Conditions Using Various Polarimetric SAR Methods
    • Tomasz Berezowski
    • Monika Gierszewska
    • Tomasz Bieliński
    2021 Pełny tekst

    Abstract--- One of the major limitations of remote sensing flood detection is the presence of vegetation. Our study focuses on a flood classification using Radarsat-2 Quad-Pol data in a natural floodplain during leafless, dry vegetation (early spring) state. We conducted a supervised classification of a data set composed of nine polarimetric decompositions and Shannon entropy followed by the predictors' importance estimation to reveal which decomposed component had the strongest effect on classification models. Also, we tested two variants of polarimetric speckle filtering to see if this step influences the results. The classification accuracy was 0.78 and 0.83 for the boxcar and improved Lee sigma filter respectively. The Cloude - Pottier decomposition produced the highest accuracy (0.67) in a single-decomposition scenario, but the volume component of Pauli decomposition was the most important for classification in a multi-decomposition scenario.

  • Flow cytometric approach to evaluate the impact of hydro-technical concrete compounds’ release to the freshwater microbiome
    • Barbara Wojtasik
    • Małgorzata Zbawicka
    • Lucyna Grabarczyk
    • Wojciech Juzwa
    2021 Pełny tekst ENVIRONMENTAL MONITORING AND ASSESSMENT

    The aim of this research was to test the potential of applying a flow cytometric procedure to evaluate the impact of concrete compounds’ release to the freshwater microbiome. Cells from the collected samples were stained with a fluorogenic redox indicator dye that measures the redox potential of microbial cells. This novel approach was combined with the assessment of microorganisms’ penetration into the internal structures of concrete using the Rose Bengal sodium salt staining. Rose Bengal staining revealed an intense fouling of the upper and side walls of the concrete cubes and also indicated the penetration of microorganisms inside the concrete as observed for the cubes’ cross-sections. Flow cytometric cellular redox potential measurement revealed high percentages of active cells within the concrete’s porous structures and in non-exposed water (32.7% and 30.2% of active cells) versus samples from exposed water and concrete’s outer surfaces (6.8%, 6.1%, and 3.3% of active cells). The results demonstrated a detrimental impact of hydro-technical concrete on the vitality of microbial cells within the freshwater environment. Tested protocol by analyzing the physiology of microbial cells improved the functional description of complex communities to evaluate the fate of contaminants present in the concrete-based hydro-technical infrastructure.

  • Flow Process Models for Pipeline Diagnosis
    • Zdzisław Kowalczuk
    • Marek Tatara
    2021

    This chapter examines the problem of modeling and parameterization of the transmission pipeline flow process. First, the base model for discrete time is presented, which is a reference for other developed models. Then, the diagonal approximation (AMDA) method is proposed, in which the tridiagonal sub-matrices of the recombination matrix are approximated by their diagonal counterparts, which allows for a simple determination of the explicit form of the inverse matrix. Another suggestion is the Thomas model (ATM), in which the basic model is reformulated to a form to which the Thomas algorithm applies, at which the computational complexity of the order O(N) can be obtained. The fourth suggestion is a steady state analytical model (AMSS), characterizing the steady state after transient processes. In addition, the parameterization of the discrete models in space and time is analyzed, proposing a method ensuring the maximum margin of numerical stability. This model is verified by means of simulation tests. Finally, the developed model is compared with the basic model, taking into account the accuracy and time of calculations.

  • Fluorine ions in photocatalysts’ synthesis: an obstacle or an ally? The investigation of photocatalysts in Ti-O-F system
    • Marta Kowalkińska
    • Szymon Dudziak
    • Jakub Karczewski
    • Agnieszka Fiszka Borzyszkowska
    • Anna Zielińska-Jurek
    2021 Pełny tekst

    Titanium(IV) oxide (TiO2) is one of the most promising photocatalysts, which is expected to be applied in the photocatalytic degradation of xenobiotics. For sustainable development and green chemistry approach recently, much effort has been paid to enhance TiO2 photocatalytic activity in UV-vis light by modifying its structure. The photocatalytic process’s complexity cannot be simply described as electron-hole pairs generations and •OH formation; therefore, the interaction between the surface structure of photocatalyst and reactant molecules needs further investigation. The surface chemistry and morphology of TiO2 are crucial factors that can affect its photocatalytic performance by influencing the selective adsorption and photocatalytic oxidation of substrates. In this regard, considering the strong complexation between F- and Ti and the high electronegativity of fluorine, the present study focused on Ti-O-F photocatalytic system. An advantage of introducing fluorine compounds inside the reaction system is the stabilization of thermodynamically unfavoured {0 0 1} facets, which are described as more active than other TiO2 facets with defined morphology. The obtained results for anatase nanosheets with exposed {0 0 1} facets have shown that a higher amount of surface fluorine enhances the photocatalytic degradation of phenol and its mineralization. This observation can be explained by F atoms influencing the surface charge distribution and raising charge separation in the 2D structure of TiO2. Meanwhile, samples with a lower F/Ti ratio on the surface and the presence of Ti3+ exhibited lower photocatalytic activity. On the other hand, titanium oxyfluoride (TiOF2) used as a precursor for the synthesis of 2D TiO2 had a negative effect on phenol photocatalytic degradation and TOC mineralization. In this case, fluorine ions could induce the surface formation of nonstoichiometric TiO2−x, which decreased photocatalytic activity of TiO2 particles with exposed {0 0 1} facets.

