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Repozytorium publikacji
Politechniki Gdańskiej

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Ostatnie pozycje

  • Druk 3D części z tworzyw sztucznych na skalę przemysłową w technologii SLS
    • Dawid Zieliński
    2020 Pełny tekst Tworzywa Sztuczne w Przemyśle

    Firma EOS, wiodący i światowy dostawca technologii przemysłowego wykorzystania druku 3D dla materiałów metalicznych i polimerowych, zaprezentowała na targach formnext 2017 nowy system EOS P500, przeznaczony do addytywnego wytwarzania modeli. Drukarka 3D adresowana jest dla przedsiębiorstw chcących wytwarzać na skalę przemysłową części i elementy z tworzyw sztucznych o wysokiej jakości.

  • Dynamic analysis of temporary steel grandstand subjected to human-induced excitations due to jumping
    • Natalia Lasowicz
    • Robert Jankowski
    2020 Pełny tekst AIP Conference Proceedings

    Steel grandstands are structures that are frequently used during sport games and many other non-sporting events, such as festivals, music concerts, or even politicians rallies, with participation of a large number of attendees. Unfortunately, the presence of unexpected excessive dynamic loads due to unpredictable behaviour of spectators (e.g. synchronized harmonic jumping or swaying) may lead to serious structural damage or even total collapse of a structure, and such cases were observed in the past. Given that, steel grandstands should be designed so as to withstand the unexpected dynamic loads leading to damage and, therefore, ensure maximum safety for all participants. Building codes, however, apply different approaches. According to the Polish Standard, an additional horizontal load equal to 6% of the total vertical load acting on a grandstand has to be considered at the design stage. The British Standard, on the other hand, specifies a higher value of horizontal load, i.e. 10% of the total vertical load that should be taken into account. Therefore, the aim of the present paper is to conduct a dynamic numerical investigation focused on the response of a steel temporary grandstand subjected to human-induced vibrations due to jumping with two different values of horizontal load (6% and 10% of the total vertical load) as well as for two different bracing elements (typical tubular member and polymer damper). The results of the study clearly show that the response of a temporary steel scaffolding grandstand equipped with two different bracing elements taking into account two different approaches is substantially different.

  • Dynamic Charging of Electric Buses as a Way to Reduce Investment Risks of Urban Transport System Electrification
    • Mikołaj Bartłomiejczyk
    • Marcin Połom
    2020

    Night charging and fast charging are currently the two most common systems for charging electric buses. Despite the fact that numerous trial installations were started, neither of these two systems has obtained unqualified approval of the users. The alternative is to charge vehicles in motion - dynamic charging which combines the advantages of trolleybus transport and of electric buses. One of the advantages is the reduction of risks associated with the electrifica-tion of urban transport. The investment in the construction of the traction net-work allows you to reduce the costs associated with the purchase and replace-ment of traction batteries, as well as increase the flexibility of the transport system. The article presents the financial benefits resulting from the use of a dynamic charging system.

  • Dynamic Response of the Suspended on a Single Cable Footbridge
    • Mikołaj Miśkiewicz
    • Łukasz Pyrzowski
    • Krzysztof Wilde
    2020

    The article presents numerical simulations, dynamic in situ load tests and a structural health monitoring (SHM) system installed in a suspended on a single cable footbridge. Numerical simulations performed prior to construction indicated the possibility of structural dynamics problems, finally confirmed in the course of dynamic test loading. In the dynamic load course the bridge deck developed vibrations displaying accelerations up to 4.5 m/s2. Such footbridge behavior causes unacceptable discomfort to the users and risk of structural damage. The tests brought about the need for repair works and the use of a monitoring system to increase operational safety of the object.

  • Dynamic Tests and Technical Monitoring of a Novel Sandwich Footbridge
    • Jacek Chróścielewski
    • Mikołaj Miśkiewicz
    • Łukasz Pyrzowski
    • Magdalena Rucka
    • Bartosz Sobczyk
    • Krzysztof Wilde
    • Błażej Meronk
    2020

    A novel sandwich composite footbridge is described in this paper, for the first time after it has been put into operation over the Radunia River in the Pruszcz Gdański municipality. This paper presents results of dynamic tests and describes technical monitoring of the footbridge. The dynamic tests were conducted to estimate pedestrian comfort and were compared with the ones from numerical simulations made in the environment of Finite Element Method. A discussion of the obtained results is made then. The characteristics and capabilities of the network of sensors spread over the bridge to monitor its long-term behavior are described.

  • Dziedzictwo 150 lat rozwoju techniki wodociągowej na terenie Gdańska i Sopotu
    • Michał Klugmann
    2020

    Publikacja prezentuje historię nowoczesnych (czyli powstałych na fali rewolucji przemysłowej) wodociągów Gdańska i Sopotu. Wzmiankowane są najważniejsze zabytki techniki, związane z rozwojem systemu od II połowy XIX wieku. Na ich przykładzie poruszana jest szersza problematyka ochrony takich obiektów w polskich realiach. Opisany został zabytkowy zasób, w zakresie obiektów nieruchomych i dokumentacji, stan zachowania tego zasobu, działania dotychczas podjęte dla jego ochrony i elementy trwale utracone.

  • Early prediction of macrocrack location in concrete and other granular composite materials
    • A. Tordesillas
    • S. Kahagalage
    • C. Ras
    • Michał Nitka
    • Andrzej Tejchman-Konarzewski
    2020 Pełny tekst Scientific Reports

    Heterogeniczne kruche kompozyty, takie jak beton, ceramika i skały składają się z ziaren połączonych wiązaniami. Pytanie, czy ścieżka pęknięcia, która prowadzi do zniszczenia może być przewidziania na podstawie znanych cech mikrostrukturalnych, a mianowicie łączności wiązań, rozmiaru, energii pękania, wytrzymałości pozostają otwarte. Istnieje wiele kryteriów pęknięć. Najczęściej używane są oparte na postulowanym ekstremum naprężenia i/lub energii. Ponieważ siła i energia mają wspólne ścieżki przekazu, ich wąskie gardło przepływu może być prekursorskim mechanizmem zniszczenia, które pogodzi te kryteria optymalności w jednej ujednoliconej strukturze. Badamy to w ramach teorii przepływu sieci, używając dane mikrostrukturalne z trójwymiarowych modeli elementów dyskretnych betonu podczas rozciągania jednoosiowego. Znajdujemy wąskie gardło siły i energii na tej samej ścieżce, które zapewnia wczesną i dokładną prognozę ostatecznej ścieżki makropęknięcia w betonie.

  • ECOLOGY OR ECONOMICS? THE ASPECT DETERMINING THE USE OF DISPLACEMENT PILES FOR THE FOUNDATIONS OF BRIDGE STRUCTURES
    • Paweł Więcławski
    • Kazimierz Gwizdała
    2020 Pełny tekst

    W ostatnich latach rzadko wykonuje się pale wiercone o bardzo dużych średnicach ze względu na: wymagany sprzęt, transport wydobytego urobku gruntowego, duże ilości stali zbrojeniowej. Konstrukcje inżynierskie na autostradzie A-1, na drodze ekspresowej S-7 i Obwodnicy Południowej Gdańska posadowiono na palach prefabrykowanych. Fundamenty największych mostów na autostradzie A-1 zbudowano na palach Vibro i Franki. W artykule zwrócono uwagę na pale w pełni przemieszczeniowe, charakteryzujące się dużą nośnością uzyskiwaną w krótkim czasie od wykonania i prostą technologią, które są stosowane w fundamentach obiektów drogowych. Spośród wszystkich, obecnie wykonywanych rodzajów pali, tę technologię można nazwać ekologiczną i ekonomiczną. Te aspekty mogą zmienić zakres zastosowania pali przemieszczeniowych w najbliższej przyszłości.

