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Gdańsk University of Technology

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  • Directions and Prospects for the Development of the Electric Car Market in Selected ASEAN Countries
    • Krystyna Gomółka
    • Piotr Kasprzak
    2021 Full text ENERGIES

    The purpose of this article is to present the current situation and evaluate the opportuni‐ ties for the development of the electric car market in selected Southeast Asian countries in the con‐ text of the current situation in the rest of the world. Currently, the electric car market is at an ad‐ vanced stage of development in regions such as Western Europe, the USA, and China. It should be noted, however, that the number of electric cars in a given country results not only from market demand and access to vehicle charging networks but also from nonmarket mechanisms such as subsidies and tax or administrative solutions. It turns out that these are important elements that influence the final shape of a country’s market. This article analyses the current situation on the electric car market taking into account the legal, administrative, and tax conditions that affect the final number of vehicles and the infrastructure necessary for the operation and use of electric cars in selected Asian countries.

  • Disaster Resilience of Optical Networks: State of the Art, Challenges, and Opportunities
    • Jacek Rak
    • Rita Girão-Silva
    • Teresa Gomes
    • Georgios Ellinas
    • Burak Kantarci
    • Massimo Tornatore
    2021 Full text Optical Switching and Networking

    For several decades, optical networks, due to their high capacity and long-distance transmission range, have been used as the major communication technology to serve network traffic, especially in the core and metro segments of communication networks. Unfortunately, our society has often experienced how the correct functioning of these critical infrastructures can be substantially hindered by massive failures triggered by natural disasters, weather-related disruptions and malicious human activities. In this position paper, we discuss the impact on optical networks of all major classes of disaster events mentioned above, and we overview recent relevant techniques that have been proposed to increase the disaster resilience of optical networks against the various classes of disaster events. We start by presenting some proactive methods to be applied before the occurrence of a disaster. Then we move our focus also on other preparedness methods that can be executed in the (typically short) time frame between the occurrence of an early alert of an incoming disaster and the time a disaster actually hits the network. Finally, we discuss reactive procedures that allow performing post-disaster recovery operations effectively. The analysis of disaster resilience mechanisms provided in this paper covers both wired and optical wireless communication infrastructures and also contains explicit remarks covering the role of emerging technologies (e.g., fixed-mobile convergence in the 5G era and beyond) in disaster resilience.

  • Discovery of small-molecule regenerative drugs using a model of complex tissue injury in mice. Transcriptomic responses of neurodevelopmental genes during pharmacologically induced regeneration
    • Paweł Sosnowski
    2021

    Despite significant development in regenerative medicine, there is a deficit of effective therapies for wound healing and tissue regeneration. Research performed using animal wound models allows for a better understanding of this complex process, searching for compounds with pro-regenerative properties, and assessing their efficacy and safety. Unfortunately, the lack of adequate preclinical models proves to be an issue as no animal model can fully replicate human wounds. Nevertheless, new experimental therapies for enhancing wound healing and regeneration emerge, and animal models play an important role. Growth factors, cytokines, transcriptional activators in addition to small-molecule compounds such as epigenetic modulators seem to be of particular interest. In the presented work, I used an ear pinna punch wound in mice, a simple model of complex tissue injury, to examine the pro-regenerative effects for a selection of small-molecule compounds. One of the tested compounds, zebularine, a DNA methyltransferase inhibitor, administered intraperitoneally, significantly promoted wound closure in ear pinna. Furthermore, a combination treatment of zebularine and retinoic acid resulted in complete wound closure by day 21 after injury, whereas without treatment ear pinna holes in mice remain for life. To the best of my knowledge, this research is the first example demonstrating the potential of an epigenetic modulator to stimulate endogenous regenerative potential in animals, thus indicating a new pharmacological strategy for regenerative therapies.

