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Gdańsk University of Technology

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  • The effect of dehydration/rehydration of bacterial nanocellulose on its tensile strength and physicochemical properties
    • Alicja Stanisławska
    • Hanna Staroszczyk
    • Marek Szkodo
    2020 Full text CARBOHYDRATE POLYMERS

    Bacterial nanocellulose (BNC) is a natural biomaterial with a wide range of biomedical applications. BNC contains 99 % of water which makes it too thick to be used as a bioimplant material. The aim of the work was to determine the effect of the BNC dehydration followed by rehydration on its mechanical and physicochemical properties, in the context of the use of BNC as bio-prostheses in the cardiovascular system. Dehydration involved the convection-drying at 25 and 105 °C, and the freeze-drying, while rehydration - the soaking in water. All modified BNC samples had reduced thickness, and results obtained from FT-IR, XRD, and SEM analysis revealed that 25 °C BNC convection-dried after soaking in water was characterized by the highest: tensile strength (17.4 MPa), thermal stability (253 °C), dry mass content (4.34 %) and Iα/Iβ ratio (1.10). Therefore, 25 °C convection-dried BNC followed by soaking in water can be considered as a material suitable for cardio- vascular implants.

  • THE EFFECT OF DRYING INTENSITY ON THE COLOR CHANGES OF PINE WOOD (PINUS SYLVESTRIS L.)
    • Aleksandra Konopka
    • Jacek Barański
    • Kazimierz Orłowski
    • Daniel Chuchała
    2020 Full text Trieskove a Beztrieskove Obrabanie Dreva

    The effect of the selection of drying process parameters on the color change of Scots pine wood (Pinus Sylvestris L.) is presented. In this work the experimental studies have been performed. The research focused on the influence of drying intensity on the changes of color after drying process. Intensity of drying process was determined on the basis of the average drying gradient. To determine the color of wood before and after drying process the series of experiments have been performed, using color reader device. The wood samples were dried according to three different drying modes, namely: mild, normal and intense. Experiments were conducted in the laboratory dryer. The measurement of wood samples was made using international standards: ISO 11664-2 and ISO 11664-4 of total color change after drying. As a result of the performed statistical tests, there were observed statistically significant color changes of the wood surface for intensive drying mode.

  • The Effect of Fly Ash Microspheres on the Pore Structure of Concrete
    • Elżbieta Haustein
    • Aleksandra Kuryłowicz-Cudowska
    2020 Full text Minerals

    The fly ash microspheres (FAMs) formed during the mineral transformation stage in coal combustion are hollow spherical particles with a density less than water. This paper presents the results of X‐ray micro‐computed tomography and an automatic image analysis system of the porosity in the structure of hardened concrete with microspheres. Concrete mixtures with ordinary Portland cement and two substitution rates of cement by microspheres—5% and 10%—are investigated. For all considered mixes, a constant water/binder ratio (w/b) equal to 0.50 was used. The distribution of the air voids and the compressive strength of the concrete were tested after 28 days. With the increasing mass of cement replacement by FAMs, the compressive strength decreases after 28 days. The total volume of the air voids in hardened concrete with fly ash microspheres tested by X‐ray varies from 5.1% to 7.4%. The closed pores constitute more than 80% of the total content of air pores. The study proves that the use of microspheres grains with specific dimensions has a significant impact on concrete porosity. Their application in concrete technology can be an alternative aeration solution for fresh concrete mixes and an effective method for utilization.

  • The Effect of Laser Re-Solidification on Microstructure and Photo-Electrochemical Properties of Fe-Decorated TiO2 Nanotubes
    • Piotr Kupracz
    • Katarzyna Grochowska
    • Jakub Karczewski
    • Jakub Wawrzyniak
    • Katarzyna Siuzdak
    2020 Full text Materials

    Fossil fuels became increasingly unpleasant energy source due to their negative impact on the environment; thus, attractiveness of renewable, and especially solar energy, is growing worldwide. Among others, the research is focused on smart combination of simple compounds towards formation of the photoactive materials. Following that, our work concerns the optimized manipulation of laser light coupled with the iron sputtering to transform titania that is mostly UV-active, as well as exhibiting poor oxygen evolution reaction to the material responding to solar light, and that can be further used in water splitting process. The preparation route of the material was based on anodization providing well organized system of nanotubes, while magnetron sputtering ensures formation of thin iron films. The last step covering pulsed laser treatment of 355 nm wavelength significantly changes the material morphology and structure, inducing partial melting and formation of oxygen vacancies in the elementary cell. Depending on the applied fluence, anatase, rutile, and hematite phases were recognized in the final product. The formation of a re-solidified layer on the surface of the nanotubes, in which thickness depends on the laser fluence, was shown by microstructure studies. Although a drastic decrement of light absorption was recorded especially in UV range, laser-annealed samples have shown activity under visible light even 20 times higher than bare titania. Electrochemical analysis has shown that the improvement of photoresponse originates mainly from over an order of magnitude higher charge carrier density as revealed by Mott-Schottky analysis. The results show that intense laser light can modulate the semiconductor properties significantly and can be considered as a promising tool towards activation of initially inactive material for the visible light harvesting.

  • THE EFFECT OF LOG SORTING STRATEGY ON THE FORECASTED LUMBER VALUE AFTER SAWING PINE WOOD
    • Piotr Taube
    • Kazimierz Orłowski
    • Daniel Chuchała
    • Jakub Sandak
    2020 Full text ACTA FACULTATIS XYLOLOGIAE ZVOLEN

    The optimal transformation path for the resource is determined by the quality of a log combined with its dimension. The commercial value of derived products is also closely connected with the size and extent of containing wood deficiencies. The results of studies with three diverse strategies for log sorting are presented in the paper. Resource assessment by a worker without extensive experience in sorting logs, the certified grading expert, and the automatic in-line system including optical scanner with dedicated software are compared. It was shown that the lack of experience of the person performing the sorting operation results in reducing the potential economic profits of a sawmill. On the contrary, the overall efficiency of the log conversion process is considerably improved by the automated sorting systems with scanners. Early identification of logs optimal for specific lumber production is assured by reducing the human errors and subjective evaluation. Both, the yield of produced timber and profits of the sawmill are directly affected this way. It was demonstrated that the log sorting rate performed by the scanner is four times higher in comparison to grading by the certified expert, as well as three times higher compared to employee with no experience. The finding that the volume of high-quality lumber of elevated value is the lowest in the case the log is sorted by a human was proved.

  • The effect of morphology and crystalline structure of Mo/MoO3 layers on photocatalytic degradation of water organic pollutants
    • Mariusz Szkoda
    • Konrad Trzciński
    • Andrzej Nowak
    • Maria Gazda
    • Mirosław Sawczak
    • Anna Lisowska-Oleksiak
    2020 Full text MATERIALS CHEMISTRY AND PHYSICS

    Molybdenum oxide layers were formed by anodization of the Mo metallic foil in a water/ethylene glycol-based electrolyte containing fluoride ions. The as-prepared, amorphous samples were annealed in air at different temperatures in a range from 100 �C to 700 �C. The crystal phase and morphology of anodized and annealed MoO3 layers were investigated using X-ray diffraction, Raman spectroscopy, and scanning electron microscopy. The photoactivity of obtained materials was tested during a photocatalytic process of methylene blue (MB) decomposition. The increase of annealing temperature led to the production of films characterized by improved photocatalytic properties, with maximum photocatalytic efficiency observed for MoO3 annealed at 600 �C. The studies on the use of MoO3 as a photoelectrocatalyst for degradation of dye were performed. Furthermore, the photocatalytic activity of the MoO3 annealed at 600 �C was investigated during a photodegradation of diclofenac acting as a model pharmaceutical compound

  • The Effect of Posaconazole, Itraconazole and Voriconazole in the Culture Medium on Aspergillus fumigatus Triazole Resistance
    • Martyna Mroczyńska
    • Ewelina Kurzyk
    • Magdalena Śliwka-Kaszyńska
    • Urszula Nawrot,
    • Marta Adamik
    • Anna Brillowska-Dąbrowska
    2020 Full text Microorganisms