  • Ecotoxicological equilibria of triclosan inMicrotox, XenoScreen YES/YAS, Caco2, HEPG2 and liposomal systems are affected by the occurrence of other pharmaceutical and personal care emerging contaminants
    • Miquel Oliver
    • Błażej Kudłak
    • Monika Wieczerzak
    • Salette Reis
    • Sofia Lima
    • Marcela Segundo
    • Manuel Miro
    2020 Pełny tekst SCIENCE OF THE TOTAL ENVIRONMENT

    Contaminants of emerging concernmay be considered as any chemicals or factorswhose unintended continuous release and persistence in the environmentmay lead to any observable undesirable response of living beings. Still not much is known on reciprocal toxicological impact of given chemicals when present in binary or more complex mixtures. In thiswork, an attemptwas thus undertaken to study the impact of butylparaben,methylparaben and diclofenac on toxicological behavior and properties of triclosan (at varying concentration levels)with respect to Microtox, XenoScreen YES/YAS, Caco-2, HEPG2, and liposomal systems.

  • ECU calibration for gaseous dual fuel supply system in compression ignition engines
    • Denys Stepanenko
    • Zbigniew Kneba
    2020 Pełny tekst Combustion Engines

    The dual fuel (DF) combustion mode is proven solution that allows to improve or get at the same level engine performance and reduce toxic compounds in exhaust gases which is confirmed by researchers and end-users. DF combustion mode uses two fuels gaseous fuel as a primary energy source and a pilot quantity of diesel fuel as ignition source. However, in order, to fully take advantage of the potential of the dual fuel mode, DF system must be proper calibrated. Despite the existence of commercial control systems for dual fuel engines on the market, the literature on the important parameters for the engine's operation introduced during calibration is scarce. This article briefly describes a concept of working algorithm and calibration strategy of a dual fuel electronic control unit (ECU) The purpose of calibration is to achieve the greatest possible use of an alternative gaseous fuel without causing accelerated engine wear.

  • Editorial for the special issue on advances in forward and inverse surrogate modeling for high-frequency design
    • Sławomir Kozieł
    • Anna Pietrenko-Dąbrowska
    2020 INTERNATIONAL JOURNAL OF NUMERICAL MODELLING-ELECTRONIC NETWORKS DEVICES AND FIELDS

    The design of modern‐day high‐frequency devices and circuits, including microwave/RF, antenna and photonic components, historically has relied on full‐wave electromagnetic (EM) simulation tools. Initially used for design verification, EM simulations are nowadays used in the design process itself, for example, for finding optimum values of geometry and/or material parameters of the structures of interest. In a growing number of cases, EM‐driven design closure is mandatory because alternative ways of evaluating the circuit performance (such as through equivalent network modeling) are grossly inaccurate and unable to account for cross‐coupling effects (eg, in densely arranged layouts of compact circuits or antenna arrays), or various environmental components that affect the circuit performance (eg, connectors or housing for antenna structures). Despite being imperative, simulation‐based design poses significant challenges, mostly due to the high computational cost of accurate, high‐fidelity analysis. Repetitive simulations entailed by conventional optimization routines and even more by uncertainty quantification procedures (eg, Monte Carlo analysis) or tolerance‐aware design tasks may generate the costs that are unmanageable or at least impractical. The availability of massive computational resources does not always translate into design speedup due to the need to account for interactions between devices and their surroundings as well as multiphysics (eg, EM‐thermal) effects.

  • EduAkcja. Historia pewnego czasopisma
    • Agnieszka Landowska
    • Maria Wilkin
    2020

    Rozdział przedstawia przebieg inicjatywy powołania czasopisma poświęconego zdalnemu nauczaniu o nazwie EduAkcja. Magazyn edukacji elektronicznej

  • E-dyplomy: uwarunkowania administracyjne i funkcjonalne ich wprowadzenia na polskich uczelniach
    • Wioletta Braun
    • Katarzyna Górak-Sosnowska
    2020

    Pandemia COVID-19 wymusiła na polskim systemie szkolnictwa wyższego szereg zmian, z których główne dotyczą zmian w zakresie organizacji pracy, cyfryzacji procesów obsługi toku studiów. Przepisy prawa stanowią już o e-teczce, mamy rozporządzenia dotyczące jej prowadzenia, niemniej niewiele uczelni, o ile w ogóle, prowadzi na chwilę obecną akta osobowe studentów w postaci elektronicznej. Jednym z elementów składowych e-teczki jest dyplom ukończenia studiów. Publikacja traktuje o obecnym systemie prawnym dotyczącym dyplomów oraz e-dyplomów. Wskazuje na konieczność wprowadzenia dodatkowych zapisów prawnych, które umożliwiłyby na wdrożenie tego rozwiązania. W artykule dokonano również przeglądu istniejących rozwiązań stosowanych w innych krajach i ewentualnych potencjalnych istniejących możliwościach cyfrowego odwzorowania dyplomu. Wprowadzenie e-dyplomów, bądź do ich całkowitego wdrożenia cyfrowych odwzorowań tych dokumentów, jest kwestią czasu. W artykule wskazano na potencjalne ścieżki procedowania tego rozwiązania.

  • E-Estonia as a role model? Some general considerations and applicability in France
    • Aleksandro Cepilovs
    • David Duenas Cid
    2020

    Estonia has recently been widely recognised – in the policy circles, academia, as well as the media space – as one of the more advanced nation states when it comes to digital government (and governance) transformation (e.g. Margetts and Naumann, 2017; Heller, 2017). Ever greater attention Estonia attracted with the two most recent digital government initiatives, namely the e-Residency and the virtual data embassy, both first of their kind in the world. Estonia thus placed itself among such leaders in digital government as Singapore and Denmark, despite the fact that it is both significantly smaller as well as relatively poorer in terms of GDP per capita1. This high level of development of digital government seems even more surprising considering the fact that Estonia has re-gained its independence less than 30 years ago.

  • Effect of Aromatic System Expansion on Crystal Structures of 1,2,5-Thia- and 1,2,5-Selenadiazoles and Their Quaternary Salts: Synthesis, Structure, and Spectroscopic Properties
    • Jan Alfuth
    • Beata Zadykowicz
    • Artur Sikorski
    • Tadeusz Połoński
    • Katarzyna Eichstaedt
    • Teresa Olszewska
    2020 Pełny tekst Materials

    Rational manipulation of secondary bonding interactions is a crucial factor in the construction of new chalcogenadiazole-based materials. This article reports detailed experimental studies on phenanthro[9,10-c][1,2,5]chalcogenadiazolium and 2,1,3-benzochalcogenadiazolium salts and their precursors. The compounds were synthesized, characterized employing NMR and UV-Vis spectroscopy. TD-DFT calculations were also performed. The influence of the size of the aromatic system on the molecular motifs formed by the compounds in the solid state has been studied by means of single-crystal X-ray diffraction. In case of the salts, the nature of an anion was also taken into consideration. The results show that cyclic [E···N]2 supramolecular synthon connects neighboring molecules of phenanthro[9,10-c][1,2,5]chalcogenadiazoles, with a relatively large aromatic system, in dimers regardless of the chalcogen atom in the molecule. Both N-methyl-2,1,3-benzothiadiazolium and N-methylphenanthro[9,10-c][1,2,5]chalcogenadiazolium cations have a strong affinity for triflate and iodide anions, therefore the formation of S···N or Se···N secondary bonding interactions is observed only in two out of the eight quaternary salts. Less coordinating anions must be used to enable the building blocks studied to form cyclic [E···N]2 synthons. Moreover, for two of the triflate salts, which are isostructural, a new supramolecular motif has been observed.

