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Gdańsk University of Technology

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  • Analiza produktów degradacji emitowanych podczas regeneracji gumy
    • Krzysztof Formela
    • Marta Przybysz-Romatowska
    • Łukasz Zedler
    • Mariusz Marć
    2019 Full text Tworzywa Sztuczne w Przemyśle

    Wyznaczenie profilu emisji oraz wytypowanie charakterystycznych związków chemicznych uwalnianych z powierzchni opracowanych materiałów polimerowych może stanowić jeden z elementów kontroli ich jakości. W pracy przedstawiono wyniki badań emisji związków chemicznych z grupy lotnych związków organicznych uwalnianych z odpadów gumowych podczas ich przetwórstwa przy użyciu współbieżnej wytłaczarki dwuślimakowej. Ponadto, przedstawiono wyniki badań wstępnych nad wykorzystaniem próbników pasywnych podczas kontroli jakości otrzymanych produktów recyklingu materiałowego odpadów gumowych.

  • Analiza rezonansowego układu emisji impulsów pola elektromagnetycznego
    • Mikołaj Nowak
    • Kazimierz Jakubiuk
    • Daniel Kowalak
    • Mirosław Wołoszyn
    2019 Full text Poznan University of Technology Academic Journals. Electrical Engineering

    W literaturze przedmiotu są opisane właściwości emiterów impulsów pola elektromagnetycznego w postaci układów bazujących na antenach wysokonapięciowych HVR (ang. High Voltage Radiator) [2, 5]. W celu podniesienia skuteczności emisji poprzez wydłużenie czasu trwania impulsu oraz zwiększenie jego amplitudy możliwe jest zastosowanie systemów rezonansowych dostrojonych do parametrów sygnału kształtowanego w układzie formowania impulsu wysokiego napięcia [2, 3]. W pracy dokonano syntezy modelu symulacyjnego systemu emisji impulsów pola elektromagnetycznego dużej mocy oraz zweryfikowano jego skuteczność w ramach badań eksperymentalnych przeprowadzonych na układzie fizycznym.

  • Analiza sentymentu jako narzędzie monitorowania wyników finansowych przedsiębiorstwa
    • Anna Baj-Rogowska
    2019 Full text Przedsiębiorczość i Zarządzanie

    Media społecznościowe tworzą globalną platformę do dzielenia się interesującymi pomysłami lub nowościami, komentarzami i recenzjami. Stanowią bogate źródło danych do eksploracji opinii w celu pozyskania wcześniej nieznanej i użytecznej wiedzy biznesowej, która umożliwi nie tylko zwinne zarządzanie na rzecz skutecznej obsługi klienta, ale również powinna mieć odzwierciedlenie w finansowych wynikach przedsiębiorstwa. Za główny cel pracy przyjęto zbadanie czy opinie o firmie pozyskane z Facebooka, poddane analizie sentymentu (ang. Sentiment Analysis) są skorelowane z wynikami finansowymi przedsiębiorstwa. W części empirycznej do badania wybrano firmę Adidas, dla której z serwisu społecznościowego Facebook zebrano posty użytkowników w okresie od 1 października 2014 do 30 wrzesień 2017. Stwierdzone korelacje pomiędzy wydźwiękiem opinii użytkowników na temat firmy Adidas a wskaźnikami finansowymi tego podmiotu wyraźnie pokazują, że media społecznościowe pełnią rolę narzędzi, które odpowiednio wykorzystane dzięki stosowaniu social listeningu, przyniosą korzyści finansowe przedsiębiorstwu.

  • Analiza siłowni nadkrytycznych oraz ultranadkrytycznych
    • Stanisław Głuch
    2019 Full text

    Niniejszy artykuł zawiera przegląd istniejących rozwiązań siłowni nadkrytycznych oraz ultra nadkrytycznych. Przedstawiono historię rozwoju bloków na parametry nadkrytyczne. Obecny stan technologii został zaprezentowany – są to następujące parametry pary świeżej: 650°C oraz 330 bar. W Polsce istnieje 8 bloków pracujących na parametry nadkrytyczne. Ich parametry pracy zostały przedstawione w tekście. Z kolei elektrownią parową posiadającą najwyższą sprawność netto jest Avedoere 2. Funkcjonowanie nadkrytycznych obiegów parowych jest przedstawione w publikacji, z uwzględnieniem nowej koncepcji o nazwie Master Cycle. Autor przedstawia wybrane komponenty bloku nadkrytycznego. Obecnie jest prowadzony program AD700 mający an celu zbudowanie bloku parowego mogącego przekroczyć 50% sprawności netto.

  • Analiza skuteczności wybranych strategii kontrariańskich na warszawskiej GPW w latach 2014–2018
    • Błażej Prusak
    • Magdalena Kusowska
    2019 Full text Zeszyty Naukowe Małopolskiej Wyższej Szkoły Ekonomicznej w Tarnowie

    Capital multiplication is the main goal of investors and for many years they have been looking for methods and strategies that would enable them to achieve it to the greatest possible extent. Due to the fact that the expectations and characteristics of investors, including those concerning the investment period, are diverse, multiple strategies have emerged. One of such strategies, mainly long-term in nature, is the so-called contrarian investment, consisting in building the portfolio on the basis of selected shares with prices that have not been increasing recently, which has resulted in undervaluation in the context of otherwise relatively positive development prospects of the company. The aim of this article is to examine the efficiency of selected contrarian strategies on the Polish capital market in the years 2014–2018. The analysis was conducted for large companies, i.e. those included in the WIG30 index, and portfolios were constructed using 20% of companies with the lowest P/E and P/BV ratios. The efficiency of the strategy was examined on the basis of the value of portfolios and cumulative rates of return. It has been shown that investments made in accordance with contrarian strategies generate higher rates of return than the allocation of cash in the WIG30 index, which was the benchmark. Among the two investment strategies, much better results were achieved using the P/BV ratio.

  • Analiza sprzężenia czynnościowego pomiędzy podatnością dużych tętnic i rytmem serca
    • Tomasz Wierzba
    • Stanisław Zajączkowski
    • Artur Poliński
    2019

    W pracy przedstawiono wstępną analizę sprzężenia czynnościowego pomiędzy podatnością dużych tętnic i rytmem serca

  • Analiza stateczności i stabilizacji zbocza osuwiskowego na trasie linii kolejowej w Świnnej Porębie
    • Lesław Zabuski
    • Jarosław Przewłócki
    2019 Full text Inżynieria Morska i Geotechnika

    W artykule przedstawiono wyniki obliczeń stateczności zbocza na odcinku obejmującym trzy osuwiska trasy linii kolejowej, w rejonie zbiornika wodnego w Świnnej Porębie na rzece Skawie. Obliczenia wykonano w układzie płaskim programem FLAC2D opartym na metodzie różnic skończonych. Rozpatrzono kilka metod zabezpieczenia zbocza dokonując oceny ich skuteczności.

  • Analiza stosowania uchwytów modułowych i specjalnych w operacjach obróbkowych.
    • Adam Barylski
    2019 Full text Autobusy. Technika, Eksploatacja, Systemy Transportowe

    Przedstawiono konstrukcje i montaż zaprojektowanych uchwytów modułowych i specjalnych. Analizowano uchwyty dla wybranych operacji obróbki dźwigni i korpusu. Wyznaczono również koszt uchwytów dla tego samego typu obrabianego elementu. Zastosowana metodyka może być stosowana między innymi w procesie kształcenia inżynierskiego mechaników technologów.