    Triazoles are the only compounds used as antibiotics in both medicine and agriculture. The presence of triazoles in the environment can contribute to the acquisition of azole resistance among isolates of Aspergillus fumigatus. The objective of this study was to investigate the effect of A. fumigatus exposure to triazoles on susceptibility to these compounds. Seventeen triazole-resistant and 21 triazole-sensitive A. fumigatus isolates were examined. The isolates were transferred 20 times on the Sabouraud medium supplemented with posaconazole, itraconazole or voriconazole, followed by five times on the medium not supplemented. The minimum inhibitory concentrations of antimycotics were examined according to the EUCAST broth microdilution method after the 20th transfer and also the 25th transfer. In addition, the expression levels of genes mdr1, mdr2, mdr3, atrF, cyp51A and cyp51B were determined. Cultivation of A. fumigatus on media supplemented with posaconazole, itraconazole and voriconazole resulted in the acquisition of resistance to the tested triazoles of all examined isolates. After recultivation on Sabouraud without azoles, most of the isolates lost their acquired resistance. The long-term use of triazole compounds in agriculture may result in the occurrence of triazole resistant A. fumigatus isolates in the environment, not only by induction or selection of mutations in the cyp51A gene, but also by contribution to changes in the gene expression.

  • The effectiveness of financial and economic regulation of land relations in the context of stimulating entrepreneurial activity in the regions of Ukraine
    • Uliana Vatamanyuk-Zelinska
    • Oleksandr Melnychenko
    2020 Full text Problems and Perspectives in Management

    Solving the problem of enhancing the efficiency of the financial and economic regulation of land relations contributes to the development of entrepreneurship in Ukraine. The purpose of the paper is to determine new incentives for encouraging entrepreneurial activity by increasing the efficiency of the financial and economic regulation of land relations by local governments. The study is based on applying the method for predicting amounts of local budget revenues in Ukraine from the land tax and lease fees through the use of communally owned land plots to stimulate entrepreneurial initiatives of the unemployed. In the process of research, the projected amounts of local budget revenues from financial transactions with plots of industrial lands in each region of Ukraine have been determined, taking into account the possibilities of leasing the lands, for which lease fees are covered by a one-time benefit provided to the unemployed for organizing entrepreneurial activity. It is proposed to determine the efficiency of the financial and economic regulation of land relations in the regions of Ukraine, applying indicators such as the use of industrial lands together with objects of lease located on them and the involvement of the unemployed from among the economically active population in entrepreneurial activity. To improve the efficiency of financial and economic regulation of land relations, local governments are proposed to establish the optimal proportion of amounts of borrowed resources, taking into account the need for their saving and rational use.

  • The effects of urban vehicle traffic on heavy metal contamination in road sweeping waste and bottom sediments of retention tanks
    • Nicole Nawrot
    • Ewa Wojciechowska
    • Shahabaldin Rezania
    • Jolanta Walkusz-miotk
    • Ksenia Pazdro
    2020 Full text SCIENCE OF THE TOTAL ENVIRONMENT

    Diffuse pollution formed during a surface runoff on paved surfaces is a source of heavy metals (HMs) of various origin. This research study indicates the connection between bottom sediments of retention tanks located on urban streams and road sweeping wastes (RSW) that migrate during surface runoff to the stormwater drainage systems with discharge to the retention tanks. Moreover, we test the primary sources of HMs in RSW by analysing the mechanical wastes (MW) produced by vehicles in order to track the relationship between car parts and HMs deposited in the retention tanks receiving the surface runoff from streets. To identify the origin ofHMs diverse source tracking approaches were used: statisticalmethods, Pb isotope ratios, and the flag element ratio approach.MWpresented a very highHMs content (max observed values inmg/kg d.w.: 10477-Zn, 3512-Cu, 412-Pb, 3.35-Cd, 226-Ni, and 633-Cr), while for RSWthe HMs content was similar to the bottom sediments. The total carcinogenic risk raises concerns due to the Cr content. The source of Zn was tyre wear and traffic. Ni, Cr, Fe, and Cd were correlated to Zn and shared a common/similar origin. PCA suggested that Cu features quasiindependent behaviour. The Pb isotopic ratios of RSWindicated Pb enrichment originating fromcoal combustion, while the gasoline and diesel source of Pb was excluded. The Pb isotopic ratios characteristic for MW were in within the following ranges: 1.152–1.165 (206Pb/207Pb), 2.050–2.085 (208Pb/206Pb), and 2.350–2.418 (208Pb/207Pb). The complex analysis of HMs origin confirmed the motorization origin of HMs: Zn, Cr, Ni, and Cd, except Pb (coal combustion as the main source) and Cu (non-uniform origin). The results of various source tracking methods were coherent, but Pb isotope ratios alone brought important information allowing to link Pb in sediments to the atmospheric deposition of coal combustion products.

  • The electrochemical determination of isatin at nanocrystalline boron-doped diamond electrodes: stress monitoring of animals
    • Michał Sobaszek
    • Siuzdak Katarzyna
    • Jacek Ryl
    • Robert Bogdanowicz
    • Greg N. Swain
    2020 SENSORS AND ACTUATORS B-CHEMICAL

    Ultra-thin nanocrystalline boron-doped diamond electrodes (B:NCD) were used for the electrochemical determination of isatin in dog urine samples using cyclic voltammetry and square wave voltammetry in a phosphate buffer saline, pH = 7.2. No additional modification or pretreatment of the electrode surface was required in this approach, being of high importance for the facile detection procedure. The increase of the peak current was linearly related to the raised concentration of isatin in phosphate buffer. The limit of isatin detection was equal to 0.2 µM and 3 µM for B:NCD and reference glassy carbon electrodes respectively. The relatively high current sensitivities of 1.32 μAcm-2 μM-1 were achieved thanks to the nanocrystalline diamond surface. We have demonstrated that isatin could be determined at B:NCD electrode in the complex urine matrix within the limit of detection having 1 μM along with sensitivity of 0.46 μAcm-2 μM-1 without pre-treatment procedure of the analyte

  • The electronic excited states of dichloromethane in the 5.8-10.8 eV energy range investigated by experimental and theoretical methods
    • E. Lange
    • Nykola C. Jones
    • Søren Hoffmann
    • Ana Lozano
    • S. Kumar
    • M Homem
    • Małgorzata Śmiałek-Telega
    • Denis Duflot
    • M. Brunger
    • Paulo Limão-Vieira
    2020 Full text JOURNAL OF QUANTITATIVE SPECTROSCOPY & RADIATIVE TRANSFER

    We present a comprehensive experimental high-resolution vacuum ultraviolet (VUV) photoabsorption spectrum of dichloromethane, CH 2 Cl 2 , with absolute cross sections determined for the full 5.8–10.8 eV energy-range. The calculations on the vertical excitation energies and oscillator strengths were performed using the equation-of-motion coupled cluster method, restricted to the single and double excitations level (EOM-CCSD), and were used to help analyse the valence and Rydberg structures in the photoab- sorption spectrum. The present spectrum additionally reveals several new features not previously re- ported in the literature, with particular reference to the valence σ∗C C l ( 10 a 1 ) ← n Cl ( 7 b 2 ) ( 1 1 B 2 ← ̃ X 1 A 1 ) and ( σ∗C C l ( 10 a 1 ) ← n Cl ( 9 a 1 ) + σ∗CH ( 11 a 1 ) ← n Cl ( 7 b 2 ) ) ( 1 1 A 1 ← ̃ X 1 A 1 ) transitions at 7.519 and 7.793 eV. A vibrational progression of the CCl 2 symmetric stretching, ν′ 3 , and CCl 2 scissoring, v ′ 4 ( a 1 ) , modes have also been assigned for the first time in the 7.4–8.6 eV energy range. The measured absolute photoabsorption cross sections have been used to calculate the photolysis lifetime of dichloromethane in the Earth’s atmo- sphere (0–50 km). Potential energy curves as a function of the C–Cl coordinate, for the four lowest-lying excited A ′ and A ′′ electronic states, have additionally been calculated at the EOM-CCSD level of theory.