  • Effect of Axial Porosities on Flexomagnetic Response of In-Plane Compressed Piezomagnetic Nanobeams
    • Mohammad Malikan
    • Victor Eremeev
    • Krzysztof Kamil Żur
    2020 Pełny tekst Symmetry-Basel

    We investigated the stability of an axially loaded Euler–Bernoulli porous nanobeam considering the flexomagnetic material properties. The flexomagneticity relates to the magnetization with strain gradients. Here we assume both piezomagnetic and flexomagnetic phenomena are coupled simultaneously with elastic relations in an inverse magnetization. Similar to flexoelectricity, the flexomagneticity is a size-dependent property. Therefore, its effect is more pronounced at small scales. We merge the stability equation with a nonlocal model of the strain gradient elasticity. The Navier sinusoidal transverse deflection is employed to attain the critical buckling load. Furthermore, different types of axial symmetric and asymmetric porosity distributions are studied. It was revealed that regardless of the high magnetic field, one can realize the flexomagnetic effect at a small scale. We demonstrate as well that for the larger thicknesses a difference between responses of piezomagnetic and piezo-flexomagnetic nanobeams would not be significant.

  • Effect of band gap on power conversion efficiency of single-junction semiconductor photovoltaic cells under white light phosphor-based LED illumination
    • Grażyna Jarosz
    • Rafał Marczyński
    • Ryszard Signerski
    2020 Pełny tekst MATERIALS SCIENCE IN SEMICONDUCTOR PROCESSING

    On the basis of the detailed balance principle, curves of efficiency limit of single-junction photovoltaic cells at warm and cool white light phosphor-based LED bulbs with luminous efficacy exceeding 100 lm/W have been simulated. The effect of energy band gap and illuminance on the efficiencies at warm and cool light is discussed. The simulations carried out show that maximum power conversion efficiency at 1000 lx reaches 52.0% for cool light and 53.6% for warm one, while the optimal energy band gap is 1.80 eV and 1.88 eV, respectively. The simulated limits are also referenced to experimental data presented in literature to show that there is still a lot of room for improving indoor photovoltaic cells.

  • Effect of Base-Connection Strength and Ductility on the Seismic Performance of Steel Moment-Resisting Frames
    • Tomasz Falborski
    • Pablo Torres-Rodas
    • Farzin Zareian
    • Amit Kanvinde
    2020 JOURNAL OF STRUCTURAL ENGINEERING-ASCE

    Column-base connections in steel moment-resisting frames (SMFs) in seismic regions are commonly designed to develop the capacity of adjoining column with an intent to develop a plastic hinge in the column member, rather than in the connection (i.e., a strong-base design). Recent research has shown base connections to possess high ductility, indicating that this practice may be not only expensive but also unnecessary. This suggests that concentrating inelastic rotations in the base connection may result in acceptable performance. Motivated by this finding, the performance of steel moment resisting frames with a weak-base design is investigated to examine the relationships between base-connection strength, deformation capacity, and structural performance. The main scientific basis of this study is nonlinear static pushover and nonlinear time history simulations on SMFs designed for high seismicity. These simulations interrogate parameters including frame height (4-, 8-, 12-, and 20-story), base-connection strength, base flexibility, and base rotation capacity, resulting in a total of 160 parametric combinations. The performance of each of these is assessed to estimate the probabilities of failure or collapse corresponding to a 2/50 (2% probability of exceedance in 50 years) intensity of shaking. The key finding is that for all frames, acceptable performance (i.e., comparable to current practice with capacity-designed bases) may be obtained by designing the base connections for overstrength seismic loads (i.e., based on the Ω factor) rather than based on column capacity; this has the potential to offer significant cost savings. For a low-rise (i.e., four-story) frame, acceptable performance is achieved even without significant rotational demands in the base connection. For the other frames, a baseconnection rotation capacity of approximately 0.05 rad is necessary to achieve acceptable performance. Implications of these findings for prospective design practices, as well as future research, are outlined, and limitations are discussed.

  • Effect of bio-based components on the chemical structure, thermal stability and mechanical properties of green thermoplastic polyurethane elastomers
    • Paulina Parcheta
    • Ewa Głowińska
    • Janusz Datta
    2020 Pełny tekst EUROPEAN POLYMER JOURNAL

    It seems to be obvious that conditions changes during polyols synthesis have impact on the polyols properties. Even the chemical formula is the same or similar, physicochemical properties and also molecular weight of polyols might be different and are significant in term of future polyurethanes properties and processing. In this work, fully bio-based poly(propylene succinate)s synthesized at different temperature conditions were used as a polyol in thermoplastic polyurethane elastomers (TPU) synthesis. Novel bio-based TPUs were synthesized with the use of mentioned bio-based linear polyester polyols, poly(propylene succinate)s and also 4,4-diphenylmethane diisocyanate (MDI) and a chain extender 1,4-butanediol (BDO) or 1,3-propanediol (PDO), both with the natural origin. Influence of synthesized bio-based polyols on thermoplastic polyurethane elastomers characteristic was determined based on investigation of chemical structure, thermal, thermomechanical, mechanical and physical properties of synthesized bio-based TPU. Fourier transform infrared spectroscopy (FTIR) and proton nuclear magnetic resonance (1H NMR) were applied to the chemical formula determination. Thermogravimetry was supportive in thermal analysis, dynamic mechanical analysis (DMA), tensile test and hardness were used to determine thermomechanical behavior and mechanical properties at static and dynamic condition. The density of the obtained materials was also measured. It was established that using obtained fully bio-based polyester polyols the thermoplastic polyurethane elastomers can be synthesis without catalyst usage. Based on the results demonstrated greater influence of type of chain extender on bio-based TPU properties than condition of bio-based polyester synthesis. Each sample was characterized by glass temperature (Tg) ca. 0-5°C and similar thermal stability ca. 320°C. The tensile strength of prepared bio-based TPUs reach even 30 MPa with an elongation at break ca. 550%.

  • Effect of bitumen characteristics obtained according to EN and Superpave specifications on asphalt mixture performance in low-temperature laboratory tests
    • Dawid Ryś
    • Mariusz Jaczewski
    • Marek Pszczoła
    • Piotr Jaskuła
    • Wojciech Bańkowski
    2020 Pełny tekst CONSTRUCTION AND BUILDING MATERIALS

    The paper aims to identify those characteristics of bitumen which have the greatest impact on asphalt mixture low-temperature performance. It was observed that stiffness and m-value of bitumen from BBR test were moderately related to stiffness and m-value of asphalt mixture obtained from 3 PB test. Simultaneously those rheological properties significantly impact on cryogenic stresses induced during TSRST test. The multiple regression model was developed and it implied that mixture failure temperature depends both on rheological properties, brittle fracture and content of bitumen, what means that only comprehensive assessment of bitumen properties enables reasonable assessment of its low-temperature performance.

  • Effect of chemical structure on complexation efficiency of aromatic drugs with cyclodextrins: The example of dibenzazepine derivatives
    • Koleta Hemine
    • Anna Skwierawska
    • Cyprian Kleist
    • Michał Olewniczak
    • Katarzyna Szwarc-Karabyka
    • Dariusz Wyrzykowski
    • Anna Mieszkowska
    • Jarosław Chojnacki
    • Jacek Czub
    • Łukasz Nierzwicki
    2020 CARBOHYDRATE POLYMERS

    It is widely believed that the hydrophobic effect governs the binding of guest molecules to cyclodextrins (CDs). However, it is also known that high hydrophobicity of guest molecules does not always translate to the formation of stable inclusion complexes with CDs. Indeed, a plethora of other factors can play a role in the efficiency of guest–CD interactions, rendering structure-based prediction of the complexation efficiency with CDs a non trivial task. In this combined experimental and computational study, we examine the major structural factors governing complexation efficiency of polycyclic aromatic drug-like compounds with natural CDs, using as an example iminostilbene and its N-substituted derivatives. We find that purely hydrophobic IS derivatives show negligible complexation efficiency with CDs and only IS with hydrophilic substituents form stable inclusion complexes in water. We show that the balance between the guest solubility and its affinity to CDs is critical for the effective formation of inclusion complexes. Finally, our results demonstrate that guest–host hydrogen bonds facilitate the formation of crystalline inclusion complexes with CDs.