  • Analiza techniczna funkcjonalności pilarki PZS-350. Ekspertyza techniczna opracowana na zlecenie REMA S.A.
    • Wojciech Blacharski
    2019

    Wykonana ekspertyza techniczna dotyczyła prototypowej pilarki tarczowej PZS-350 przeznaczonej do cięcia surowej sklejki drzewnej na arkusze o żądanym wymiarze. Celem była analiza funkcjonalności wykonanego prototypu oraz jego zgodności z przyjętymi założeniami technicznymi. Główne funkcje realizowane przez pilarkę obejmują: a) transport sklejki ze stołu podawczego do cięcia wzdłużnego; b) cięcie wzdłużne i usuwanie odpadu po tym cięciu; c) transport pakietu płyt do strefy cięcia poprzecznego; d) cięcie poprzeczne, odbiór gotowych arkuszy i usuwanie odpadów; e) pozostałe funkcje związane ze sterowaniem automatycznym i bezpieczeństwem. Stwierdzono zgodność funkcjonalności zbudowanego prototypu z przyjętymi założeniami technicznymi. Opracowanie zawiera 15 stron, 7 rysunków i 28 fotografii.

  • Analiza technologiczna i ekonomiczna wykonania stropów w budynku wpisanym do rejestru zabytków
    • Beata Grzyl
    • Jakub Grzyl
    2019 Przegląd Budowlany

    W artykule przedstawia się analizę wybranych rozwiązań technologicznych dotyczących wymiany i wzmocnienia stropów w ramach inwestycji: Przebudowa, rozbudowa i rewaloryzacja zabytkowego budynku zlokalizowanego przy ul. Lastadia 2 w Gdańsku. Analizie poddaje się trzy alternatywne rozwiązania - wykonanie nowego stropu Kleina, nowej płyty żelbetowej oraz kompleksowe wzmocnienie istniejącego stropu. Wskazuje się zalety i wady każdego z proponowanych rozwiązań technologicznych oraz porównuje się je w aspekcie pracochłonności i kosztu. W podsumowaniu przedstawia się wnioski płynące z przeprowadzonej analizy.

  • Analiza układów geometrycznych torów tramwajowych w oparciu o metodę bazy sztywnej wagonu
    • Jacek Szmagliński
    2019 Full text Przegląd Komunikacyjny

    W pracy opisano problemy występujące podczas pokonywania łuków tramwajowych, charakteryzujące się występowaniem nieprzyjemnych szarpnięć. Określono, że szarpnięcia powstają w wyniku braku analiz parametrów kinematycznych na łukach oraz zmiany schematu konstrukcyjnego tramwajów. Podano propozycję metodyki obliczeniowej, umożliwiającej ocenę najważniejszych parametrów kinematycznych, wykorzystującą stosowaną na kolei metodę bazy sztywnej wagonu. Określono parametry bazy sztywnej, związane z konstrukcją konkretnego wieloczłonowego tramwaju. Wykonano obliczenia parametrów kinematycznych dla typowych układów geometrycznych, zgodnych z Wytycznymi.

  • Analiza układów kinematycznych docierania powierzchni płaskich w aspekcie równomierności zużycia tarczy docierającej
    • Norbert Piotrowski
    2019 Full text

    Przedmiotem rozprawy doktorskiej jest analiza układów kinematycznych docierania jednotarczowego w aspekcie równomierności zużycia tarczy docierającej. W pierwszej części pracy szczegółowo opisano mechanizm docierania powierzchni płaskich oraz określono wpływ poszczególnych parametrów procesu na dokładność obróbki. Przeanalizowano dotychczas opracowane modele zużycia docieraka oraz opisano istniejące rozwiązania konstrukcyjne układów do docierania powierzchni płaskich. W kolejnej części rozprawy opracowano modele matematyczne zużycia profilowego tarczy docierającej, które pozwalają na szczegółową analizę parametrów niekonwencjonalnych układów wykonawczych, a także na sterowanie zarysem kształtu narzędzia w aspekcie wymaganej płaskości. Przeprowadzono optymalizację parametrów układu standardowego oraz układów z dodatkowym ruchem pierścienia prowadzącego wzdłuż promienia lub siecznej oraz z ruchem wahadłowym. Największą równomierność zużycia narzędzia uzyskano w układzie z ruchem obrotowym i siecznym pierścienia (dla parametrów k1=7/9 oraz k2=2). Uzyskana równomierność zużycia jest o około 11% większa niż w układzie standardowym. W pracy przedstawiono również innowacyjną koncepcję zestawienia robota i docierarki jednotarczowej. Robot oprócz funkcji załadunkowych i rozładunkowych elementów w pierścieniu prowadzącym, wykorzystany jest do obróbki powierzchni płaskich. Ponadto obliczenia modelowe i analizy symulacyjne zostały zweryfikowane doświadczalnie na specjalnie skonstruowanym stanowisku laboratoryjnym. Celem badań eksperymentalnych było określenie wpływu układu kinematycznego docierania na równomierność zużycia narzędzia oraz na chropowatość i falistość powierzchni docieranych.

  • ANALIZA WPŁYWU ŁADOWANIA POJAZDÓW ELEKTRYCZNYCH NA DYNAMIKĘ ZMIAN DOBOWEGO OBCIĄŻENIA SYSTEMU ELEKTROENERGETYCZNEGO
    • Wiktoria Stahl
    • Paweł Bućko
    2019 Full text Zeszyty Naukowe Wydziału Elektrotechniki i Automatyki Politechniki Gdańskiej

    W artykule dokonano analizy możliwego wpływu ładowania samochodów elektrycznych na dynamikę zmian obciążenia dobowego systemu elektroenergetycznego. Oceniono możliwe zmiany kształt wykresu dobowego, w przypadku gdyby 5% użytkowanych samochodów zastąpić samochodami elektrycznymi. Analizie zostały poddane dwa warianty współpracy samochodów z systemem: G2V (proste ładowanie samochodów) oraz V2G (wykorzystanie możliwości oddawania energii do sieci). W artykule zaprezentowano wpływ samochodów na tzw. gradienty obciążeń, czyli szybkość narastania lub spadku obciążenia na granicach stref czasowych.

  • Analiza wybranych jednostek bilansów zapotrzebowania wody w aspekcie zrównoważonego gospodarowania wodami opadowymi
    • Aleksandra Pieniaszek
    • Piotr Szymański
    2019 Full text Inżynieria Morska i Geotechnika

    Zaspokojenie zapotrzebowania wody na cele gospodarcze przez wykorzystanie wody o obniżonej jakości np. wody opadowe. Współczynnik sw zdefiniowany do wyznaczenia wielkości poboru wody wodociągowej przeznaczonej na mycie placów i ulic, polewanie zieleni miejskiej, czy do podlewania ogrodów, zdefiniowano. Sezonowy wzrost poboru wody wodociągowej skorelowany ze wzrostem temperatury powietrza i niedosytu wilgotności powietrza oraz ujemnie skorelowany z wilgotnością względną powietrza. Zmniejszenie wskaźników jednostkowych w bilansach zapotrzebowania wody jako możliwa przyczyna zmniejszenia poboru wody wodociągowej. Zmniejszenie ilości ujmowanej wody pod warunkiem wdrożenia systemu retencji zbiornikowej i mikroretencji wód opadowych jako alternatywnego źródła wody o obniżonej jakości.