  • Discrimination of hospital isolates of Acinetobacter baumannii using repeated sequences and whole genome alignment differential analysis
    • Roman Kotłowski
    • Nowak-zaleska Alicja
    • Grzegorz Węgrzyn
    2021 Full text JOURNAL OF APPLIED GENETICS

    An optimized method for bacterial strain differentiation, based on combination of Repeated Sequences and Whole Genome Alignment Differential Analysis (RS&WGADA), is presented in this report. In this analysis, 51 Acinetobacter baumannii multidrug-resistance strains from one hospital environment and patients from 14 hospital wards were classified on the basis of polymorphisms of repeated sequences located in CRISPR region, variation in the gene encoding the EmrA-homologue of E. coli, and antibiotic resistance patterns, in combination with three newly identified polymorphic regions in the genomes of A. baumannii clinical isolates. Differential analysis of two similarity matrices between different genotypes and resist- ance patterns allowed to distinguish three significant correlations (p < 0.05) between 172 bp DNA insertion combined with resistance to chloramphenicol and gentamycin. Interestingly, 45 and 55 bp DNA insertions within the CRISPR region were identified, and combined during analyses with resistance/susceptibility to trimethoprim/sulfamethoxazole. Moreover, 184 or 1374 bp DNA length polymorphisms in the genomic region located upstream of the GTP cyclohydrolase I gene, associated mainly with imipenem susceptibility, was identified. In addition, considerable nucleotide polymorphism of the gene encod- ing the gamma/tau subunit of DNA polymerase III, an enzyme crucial for bacterial DNA replication, was discovered. The differentiation analysis performed using the above described approach allowed us to monitor the distribution of A. baumannii isolates in different wards of the hospital in the time frame of several years, indicating that the optimized method may be useful in hospital epidemiological studies, particularly in identification of the source of primary infections.

  • Disinfection characteristics of an advanced rotational hydrodynamic cavitation reactor in pilot scale
    • Xun Sun
    • Zhengquan Wang
    • Xiaoxu Xuan
    • Li Ji
    • Xuewen Li
    • Yang Tao
    • Grzegorz Boczkaj
    • Shan Zhao
    • Joon Yong Yoon
    • Songying Chen
    2021 Full text ULTRASONICS SONOCHEMISTRY

    Hydrodynamic cavitation is a promising technique for water disinfection. In the present paper, the disinfection characteristics of an advanced hydrodynamic cavitation reactor (ARHCR) in pilot scale were studied. The effects of various flow rates (1.4–2.6 m3/h) and rotational speeds (2600–4200 rpm) on the removal of Escherichia coli (E. coli) were revealed and analyzed. The variation regularities of the log reduction and reaction rate constant at various cavitation numbers were established. A disinfection rate of 100% was achieved in only 4 min for 15 L of simulated effluent under 4200 rpm and 1.4 m3/h, with energy efficiency at 0.0499 kWh/L. A comprehensive comparison with previously introduced HCRs demonstrates the superior performance of the presented ARHCR system. The morphological changes in E. coli were studied by scanning electron microscopy. The results indicate that the ARHCR can lead to serious cleavage and surface damages to E. coli, which cannot be obtained by conventional HCRs. Finally, a possible damage mechanism of the ARHCR, including both the hydrodynamical and sonochemical effects, was proposed. The findings of the present study can provide strong support to the fundamental understanding and applications of ARHCRs for water disinfection.

  • Dissociative photo-double-ionization of isoxazole
    • Tomasz Wąsowicz
    • Antti Kivimaki
    • Robert Richter
    2021

    In the present communication, we present results on the photo-double-ionization and fragmentation of the isoxazole molecules. The experiments were carried out at the CiPo beamline at the Elettra-Sincrotrone radiation facility exploiting the VUV excitation and the ion time-of-flight spectrometry combined with the PEPICO technique. The dissociative processes where only one electron is emitted are quite well known [1]. However, double ionization is a more complex mechanism producing the doubly charged parent ion after two correlated electrons' emission. These doubly charged ions are usually very reactive objects that can dissociate into the ionic fragments. PEPICO method gives the coincidence maps plotted as the first ion arrival time vs. the second ion time-of-flight, with reference to the detection of one of the photoelectrons (see Figure 1a). As a result, the pairs of correlated ions show up as areas with a higher density of points. The calculation of the coincidence events in these “islands” gives information about the particular fragmentation channel (see Figure 1b).