  • Effect of Different Bromine Sources on the Dual Cation Mixed Halide Perovskite Solar Cells
    • Damian Głowienka
    • Francesco Giacomo Di
    • Mehrdad Najafi
    • Ilker Dogan
    • Alfredo Mameli
    • Fallon J. M. Colberts
    • Jędrzej Szmytkowski
    • Yulia Galagan
    2020 Pełny tekst ACS Applied Energy Materials

    Recent research has shown that perovskite solar cells with a mixed dual A-cation have much better structural stability without loss of efficiency than single cation devices. Mixed cation perovskites create a lot of questions about the salts being used for the formation of the best-quality layer. Here, we have investigated three sources of bromide in the perovskite absorption layer, using lead bromide (PbBr2), formamidinium bromide (FABr), and cesium bromide (CsBr). The experimental results have shown better performance for FABr and CsBr sources of bromide in comparison to the regularly used PbBr2. This effect has been explained with the complex species present in the not-annealed perovskite films which changes the defect states during the crystallization of the absorber layer. It has been found with numerical simulations that the observed phenomenon directly impacts the rates of the trap-assisted recombination. The results of this study are one more step forward in understanding the physics behind the crystallization process which is crucial in further improvement of the perovskite solar cells.

  • Effect of electrode waterproof coating on quality of underwater wet welded joints
    • Jacek Tomków
    • Dariusz Fydrych
    • Kamil Wilk
    2020 Pełny tekst Materials

    In this paper, the effects of different hydrophobic coatings on the surface of covered electrodes on the quality of wet welded carbon steel joints were discussed. Commonly available hydrophobic substances used in industrial applications were selected for the research. The aim of using waterproof coatings was to check the possibility to decreasing the susceptibility of highstrength low-alloy S460N steel to cold cracking. During experiments diffusible hydrogen content in deposited metal determination by mercury method, metallographic macro- and microscopic testing and hardness measurements were performed. Investigations showed that waterproof coatings laid on covered electrodes can improve the quality of wet welded joints, by decreasing the Vickers HV10 hardness in heat-affected zone and decreasing the diffusible hydrogen content in deposited metal, which minimalize possibility of cold cracking.

  • Effect of Ethanol Extracts of Propolis (EEPs) against Staphylococcal Biofilm—Microscopic Studies
    • Katarzyna Grecka
    • Zirui Ray Xiong
    • Hanyu Chen
    • Karolina Pełka
    • Randy Worobo
    • Piotr Szweda
    2020 Pełny tekst Pathogens

    Staphylococci growing in the form of biofilm exhibit high resistance to a plethora of antibiotics. The aim of the study was to assess the influence of ethanolic extract of propolis (EEPs) on S. epidermidis ATCC 35984 biofilm using fluorescent microscopy. Propidium iodide (PI) and SYTO 9 were used for differentiation of live and dead cells, and calcofluor white was used to stain the extracellular matrix, the self-produced extracellular polymeric substances (EPS). The outcomes of the research confirm the promising potential of EEPs for eradication of staphylococcal biofilm. However, its activity cannot be classified as fully satisfactory, either in terms of the effectiveness of elimination of bacterial cells or disturbing the EPS structure. A two or even four times higher concentration of EEPs compared to MIC (Minimum Inhibitory Concentration) against planktonic cells (128 µg/mL) was necessary for effective (estimated for 90%) elimination of living cells from the biofilm structure. Unfortunately, even at that concentration of EEPs, the extracellular matrix was only partially disturbed and effectively protected the residual population of living cells of S. epidermidis ATCC 35984. In our opinion, a combination of EEPs with agents disrupting components of EPS, e.g., proteases, lysines, or enzymes degrading extracellular DNA or PIA (polysaccharide intercellular adhesin).

  • Effect of Flow Normalization in Micro-Pin-Finned Heat Sink: Numerical Study
    • Gurjeet Singh
    • Kumar Ritunesh
    • Dariusz Mikielewicz
    2020 Pełny tekst JOURNAL OF THERMOPHYSICS AND HEAT TRANSFER

    The micro-pin-fin heat sink (MPFHS) is widely employed for the heat transfer enhancement of microchannel heat sinks. In the current paper, the effect of flow normalization on the thermohydraulic performance of micro-pin-finned heat sinks is studied numerically. Two geometries of MPFHSs, the conventional design micro-pin-fin heat sink (CD-MPFHS) with a uniform-width micro pin fin and the proposed design micro-pin-fin heat sink (PD-MPFHS) with a nonuniform-width micro pin fin, are studied. Flow distribution analysis in the primary and secondary channels of MPFHSs is carried out. More flow resistance offered by wider central micro pin fins diverts more flow toward side channels; as a result of which, better flow distribution in primary channels and higher flow across secondary channels are noticed for the PD-MPFHS as compared to the CD-MPFHS. As a result of that, maximum and average base temperatures are reduced by 4.6 and 2.2K as compared to the CD-MPFHS. The Nusselt number increased by 10.1%, and a better thermohydraulic performance index has been offered by the PD-MPFHS for the entire studied Reynolds number range.

  • Effect of interconnect coating procedure on solid oxide fuel cell performance
    • Hamid Abdoli
    • Sebastian Molin
    • Hamidreza Farnoush
    2020 Pełny tekst MATERIALS LETTERS

    Chromium (Cr) species vaporizing from chromia-forming alloy interconnects is known as a source of degradation in solid oxide fuel cell (SOFC) stacks called “cathode poisoning”. (Mn,Co)3O4 spinel coatings offer good protection against Cr evaporation during operation. In this study, Crofer 22 APU steel interconnects were electrophoretically deposited in different mediums to obtain high packing of green coating layer. The optimized sample was then sintered in air-atmosphere or dual-atmospheres (reducing-oxidizing). Anode-supported cells were exposed from cathode side to bare or coated interconnects for 100 h at 800 °C. The electrochemical performances of aged cells were compared at 800 °C. Due to higher density coating obtained by dual-atmospheres sintering process, the exposed cell showed performance similar to non-poisoned cell (0.95–0.98 W/cm2). The cell exposed to air-atmosphere sintered coating interconnect showed lower output power (0.75 W/cm2) due to coating lower density. The cell exposed to uncoated interconnect exhibited considerable degradation and the lowest power (0.66 W/cm2).

  • Effect of pine impregnation and feed speed on sound level and cutting power in wood sawing
    • Roksana Licow
    • Daniel Chuchała
    • Mariusz Deja
    • Kazimierz Orłowski
    • Piotr Taube
    2020 Pełny tekst JOURNAL OF CLEANER PRODUCTION

    The sound levels along with the cutting power registered during the sawing process of the impregnated and non-impregnated pine wood at two feed speeds are shown and compared in this paper. Statistically significant differences in the acoustic signals occurred at the lower feed rate. The differences became smaller with an increase in the feed speed. In contrast to the sound signal, the differences in the cutting power were statistically significant only for the higher feed rate. In addition, the average electric power of the main drive allowed for the identification of knots during the sawing process. Obtained results indicated that monitoring based on the analysis of sound signals can be used as a supplementary source of information related to the wood cutting processes. This kind of independently used monitoring could be recommended for long-running and stabilized sawing processes, due to high noise level generated during the transition states when the tool enters and exits the material - transition states.