  • The experience of movement in orbital space architecture: A narrative of weightlessness
    • Mosleh Ahmadi
    • Nomusa Makhubu
    2020 Full text Cogent Arts & Humanities

    Based upon a combination of architectural theories, the knowledge of space environment, and psychology of isolated and confined environments, this qualitative research aims to study orbital space settlement in a way to get the built space congenial to the human experience of movement. In this sense, sensors, self-propulsion or mechanical actuators, the inhabitant’s mental and visual capacity for movement, as well as the represented and imbedded movement in the built environment—including pictorial representation, kinetic formation, and the movement of natural factors—are variables. So far, most of the studies on counter-measures for minimizing stress, which are stumbling blocks to the architectural promenade, have been based on pre-launch training focusing on professional training and selection of astronauts, planning for their in-flight challenges, and protecting them from dangers. Meanwhile, if we want to promote the experience of architecture in the outer space, narratives of movement need to be enriched, because not all occupants are professional astronauts. One way to study this matter is through analyzing movement in the built space and then synthesizing the results to gain an overview of a spatial montage in which motor planning for movement and route navigation have been facilitated. Narrative, in this sense, is a proper method to investigate this context of design. Therefore, analysis has been framed in the shape of a taxonomy of movement in weightlessness. Through a qualitative investigation in Cupola Module, it has been thrown into relief that movement with regard to space has not been enriched as much as movement with regard to the form.

  • The geometry of free-standing titania nanotubes as a critical factor controlling their optical and photoelectrochemical performance
    • Jakub Wawrzyniak
    • Katarzyna Grochowska
    • Jakub Karczewski
    • Piotr Kupracz
    • Jacek Ryl
    • Anna Dołęga
    • Siuzdak Katarzyna
    2020 SURFACE & COATINGS TECHNOLOGY

    Titanium dioxide nanotubes are regarded as one of the most important functional materials and due to their unique electronic properties, chemical stability and photocorrosion resistance, they find applications in, for example, highly efficient photocatalysis or perovskite solar cells. Nevertheless, modification of TiO2 nanotubes is required to overcome their main drawback, i.e. large energy bandgap (>3.2 eV) limiting their ability to capture solar light. In this work, we report the changes in optical and photoelectrochemical properties of well-separated TiO2 nanotubes that are tuned by varying the geometry of the material. The ordered tubular titania is formed via anodization in the presence of fluoride ions in diethylene glycol at elevated temperature. Length, inner diameter, wall thickness, and separation distance are described in function of synthesis parameters such as applied voltage and duration. The morphology and optical properties are characterized by means of scanning electron microscopy and UV–Vis spectroscopy techniques, respectively, while cyclic voltammetry, linear voltammetry and chronoamperometry are used to determine electrochemical/photoelectrochemical activity in different light conditions. The obtained results suggest a link between specific surface area, the width of the band-gap, and photoactivity, each of which could be individually optimised via anodization conditions. Moreover, the behaviour of the Mott-Schottky plot before and after 3 min of irradiation is studied indicating the positive shift of the flat band position and an increase in donor density values for all the obtained materials. The Mott-Schottky analysis was correlated with the linear voltammetry scans suggesting the important role of surface trapped holes. Presented in here results significantly supplement the current state-of-art regarding separated TiO2 nanotubes that are considered as not fully investigated and unappreciated class of titania materials which due to the exposure of inner and outer wall can be used for further modifications.

  • The hydration properties of protein stabilizer, trimethylamine-N-oxide in aqueous solutions of N-methylacetamide – The volumetric and compressibility studies between 288.15 and 308.15 K
    • Emilia Kaczkowska
    • Jarosław Wawer
    • Magdalena Tyczyńska
    • Małgorzata Jóźwiak
    • Agnieszka Boruń
    • Joanna Krakowiak
    2020 Full text THERMOCHIMICA ACTA

    Apparent molar volumes and apparent molar isentropic compressions of the protein stabilizer, trimethylamine-N-oxide (TMAO) were determined from the densities and speed of sound measured at T = (288.15, 298.15 and 308.15) K in aqueous solutions of N-methylacetamide (NMA) at four different concentrations (2, 4, 6 and 8 mol/kg). The concentration dependencies of the calculated quantities extrapolated to the infinite dilution lead to the standard partial molar properties. The latter values were combined with the previously published data for TMAO in pure water, to obtain the partial molar properties of transfer from water to aqueous NMA solutions. From the transfer data the interaction parameters were determined according to the McMillan-Mayer theory formalism. The calculated parameters and their temperature characteristics are discussed in terms of solute-solvent, solute-solute and solute-cosolute interactions and compared with analogous data for protein denaturant, n-butylurea.

  • The Immunogenic and Immunoprotective Activities of Recombinant Chimeric T. gondii Proteins Containing AMA1 Antigen Fragments
    • Justyna Gatkowska
    • Katarzyna Dzitko
    • Bartłomiej Ferra
    • Lucyna Holec-Gąsior
    • Malwina Kawka
    • Bożena Dziadek
    2020 Full text Vaccines

    Toxoplasmosis, one of the most common parasitoses worldwide, is potentially dangerous for individuals with a weakened immune system, but specific immunoprophylaxis intended for humans is still lacking. Thus, efforts have been made to create an efficient universal vaccine for both animals and humans to overcome the shortcomings of currently used treatment methods and protect all hosts against toxoplasmosis. The current work represents a relatively new approach to vaccine development based on recombinant chimeric Toxoplasma gondii antigens. In the present research, three tetravalent chimeric proteins containing different portions of the parasite’s AMA1 antigen: AMA1N-SAG2-GRA1-ROP1L (ANSGR), AMA1C-SAG2-GRA1-ROP1L (ACSGR) and AMA1-SAG2-GRA1-ROP1L (AFSGR) were tested for their immunogenic and immunoprotective capacities. All tested proteins were immunogenic, as evidenced by the triggering of specific humoral and cellular immune responses in vaccinated C3H/HeOuJ mice, defined by the production of specific IgG (IgG1/IgG2a) antibodies in vivo and synthesis of key Th1/Th2 cytokines by Toxoplasma lysate antigen-stimulated splenocytes in vitro. Although all tested preparations provided partial protection against chronic toxoplasmosis in immunized and T. gondii-challenged mice, the intensity of the generated immunoprotection depended on the fragment of the AMA1 antigen incorporated into the chimeric antigen’s structure.

  • The impact of air humidity on the operation of proton exchange membrane fuel cells determined using dynamic electrochemical impedance spectroscopy
    • Ewa Janicka
    • Michał Mielniczek
    • Łukasz Gaweł
    • Kazimierz Darowicki
    • Paulina Landowska
    2020 ELECTROCHIMICA ACTA

    This paper describes the changes in the fuel cell impedance across a range of current loads and humidity changes. The changes of each equivalent circuit parameters representing specific processes occurring in fuel cells, as a function of humidity and current changes, were determined. Within the combined scope of current and humidity, the optimal working conditions of the cells were determined, corresponding to the lowest impedance values. The influence of humidity on the charge transfer resistance behavior and the Warburg coefficient for varying current load values were analyzed in detail.

  • THE IMPACT OF GROUND TIRE RUBBER TREATMENT ON THE THERMAL CONDUCTIVITY OF FLEXIBLE POLYURETHANE/GROUND TIRE RUBBER COMPOSITES
    • Aleksander Hejna
    • Paulina Kosmela
    • Adam Olszewski
    • Łukasz Zedler
    • Krzysztof Formela
    2020 Full text

    Waste car tires are burdensome waste, and their utilization is crucial for the natural environment. In many countries, the primary method of their recycling is energy recovery, performed by simple combustion. However, material recycling is much more effective and significantly more beneficial for the natural environment. It results in the generation of ground tire rubber, which can be used to produce polymerrubber composites. It should be considered as a method of waste rubber utilization. Moreover, it may significantly reduce the use of petroleum-based polymers. Therefore, the environment's total impact could be noticeably reduced, which should be considered a convenient step towards more “green” polymer composites. In the presented paper, the impact of ground tire rubber treatment on the structure and insulation properties of flexible polyurethane/ground tire rubber composite foams was evaluated.