  • Distance learning trends: introducing new solutions to data analysis courses
    • Karol Flisikowski
    2021 Full text Zeszyty Naukowe Wydziału Elektrotechniki i Automatyki Politechniki Gdańskiej

    Nowadays data analysis of any kind becomes a piece of art. The same happens with the teaching processes of statistics, econometrics and other related courses. This is not only because we are facing (and are forced to) teach online or in a hybrid mode. Students expect to see not only the theoretical part of the study and solve some practical examples together with the instructor. They are waiting to see a variety of tools, tutorials, interactive laboratory instructions, books, exams online. In this study I am going to show the latest technical solutions for instructors using R and/or Python in their online data analysis labs.

  • Do mistakes acceptance foster innovation? Polish and US cross-country study of tacit knowledge sharing in IT
    • Wioleta Kucharska
    2021 Full text Journal of Knowledge Management

    Abstract Purpose – This study aims to understand and compare how the mechanism of innovative processes in the information technology (IT) industry – the most innovative industry worldwide – is shaped in Poland and the USA in terms of tacit knowledge awareness and sharing driven by a culture of knowledge and learning, composed of a learning climate and mistake acceptance. Design/methodology/approach – Study samples were drawn from the IT industry in Poland (n = 350) and the USA (n = 370) and analyzed using the structural equation modeling method. Findings – True learning derives from mistake acceptance. As a result of a risk-taking attitude and critical thinking, the IT industry in the USA is consistently innovation-oriented. Specifically, external innovations are highly correlated with internal innovations. Moreover, a knowledge culture supports a learning culture via a learning climate. A learning climate is an important facilitator for learning from mistakes. Originality/value – This study revealed that a high level of mistake acceptance stimulates a risk-taking an attitude that offers a high level of tacit knowledge awareness as a result of critical thinking, but critical thinking without readiness to take a risk is useless for tacit knowledge capturing.

  • Dold sequences, periodic points, and dynamics
    • Jakub Byszewski
    • Grzegorz Graff
    • Thomas Ward
    2021 Full text BULLETIN OF THE LONDON MATHEMATICAL SOCIETY

    In this survey we describe how the so-called Dold congruence arises in topology, and how it relates to periodic point counting in dynamical systems.

  • DOM KASZUBSKI NA ZIEMI ZABORSKIEJ. smaki dziedzictwa
    • Agnieszka Kurkowska
    2021

    Ogólnopolska wystawa plastyczna miała miejsce w Wielu jako element projektu pt. „Smaki ziemi zaborskiej. Dziedzictwo przyrodnicze i kulturowe” zaplanowanego w ramach 19. Europejskich Dni Dziedzictwa. Współorganizatorami byli: Wydział Architektury Politechniki Gdańskiej - Agnieszka Kurkowska,kuratorka ) i Dom Kultury im. H. Derdowskiego w Wielu/ Muzeum Ziemi Zaborskiej. Wystawa tematycznie dotyczyła wysmakowanej architektury kaszubskiej na ziemi zaborskiej: domu kaszubskiego, zagrody i szerzej krajobrazu w kontekście tytułowych ‘smaków dziedzictwa’.

  • DOP and Pseudorange Error Estimation in Mobile GNSS Systems for Android OS Applications
    • Przemysław Falkowski-Gilski
    • Zbigniew Łubniewski
    2021

    In the near past, GNSS (Global Navigation Satellite Systems) were only offered for a narrow group of recipients. Nowadays, thanks to mobile devices, they are available to anyone and everywhere. Personal navigation, searching for POI (Point of Interest), etc., had become a basic essential activity. Thanks to the widespread and availability of smartphones each user can obtain information considering his or her location even in an unknown environment. Furthermore, network operators and providers use this location-based information for monitoring and maintenance purposes. This paper is focused on a study, considering the DOP (Dilution of Precision) and pseudorange error estimation in case of Android-powered mobile devices operating outdoors. It describes a measurement campaign, carried out in varying urban environments while driving a car, including two popular consumer devices from different manufacturers running Android OS. Based on this, respective conclusions and remarks are given. This work aims to aid not only users, but also application developers as well as device manufacturers and retailers, when it comes to providing precise and reliable products and services.