  • Effect of selected ammonia escape inhibitors on carbon dioxide capture and utilization via calcium carbonate precipitation
    • Natalia Czaplicka
    • Donata Konopacka-Łyskawa
    • Barbara Kościelska
    • Marcin Łapiński
    2020 Journal of CO2 Utilization

    Carbon dioxide was used to precipitate CaCO3 with CaCl2 solution in the presence of NH3 as a CO2 absorption promoter. Compounds that were previously indicated as inhibitors of ammonia escape during CO2 absorption were also added to the reaction mixture. Inorganic salts, i.e. ZnCl2, CuCl2, CoCl2, and organic substances, i.e. glycerol, ethylene glycol and triethanolamine were tested inhibitors in this work. A model post-distillation liquid from the Solvay process was used as the reaction mixture, while the gas stream fed into the system had a composition corresponding to the exhausted gases produced by the fossil fuels combustion. The purpose of this research was to investigate the efficiency of CO2 sequestration and the consumption of calcium ions during precipitation in the carbonation processes and determine the characteristics of produced CaCO3 particles. Of the tested additives, glycerol turned out to be the most effective, because its presence resulted in increased calcium ion consumption and CO2 sequestration compared to the control process. 90.5 % CO2 sequestration and 88.1 % Ca2+ consumption were obtained. The CaCO3 particles obtained in the presence of all tested organic inhibitors were in the form of vaterite and were characterized by a significantly larger specific surface area and larger pore volume.

  • Effect of sintering temperature on electrochemical performance of porous SrTi1-xFexO3-δ (x = 0.35, 0.5, 0.7) oxygen electrodes for solid oxide cells
    • Aleksander Mroziński
    • Sebastian Molin
    • Piotr Jasiński
    2020 Pełny tekst JOURNAL OF SOLID STATE ELECTROCHEMISTRY

    This work evaluates the effects of the sintering temperature (800 °C, 900 °C, 1000 °C) of SrTi1-xFexO3-δ (x = 0.35, 0.5, 0.7) porous electrodes on their electrochemical performance as potential oxygen electrode materials of solid oxide cells. The materials were prepared by a solid-state reaction method and revealed the expected cubic perovskite structure. After milling, the powders were characterised by a sub-micrometre particle size with high sinter-activity. It was shown that the lowest area specific resistance was achieved after sintering SrTi0.65Fe0.35O3 electrodes at 1000 °C, and SrTi0.5Fe0.5O3 and SrTi0.30Fe0.70O3 electrodes at 800 °C, which can be considered to be a relatively low temperature. In general, EIS measurements showed that increasing the Fe content results in lowered electrode polarisation and a decrease of the series resistance. Even though the studied materials have much lower total conductivities than state-of-the-art electrode materials (e.g. (La,Sr)(Co,Fe)O3), the polarisation resistances obtained in this work can be considered low.

  • Effect of Surface Treatment of Halloysite Nanotubes (HNTs) on the Kinetics of Epoxy Resin Cure with Amines
    • Vahideh Akbari
    • Maryam Jouyandeh
    • Seyed Paran
    • Mohammad Ganjali
    • Hossein Abdollahi
    • Henri Vahabi
    • Zahed Ahmadi
    • Krzysztof Formela
    • Amin Esmaeili
    • Ahmad Mohaddespour
    • Sajjad Habibzadeh
    • Mohammad Saeb
    2020 Pełny tekst Polymers

    The epoxy/clay nanocomposites have been extensively considered over years because of their low cost and excellent performance. Halloysite nanotubes (HNTs) are unique 1D natural nanofillers with a hollow tubular shape and high aspect ratio. To tackle poor dispersion of the pristine halloysite (P-HNT) in the epoxy matrix, alkali surface-treated HNT (A-HNT) and epoxy silane functionalized HNT (F-HNT) were developed and cured with epoxy resin. Nonisothermal differential scanning calorimetry (DSC) analyses were performed on epoxy nanocomposites containing 0.1 wt.% of P-HNT, A-HNT, and F-HNT. Quantitative analysis of the cure kinetics of epoxy/amine system made by isoconversional Kissinger–Akahira–Sunose (KAS) and Friedman methods made possible calculation of the activation energy (Eα) as a function of conversion (α). The activation energy gradually increased by increasing α due to the diffusion-control mechanism. However, the average value of Eα for nanocomposites was lower comparably, suggesting autocatalytic curing mechanism. Detailed assessment revealed that autocatalytic reaction degree, m increased at low heating rate from 0.107 for neat epoxy/amine system to 0.908 and 0.24 for epoxy/P-HNT and epoxy/A-HNT nanocomposites, respectively, whereas epoxy/F-HNT system had m value of 0.072 as a signature of dominance of non-catalytic reactions. At high heating rates, a similar behavior but not that significant was observed due to the accelerated gelation in the system. In fact, by the introduction of nanotubes the mobility of curing moieties decreased resulting in some deviation of experimental cure rate values from the predicted values obtained using KAS and Friedman methods.

  • Effect of the Drying Method of Pine and Beech Wood on Fracture Toughness and Shear Yield Stress
    • Daniel Chuchała
    • Jakub Sandak
    • Kazimierz Orłowski
    • Tomasz Muziński
    • Marcin Lackowski
    • Tomasz Ochrymiuk
    2020 Pełny tekst Materials

    The modern wood converting processes consists of several stages and material drying belongs to the most influencing future performances of products. The procedure of drying wood is usually realized between subsequent sawing operations, affecting significantly cutting conditions and general properties of material. An alternative methodology for determination of mechanical properties (fracture toughness and shear yield stress) based on cutting process analysis is presented here. Two wood species (pine and beech) representing soft and hard woods were investigated with respect to four diverse drying methods used in industry. Fracture toughness and shear yield stress were determined directly from the cutting power signal that was recorded while frame sawing. An original procedure for compensation of the wood density variation is proposed to generalize mechanical properties of wood and allow direct comparison between species and drying methods. Noticeable differences of fracture toughness and shear yield stress values were found among all drying techniques and for both species, but only for beech wood the differences were statistically significant. These observations provide a new highlight on the understanding of the effect of thermo-hydro modification of wood on mechanical performance of structures. It can be also highly useful to optimize woodworking machines by properly adjusting cutting power requirements.

  • Effect of the integration into Global Value Chains on the employment contract in Central and Eastern European countries
    • Dagmara Nikulin
    • Sabina Szymczak
    2020 Pełny tekst EQUILIBRIUM Quarterly Journal of Economics and Economic Policy

    Research background: In the era of globalization, there is a need to address decent work deficits in Global Value Chains (GVCs). The forms of working conditions reveal a broad dispersion of contents. The literature review exposes hardly any Europe-focused research assessing the socioeconomic impact of global production links and going beyond their pure economic effects assessed in terms of employment, productivity or wages. Purpose of the article: This paper investigates how involvement in GVCs affects labour standards. In particular, we assess how the integration into GVCs impacts the probability of having indefinite type of employment contract, which stands for one of the decent work indicator. Moreover, we draw individual and firm-level characteristics determining the type of employment contract. Methods: We use linked employer-employee data from the Structure of Earnings Survey merged with industry-level statistics on GVCs based on World Input-Output Database — the sample is composed of over 5 million workers from 10 Central and Eastern European countries (CEEC) observed in 2014. The involvement into GVCs is measured using a novel approach based on the concepts of global import intensity (GII). We employ logistic regression with robust standard errors. Findings & Value added: Controlling for individual and firm-level characteristics (sex, age, education level, length of service in enterprise, size of the enterprise) we find that greater integration into GVCs increases the probability of having temporary type of employment contract, mainly in tradable sectors. However, across CEE countries the relation between GVC and employment type is mixed. In this way we expand the existing literature by reporting the effects of GVCs on labour standards in CEEC.