  • The Impact of Lexicon Adaptation on the Emotion Mining From Software Engineering Artifacts
    • Michał Wróbel
    2020 Full text IEEE Access

    Sentiment analysis and emotion mining techniques are increasingly being used in the field of software engineering. However, the experiments conducted so far have not yielded high accuracy results. Researchers indicate a lack of adaptation of the methods of emotion mining to the specific context of the domain as the main cause of this situation. The article describes research aimed at examining whether the adaptation of the lexicon with emotional intensity of words in the context of software engineering improves the reliability of sentiment analysis. For this purpose, a new lexicon is developed in which words are evaluated as if they were used in the field of software engineering. A comparative experiment of emotion mining based on a generic and a software engineering specific lexicon does not reveal any significant differences in the results.

  • The Impact of Material Selection on Durability of Exhaust Valve Faces of a Ship Engine – A Case Study
    • Hanna Smoleńska
    • Włodzimierz Kończewicz
    • Sylwia Bazychowska
    2020 Full text Advances in Science and Technology Research Journal

    wo alloys were used in order to extend the service life of marine engine exhaust valve head. Layers of cobalt base alloys were made of the powders with with chemical composition as follow: the layer marked L12; C-1,55%; Si-1,21%; Cr-29,7%; W-9%; Ni-2%; Mo<0,01%; Fe-1,7%; Co-54,83% and the layer marked N; C-1,45%; Co-38,9%; Cr-24,13%; Ni-10,43%; W-8,75%; Fe-7,64%; Mo-7,56%; Si-2,59%. Base metal was valve steel after heat treatment. It was consisted of: C-0,374%; Cr-9,34%; Mn-0,402%; Ni-0,344%; Si-2,46%; Mo-0,822%; P0,0162%; S-0,001%. Layers on the valve faces were produced by laser cladding using the HPDL ROFIN DL020 laser. Grinding treatment is a very popular form of regeneration of seat and valve plug adhesions. Properly performed grinding operation ensures dimensional and shape accuracy of the surface from 7 to 5 accuracy class and surface roughness Ra not less than 0,16 μm, depending on the object and method of grinding. The 75H and 150S types are a significantly simplified form of valve plug face grinders. Finishing treatment was carried out with a Chris-Marine AB75H sander on a sanding stand equipped with a compressed air system - the stand was designed by the author. The sander has been set up to the surface of the valve stem so that the grinding angle of the valve faces is 30°+10°. A flat grinding wheel T1CRA54–K was used for machining. The plunge feed was g = 0,01 mm/rev. The thickness of the welded layer after grinding was 1,2 mm. Both valves were installed in the ship's engine and were used in real life. After 2000 hours of operation, the valve marked N was damaged. The valve marked L12 showed no damage and was in operation for the next 1000 hours.

  • The Impact of Micro-Sources on Voltage Distortions in a Power Grid
    • Magdalena Grzymkowska
    • Jacek Klucznik
    2020 Full text Acta Energetica

    The increase in the number of photovoltaic (PV) systems integrated with low voltage (LV) grids has led to a great need to analyse the impact of these systems on the quality of electricity and the reliability of its supply. This paper presents and compares the energy quality requirements imposed by various countries on photovoltaic plants. Then, based on real object tests and simulation in DIgSILENT PowerFactory, the impact has been identified of insolation on the generation output, range of harmonic emissions, changes in voltage levels, and total harmonic distortion (THD) in current and voltage. The results depended on the micro-source power and location, and the grid load.

  • The Impact of Spatiotemporal Changes in Land Development (1984–2019) on the Increase in the Runoff Coefficient in Erbil, Kurdistan Region of Iraq
    • Andam Mustafa
    • Michał Szydłowski
    2020 Full text Remote Sensing

    Nowadays, geospatial techniques are a popular approach for estimating urban flash floods by considering spatiotemporal changes in urban development. In this study, we investigated the impact of Land Use/Land Cover (LULC) changes on the hydrological response of the Erbil basin in the Kurdistan Region of Iraq (KRI). In the studied area, the LULC changes were calculated for 1984, 1994, 2004, 2014 and 2019 using the Digital Elevation Model (DEM) and satellite images. The analysis of LULC changes showed that the change between 1984 and 2004 was slower than that between 2004 and 2019. The LULC analysis revealed a 444.4% growth in built-up areas, with a 60.4% decrease in agricultural land between 1984 and 2019. The influence of LULC on urban floods caused by different urbanization scenarios was ascertained using the HEC-GeoHMS and HEC-HMS models. Over 35 years, there was a 15% increase in the peak discharge of outflow, from 392.2 m3/sec in 1984 to 450 m3/sec in 2014, as well as the runoff volume for a precipitation probability distribution of 10%, which increased from 27.4 mm in 1984 to 30.9 mm in 2014. Overall, the probability of flash floods increased in the center of the city due to the large expansion of built-up areas.

  • The impact of the AC922 Architecture on Performance of Deep Neural Network Training
    • Paweł Rościszewski
    • Michał Iwański
    • Paweł Czarnul
    2020

    Practical deep learning applications require more and more computing power. New computing architectures emerge, specifically designed for the artificial intelligence applications, including the IBM Power System AC922. In this paper we confront an AC922 (8335-GTG) server equipped with 4 NVIDIA Volta V100 GPUs with selected deep neural network training applications, including four convolutional and one recurrent model. We report performance results depending on batch sizes and GPU selection and compare them with the results from another contemporary workstation based on the same set of GPUs – NVIDIA® DGX Station ™ . The results show that the AC922 performs better in all tested configurations, achieving improvements up to 10.3%. Profiling indicates that the improvement is due to the efficient I/O pipeline. The performance differences depend on the specific model, rather than on the model class (RNN/CNN). Both systems offer good scalability up to 4 GPUs. In certain cases there is a significant difference in performance depending on exactly which GPUs are used for computations.

  • The Impact Of The Selected Parameters Of Fdm Manufacturing Technology On Tribological Performance Of Abs–Steel Pair Under Dry Friction
    • Katarzyna Suwińska
    • Jacek Łubiński
    2020 Full text TRIBOLOGIA

    The paper presents the result of tribological test of ABS and steel samples sliding under dry friction. Polymeric samples were manufactured of ABS material using FDM technology. Testing was carried out in unidirectional sliding in a ring-on-flat contact in a PT-3 tribometer. The scope of tested parameters included volumetric and mass wear, the friction coefficient, and polymeric specimen temperature. Polymeric specimens used in the study were manufactured at various settings of the 3D printing process such as the orientation of the specimen in print with respect to the printer building tray and the thickness of a single layer of the deposited material. Comparisons of the impact of these parameters on tribological performance of the sliding contact were analysed.

  • The impedance of hydrogen oxidation reaction in a proton exchange membrane fuel cell in the presence of carbon monoxide in hydrogen stream
    • Kazimierz Darowicki
    • Łukasz Gaweł
    • Michał Mielniczek
    • Artur Zieliński
    • Ewa Janicka
    • Jurgen Hunger
    • L. Jorissen
    2020 Full text APPLIED ENERGY

    Evaluation of performance of a proton exchange membrane fuel cell, which is affected by carbon monoxide that pollutes the hydrogen stream, was presented. This influence was studied for carbon monoxide concentration of 125–325 ppb, which are close to values specified in ISO 14687:2019 standard. Performed studies provided crucial information for further development of fuel cell as an energy source for automotive application. Impedance with the use of Dynamic Electrochemical Impedance Spectroscopy profile measurements were completed for chosen carbon monoxide concentration under a constant current load and anode impedance variations were determined as a function of the time exposed to carbon monoxide. A method to determine the impedance of hydrogen oxidation was proposed. It was determined how the carbon monoxide surface coverage of anodic catalyst varies as a function of time. The capacitance of the double electrical layer and the charge transfer resistance of anodic reaction are discussed to evaluate them with respect to exposure time and surface coverage. It has been shown that proposed methodology can be used as a universal tool for testing fuel cells for both research and industrial applications, with the overall aim of optimization, monitoring, and diagnostics of the fuel cell.