  • ANALIZA ZANIKÓW SYGNAŁÓW W RADIOWYCH SIECIACH BAN TYPU OFF-BODY PRACUJĄCYCH W ŚRODOWISKU KORYTARZA PROMU PASAŻERSKIEGO
    • Paweł Kosz
    • Sławomir Ambroziak
    • Jacek Stefański
    • Luis M. Correia
    2019 Przegląd Telekomunikacyjny + Wiadomości Telekomunikacyjne

    W referacie zaprezentowano analizę zaników sygnałów dla radiowych sieci BAN pracujących w środowisku promu pasażerskiego na częstotliwości nośnej 2,45 GHz dla komunikacji typu off-body (w łączu pomiędzy węzłem nasobnym, a węzłem zewnętrznym). Wyniki, na podstawie których przeprowadzono analizę, uzyskano w ramach badań pomiarowych dla scenariuszy dynamicznych w korytarzu promu pasażerskiego. Wyznaczono dwie składowe zaników: zaniki wolno- oraz szybkozmienne, które następnie poddano analizie statystycznej poprzez dopasowanie znanych w radiokomunikacji funkcji gęstości prawdopodobieństwa do rozkładów empirycznych.

  • Analiza zaników w sieciach WBAN typu off-body z przestrzennym odbiorem zbiorczym w środowisku wewnątrzbudynkowym
    • Szymon Wiszniewski
    • Sławomir Ambroziak
    2019 Przegląd Telekomunikacyjny + Wiadomości Telekomunikacyjne

    W artykule przedstawiono analizę zaników w sieciach WBAN typu off-body z przestrzennym odbiorem zbiorczym w środowisku wewnątrzbudynkowym. Przeprowadzono analizę zaników szybkozmiennych oraz wolnozmiennych. Wykazano, że zaniki szybkozmienne można scharakteryzować przy użyciu rozkładu Rice’a, natomiast zaniki wolnozmienne za pomocą rozkładu log-normalnego

  • Analiza zmienności generacji energii elektrycznej w okresie pierwszych pięciu miesięcy 2019 r. ze szczególnym uwzględnieniem generacji energii ze źródeł wiatrowych
    • Badur Janusz
    • Rafał Hyrzyński
    • Bartosz Kraszewski
    • Paweł Ziółkowski
    • Waldemar Dudda
    2019 Nowa Energia

    W artykule przedstawiono zagadnienia związane z szeroko pojętym rozwojem energetyki wiatrowej. Omówiono stan rozwoju energetyki wiatrowej na świecie. Na podstawie dostępnych badań przybliżono także zagadnienia związane z czynnikami wpływającymi na rozwój odnawialnych źródeł energii oraz ich oddziaływanie na środowisko naturalne. Główny nacisk położono jednakże na analizę zjawisk w pracy Krajowego Systemu Elektroenergetycznego (KSE) w okresie od 1 stycznia 2019 r. do dnia 21 maja 2019 r. Analiza ta była zogniskowana przede wszystkim na uchwyceniu korelacji pomiędzy zapotrzebowaniem na moc KSE, a mocą generowaną przez farmy wiatrowe. W ramach analizy przedstawiono charakterystyczne stany pracy dla KSE, jak też z punktu widzenia generacji energii przez źródła wiatrowe. Praca nie podejmuje zagadnień związanych z bezpieczeństwem pracy systemu elektroenergetycznego.

  • Analizy epidemiologiczne w środowisku MATLAB/Octave
    • Agnieszka Bartłomiejczyk
    • Marcin Wata
    2019 Full text Zeszyty Naukowe Wydziału Elektrotechniki i Automatyki Politechniki Gdańskiej

    W artykule skonstruowano proste modele matematyczne rozprzestrzeniania się chorób zakaźnych oparte na równaniach różniczkowych oraz automatach komórkowych. Na przykładzie modeli SIS i SIR zilustrowano praktyczne zastosowanie pojęć matematycznych nauczanych w toku studiów. Za pomocą symulacji komputerowych, do których użyto pakietów matematycznych MATLAB i Octave, uzyskano wizualizacje tempa rozwoju danej choroby oraz zasięgu epidemii. Ponadto przedstawiono informacje o zastosowaniu e-technologii w kształceniu studentów.

  • Analysing Ways to Achieve a New Urban Agenda-Based Sustainable Metropolitan Transport
    • Romanika Okraszewska
    • Kazimierz Jamroz
    • Lech Michalski
    • Joanna Żukowska
    • Krzysztof Grzelec
    • Krystian Birr
    2019 Full text Sustainability

    The New Urban Agenda (NUA) sets a new vision of sustainable urban development to help cities deal with the challenges of changing demography. While numerous articles have addressed how the NUA can be implemented at different levels and in different areas, this article points out the potential limitations in incorporating the NUA into metropolitan transport policies. The relevance of the limitations can be seen in three main fields: incompatibility between legal and financial frameworks and the functional and spatial structures of metropolitan areas, the characteristics of how transport systems are developed as part of metropolitan functional and spatial structures and the inconsistency and inadequacy between political declarations (NUA) which are based on ideas and programmes and the objectives of strategy papers which are based on diagnoses, data analyses and predictive models. The authors put forward the thesis that by concentrating on cities, the NUA leaves out some of the characteristics of metropolitan areas. As a consequence, although the NUA can work successfully for metropolitan cores, outer areas are not covered directly. In order to verify the thesis, a comparison was made between the NUA’s transport system approach with experience from running and planning metropolitan transport systems described in the literature. The results of the comparative analysis, confirmed the thesis of the authors and made it possible to formulate general conclusions regarding the specific conditions of metropolitan areas for the running and developing of the transport system. By using explanatory case study of Tri-City Metropolitan Area (TMA) and the Strategy for Transport and Mobility for TMA 2030 general assumptions were confirmed and explain in more details. The NUA and STM were compared for how they address the main areas of intervention related to transport. Differences were identified and recommendations were formulated, should the documents be updated. The STM must be updated in areas such as equity and climate change mitigations while the NUA should be expanded to cover the specific conditions that prevail in functional and metropolitan areas.

  • Analysis and interpretation of radiometric signals in a liquid-gas bubble flow
    • Marcin Zych
    • Robert Hanus
    • Marek Jaszczur
    • Anna Golijanek-Jędrzejczyk
    • Dariusz Świsulski
    • Gholam Roshani
    2019 Full text EPJ Web of Conferences

    The article presents the analysis of signals from a radiometric system consisting of two scintillation probes and two gamma radiation sealed sources. Calculations and interpretation were carried out for the bubble flow of the water-air mixture in the horizontal pipeline. The analysis of the obtained signals was done in time and frequency domain. In the frequency domain, a range of usable frequencies was identified, which were associated with changes in gamma-ray intensity recorded in the time domain. The gas phase velocity, void fraction and statistical parameters of the signal were also calculated.