  • Effect of Thermal Treatment of Birch Wood by Saturated Water Vapor on Granulometric Composition of Chips from Sawing and Milling Processes from the Point of View of Its Processing to Composites
    • Richard Kminiak
    • Kazimierz Orłowski
    • Ladislav Dzurenda
    • Daniel Chuchała
    • Adrian Banski,
    2020 Pełny tekst Applied Sciences-Basel

    The goal of this work is to investigate the impact of thermal modification of birch wood with saturated steam on the particle size distribution of the sawing and milling process. Birch wood (Betula pendula Roth) is an excellent source to produce plywood boards. Wastes from mechanical processing of birch wood are suitable to produce composite materials. Granulometric analyses of chips from sawing processes on the PRW 15M frame saw, as well as on the 5-axis CNC machining centre SCM TECH Z5 and the 5-axis CNC machining centre AX320 Pinnacle, proved that more than 95% of chips are chips of coarse and medium coarse chip fractions with dimensions above 0.125 mm. Depending on the shape, coarse and medium-thick chips belong to the group of fiber chips, the length of which is several times greater than the width and thickness. Fine fractions with dimensions smaller than 125 μm are isometric chips that are approximately the same size in all three dimensions. Thoracic dust fractions below 30 μm were not measured. The performed analyses showed that the heat treatment of birch wood with saturated steam did not affect the grain size of chips formed in sawing and milling processes on CNC machining centre and can be used as a raw material for the production of composite materials. Fabric filters are suitable for separating chips extracted from frame saws, PRW-15M or machining centre. Environmental criteria for the separation of chips from transport air in textile filters are met by filters with a fabric classified in class G4.

  • Effective Collaboration of Entrepreneurial Teams—Implications for Entrepreneurial Education
    • Beata Krawczyk-Bryłka
    • Katarzyna Stankiewicz
    • Paweł Ziemiański
    • Michał Tomczak
    2020 Pełny tekst Education Sciences

    In the situation of a permanent change and increased competition, business ventures are more and more often undertaken not by individuals but by entrepreneurial teams. The main aim of this paper is to examine the team principles implemented by eective entrepreneurial teams and how they dier in nascent and established teams. We also focused on the relationship between the implementation of these rules by entrepreneurial team members and their evaluation of venture performance and personal satisfaction. The quantitative method was used: a list of nine items describing the principles important for the entrepreneurial teams’ collaboration was included in a questionnaire conducted in a group of 106 Polish entrepreneurs who run their businesses as members of entrepreneurial teams. The results of the research showed that all the collaboration principles included in the prepared scale are implemented by the tested entrepreneurial teams; in the case of two particular items, the obtained scores were higher in nascent teams. The correlation between principle implementation and venture performance as well as the correlation between principle implementation and entrepreneurs’ professional satisfaction was confirmed. In addition, the goal was to emphasize the importance of the entrepreneurial team’s collaboration due to its eectiveness, and propose the prepared scale as a tool for entrepreneurial reflective learning. Finally, statements by members of two entrepreneurial teams concerning team collaboration are presented to deliver case studies that can be used during entrepreneurship courses.

  • Effective Permeability of Multi Air Gap Ferrite Core 3-Phase Medium Frequency Transformer in Isolated DC-DC Converters
    • Piotr Dworakowski
    • Andrzej Wilk
    • Michał Michna
    • Bruno Lefebvre
    • Fabien Sixdenier
    • Michel Mermet-Guyennet
    2020 Pełny tekst ENERGIES

    The magnetizing inductance of the medium frequency transformer (MFT) impacts the performance of the isolated dc-dc power converters. The ferrite material is considered for high power transformers but it requires an assembly of type “I” cores resulting in a multi air gap structure of the magnetic core. The authors claim that the multiple air gaps are randomly distributed and that the average air gap length is unpredictable at the industrial design stage. As a consequence, the required effective magnetic permeability and the magnetizing inductance are difficult to achieve within reasonable error margins. This article presents the measurements of the equivalent B(H) and the equivalent magnetic permeability of two three-phase MFT prototypes. The measured equivalent B(H) is used in an FEM simulation and compared against a no load test of a 100 kW isolated dc-dc converter showing a good fit within a 10% error. Further analysis leads to the demonstration that the equivalent magnetic permeability and the average air gap length are nonlinear functions of the number of air gaps. The proposed exponential scaling function enables rapid estimation of the magnetizing inductance based on the ferrite material datasheet only.

  • Effectiveness of toluene separation from gas phase using supported ammonium ionic liquid membrane
    • Iwona Cichowska-Kopczyńska
    • Robert Aranowski
    2020 Pełny tekst CHEMICAL ENGINEERING SCIENCE

    Ammonium ionic liquids (ILs) are relatively cheap in synthesis and environmentally benign and despite that they have been very rarely used in gas separation. In this research we used several ammonium ILs as liquid membranes for removal of residual toluene from gas phase. Ionic liquids used in this study were composed of bis(trifluoromethylsulfonyl)imide anion [Tf2N] and trimethylbutylammonium [N1114], trietylbutylammonium [N2224], trietylhexylammonium [N2226], trietyloctylammonium [N2228] cations. Selected ILs formed stable membranes with limited swelling effect and good performance. The highest toluene permeability was recorded for [N2228][Tf2N] of 2666 barrers and for triethyl based ILs it was decreasing with carbon atoms number. The selectivity of toluene/N2 separation was in a range of 29 to 120. For better process illustration, the factors influencing the permeation process, namely viscosity and partition coefficients were examined.

  • Effects of Bromine Doping on the Structural Properties and Band Gap of CH3NH3Pb(I1–xBrx)3 Perovskite
    • Miłosz Martynow
    • Damian Głowienka
    • Yulia Galagan
    • Julien Guthmuller
    2020 Pełny tekst ACS Omega

    An experimental and theoretical study is reported to investigate the influence of bromine doping on CH3NH3Pb(I1−xBrx)3 perovskite for Br compositions ranging from x = 0 to x = 0.1, in which the material remains in the tetragonal phase. The experimental band gap is deduced from UV−vis absorption spectroscopy and displays a linear behavior as a function of bromine concentration. Density functional theory calculations are performed for five different series of randomly doped structures in order to simulate the disorder in bromine doping sites. The computations predict a linear variation of the lattice parameters, supercell volume, density, band gap, and formation energy in the considered doping range. The calculated evolution of the band gap as the function of Br doping is in excellent agreement with the experimental data, provided that different Br doping configurations are included in the simulations. The analysis of the structural and electronic properties shows a correlation between the increase of the band gap and the increased distortion of the Pb(I1−xBrx)6 octahedrons. Additionally, the simulations suggest that in CH3NH3Pb(I1−xBrx)3 bromine doping is likely to occur at both the equatorial and apical positions of the octahedrons.

  • Effects of Ca2+, Mg2+, Na+, and K+ substitutions on the microstructure and electrical properties of GdCoO3 ceramics
    • Sea-Fue Wang
    • Yung-Fu Hsu
    • Yi-Le Liao
    • Tung Lin
    • Piotr Jasiński
    2020 JOURNAL OF ELECTROCERAMICS

    GdCoO3-δ, Gd0.975Na0.025CoO3-δ, Gd0.98K0.02CoO3-δ, Gd0.98Ca0.02CoO3-δ, and GdCo0.99Mg0.01O3-δ ceramics were prepared via a solid-state reaction route. Among the dopants studied, substitution with Ca2+ slightly enhanced the densfication of GdCoO3 ceramics. All the lattice parameters of the doped ceramics were larger than those of pure GdCoO3-δ ceramic (a = 5.223 Å, b = 5.389 Å and c = 7.451 Å), and their cell volumes increased by 0.30% to 1.40% because the substitution ions were larger in size. X-ray diffraction and scanning electron microscopy results indicate that no second phase is present. The average grain size of the GdCoO3 ceramics (7.6 μm) slightly increased by the Na+, K+ and Mg2+ substitutions and decreased by the Ca2+ substitution. In all cases, the intergranular fracture surfaces revealed the presence of trapped pores due to rapid grain growth. The oxidation states and percentages of Co ions were determined from the Co 2p X-ray photoelectron spectra. Na+, K+, Ca2+, and Mg2+ substitution in the GdCoO3-δ ceramic resulted in slight oxidation of the Co ions accompanied by a decrease in oxygen vacancies. After porosity correction using the Bruggeman effective medium approximation, Gd0.98Ca0.02CoO3-δ had the largest electrical conductivity at all measured temperatures among the compositions studied, which was 144% higher at 500 °C and 16% higher at 800 °C compared to those of GdCoO3-δ ceramic (500 °C: 133.3 S·cm−1; 800 °C: 692.4 S·cm−1). The substantial increase in the electrical conductivity of the doped GdCoO3-δ ceramics is due to the electronic compensation of acceptor doping, Na′′Gd, K′′Gd, and Ca′Gd, which resulted in the formation of hole carriers and the elimination of oxygen vacancies (V∙∙o), which generated additional Co4+ (Co∙Co).