  • The In-Depth Studies of Pulsed UV Laser-Modified TiO2 Nanotubes: The Influence of Geometry, Crystallinity, and Processing Parameters
    • Łukasz Haryński
    • Katarzyna Grochowska
    • Piotr Kupracz
    • Jakub Karczewski
    • Emerson Coy
    • Katarzyna Siuzdak
    2020 Full text Nanomaterials

    The laser processing of the titania nanotubes has been investigated in terms of morphology, structure, and optical properties of the obtained material. The length of the nanotubes and crystallinity, as well as the atmosphere of the laser treatment, were taken into account. The degree of changes of the initial geometry of nanotubes were checked by means of scanning electron microscopy, which visualizes both the surface and the cross-section. The phase conversion from the amorphous to anatase has been achieved for laser-treated amorphous material, whereas modification of calcined one led to distortion within the crystal structure. This result is confirmed both by Raman and grazing incident XRD measurements. The latter studies provided an in-depth analysis of the crystalline arrangement and allowed also for determining the propagation of laser modification. The narrowing of the optical bandgap for laser-treated samples has been observed. Laser treatment of TiO2 nanotubes can lead to the preparation of the material of desired structural and optical parameters. The usage of the motorized table during processing enables induction of changes in the precisely selected area of the sample within a very short time.

  • The Indicators Assessment of Safety and Functionality of Tram Loops
    • Agnieszka Tubis
    • Mateusz Rydlewski
    • Marcin Budzyński
    2020 Full text Journal of KONBiN

    The new requirements set for tram loops mean that all stakeholders' expectations regarding their safety and functionality change. This creates a need for new tools for tram loop assessment, which are important interchanges, especially for people living outside the city limits or on their outskirts. The aim of the authors ’research is to create a indicators for assessing the safety and functionality of tram loops. Therefore, the article presents an overview of the research results in the area of tram transport and interchanges safety. Then the proposed indicator assessment for tram loops was described.

  • The Influence of Camera and Optical System Parameters on the Uncertainty of Object Location Measurement in Vision Systems
    • Jacek Skibicki
    • Anna Golijanek-Jędrzejczyk
    • Ariel Dzwonkowski
    2020 Full text SENSORS

    The article presents the influence of the camera and its optical system on the uncertainty of object position measurement in vision systems. The aim of the article is to present the methodology for estimating the combined standard uncertainty of measuring the object position with a vision camera treated as a measuring device. The identification of factors affecting the location measurement uncertainty and the determination of their share in the combined standard uncertainty will allow determining the parameters of the camera operation, so that the expanded uncertainty is as small as possible in the given measurement conditions. The analysis of the uncertainty estimation presented in the article was performed with the assumption that there is no influence of any external factors (e.g., temperature, humidity, or vibrations).

  • The Influence of COD Fraction Forms and Molecules Size on Hydrolysis Process Developed by Comparative OUR Studies in Activated Sludge Modelling
    • Jakub Drewnowski
    • Bartosz Szeląg
    • Li Xie
    • Xi Lu
    • Mahesh Ganesapillai
    • Chinmoy Kanti Deb
    • Joanna Szulżyk-Cieplak
    • Grzegorz Łagód
    2020 Full text MOLECULES

    The activated sludge models (ASMs) commonly used by the International Water Association (IWA) task group are based on chemical oxygen demand (COD) fractionations. However, the proper evaluation of COD fractions, which is crucial for modelling and especially oxygen uptake rate (OUR) predictions, is still under debate. The biodegradation of particulate COD is initiated by the hydrolysis process, which is an integral part of an ASM. This concept has remained in use for over 30 years. The aim of this study was to verify an alternative, more complex, modified (Activated Sludge Model No 2d) ASM2d for modelling the OUR variations and novel procedure for the estimation of a particulate COD fraction through the implementation of the GPS-X software (Hydromantis Environmental Software Solutions, Inc., Hamilton, ON, Canada) in advanced computer simulations. In comparison to the original ASM2d, the modified model more accurately predicted the OUR behavior of real settled wastewater (SWW) samples and SWW after coagulation–flocculation (C–F). The mean absolute relative deviations (MARDs) in OUR were 11.3– 29.5% and 18.9–45.8% (original ASM2d) vs. 9.7–15.8% and 11.8–30.3% (modified ASM2d) for the SWW and the C–F samples, respectively. Moreover, the impact of the COD fraction forms and molecules size on the hydrolysis process rate was developed by integrated OUR batch tests in activated sludge modelling.

  • The influence of combination of binding agents on fatigue properties of deep cold in-place recycled mixtures in Indirect Tensile Fatigue Test (ITFT)
    • Bohdan Dołżycki
    • Cezary Szydłowski
    • Mariusz Jaczewski
    2020 Full text CONSTRUCTION AND BUILDING MATERIALS

    The publication presents fatigue properties of cold recycled mixtures for eight combinations of binding agents (cement and bituminous emulsion). Cold recycled mixtures were evaluated in Indirect Tensile Fatigue Test (ITFT) at the temperature of 20 C in controlled stress mode. As a function of horizontal stress, fatigue life is strongly influenced by combination of the binding agents. When fatigue life is analyzed as a function of initial horizontal strain, the difference between different combinations decreases. In all cases, the influence of a specific binding agent is more visible for combinations with lower total amounts of the two agents.

  • The influence of polypropylene-block/graft-polycaprolactone copolymers on melt rheology, morphology, and dielectric properties of polypropylene/polycarbonate blends
    • Anton Ginzburg
    • Vaidyanath Ramakrishnan
    • Luca Rongo
    • Artur Rozanski
    • Miloud Bouyahyi
    • Lidia Jasinska-Walc
    • Rob Duchateau
    2020 RHEOLOGICA ACTA

    The paper discusses the relationship between rheology and morphology of immiscible polypropylene (matrix))/polycarbonate (dispersed phase) blends compatibilized with novel polypropylene-polycaprolactone block and graft copolymers. Transmission electron microscopy (TEM) experiments revealed uniform droplet morphologies and a reduction of the average size of the dispersed phase upon addition of the compatibilizer. The results suggested the influence of the molecular weight distribution (MWD)/chemical composition distribution (CCD) and topology of the compatibilizer on the compatibilizing performance. Graft copolymers were found to be most effective in reducing the size of the dispersed phase, whereas the performance of block copolymers appeared to be highly dependent on the block length of PP. Small-amplitude oscillatory rheological experiments revealed an increase in elasticity at low frequencies caused by the interfacial interactions induced by the compatibilizer. The effect was quantified using the relaxation time spectrums that displayed the additional peak at longer relaxation times via Gramespacher-Meissner method. Broadband dielectric spectroscopy (BDS) revealed the influence of the copolymer architecture and molecular weight of the polypropylene blocks on the properties of the interfacial polarization, which was in line with both rheology and morphology data.

  • The Influence of Sulfate on Anaerobic Ammonium Oxidation in a Sequencing Batch Reactor
    • Dominika Grubba
    • Joanna Majtacz
    2020 Full text Water

    Anaerobic ammonia-oxidizing bacteria have a more comprehensive metabolism than expected - there may be other electron acceptors that oxidize ammonium nitrogen under anaerobic conditions, in addition to the well-known nitrite nitrogen, one of which is sulfate in the sulfammox process. Sulfate-containing compounds are part of the medium for the anammox process, but their concentrations are not particularly high (0.2 g MgSO4 ∙ 7H2O/dm3 and 0.00625 g FeSO4/dm3). They can react to some extent with influent ammonium nitrogen. In this work, tests were carried out in two sequencing batch reactors with granular sludge. The first reactor (R1) operated in a 6 hour cycle, and the concentration of the inflowing sulfate was kept at 44 mg/dm3∙d. The second reactor (R2) was operated until the 36th day in a 6 hour cycle; the influencing concentration was 180 mg SO42−/dm3∙d from the 37th to 64th day in a 3 hour cycle, with an influencing concentration of 360 mg SO42−/dm3∙d; and from the 65th to 90th day, the reactor was operated again in a 6 hour cycle with an influencing concentration of 180 mg SO42−/dm3∙d. Along with the increased share of sulfate, both the ammonium utilization rate and specific anammox activity showed an increasing trend. As soon as the sulfate dosage was reduced, the ammonium utilization rate and specific anammox activity values dropped. Therefore, it can be concluded that sulfate-containing compounds contribute to the efficiency and rate of the anammox process.