  • ANALYSIS OF BONE WEDGE DIMENSIONS SELECTION METHODS IN HIGH TIBIAL OSTEOTOMY
    • Sebastian Urbanowski
    • Piotr Łuczkiewicz
    • Szymon Grymek
    2019 Full text Advances in Materials Science

    The article presents the analysis of methods for selecting dimensions of bone wedge for high tibial osteotomy. The existing methods are described along with the procedure. In the following paragraphs, deficiencies in the selection of bone wedge dimensions and global trends in this field have been demonstrated. Based on the numerical analysis, the problem appearing in the wrong choice of bone wedge imensions was illustrated.

  • Analysis of circular polarization antenna design trade‐offs using low‐cost EM‐driven multiobjective optimization
    • Adrian Bekasiewicz
    • Sławomir Kozieł
    • Quingsha. S. Cheng
    2019 INTERNATIONAL JOURNAL OF RF AND MICROWAVE COMPUTER-AIDED ENGINEERING

    Circular polarization (CP) antennas are vital components of modern communication systems. Their design involves handling several requirements such as low reflection and axial ratio (AR) within the frequency range of interest. Small size is an important criterion for antenna mobility which is normally achieved as a by‐product of performance‐oriented modifications of the structure topology. In this work, multiobjective optimization is used in order to identify and analyze design trade‐offs for miniaturized CP antenna including the antenna capability for maintaining small size while retaining acceptable levels of other performance figures. We use a population‐based metaheuristic algorithm to obtain a set of designs which represent the best attainable compromise between the imposed requirements. To maintain a low optimization cost, the algorithm is executed on a cheap approximation model and the results are further corrected to bring them to the EM model accuracy level. Here, the analysis is carried out for a planar CP antenna. Achievable size reduction of the considered structure—while maintaining acceptable performance—is around 11%. Antenna performance in terms of in‐band reflection and AR varies from −14 to −10 dB and from 1.3 to 3 dB, respectively. The numerical results are validated by measurements of fabricated antenna prototypes.

  • Analysis of compressive forces in CFGFT cylindrical pillars and their coatings using laboratory tests and metric spaces
    • Marcin Abramski
    • Eligiusz Mieloszyk
    • Anita Milewska
    2019 Full text MEASUREMENT

    The article discusses compressive forces tests in composite-concrete pillars with the use of laboratory active experiment including the factors and properties of materials which have a significant impact on the test results and their repeatability. A polymer composite based on glass fiber reinforced resin with different fiber beam angles (20, 55 and 85) was used as a buffer/coat of the pole. Due to the problems with direct comparison of the obtained discrete measurement results for different angles of the fiber winding, a transition from the measured discrete signals to the continuous description was proposed. Using this approach, it was possible to include control systems, identification theory and finally metric spaces in the research methodology. The latter made it possible to determine the relations between compressive forces for the various examined poles and their coats, and further, to define the partial order in the space of the poles studied and their coverings. The obtained results indicated the wide possibilities of the proposed test methods for compressive forces in composite-concrete pillars and their glass-fiber reinforced coats

  • Analysis of GNSS sensed precipitable water vapour and tropospheric gradients during the derecho event in Poland of 11th August 2017
    • Grzegorz Nykiel
    • Mariusz Figurski
    • Zofia Baldysz
    2019 Full text JOURNAL OF ATMOSPHERIC AND SOLAR-TERRESTRIAL PHYSICS

    Nowadays, one of the techniques that meets the increasing requirements of meteorologist in terms of monitoring of severe weather events is global navigation satellite systems (GNSS), which can provide information about the tropospheric state independently of the weather conditions and even in real time. In this paper we present the usage of GNSS sensed tropospheric data to monitor sudden and intense weather events. Our analyses were performed on the example of a derecho event in Poland of 11th August 2017. We used GPS/GLONASS observations from 278 GNSS reference stations located in Poland and, using Bernese GNSS Software ver. 5.2, we estimated the zenith tropospheric delays (ZTD) and tropospheric gradients with 5 and 15-min intervals respectively. Next, using meteorological data from the synoptic stations, we estimated the precipitable water vapour (PWV) which gives information about the amount of water vapour in the atmosphere. By applying a dense network of GNSS receivers, we were able to create the PWV, rate of the PWV (ROP), and the tropospheric gradients maps, which in turn allowed us to monitor the derecho event. We also conducted case studies for the selected GNSS stations where a comparison between PWV, reflectivity, and microwave radiometer were performed. During the main phase of the event we obtained the maximum value of PWV equal to 52.1 mm at 20:30 UTC. We also acquired high agreement between the PWV/ROP maps and reflectivity derived from meteorological radars. This applies to both the direction and speed of the phenomena as well as the time and place of the occurrence of the main phase of the derecho. This was possible only owing to the use of data derived from the dense network of the GNSS receivers.

  • ANALYSIS OF IMPACT of SHIP model parameters on changes of control quality index in ship dynamic positioning system
    • Tacjana Niksa-Rynkiewicz
    • Anna Witkowska
    2019 Full text Polish Maritime Research

    In this work there is presented an analysis of impact of ship model parameters on changes of control quality index in a ship dynamic positioning system designed with the use of a backstepping adaptive controller. Assessment of the impact of ship model parameters was performed on the basis of Pareto-Lorentz curves and ABC method in order to determine sets of the parameters which have either crucial, moderate or low impact on objective function. Simulation investigations were carried out with taking into account integral control quality indices.

  • Analysis of ring cracks in ceramic rolling elements using the boundary element method
    • Waldemar Karaszewski
    2019 Full text TRIBOLOGIA

    Ceramic materials have been increasingly used in bearing technology for over a dozen years. This is due to the characteristic properties of ceramic materials such as: high hardness, corrosion resistance, the possibility of use in aggressive chemical environments, as well as due to the lower specific weight compared to steel materials. However, the use of ceramic materials is connected with many limitations. The main disadvantages are surface cracks and low fracture toughness value. The paper presents a numerical analysis of crack propagation in silicon nitride balls. The directions of propagation were analyzed for the cracks that are most commonly found on the surface of the ceramic balls. The directions were analyzed along crack front and due to the location of the crack in relation to the contact point of the balls in the rolling contact. The numerical calculations are based on a three-dimensional model of the ring crack. Numerical calculations were carried out using boundary element method. Numerical solutions were compared with the results of experimental research.

  • Analysis of server-side and client-side Web-GIS data processing methods on the example of JTS and JSTS using open data from OSM and geoportal
    • Marcin Kulawiak
    • Agnieszka Dawidowicz
    • Marek Pacholczyk
    2019 Full text COMPUTERS & GEOSCIENCES

    The last decade has seen a rapid evolution of processing, analysis and visualization of freely available geographic data using Open Source Web-GIS. In the beginning, Web-based Geographic Information Systems employed a thick-client approach which required installation of platform-specific browser plugins. Later on, research focus shifted to platform-independent thin client solutions in which data processing and analysis was performed by the server machine. More recently, however, the rapid development of computer hardware as well as software technologies such has HTML5 has enabled the creation of platform-independent thick clients which offer advanced GIS functionalities such as geoprocessing. This article aims to analyse the current state of Open Source technologies and publicly available geographic data sources in the context of creating cost-effective Web-GIS applications for integration and processing of spatial data. For this purpose the article discusses the availability and potential of Web-GIS architectures, software libraries and data sources. The analysis of freely available data sources includes a discussion of the quality and accuracy of crowd-sourced as well as public sector data, while the investigation of software libraries and architectures involves a comparison of server-side and client-side data processing performance under a set of real-world scenarios. The article concludes with a discussion of the choice of cost-effective Web-GIS architectures, software libraries and data sources in the context of the institution and environment of system deployment.