  • Effects of CO2 and Nd:YAG Laser Remelting of the Ti6Al4V Alloy on the Surface Quality and Residual Stresses
    • Magdalena Jażdżewska
    2020 Pełny tekst Advances in Materials Science

    The titanium alloys are materials susceptible to tribological wear and the laser treatment can be applied in surface treatment processes to obtain for example higher hardness level. From the other side, it is important to take into consideration, that hardness increase that can be connected with cracks . The aim of this research was to investigate the effects of different lasers and the process parameters on the form and level of residual stresses in the Ti6Al4V alloy, which determine the initiation and propagation of cracking. Two lasers were used, the CO2 and Nd:YAG lasers. The specimens were remelted in liquid nitrogen, water or calm air at different pre-heating temperature. The different laser power and scan rates were applied. The increase in energy density increased the number of cracks, the change of an environment and pre-heating affected alo the surface cracking. The cracks observed after remelting with Nd:YAG laser were longer than those observed after treatment with CO2 laser. The compressive stresses after the CO2 laser treatment, and tensile stresses after treatment with the Nd:YAG laser, were found. The appearance of cracks was attributed to an excessive energy density. The different distribution of heat energy inside and around the laser tracks was discussed as the origin of presence either tensile or compressive stresses in the alloy treated with different lasers

  • Effects of Micro-Arc Oxidation Process Parameters on Characteristics of Calcium-Phosphate Containing Oxide Layers on the Selective Laser Melted Ti13Zr13Nb Alloy
    • Magda Dziaduszewska
    • Andrzej Zieliński
    • Tomasz Seramak
    • Masaya Shimabukuro
    • Takao Hanawa
    2020 Pełny tekst Coatings

    Titania-based films on selective laser melted Ti13Zr13Nb have been formed by micro-arc oxidation (MAO) at different process parameters (voltage, current, processing time) in order to evaluate the impact of MAO process parameters in calcium and phosphate (Ca + P) containing electrolyte on surface characteristic, early-stage bioactivity, nanomechanical properties, and adhesion between the oxide coatings and substrate. The surface topography, surface roughness, pore diameter, elemental composition, crystal structure, surface wettability, and the early stagebioactivity in Hank’s solution were evaluated for all coatings. Hardness, maximum indent depth, Young’s modulus, and Ecoating/Esubstrate, H/E, H3 /E2 ratios were determined in the case of nanomechanical evaluation while the MAO coating adhesion properties were estimated by the scratch test. The study indicated that the most important parameter of MAO process influencing the coating characteristic is voltage. Due to the good ratio of structural and nanomechanical properties of the coatings, the optimal conditions of MAO process were found at 300 V during 15 min, at 32 mA or 50 mA of current, which resulted in the predictable structure, high Ca/P ratio, high hydrophilicity, the highest demonstrated early-stage bioactivity, better nanomechanical properties, the elastic modulus and hardness well close to the values characteristic for bones, as compared to specimens treated at a lower voltage (200 V) and uncoated substrate, as well as a higher critical load of adhesion and total delamination.

  • Effects of the Origin and Deacetylation Degree of Chitosan on Properties of Its Coatings on Titanium
    • Milena Supernak-Marczewska
    • Andrzej Zieliński
    2020 Pełny tekst Coatings

    The properties of chitosan coatings on titanium surfaces may be influenced by a variety of factors, including their chemical characteristics and the deposition method. The aim of this research was to determine the influence of a chitosan’s origin (a type of shrimp) and deacetylation degree (DD), when deposited on a very smooth titanium surface, on adhesion and biological behavior. The tests were performed using chitosan of a degree of 87% or 84% of deacetylation and that originated from armor crabs or shrimp armor. The technology of fabrication of chitosan coatings was by surface polishing to a smooth surface, oxidation in air, and immersion in a chitosan solution. The surface topographies were analyzed with an atomic force microscope and their water contact angles were measured by a falling drop method with a goniometer. The bioactivity tests were done in in vitro on osteogenic cells, type MC3T3-E1, with a biological microscope. The abrasion of the coatings was examined using a nano tribotester. The obtained results revealed that the adhesion of the coatings onto a smooth, oxidized titanium surface is appropriate as they remain sufficiently adjacent to the surface after wear tests. The source of chitin has a significant influence on biological properties, and the deacetylation degree is much less critical. The performed tests demonstrated the crucial role that the source of chitosan and the applicability of the applied surface treatment play in the preparation of chitosan coatings.

  • Efficiency of pollutants removal from landfill leachates using Nb/BDD and Si/BDD anodic oxidation
    • Barbara Wilk
    • Sylwia Fudala-Książek
    • Małgorzata Szopińska
    • Michał Sobaszek
    • Robert Bogdanowicz
    • Aneta Łuczkiewicz
    2020

    Landfill leachates (LLs) is a complex, refectory and difficult to depurate liquid generated from sanitary landfills. It contains excessive levels of biodegradable and in particular non-biodegradable products (e.g. heavy metals, phenols, sulphide, plasticisers). LLs are among the effluents that may pose major environmental concerns, they can be a dangerous source of pollution e.g. due to infiltration into soil and underlying water. The biological refractory nature of LLs makes it necessary to search effective, alternative (other than biodegradation) methods to reduce the contaminant loading of these effluents.In this study, the role of the BDD anodes, with different content of boron and substrates such as silicone and niobium was evaluated in the removal of macropollutants and selected MPs from LLs. By-products formed during electrolysis have been identified, too. The investigations have shown that macropollutants removal efficiency increases with higher applied current density (but also the energetic costs do). The best anode substrate was Nb, yielding very positive pollutants reduction results (better than Si substrate). Moreover, this substrate was durable and resistant to damage. The highest efficiency of macropollutants removal was achieved at 100mA/cm2 current density by BDD 0.5k, Nb (COD= 97.1%, BOD20=93.8%, N-NH4+=62%, TN=29.3%) followed by BDD 10k, Nb (COD= 86.3%, BOD20=63.5%, N-NH4+=40%, TN=34.5%). BDD electrodes were also tested in terms of MPs removal. The obtained results indicate that the BDD10k/Nb anodic oxidation in 0.1 M phosphate buffer solution (pH 7.8) is able to degrade BPA with approximately 80% efficiency, diclofenac sodium with 60%, trimethoprim 96%, sulfamethoxazole 94%, PFOA 90% and PFOS 90%. It was preliminarily found that BDD 0.5k electrode is the most efficient at investigated MPs removal (e.g. BPA removal with 90% efficiency, diclofenac sodium with 85%). Formation of by-products during this process was also observed, e.g. m/z=243 and m/z=241 for BPA, m/z=264 for diclofenac sodium, m/z=284 and m/z =299 for sulfamethoxazole. It can be concluded that BDD/Nb is a promising material in wastewater treatment. The results confirmed high performance of BDD electrodes in pollutants removal from the studied matrixes, nevertheless this method still requires further optimization.