  • The Influence of the Aircraft Operating Fluids on the Mechanical Parameters of the Airport Surface Concrete
    • Wojciech Żebrowski
    • Paweł Wolka
    • Marzena Kurpińska
    2020 Full text Materials

    The authors of the article assessed the impact of operating fluids used to service aircraft on changing mechanical parameters of cement concrete intended for airport pavement. The research concerned concrete designed with the use of CEM I 42.5N LH NA low-alkali cement, broken granite aggregate, fine washed aggregate, and admixtures. The analysis included the assessment of changes in dierences in endurance parameters over various research periods of up to 140 days. The obtained results allowed to carry out statistical analysis using the student’s T-test. Research has shown a significant impact of operational fluids used in aircraft on the surface concrete properties of the airport. A reduction in the compressive strength of concrete exposed to one of the tested operating liquid to a reduction of 7.2% was observed over a period of 140 days, while there was no significant impact of operating fluids on tensile strength at splitting.

  • The influence of the Cu2O deposition method on the structure, morphology and photoresponse of the ordered TiO2NTs/Cu2O heterojunction
    • Zuzanna Molenda
    • Katarzyna Grochowska
    • Jakub Karczewski
    • Jacek Ryl
    • Kazimierz Darowicki
    • Jakub Rysz
    • Adam Cenian
    • Katatrzyna SiuzdaK
    2020 Materials Research Express

    The increased interest in highly ordered titania structures exhibiting tubular shape that could be directly formed onto the stable substrate is related with the intensive research on their modification enabling absorption of light within the wide solar spectrum and its further conversion into electric or chemical energy. Among others, formation of uniform 3D heterojunctions based on the TiO2 nanotubes attracts attention since porous structure provides highly developed surface area whereas tubular shape ensures facilitated charge transport. Following that, we focus on the comparison of different electrochemical routes leading to the formation of Cu2O onto the titania nanotubes platform to improve energy harvesting. Proposed approach includes optimized potentiostatic and pulsed polarization of titania immersed in the basic electrolyte composed of Cu2+ ions stabilized by lactic acid. In this work, we demonstrate that at strictly selected deposition parameters, namely time, pulse width and cycle number, one can obtain titania nanotubes overgrown by Cu2O species uniformly distributed across the whole TiO2 layer as proved by secondary ion mass-spectrometry. X-ray photoelectron spectroscopy studies indicated purely Cu(I) oxide formation for pulsed deposition route. The photoactivity of obtained materials was verified both under vis and UV–vis irradiation. Depending on the incident light spectrum, variation in photoactivity was observed that is directly related with the charges generation and their transport within the junction. The transient photocurrent measurements show strong photocurrent enhancement for Cu2O modified titania comparing to pristine support and satisfactory photostability under visible light without any protective coating.

  • The Influence of the Cuboid Float’s Parameters on the Stability of a Floating Building
    • Artur Karczewski
    • Łukasz Piątek
    2020 Full text Polish Maritime Research

    Usually, the concept of sufficient stability of a floating structure is connected with the capacity to keep a small heel angle despite the moment of heeling. The variable responsible for these characteristics is the initial metacentric height, which is the relation between the hydrostatic features of the pontoon and the mass properties of the entire object. This article answers the questions of how heavy the floating system should be, what the minimum acceptable draft is, and whether it is beneficial to use internal fixed ballast. To cover various technologies, a theoretical model of a cuboid float with average density representing different construction materials was analysed. The results indicate that the common practice of using heavy and deep floating systems is not always reasonable. In the case of floating buildings, which, unlike ships, can be exploited only under small heel angles, the shape and width of the submerged part of the object may influence the stability more than the weight or draft.

  • The Influence of the Depth of Cut in Single-Pass Grinding on the Microstructure and Properties of the C45 Steel Surface Layer
    • Marek Szkodo
    • Karolina Chodnicka-Wszelak
    • Mariusz Deja
    • Alicja Stanisławska
    • Michał Bartmański
    2020 Full text Materials

    The paper contains the results of a metallographic examination and nanoindentation test conducted for the medium carbon structural steel with low content of Mn, Si, Cu, Cr, and Ni after its grinding to a depth ranging from 2 μm to 20 μm, at constant cutting speed (peripheral speed) of vs = 25 ms−1 and constant feed rate of vft = 1 m/min. Applied grinding parameters did not cause the surface layer hardening, which could generate an unfavorable stress distribution. The increase in the surface hardness was obtained due to the work hardening effect. Microstructure, phase composition, and chemical composition of the grinded surface layer were examined using an X‐ray diffractometer, light microscope, and scanning microscope equipped with X‐ray energy‐dispersive spectroscopy, respectively. Hardness on the grinded surface and on the cross‐section was also determined. It was shown that the grinding of C45 steel causes work hardening of its surface layer without phase transformation. What is more, only grinding to a depth of 20 μm caused the formation of an oxide scale on the work‐hardened surface layer. Nanoindentation test on the cross‐ section, at a short distance from the grinded surface, has shown that ferrite grains were more susceptible to work hardening than pearlite grains due to the creation of an equiaxed cellular microstructure, and that different dislocation substructure was created in the work‐hardened surface layer after grinding to different depths.

  • The Influence of the Electrodeposition Parameters on the Properties of Mn-Co-Based Nanofilms as Anode Materials for Alkaline Electrolysers
    • Karolina Cysewska
    • Maria Rybarczyk
    • Grzegorz Cempura
    • Jakub Karczewski
    • Marcin Łapiński
    • Piotr Jasiński
    • Sebastian Molin
    2020 Full text Materials

    In this work, the influence of the synthesis conditions on the structure, morphology, and electrocatalytic performance for the oxygen evolution reaction (OER) of Mn-Co-based films is studied. For this purpose, Mn-Co nanofilm is electrochemically synthesised in a one-step process on nickel foam in the presence of metal nitrates without any additives. The possible mechanism of the synthesis is proposed. The morphology and structure of the catalysts are studied by various techniques including scanning electron microscopy, X-ray diffraction, X-ray photoelectron spectroscopy, and transmission electron microscopy. The analyses show that the as-deposited catalysts consist mainly of oxides/hydroxides and/or (oxy)hydroxides based on Mn2+, Co2+, and Co3+. The alkaline post-treatment of the film results in the formation of Mn-Co (oxy)hydroxides and crystalline Co(OH)2 with a β-phase hexagonal platelet-like shape structure, indicating a layered double hydroxide structure, desirable for the OER. Electrochemical studies show that the catalytic performance of Mn-Co was dependent on the concentration of Mn versus Co in the synthesis solution and on the deposition charge. The optimised Mn-Co/Ni foam is characterised by a specific surface area of 10.5 m2·g−1, a pore volume of 0.0042 cm3·g−1, and high electrochemical stability with an overpotential deviation around 330–340 mV at 10 mA·cm−2geo for 70 h.

  • The influence of thermal treatment on electrocatalytic properties of Mn-Co nanofilms on nickel foam toward oxygen evolution reaction activity
    • Karolina Cysewska
    • Grzegorz Cempura
    • Jakub Karczewski
    • Marcin Łapiński
    • Piotr Jasiński
    • Sebastian Molin
    2020 MATERIALS LETTERS

    This work evaluates electrodeposited and differently treated Mn-Co catalysts for their oxygen evolution reaction activity. Catalysts are evaluated in the as-deposited and heat treated state: after 350 C and 600 C. Results show that the highest electrochemical activity is obtained for the as-deposited Mn-Co oxyhydroxide, which possibly possess a layered double hydroxide structure. After the heat treatment process, especially after 600 C, the electrochemical performance decreases considerably.