  • Analysis of size and shape of abrasive micrograins in lapping of assembly joints
    • Adam Barylski
    2019 Technologia i Automatyzacja Montażu

    Przedstawiono skomputeryzowana analizę wielkości i kształtu mikroziaren ściernych. W badaniach mikroziaren węglika boru, węglika krzemu i elektrokorundu zastosowano mikroskopie optyczna oraz specjalistyczne oprogramowanie MultiScan v.6.08

  • Analysis of start energy of Stirling engine type alpha
    • Jacek Kropiwnicki
    2019 Full text Archives of Thermodynamics

    The Stirling engine type alpha is composed of two cylinders (expansion space E and compression space C), regenerator that forms the space between the cylinders and the buffer space (under the pistons). Before the start-up and as a result of long-term operation, the average pressure in the working space (above the pistons) and in the buffer space is the same. However, in the initial phase of operation, the average pressure in the working space is different then the average pressure in the buffer space depending on the crankshaft starting position (starting angle). This, in turn, causes a large variation in the starting torque. An additional unfavorable factor caused by a large variation in the course of the indicated torque is the rotational speed variation and the formation of torsional vibrations in the drive system. After some time, depending on the quality of the engine piston sealing, the average pressure in the working and buffer space will equalize. The occurrence of the above-described phenomenon affects the selection of the starting electric motor, which can be significantly reduced, when the crankshaft starting position is optimized (the starting torque is several times greater than the average torque occurring in the generator operation mode). This paper presents the analysis of the impact of the crankshaft starting position on the course of the indicated torque and the resulting start-up energy. Starting the engine at an unfavorable position of the crankshaft may, in extreme cases, increase the starting torque even three times.

  • Analysis of the Application of Horizontal Directional Drilling
    • Małgorzata Bratnikow
    2019 Full text World Scientific News

    Construction works are often considered to be very intrusive for the environment. Project designers assume deep excavations, or a complete replacement of the ground within the investment, which sometimes changes the initial conditions drastically. The problem started to appear in places, where the terrain is complicated and the excavation is burdensome. Some of state authorities do not agree to carry out works by open excavation. Such as crossing the river, running a network under the street in the city center, or a necessity to cross the protected natural area. In a case of linear facilities, it is possible to minimize interference for the natural environment. An example is crossing through a river, where instead of running a network on the bottom, a controlled drilling can be used. Modern technology allows for streamlining of execution works in line with pro-ecological policy.

  • Analysis of the Impact of Charging Electric Cars on the Power System Load
    • Wiktoria Stahl
    • Paweł Bućko
    2019 Full text Acta Energetica

    The paper presents ways of integrating electric cars with the power system. In connection with this, daily load curves in the average working day have been developed in the G2V (Grid-to-Vehicle) and V2G (Vehicle-to-Grid) variants. The G2V solution consists in unidirectional energy flow from the power system to a vehicle’s battery. The V2G solution consists in bi-directional energy exchange between the power system and electric car’s battery. Each of these options may have a different impact on the system’s load. The paper presents the impact of charging a large number of electric cars on the dynamics of load changes in the period of increasing demand from the night valley to the morning peak and during its fall from the evening peak to the night valley. Also, indicators characterizing the shape of the daily load curve were analysed. The actual system load curve was compared with the G2V and V2G based on original calculations.

  • Analysis of the macrostructure of the fuel spray atomized with marine engine injector
    • Joanna Grochowalska
    2019 Full text Combustion Engines

    One of the main problem influencing the combustion process in the cylinder of the marine engine is an fuel spray phenomena. The parameters describing the shape of the fuel spray are named macro parameters. This article presents the research results of the macrostructure parameters of the fuel spray atomized with the marine engine injector. The research were carried out by optical visualization measurement method of Mie scattering. The diameter of nozzle injector was 0.375 mm and L/D coefficient 8.3. In these research were considered different parameters of injection opening pressures and backpressures in the constant volume chamber. Generally conlusions are: the opening pressure influence on maximum spray tip penetration, spray cone angle and influence on speed of the injected fuel. The increase of backpressure into the constant volume chamber causes the reduction of spray tip penetration and the increase of the spray cone angle.

  • Analysis of the possibilities in railways shape assessing using GNSS mobile measurements
    • Władysław Koc
    • Cezary Specht
    • Piotr Chrostowski
    • Jacek Szmagliński
    2019 Full text MATEC Web of Conferences

    In recent years, a dynamic development of satellite positioning techniques using both static and mobile GNSS coordinates register mode can be observed. In addition, still developing Real-time GNSS Networks, post-processing algorithms and another measurement signal analysis algorithms, make the satellite measurements increasingly used in railway industry sector. In the article the possibilities which follows from the mobile satellite measurements in railway engineering are briefly presented. In the years 2009-2015, the authors conducted a series of field investigations on operated railway lines. The obtained results of these measurements led to the development of a number of algorithms that increase the range of applicability of GNSS measurements. The analysis of obtained results also showed how the accuracy of the measurements have increased since 2009. The achieved accuracy has been increased due to a development of GNSS positioning systems as well as improvement of the measurement methodology, i.e. configurations of satellite receivers and layouts of their placement on a mobile measuring platform. It was also found that the development of data analysis algorithms contributed to the increasement in the obtained accuracy in assessment of a railway track axis shape. The authors indicate the possibilities of applying GNSS techniques at various stages of construction and operation of railways. According to the authors, the most important advantage of both the presented measurement technique and computational methodology is the ability to effectively and relatively low-cost data acquisition regarding the existing state of the railway line. These data can be successfully used to design changes to the geometry of railway lines, and therefore satellite positioning has enormous application potential in the process of modernization of operated railway lines.