  • Focus on Misinformation: Improving Medical Experts’ Efficiency of Misinformation Detection
    • Aleksandra Nabożny
    • Bartłomiej Balcerzak
    • Mikołaj Morzy
    • Adam Wierzbicki
    2021

    Fighting medical disinformation in the era of the global pandemic is an increasingly important problem. As of today, automatic systems for assessing the credibility of medical information do not offer sufficient precision to be used without human supervision, and the involvement of medical expert annotators is required. Thus, our work aims to optimize the utilization of medical experts’ time. We use the dataset of sentences taken from online lay medical articles. We propose a general framework for filtering medical statements that do not need to be manually verified by medical experts. The results show the gain in fact-checking performance of expert annotators on capturing misinformation by the factor of 2.2 on average. In other words, our framework allows medical experts to fact-check and identify over two times more non-credible medical statements in a given time interval without applying any changes to the annotation flow.

  • Folding‐upon‐repair DNA nanoswitches for monitoring DNA repair enzymes activity
    • Nada Farag
    • Rosanna Mattossovich
    • Rosa Merlo
    • Łukasz Nierzwicki
    • Giulia Palermo
    • Alessandro Porchetta
    • Giuseppe Perugino
    • Francesco Ricci
    2021 ANGEWANDTE CHEMIE-INTERNATIONAL EDITION

    We demonstrate here a new class of DNA‐based nanoswitches that, upon enzymatic repair, could undergo a conformational change mechanism leading to a change in fluorescent signal. Such folding‐upon‐repair DNA nanoswitches are synthetic DNA sequences containing O6‐methyl‐guanine (O6‐MeG) nucleobases and labelled with a fluorophore/quencher optical pair. The nanoswitches are rationally designed so that only upon enzymatic demethylation of the O6‐MeG nucleobases they can form stable intramolecular Hoogsteen interactions and fold into an optically active triplex DNA structure. We have first characterized the folding mechanism induced by the enzymatic repair activity through fluorescent experiments and Molecular Dynamics simulations. We then demonstrated that the folding‐upon‐repair DNA nanoswitches are suitable and specific substrates for different methyltransferase enzymes including the human homologue (hMGMT) and they allow the screening of novel potential methyltransferase inhibitors.

  • Food Bioactive Ingredients Processing Using Membrane Distillation
    • Emilia Gontarek-Castro
    • Marek Lieder
    2021

    Separation processes are an important part of today’s food industries, especially in the case of specific bioactive components due to their health benefits. In general, processing of bioactive food ingredients assumes the introduction of integrated system directed to their separation, fractionation, and recovery. Recently, membrane distillation (MD) has been considered as an alternative membrane-based separation and concentration process in food technology. MD separates volatile components from aqueous feed solution into the permeate through microporous hydrophobic membranes, by means of the vapor pressure difference on both membrane sides. This chapter contains the analysis of the ongoing literature related to recovery and purification of food bioactive compounds using membrane distillation. Insights into the use of different MD configurations have been discussed and typical advantages and drawbacks over conventional technologies and other membrane processes have been highlighted.

  • Formulation of Time-Fractional Electrodynamics Based on Riemann-Silberstein Vector
    • Tomasz Stefański
    • Jacek Gulgowski
    2021 Pełny tekst ENTROPY

    In this paper, the formulation of time-fractional (TF) electrodynamics is derived based on the Riemann-Silberstein (RS) vector. With the use of this vector and fractional-order derivatives, one can write TF Maxwell’s equations in a compact form, which allows for modelling of energy dissipation and dynamics of electromagnetic systems with memory. Therefore, we formulate TF Maxwell’s equations using the RS vector and analyse their properties from the point of view of classical electrodynamics, i.e., energy and momentum conservation, reciprocity, causality. Afterwards, we derive classical solutions for wave-propagation problems, assuming helical, spherical, and cylindrical symmetries of solutions. The results are supported by numerical simulations and their analysis. Discussion of relations between the TF Schrödinger equation and TF electrodynamics is included as well.

  • Fourth industrial revolution and new challenges in post-pandemic world
    • Kazimierz Kosmowski
    2021

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  • Fractal dimension for bending–torsion fatigue fracture characterisation
    • Wojciech Macek
    • Ricardo Branco
    • Mateusz Korpyś
    • Tadeusz Łagoda
    2021 Pełny tekst MEASUREMENT

    Fracture surfaces after biaxial fatigue tests were compared using fractal dimension for three types of metallic materials in smooth and notched specimens made of S355J2 and 10HNAP steels and 2017-T4 aluminium alloy, considering both proportional and nonproportional cyclic loading. High-resolution optical 3D measurement studies were performed on the entire fracture surface. A direct correlation between fractal dimension and fatigue loading was established. This systematic relationship can serve as a basis for obtaining information about fatigue loading from the fracture surfaces of failed materials and structures. Moreover, measurements of the fracture surface with an optical profilometer, quantitative analysis, and fractography contribute to a better comprehension of the fatigue failure processes. Differences in individual zones of fatigue fractures were identified while demonstrating the correctness of the total fracture surface method.

  • Fracture Areas Quantitative Investigating of Bending-Torsion Fatigued Low-Alloy High-Strength Steel
    • Wojciech Macek
    2021 Pełny tekst Metals

    In this study, the impact of pseudo-random non-proportional bending-torsion fatigue loadings proportion on the fatigue life and the fracture surface topography was analyzed. Investigation was carried out for 24 specimens made of S355J2 steel with 11 different ratios of maximum stresses λ. For these cases, after the fatigue tests, the surface topography measurements were carried out using an optical profilometer, using the focus variation method. Three fracture zones were analyzed for each specimen: (1) total; (2) propagation; (3) rupture, taking into account the root average square height Sq and void volume Vv parameters. The results pointed that ratio of maximum stresses λ is the most influenced on volume surface parameters represented by void volume at a given height Vv, in the rupture area. A new fatigue loading parameter P was used, depending on fatigue life T and ratio of maximum stresses λ, which shows very good correlation in 4th degree type of fit, to void volume Vv parameter for the rupture area.