  • The Influence of Water and Mineral Oil on Mechanical Losses in a Hydraulic Motor for Offshore and Marine Applications
    • Paweł Śliwiński
    2020 Full text Polish Maritime Research

    In this paper, mechanical losses in a hydraulic motor supplied with water and mineral oil (two liquids having significantly different viscosity and lubricating properties) are described and compared. The experimental tests were onducted using a special design (prototype) of a hydraulic satellite motor. The design of the satellite motor is presented. This motor was developed to supply both with water and mineral oil and features a non-circular tooth working mechanism. The paper also characterizes sources of mechanical losses in this motor. On this basis, a mathematical model of these losses has been developed nd presented. The results of calculation of mechanical losses according to the model are compared with the experimental results. Experimental studies have shown that the mechanical losses in the motor supplied with water are 2.8 times greater than those in the motor supplied with oil. The work demonstrates that the mechanical losses in both the motor supplied with water and the one supplied with oil are described well by the mathematical model. It has been found that for the loaded motor working at high speed, the simulation results differ from experimental ones by no more than 3% for oil and 4% for water.

  • The influence of welding heat input on the quality and properties of high strength low-alloy dissimilar steel butt joints
    • Jacek Tomków
    • Jacek Haras
    2020 Full text Przegląd Spawalnictwa

    The paper presents the results of non-destructive and destructive tests of dissimilar highstrength low-alloy S460ML and S460N steel butt joints. These steels are characterized by similar mechanical properties, but their carbon equivalent CeIIW values are much different. The joints were made using different values of heat input for each welding bead. They were tested by non-destructive methods: visual, penetrant, radiographic and ultrasonic tests. Then, the destructive tests were made: static tensile test, bending test, impact test and Vickers HV10 hardness measurements. The results of prepared examinations showed, that welding with higher heat input has significant impact on the mechanical properties of the dissimilar steel joints the joint welded with bigger heat input was characterized by better mechanical properties.

  • The Influent Effects of Flow Rate Profile on thePerformance of Microbial Fuel Cells Model
    • Szymon Potrykus
    • Sara Mateo
    • Janusz Nieznański
    • Francesco Jesus Fernández-Morales
    2020 Full text ENERGIES

    The energy contained in wastewaters has been identified as a promising sustainableenergy resource that could be harvested by using microbial fuel cells (MFC). When dealing with realwastewaters, the MFCs should be able to manage high flow rates and flow rates fluctuations. In thiswork, the short-term effects of the influent flow rate variations on the performance of a microbialfuel cell has been studied. With this aim, the influent flow rate was stepwise increased from 0.72 to7.2 L/d and then stepwise decreased. The obtained results indicate that, on the one hand, an increasein the influent flow rate leads to higher chemical oxygen demand removal rates up to 396 g/(L/d) andhigher electric power generation almost 18 mW/m2, but to lower coulombic efficiencies. On the otherhand, the reduction of the flow rate increases the coulombic efficiencies, as well as the percentageof chemical oxygen demand removed, but decreases electric power generation. In the short-term,the exposition to higher influent flow rates causes the growth of the microbial population of the MFC,the growth of the non-electrogenic microorganisms being higher than that of the electrogenic ones.The higher growth of non-electrogenic microorganisms may lead to lower coulombic efficiencies.

  • The interaction parameters for solutions of n-butylurea in aqueous solutions of N-methylacetamide – The volumetric and compressibility studies between 288.15 K and 308.15 K
    • Emilia Kaczkowska
    • Jarosław Wawer
    • Magdalena Tyczyńska
    • Małgorzata Jóźwiak
    • Joanna Krakowiak
    2020 JOURNAL OF CHEMICAL THERMODYNAMICS

    Densities and speed of sound were measured for solutions of n-butylurea in aqueous solution of Nmethylacetamide 2, 4, 6 and 8 (mol/kg) at T = (288.15, 298.15 and 308.15) K. From these data the apparent molar volumes, Vf, the apparent molar isentropic compressions, KSf, of the solute were determined. The concentration dependencies of the calculated quantities have been used to obtain the standard partial molar parameters. The latter values were combined with the previously published volumetric and compressibility data for n-butylurea in pure water to obtain the partial molar properties of transfer from water to aqueous N-methylacetamide solutions. These parameters were used to determine the interaction parameters according to the McMillan-Mayer theory. The calculated parameters and their temperature characteristics are discussed in terms of solute–solvent, solute–solute and solute–cosolute interactions.

  • The managerial role in organizational culture as perceived by management students
    • Marta Szeluga-Romańska
    • Anna Modzelewska
    2020 Full text Journal of Entrepreneurship, Management and Innovation

    This paper aims at illustrating the multidimensional role of the manager and its mutual influence on organizational culture from amanagement students’ perspective. The main part of the text was based on own qualitative research – interviews, a questionnaire, and a narrative collage – which was conducted over a 10 year period among management students. Ninety-seven students from the Jagiellonian University and the Gdańsk University of Technology took part in the research. In order to gather, analyze and interpret the data, and to achieve reliable results, we followed the thematic analysis rules. We investigated the empirical material, provided by the management students responses to the research questions posed in the questionnaire, in the search for interesting threads, seeking a definition and an understanding of the term “manager” and the specifics of a manager’s work. We also presented several quotes from the data in accordance with the principles of data analysis in qualitative research methodology. Four different prisms were identified: gender, relational, constant learning and professional, described as the areas of managerial duties, features, and expectations. The article’s key value is the focus on students’ perception – an idealized construct of the managerial role, which states a benchmark for their own actual and prospect managerial performance. Such a perspective is very important for practice as well as for education. From a practical point of view, some management students will manage teams or organizations in the future. They should be aware of managerial duties’ elaborate character and the multiple demands on the role’s performance. They will shape the role by themselves. On the other hand, from an educational point of view, it is essential to give students some insight into their prospective role, understand the elaborate organizational relations, and the activities that appear in organizational culture that always influence management.

  • The mechanical properties and bactericidal degradation effectiveness of tannic acid-based thin films for wound care
    • B. Kaczmarek
    • Marcin Wekwejt
    • K. Nadolna
    • A. Owczarek
    • O. Mazur
    • Anna Pałubicka
    2020 Full text Journal of the Mechanical Behavior of Biomedical Materials

    The surface area is the most important aspect when considering the interactions between a material and the surrounding environment. Chitosan (CTS) and tannic acid (TA) were previously successfully tested by us to obtain thin films to serve as wound dressings or food packaging materials. However, surface properties as well as the antimicrobial activity of the material were not considered. They are important if the material is likely to find application in biomedical or food packaging application. Thereby, this study is a further investigation of chitosan/tannic acid films surface properties. The results showed that higher content of tannic acid increases the surface free energy and roughness, which is beneficial when considering the application of the materials as wound dressings. However, higher content of chitosan provides better antibacterial properties. Hence, the most optimal complex of chitosan and tannic acid for proposed application is the ratio 80/20.

  • The mechanisms of degradation of titanium dental implants
    • Agnieszka Ossowska
    • Andrzej Zieliński
    2020 Full text Coatings

    Titanium dental implants show very good properties, unfortunately there are still issues regarding material wear due to corrosion, implant loosening, as well as biological factors—allergic reactions and inflammation leading to rejection of the implanted material. In order to avoid performing reimplantation operations, changes in the chemical composition and/or modifications of the surface layer of the materials are used. This research is aimed at explaining the possible mechanisms of titanium dissolution and the role of oxide coating, and its damage, in the enhancement of the corrosion process. The studies of new and used implants were made by scanning electron microscopy and computer tomography. The long-term chemical dissolution of rutile was studied in Ringer’s solution and artificial saliva at various pH levels and room temperature. Inductively coupled plasma mass spectrometry (ICP-MS) conjugated plasma ion spectrometry was used to determine the number of dissolved titanium ions in the solutions. The obtained results demonstrated the extremely low dissolution rate of rutile, slightly increasing along with pH. The diffusion calculations showed that the diffusion of titanium through the oxide layer at human body temperature is negligible. The obtained results indicate that the surface damage followed by titanium dissolution is initiated at the defects caused by either the manufacturing process or implantation surgery. At a low thickness of titanium oxide coating, there is a stepwise appearance and development of cracks that forms corrosion tunnels within the oxide coating.