  • Analysis of the possibility of creep damage detection in T24 heat resistant steel with the help of magnetic nondestestructive testing methods
    • Leszek Piotrowski
    • Marek Chmielewski
    • Grzegorz Golański
    • Paweł Wieczorek
    2019 Full text ENGINEERING FAILURE ANALYSIS

    The paper presents the result of an analysis of applicability of various electromagnetic methods of nondestructive evaluation for creep damage detection in a novel heat resistant steel - T24 grade. Two sample sets, cut out from membrane wall tubes, were investigated – the as-delivered one and another exploited for 36,000 h in a power plant. There are described results of magnetic hysteresis loops B(H), Barkhausen noise (BN) and magnetoacoustic emission (MAE) signals measurements. Changes of the B(H) loops shape are observed mainly in the “knee” regions. The BN signal is practically unaffected by exploitation. The most strongly changing signal is the MAE signal, yet the change is not very easy to quantify as it concerns signal envelopes shape not overall intensity. The paper describes various possible signal parameters that can be used. The best one seems to be the ratio of the total pulse count for a quarter of magnetisation (demagnetisation) to the one for the magnetisation half-period. The important issue is in that case a proper choice of the threshold level in order to obtain good sensitivity to creep damage level and reasonably low stochastic pulse count scatter. 1. Introduction

  • ANALYSIS OF THE PROJECT OF INNOVATIVE FLOATING TURBINE
    • Andrzej Tomporowski
    • Ali Al - Zubiedy
    • Józef Flizikowski
    • Weronika Kruszelnicka
    • Patrycja Bałdowska-Witos
    • Jacek Rudnicki
    2019 Full text Polish Maritime Research

    The design of a floating, innovative device for river water aeration and conversion of mechanical energy to electrical energy required the analysis of a number of geometrical and dynamic features. Such an analysis may be carried out on the basis of existing methods of numerical fluid mechanics. Models of pressures, forces and torques characteristic for the conversion of watercourse energy were developed for two basic concepts of innovation. These pressures, forces and torques were calculated, designed, and experimentally determined for the variable geometric form and dimensions of the designed working elements of the innovative roller-blade turbine rotor.

  • Analysis of the regenerative braking process for the urban traffic conditions
    • Jacek Kropiwnicki
    • Mariusz Furmanek
    2019 Full text Combustion Engines

    In a regular drive system, with an internal combustion engine, vehicle braking is connected with the unproductive dissipation of kinetic and potential energy accumulated in the mass of the vehicle into the environment. This energy can constitute up to 70% of the energy used to drive a vehicle under urban conditions. Its recovery and reuse is one of the basic advantages of hybrid and electric vehicles. Modern traffic management systems as well as navigation systems should take into account the possibility of the energy recovery in the process of regenerative braking. For this purpose, a model of a regenerative braking process may be helpful, which on the one hand will enable to provide information on how traffic conditions will affect the amount of energy dissipated (wasted) into the atmosphere, on the other hand will help to optimize the route of vehicles with regenerative braking systems. This work contains an analysis of the process of the regenerative braking for the urban traffic conditions registered in Gdańsk. A model was also presented that allows calculating the amount of energy available from the braking process depending on the proposed variables characterizing the vehicle traffic conditions.

  • ANALYSIS OF WIND CONDITIONS AROUND A BUILDING DEVELOPMENT AS A PART OF ITS FORM DESIGNING PROCESS, A CASE STUDY
    • Katarzyna Zielonko-Jung
    2019 Full text Architecture Civil Engineering Environment

    Aerodynamic phenomena that occurs around building developments exert a significant impact on the quality of climate in cities. Environmental wind engineering is a dynamically developing field of knowledge that offers a chance to study and, in consequence, regulates the air flow around buildings and complexes of building developments. The following paper discusses the issue of wind conditions that may be experienced on pedestrian level. Such conditions should allow for a proper ventilationofcityspaces,atthesametimeeliminatinguncomfortable,suddenaccelerationsinthewindspeedandwindturbulence. Thepresentpaperdiscusseswhetheritispossibletoincludetheabovementionedissuesintheprocessofurbanandarchitectural design of medium-high urban building development units on the example of a particular project. The paper is aimed to test the validity of the use of aerodynamic tests and the possibilities of their introduction in the conceptual phase ofarchitectonicdesign.DesignmethodsbasedontherealitiesofcommonpracticesandlegalconditionsinPolandhavebeen juxtaposed to research methods in the field of aerodynamics. Experimental studies in wind tunnel, using oil visualization method have been applied, as such a method allows to promptly arrive at a qualitative identification of the airflow around the building on pedestrian level.

  • Analytical applications and physicochemical properties of ionic liquid-based hybrid materials: A review
    • Kateryna Yavir
    • Łukasz Marcinkowski
    • Renata Marcinkowska
    • Jacek Namieśnik
    • Adam Kloskowski
    2019 ANALYTICA CHIMICA ACTA

    Ionic liquids with their unique properties found so far numerous analytical applications. Among them ionic liquids immobilized on the surface or within the pores of a solid support were successfully utilized in extraction techniques dedicated to preconcentration of the analytes from food, environmental and biological samples. In this review we focus on comprehensive summarizing of available literature data on the examples of ionic liquid-based hybrid materials implementation in selected analytical extraction techniques, namely solid-phase extraction, solid-phase microextraction, hollow-fiber solid-phase microextraction, stir-bar sorptive extraction and biosensors. Additionally, this work is supported by concise discussion on strategies of ionic liquids immobilization in order to form hybrid materials (both chemical and physical) and the effects of confinement on structures along with ionic liquids physicochemical properties. This work allows for identifying the opportunities, challenges and shortcomings of this powerful and convenient, yet still not fully discovered analytical approach.

  • Analytical chemistry with biosolvents
    • Marek Tobiszewski
    2019 Full text ANALYTICAL AND BIOANALYTICAL CHEMISTRY

    One of the current trends in green analytical chemistry is the introduction of green solvents, some of which are biobased. At the same time, the development of the biorefinery concept has allowed more biochemicals to be obtained with increased efficiency and from a wider range of feedstocks. The first examples of the use of biosolvents in analytical applications included extractions performed with alcohols, esters, and terpenes. However, many more applications of biosolvents in extractions of bioactive compounds from various plant materials have also been reported, which hints at a wider range of potential analytical applications of biosolvents. It should also be noted that the biobased solvents applied in analytical chemistry are not always green, as some of them are toxic towards aquatic organisms.

  • Analytical design method for widening the intertrack space
    • Władysław Koc
    2019 Full text Current Journal of Applied Science and Technology (British Journal of Applied Science & Technology)

    The paper involved the issue of arching of the railway turnouts. This is an issue which is given relatively less attention to scientific and research activities. Reference has been made to the book by Wladyslaw Rzepka, under the title „Curved turnouts in plan and profile”, which has been used in Poland for more than 50 years as the main source of information relating to the turnouts on the curve. The book is a compilation of elaborations describing the contemporary state of knowledge being to a large extent a display of German achievements of the forties and fifties of the twentieth century. It has been pointed out that the theory accumulated in the book was adapted to the contemporary calculation needs. The major drawback in the given solutions seems to be ambiquity in the adopted reference system. In the present study an analytical approach is made to the subject matter, and the adopted system of coordinates is connected to the initial position of the turnout being arched. Three possible turnout arching variants have been analyzed to determine some universal mathematical relations. They describe the coordinates of the main track end and the diverging one, the value of the circular arc radius of the diverging track and equations of both the tracks. The analytical record also proves useful for authentic applications. It should be noted that it may be particularly beneficial to use the analytical method to design connections of parallel tracks located in a circular arc (using curved turnouts).