  • Efficient Method for the Concentration Determination of Fmoc Groups Incorporated in the Core-Shell Materials by Fmoc–Glycine
    • Elzbieta Szczepanska
    • Beata Grobelna
    • Jacek Ryl
    • Amanda Kulpa
    • Tadeusz Ossowski
    • Pawel Niedzialkowski
    2020 Pełny tekst MOLECULES

    In this paper, we described the synthesis procedure of TiO2@SiO2 core-shell modified with 3-(aminopropyl)trimethoxysilane (APTMS). The chemical attachment of Fmoc–glycine (Fmoc–Gly–OH) at the surface of the core-shell structure was performed to determine the amount of active amino groups on the basis of the amount of Fmoc group calculation. We characterized nanostructures using various methods: transmission electron microscope (TEM), scanning electron microscopy (SEM), Fourier-transform infrared spectroscopy (FTIR), thermogravimetric analysis (TGA) and X-ray photoelectron spectroscopy (XPS) to confirm the modification effectiveness. The ultraviolet-visible spectroscopy (UV-vis) measurement was adopted for the quantitative determination of amino groups present on the TiO2@SiO2 core-shell surface by determination of Fmoc substitution. The nanomaterials were functionalized by Fmoc–Gly–OH and then the fluorenylmethyloxycarbonyl (Fmoc) group was cleaved using 20% (v/v) solution of piperidine in DMF. This reaction led to the formation of a dibenzofulvene–piperidine adduct enabling the estimation of free Fmoc groups by measurement the maximum absorption at 289 and 301 nm using UV-vis spectroscopy. The calculations of Fmoc loading on core-shell materials was performed using different molar absorption coefficient: 5800 and 6089 dm3 × mol−1 × cm−1 for λ = 289 nm and both 7800 and 8021 dm3 × mol−1 × cm−1 for λ = 301 nm. The obtained results indicate that amount of Fmoc groups present on TiO2@SiO2–(CH2)3–NH2 was calculated at 6 to 9 µmol/g. Furthermore, all measurements were compared with Fmoc–Gly–OH used as the model sample

  • EIA in teaching sustainable development and environmental protection in engineering education
    • Aleksandra Sas-Bojarska
    2020 Pełny tekst World Transactions on Engineering and Technology Education

    A multifaceted approach in teaching the environmental impact assessment (EIA) as a way to stress the role of environmental education in technical sciences is the focus of this article. The EIA is an example of an effective tool that supports spatial planning in implementing sustainable development. The aim is to present the idea and benefits of a facilitative and collaborative approach in teaching the EIA, stressing the role of student co-operation and involvement, as well as a participatory and interdisciplinary approach. Inspiring controversial case studies present different problems and approaches as examples of best practice. The teaching method underlies the necessity of understanding wider processes leading to environmental threats and the ways to prevent them, crossing different disciplines. Such an approach, attractive to students, can present the EIA not only as a formal procedure, but as a useful tool for environmental protection. Consequently, it may strengthen the student’s future activities in implementing the idea of sustainable development in practice.

  • Ekspertyza dotycząca opinii geotechnicznej na temat stanu podłoża gruntowego pod budynkiem w północnej części Dworca Głównego w Gdańsku.
    • Rafał Ossowski
    • Marcin Cudny
    • Mariusz Wyroślak
    2020

    Opinia przygotowana na podstawie umowy zawartej w Gdańsku, pomiędzy Mostostal Warszawa Spółka Akcyjna z siedzibą: 02-673 Warszawa, ul. Konstruktorska 12A oraz Politechniką Gdańską, Wydział Inżynierii Lądowej i Środowiska z siedzibą przy ul. Gabriela Narutowicza 11/12, 80-233 Gdańsk.

  • Ekspertyza dotycząca ustalenia przyczyn nieszczelności ścian szczelinowych oraz płyty fundamentowej wraz z propozycją rozwiązania naprawczego mającego na celu skuteczne uszczelnienie (likwidację przecieków) kondygnacji podziemnych budynku biurowego LPP FASHION LAB zlokalizowanego w Gdańsku przy ulicy Łąkowej 35/26 i 37/38
    • Marcin Cudny
    • Mariusz Wyroślak
    • Maciej Niedostatkiewicz
    • Rafał Ossowski
    2020

    Zlecenie firmy Mostostal SA z siedzibą w Warszawie przy ulicy Konstruktorskiej 12A na wykonanie ekspertyzy technicznej dotyczącej ustalenia przyczyn nieszczelności ścian szczelinowych oraz płyty fundamentowej wraz z propozycją rozwiązania naprawczego mającego na celu skuteczne uszczelnienie (likwidacje przecieków) kondygnacji podziemnych budynku biurowego LPP FASHION LAB zlokalizowanego w Gdańsku przy ulicy Łąkowej 35/36 i 37/38.

  • Ekspertyza techniczna w zakresie wyjaśnienia oznaczeń „j.mb.”, „j.bt.” i „bet.” znajdujących się na mapie zasadniczej, w odniesieniu do przepisów Prawa Budowlanego i stanu faktycznego.
    • Joanna Wojtas
    • Stefan Niewitecki
    2020

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    • Krzysztof Wróblewski
    2020

    Eksperyment: Ekslibris Wystawa online 12 eksperymentalnych ekslibrisów inspirowanych wybranymi książkami Güntera Grassa, stworzonych specjalnie dla Gdańskiej Galerii Miejskiej przez zaproszonych do projektu artystów. Przy okazji cotygodniowej inauguracji poszczególnych ekslibrisów, będziemy przybliżać Wam sylwetki każdego z artystów, a także przypominać ważne dla nich projekty, w których wzięli udział. Produktem finalnym całego projektu, oprócz wystawy online, będzie kalendarz na rok 2021 ilustrowany powstałymi ekslibrisami i opatrzony komentarzem kuratorskim. Wszystkie powstałe prace trafią do kolekcji Gdańskiej Galerii Miejskiej. Artyści: Alicja Karska i Aleksandra Went, Tomasz Kopcewicz, Agata Nowosielska, Anna Orbaczewska, Patrycja Orzechowska, Maciek Salamon, Dominika Skutnik, Dorota Walentynowicz, Adam Witkowski, Ania Witkowska, Krzysztof Wróblewski, Marcin Zawicki Kuratorka: Marta Wróblewska Projekt animacji: Katarzyna Łygońska Projekt identyfikacji wizualnej: Patrycja Orzechowska Udźwiękowienie animacji: Piotr Kaliński Kuratorka pragnie szczególnie podziękować Dominice Skutnik za impuls do odkrycia potencjału sztuki ekslibrisu i podjęcia próby przeniesienia jej we współczesne realia artystyczne.

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    • Anita Dąbrowicz-Tlałka
    • Anna Grabowska
    2020 Pełny tekst

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  • Electric and magnetic properties of Lanthanum Barium Cobaltite
    • Iga Szpunar
    • Sebastian Lech Wachowski
    • Tadeusz Miruszewski
    • Kacper Dzierzgowski
    • Karolina Górnicka
    • Tomasz Klimczuk
    • Magnus H. Sorby
    • Maria Balaguer
    • José M Serra
    • Ragnar Strandbakke
    • Aleksandra Dorota Mielewczyk-Gryń
    • Maria Gazda
    2020 Pełny tekst JOURNAL OF THE AMERICAN CERAMIC SOCIETY

    The cubic Ba0.5La0.5CoO3‐δ was synthesized using solid state reaction. The structural properties were determined by the simultaneous refinement of Synchrotron Powder X‐ray Diffraction and Neutron Powder Diffraction data. Iodometric titration was used to examine the oxygen stoichiometry and average cobalt oxidation state. Low‐temperature magnetic studies show soft ferromagnetic character of fully oxidized material, with θP = 198(3) K and μeff = 2.11(2) μB. Electric measurements show the thermally activated nature of conductivity at low temperatures, whereas, due to the variable oxidation and spin state of cobalt, a single charge transport mechanism cannot be distinguished. Around room temperature, a wide transition from thermally activated conductivity to semi‐metallic behavior is observed. Under the inert atmos-phere, the oxygen content lowers and the cation ordering takes place, leading to coex-istence of two, ordered and disordered, phases. As a result of this change, thermally activated conductivity is observed also at high temperatures in inert atmosphere.