  • THE MELT FLOWABILITY AND TENSILE PERFORMANCE OF POLY (-CAPROLACTONE)/BREWERS’ SPENT GRAIN COMPOSITES AS A FUNCTION OF FILLER MODIFICATION
    • Aleksander Hejna
    2020 Full text

    Nowadays, it is essential to reduce the environmental impact of products and technologies. Such an approach should be highlighted in all research activities. In the case of polymer composites, it can be realized by introducing by-products or waste materials as fillers. An auspicious example of such material is the brewers’ spent grain, the major byproduct of the beer production. Its chemical composition, relatively similar to conventional lignocellulose fillers, enables its application to manufacturing wood-polymer composites. However, to enhance its compatibility with polymer matrices, it could be modified. Therefore, in the presented paper, the impact of the extrusion grinding of brewers’ spent grain on the processing and mechanical performance of polymer composites was evaluated.

  • The Method of Selecting the Interval of Functional Tests Taking into Account Economic Aspects and Legal Requirements
    • Jan Piesik
    • Emilian Piesik
    • Marcin Śliwiński
    2020 Full text Journal of Automation, Mobile Robotics and Intelligent Systems - JAMRIS

    The article discusses the problem of choosing the optimal frequency of functional tests, taking into account the reliability and law requirements, but also the impact of business aspects in the company. The subject of functional test interval is well described for purposes of the process industry. Unfortunately, this is not the case for the machinery safety functions with low demand mode. This is followed by a presentation of the current business approach, which, in order to achieve industrial excellence, monitor their performance through the appropriate selection of key performance indicators. In addition, companies are increasingly exploring potential risks in the following areas: new challenges in advanced risk management, including the perception of the company’s facilities as a safe workplace insight of customers and business partners. Eliminating potential hazards is increasingly taking into account, especially the impact of human activity and its interaction with machines. The case study has been presented based on the machines used for the production of tire semi-finished products. In this article, the authors propose a solution for selecting the interval of functional tests of safety functions and additional machine protection measures as a compromise to achieve satisfactory results in terms of safety requirements, performance and legal requirements.

  • The Neural Knowledge DNA Based Smart Internet of Things
    • Haoxi Zhang
    • Fei Li
    • Juan Wang
    • Zuli Wang
    • Lei Shi
    • Cesar Sanin
    • Edward Szczerbicki
    2020 Full text CYBERNETICS AND SYSTEMS

    ABSTRACT The Internet of Things (IoT) has gained significant attention from industry as well as academia during the past decade. Smartness, however, remains a substantial challenge for IoT applications. Recent advances in networked sensor technologies, computing, and machine learning have made it possible for building new smart IoT applications. In this paper, we propose a novel approach: the Neural Knowledge DNA based Smart Internet of Things that enables IoT to extract knowledge from past experiences, as well as to store, evolve, share, and reuse such knowledge aiming for smart functions. By catching decision events, this approach helps IoT gather its own daily operation experiences, and it uses such experiences for knowledge discovery with the support of machine learning technologies. An initial case study is presented at the end of this paper to demonstrate how this approach can help IoT applications become smart: the proposed approach is applied to fitness wristbands to enable human action recognition.

  • The New Klebsiella pneumoniae ST152 Variants with Hypermucoviscous Phenotype Isolated from Renal Transplant Recipients with Asymptomatic Bacteriuria-Genetic Characteristics by WGS.
    • Magdalena Wysocka
    • Roxana Zamudio
    • Marco R Oggioni
    • Justyna Gołębiewska
    • Aleksandra Dudziak
    • Beata Krawczyk
    2020 Full text Genes

    Klebsiella pneumoniae (Kp) is one of the most important etiological factors of urinary tract infections in renal transplant (RTx) recipients. We described the antimicrobial susceptibility phenotypes and genomic features of two hypermucoviscous (HM) Kp isolates recovered from RTx recipients with asymptomatic bacteriuria (ABU). Using whole genome sequencing (WGS) data, we showed that the strains belong to the ST152 lineage with the KL149 capsular serotype, but without rmpA/magA genes, which is typical for HM+ hypervirulent Kp. These new strains carried virulence-associated genes that predispose for urinary tract infections (UTIs). Likewise, both strains carried the ecp gene encoding pilus common for extended-spectrum β-lactamase (ESBL) Escherichia coli. Although the two ST152 isolates were closely related and differed by only nine single nucleotide polymorphisms (SNPs) in their chromosomes, they had different plasmid compositions and chromosomal elements, with isolate KP28872 carrying an ESBL plasmid and an integrative conjugative element. These two isolates are an example of the high plasticity of the K. pneumoniae accessory genome. The identification of patients with ABU matched with the correct epidemiological profiling of isolates could facilitate interventions to prevent or rapidly treat K. pneumoniae infections.

  • The new silica-based coated SPME fiber as universal support for the confinement of ionic liquid as an extraction medium
    • Karolina Konieczna
    • Kateryna Yavir
    • Mansoureh Kermani
    • Aleksandra Mielewczyk-Gryń
    • Adam Kloskowski
    2020 SEPARATION AND PURIFICATION TECHNOLOGY

    The new silica-based SPME fiber coating is reported for the first time as universal support purposed to confinement of ionic liquid as an extraction medium. Fiber coating was prepared by the sol-gel process, using potassium silicate (K2SiO3) as a precursor and dimethylformamide (DMF) as a pore-forming medium. The concept of synthesis assumes obtaining a solid porous material on the surface of the glass rod and, being characterized by high porosity, mechanical strength, and uniformity of shape. In the course of the research, several parameters were optimized, like the type of silica precursor, drying steps, time and temperature of aging. Properties of obtained coatings were evaluated using optical and scanning electron microscopies and thermal adsorption/desorption measurements. Finally, the ionic liquid 1-ethyl-3-methylimidazolium tetrafluoroborate [C2C1IM][BF4] was immobilized in silica pores of the prepared fiber. The usefulness of the obtained SPME silica-IL fibers was investigated by its utilization in model analytical procedures. Robustness of produced fibers is supported by high fiber-to-fiber reproducibility (%) as well as by a long lifetime reaching over 50 extraction/desorption cycles.

  • The New Test Procedure for Group-Type Composition of Base Oils of Lubricating Oils, Especially Emitted into the Environment
    • Paulina Nowak
    • Karolina Kucharska
    • Marian Kamiński
    2020 Full text ENERGIES

    Mineral base oil, a product of multistep fine refining of the relevant fractions from vacuum distillation of crude oil, is a main component of so-called mineral lubricating oils containing aliphatic and alicyclic substituted aromatic hydrocarbons, i.e., derivatives of benzene and biphenyl. Mineral lubricating oil is composed mostly of mineral base oil and a low amount of enriching additives, most often products of advanced organic chemical technology. The application of mineral lubricating oils in open cutting systems has a very negative impact on environment and on the operator’s health. This work presents a simple, cheap and fast methodology allows identification of the group-type composition of base oil in lubricating oil and to estimate the content or total absence of base oil of mineral and vegetable origin in lubricating oil. The first step of the test is an in-situ screening for fluorescence of petroleum fraction under the 365 nm light. The next is the performance of infrared spectra with Fourier transformation (FT-MIR) to identify and estimate the content of vegetable oil and its derivatives and the performance of UV-Vis spectra to identify and determine the content of aromatic hydrocarbons, as well as dyes present in the lubricating oil. The last stage is normal phase thin layer chromatography (NP-TLC) using different visualization methods to evaluate the group-type composition of lubricating oil. Effectivity of the developed procedure has been confirmed during control of group-type composition evaluation of lubricating oils in cutting systems. The procedure can be also applied with respect to different oil matrices.