  • Analytical procedures for short chain chlorinated paraffins determination - How to make them greener?
    • Kaja Kalinowska
    • Paweł Lenartowicz
    • Jacek Namieśnik
    • Mariusz Marć
    2019 Full text SCIENCE OF THE TOTAL ENVIRONMENT

    The aim of the following paper was to gather current scientific information about the analytical protocols dedicated to measuring the content level of short-chain chlorinated paraffins (SCCPs) in various types of environmental samples. Moreover, the data about the basic validation parameters of applied procedures for SCCPs determination are listed. The main issue which is highlighted in the paper is the possibility of the application of green analytical chemistry (GAC) principals in the SCCPs measuring process to reduce the environmental impact of the applied methodology. Analytical methods dedicated to SCCPs determination contain a significant number of steps and require advanced analytical equipment during the quantitative and qualitative analysis. In addition, there is a substantial issue associated with the reliability of the obtained results, especially in the case of the quantification of individual SCCPs in the studied samples. Due to this fact, the paper attempts to discuss the various stages of the analytical procedure, in which appropriate changes in the formula or equipment solutions might be introduced to ensure a better quality of the analytical results, as well as to meet the requirements of the philosophy of green analytical chemistry. The most important case which concerns this subject is finding an optimal consensus between the economic and logistic aspects and the quality and “greenness” of the analytical procedure employed in SCCPs determination process.

  • Anisotropic mechanical behavior and auxeticity of penta-graphene: Molecular statics/molecular dynamics studies
    • Szymon Winczewski
    • Jarosław Rybicki
    2019 Full text CARBON

    We investigate the mechanical properties of penta-graphene (PG), a recently proposed two-dimensional carbon allotrope using atomistic simulation techniques combined with the empirical description of interatomic interactions. We report on the dependence of its three in-plane mechanical moduli (i.e. Young's modulus, Poisson's ratio and shear modulus) on the deformation direction, strain and temperature. We show that PG displays a strongly manifested mechanical anisotropy, being characterized by Poisson's ratio and the shear modulus which both depend strongly on the deformation direction. By analyzing bond energies we study the influence of different carbon-carbon bonds on the mechanical response of PG and based on that we explain the origins of the observed anisotropy. We show that it is mostly a consequence of the characteristics of the sp3 -hybridizied bonds, which form the diamond-like tetrahedral blocks. We investigate the auxeticity of PG in detail and show that it displays complete auxetic behavior, having negative Poisson's ratio for all the deformation directions. We show that the auxeticity of PG is similar to that of defective graphene containing 5-8-5 double vacancies, as it also originates from the so-called de-wrinkling mechanism. We study the influence of temperature and show that it only slightly affects the mechanical moduli of PG.

  • Antecedents to Achieve Kanban Optimum Benefits in Software Companies
    • Muhammad Ahmad
    • Anna Rohunen
    • Päivi Raulamo-jurvanen
    2019

    In 2004, Kanban successfully entered into the Agile and Lean realm. Since then software companies have been increasingly using it in software development teams. The goal of this study is to perform an empirical investigation on antecedents considered as important for achieving optimum benefits of Kanban use and to discuss the practical implications of the findings. We conducted an online survey with software professionals from the Lean Software Development LinkedIn community to investigate the importance of antecedents of using Kanban for achieving optimum benefits. Our study reveals that subjective norm, organizational support, ease of use, Kanban use experience and training are the antecedents for achieving expected benefits of Kanban. The potential benefits of Kanban use can only be realized when the key antecedents are not only identified, but also infused across an organization. When managing the transition to or using Kanban, practitioners need to adapt their strategies on the extent of various antecedents, a few identified in this study.

  • Anthra[1,2-d][1,2,3]triazine-4,7,12(3H)-triones as a New Class of Antistaphylococcal Agents: Synthesis and Biological Evaluation
    • Viktor Zvarych
    • Maryna Stasevych
    • Volodymyr Novikov
    • Eduard Rusanov
    • Mykhailo Vovk
    • Piotr Szweda
    • Katarzyna Grecka
    • Slawomir Milewski
    2019 Full text MOLECULES

    The development and spread of resistance of human pathogenic bacteria to the action of commonly used antibacterial drugs is one of the key problems in modern medicine. One of the especially dangerous and easily developing antibiotic resistant bacterial species is Staphylococcus aureus. Anthra[1,2-d][1,2,3]triazine-4,7,12(3H)-triones 22–38 have been developed as novel effective antistaphylococcal agents. These compounds have been obtained by sequential conversion of 1-amino-9,10-dioxo-9,10-dihydroanthracene-2-carboxylic acid (1) and 1-amino-4-bromo-9,10-dioxo-9,10-dihydroanthracene-2-carboxylic acid (2) into the corresponding amides 5–21, followed by subsequent endo-cyclization under the influence of sodium nitrite in acetic acid. Evaluation of the antimicrobial activity of the synthesized compounds against selected species of Gram-positive and Gram-negative bacteria as well as pathogenic yeasts of the Candida genus has been carried out by the serial dilution method. It has been established that anthra[1,2-d][1,2,3]triazine-4,7,12(3H)-triones exhibit selective antibacterial activity against Gram-positive bacteria. Eight, six and seven, out of seventeen compounds tested, effectively inhibited the growth of S. aureus ATCC 25923, S. aureus ATCC 29213 and S. epidermidis ATCC12228, respectively, at a concentration equal to 1 µg/mL or lower. The high antistaphylococcal potential of the most active compounds has been also confirmed against clinical isolates of S. aureus, including the MRSA strains. However, bacteria of the Staphylococcus genus have demonstrated apparent resistance to the novel compounds when grown as a biofilm. None of the four selected compounds 3234 and 36 at a concentration of 64 µg/mL (128 or 256 × MIC—against planktonic cells) has caused any decrease in the metabolic activity of the staphylococcal cells forming the biofilm. The kinetic time–kill assay revealed some important differences in the activity of these substances. Compound 33 is bacteriostatic, while other demonstrate bactericidal activity.

  • Antibacterial Activity and Cytocompatibility of Bone Cement Enriched with Antibiotic, Nanosilver, and Nanocopper for Bone Regeneration
    • Marcin Wekwejt
    • Anna Michno
    • Karolina Truchan
    • Anna Pałubicka
    • Beata Świeczko-Żurek
    • Anna Maria Osyczka
    • Andrzej Zieliński
    2019 Full text Nanomaterials

    Bacterial infections due to bone replacement surgeries require modifications of bone cement with antibacterial components. This study aimed to investigate whether the incorporation of gentamicin or nanometals into bone cement may reduce and to what extent bacterial growth without the loss of overall cytocompatibility and adverse effects in vitro. The bone cement Cemex was used as the base material, modified either with gentamicin sulfate or nanometals: Silver or copper. The inhibition of bacterial adhesion and growth was examined against five different bacterial strains along with integrity of erythrocytes, viability of blood platelets, and dental pulp stem cells. Bone cement modified with nanoAg or nanoCu revealed greater bactericidal effects and prevented the biofilm formation better compared to antibiotic-loaded bone cement. The cement containing nanoAg displayed good cytocompatibility without noticeable hemolysis of erythrocytes or blood platelet disfunction and good viability of dental pulp stem cells (DPSC). On the contrary, the nanoCu cement enhanced hemolysis of erythrocytes, reduced the platelets aggregation, and decreased DPSC viability. Based on these studies, we suggest the modification of bone cement with nanoAg may be a good strategy to provide improved implant fixative for bone regeneration purposes.

  • Antibiotic-Based Conjugates Containing Antimicrobial HLopt2 Peptide: Design, Synthesis, Antimicrobial and Cytotoxic Activities
    • Natalia Ptaszyńska
    • Katarzyna Gucwa
    • Katarzyna Olkiewicz
    • Anna Łȩgowska
    • Joanna Okońska
    • Jarosław Ruczyński
    • Agata Gitlin-Domagalska
    • Dawid Dȩbowski
    • Sławomir Milewski
    • Krzysztof Rolka
    2019 ACS Chemical Biology

    Recent studies have shown that modified human lactoferrin 20−31 fragment, named HLopt2, possesses antibacterial and antifungal activity. Thus, we decided to synthesize and evaluate the biological activity of a series of conjugates based on this peptide and one of the antimicrobials with proven antibacterial (ciprofloxacin, CIP, and levofloxacin, LVX) or antifungal (fluconazole, FLC) activity. The drugs were covalently connected to the peptide via amide, methylenecarbonyl moieties, or a disulfide bridge. The antibacterial and antifungal activities were evaluated under Clinical and Laboratory Standard Institute (CLSI) recommended conditions or in a low-salt brain−heart infusion diluted medium (BHI1/100). Results showed that conjugation of the peptide with the drug increased its antimicrobial activity up to 4-fold. Under CLSI-recommended conditions, all the compounds revealed rather low efficiency. Among conjugates, the highest antibacterial activity was recorded for the CIP-Cys-S-S-HLopt2-NH2 (III). In BHI1/100, which had lower differentiating properties, all of the conjugates revealed low MIC and MMC (minimum inhibitory and microbicidal concentrations) values. The disulfide bridge used as a linker in the most active conjugate (III) upon incubation with S. aureus cells is reduced, releasing constituent peptide and CIP-Cys. In addition, we showed that its fluorescently labeled analogue and constituent peptide are able to be internalized into both C. albicans and S. aureus cells. Moreover, the invaluable advantage of the presented conjugates was their low toxicity to mammalian cells and very low hemolytic activity. The current research can form a solid basis for further in vivo studies and drug development.

  • Anticancer and antimicrobial properties of novel η6-p-cymene ruthenium(ii) complexes containing a N,S-type ligand, their structural and theoretical characterization
    • Ewelina Namiecińska
    • Beata Sadowska
    • Marzena Więckowska-Szakiel
    • Anna Dołęga
    • Beata Pasternak
    • Magdalena Grazul
    • Elzbieta Budzisz
    2019 Full text RSC Advances

    Ruthenium(II) complexes are lately of great scientific interest due to their chemotherapeutic potential asanticancer and antimicrobial agents. Here we present the synthesis of new pyrazole carbothioamidederivatives and their four arene–ruthenium complexes. The title compounds were characterized with theapplication of IR, NMR, mass spectrometry, elemental analysis and X-ray diffraction. Additionally, for newcomplexes DFT calculations were done. Their antimicrobial activity (MIC, MBC/MFC) was examinedinvitroagainstStaphylococcus aureus,Staphylococcus epidermidis,Enterococcus faecalis,Pseudomonasaeruginosa,Proteus vulgarisandCandida albicans. Their cytotoxic effects, using the MTT assay, againstthree cancer cell lines: HL-60, NALM-6, WM-115 and normal human foreskinfibroblasts (HFF-1) werealso investigated. The influence of the new arene–ruthenium(II) complexes on the DNA structure wasalso tested. From our results, compound2dshowed higher cytotoxicity against melanoma cell line WM-115 than cisplatin. Strong biostatic and biocidal activity of the tested complexes against Gram-positivebacteria, includingS. aureus,S. epidermidisandE. faecaliswas demonstrated. The new arene–ruthenium(II) compounds could not only inhibit proliferation of cancer cells, but also protect patientsagainst malignant wound infections.

  • ANTIOXIDANT POWER SERIES (APS) AS A TOOL FOR RATIONAL DESIGN AND ASSESSMENT OF HEALTH PROMOTING PROPERTIES OF FUNCTONAL FOODS BASED ON ANTIOXIDANT PHYTOCHEMICALS
    • Agnieszka Bartoszek-Pączkowska
    • Monika Baranowska
    • Klaudia Suliborska
    • Wojciech Chrzanowski
    • Barbara Kusznierewicz
    • Agata Kot-Wasik
    2019

    Over past decades, plantborne antioxidants dominated so called "translational research" in the area of food, nutrition, and disease prevention. Among consumers and producers, such phytochemicals are synonyms of nutriceuticals. Popularity and commercial success of antioxidants stems from mechanistic studies suggesting the involvement of reactive oxygen species in etiology of chronic diseases. However, epidemiology failed to provide unequivocal confirmation of protective role of plantborne antioxidants in people exposed to oxidative stress. This ambiguity results from still insufficient understanding of relationships between chemical nature, redox potential in particular, and biological or physiological activity of antioxidants in the reducing environment of respectively cell or whole organism. To fill in this gap, we elaborate Antioxidant Power Series (APS) for antioxidants produced endogenously and found in edible or medicinal plants. APS is supposed to resemble the electrochemical series, which enables chemists to predict behavior of redox pairs in different systems. Similarly as hydrogen constitutes the point "zero" in electrochemical series, in the case of APS as such a reference point glutathione (GSH), the main physiological antioxidant, is proposed. The current version of APS for over 30 antioxidants and its relation to biological activities associated with redox homeostasis exhibited by these compounds will be presented and predictive value discussed.

  • Anti-plane surface waves in media with surface structure: Discrete vs. continuum model
    • Victor Eremeev
    • Basant Lal Sharma
    2019 Full text INTERNATIONAL JOURNAL OF ENGINEERING SCIENCE

    We present a comparison of the dispersion relations derived for anti-plane surface waves using the two distinct approaches of the surface elasticity vis-a-vis the lattice dynamics. We consider an elastic half-space with surface stresses described within the Gurtin–Murdoch model, and present a formulation of its discrete counterpart that is a square lattice half-plane with surface row of particles having mass and elastic bonds different from the ones in the bulk. As both models possess anti-plane surface waves we discuss similarities between the continuum and discrete viewpoint. In particular, in the context of the behaviour of phase velocity, we discuss the possible characterization of the surface shear modulus through the parameters involved in lattice formulation.

  • Antybiotyki aminoglikozydowe - problemy i wyzwania współczesnej analityki
    • Marta Glinka
    • Andrzej Wasik
    2019 Analityka: Nauka i Praktyka

    Zwiększające się zużycie produktów farmaceutycznych i ich przedostawanie się do środowiska naturalnego, jest jednym z istotnych problemów współczesnego świata. Legislacja dotycząca zawartości antybiotyków w środowisku naturalnym, żywności pochodzenia zwierzęcego, jak również w przypadku kontroli składu produktów farmaceutycznych ulega ciągłym zaostrzeniom. Stawia to przed analitykami coraz to nowe wyzwania polegające na opracowaniu możliwie czułych oraz selektywnych metod ich oznaczania. Jednak czy w każdym przypadku jest to możliwe i łatwe do osiągnięcia? Z punktu widzenia analityka, szczególnie trudne do oznaczenia są farmaceutyki charakteryzujące się wysoką polarnością oraz zdolnością do tworzenia kompleksów ze składnikami matrycy. Doskonałym przykładem tego typu substancji są antybiotyki aminoglikozydowe.