  • DOP and Pseudorange Error Estimation in Urban Environments for Mobile Android GNSS Applications
    • Przemysław Falkowski-Gilski
    • Zbigniew Łubniewski
    2021

    Just a couple of years ago, GNSS (Global Navigation Satellite Systems) were available only for a narrow group of users. Currently, with the outbreak of mobile devices, they are accessible to anyone and everywhere. Urban navigation or searching for POIs (Points of Interest) had become an everyday activity. With the availability of consumer electronics and wireless technologies, each user can obtain information considering his or her location even in an unknown environment. Additionally, network operators and service providers utilize this location-based information for monitoring and maintenance purposes. This paper is focused on a study, considering the DOP (Dilution of Precision) and pseudorange error estimation in case of Android-powered smartphones operating outdoors. It describes a measurement campaign, carried out in varying urban environments, with two types of excursions (by car and bicycle), including two popular consumer devices from different manufacturers. Based on this, respective conclusions and remarks are given. This work aims to aid not only users, but also application developers as well as device manufacturers and retailers, when it comes to providing precise and reliable products and services.

  • Dostępność transportowa węzłów przesiadkowych dla osób ze specjalnymi potrzebami
    • Kazimierz Jamroz
    • Romanika Okraszewska
    • Krystian Birr
    • Marek Sitarz
    • Katarzyna Chruzik
    • Iwona Krzyżewska
    • Miusz Zieja
    • Justyna Tomaszewska
    2021

    W artykule przedstawiono główne założenia, cele, zakres oraz oczekiwane rezultaty projektu „Przesiadka bez Barier”, wskazanego do realizacji w ramach konkursu NCBiR „Rzeczy są dla ludzi”. Ogólnym celem projektu jest przeciwdziałanie wykluczeniu społecznemu osób ze szczególnymi potrzebami (OzSP) poprzez zwiększenie możliwości realizacji podróży, poprawę bezpieczeństwa i komfortu podróży oraz zwiększenie dostępności do infrastruktury transportu w zintegrowanych węzłach przesiadkowych (ZWP). W ramach projektu zaproponowano nowatorskie podejście pozwalające na obiektywną ocenę poziomu dostępności całego ZWP poprzez identyfikację barier i udogodnień dla użytkowników ze szczególnymi potrzebami. Zaproponowano sześć narzędzi służących realizacji tak określonego celu: standardy dostępności, metody wykonywania audytu dostępności, metody wykonywania kontroli dostępności, katalog rozwiązań i dobrych praktyk, baza danych o dostępności ZWP oraz aplikacja - mapa dostępności.

  • Drukowanie trwałych elementów z tworzyw termoplastycznych w technologii FDM/FFF
    • Dawid Zieliński
    2021 Full text Tworzywa Sztuczne w Przemyśle

    Drukowanie detali z tworzyw sztucznych stanowi aktualnie jedną z najczęściej wykorzystywanych form druku 3D, która znajduje szerokie zastosowanie zarówno w obszarze amatorskim, jak i również przemysłowym. Omawiane w pracy zagadnienia dotyczą zasady działania oraz charakterystyki najważniejszych czynników technologii FDM/FFF. Przedstawiono najczęściej występujące błędy oraz defekty drukowanych elementów. Wskazano ponadto najważniejsze korzyści i ograniczenia wykorzystania metody, rodzaje przetwarzanych materiałów, a także szereg praktycznych wskazówek umożlwiających drukowanie trwałych elementów z tworzyw sztucznych.

  • Dwa prestiżowe stanowiska dr Anny Wałek, dyrektor Biblioteki PG
    • Katarzyna Dudek
    • Robert Szczodruch
    2021 Full text Pismo PG

    Artykuł prezentuje sukcesy zawodowe dr Anny Wałek, Dyrektor Biblioteki Politechniki Gdańskiej, która w 2021 r. została wybrana na Prezydenta International Association of University Libraries (od stycznia 2022 r.) oraz Przewodniczącą Rady Dyrektorów Polskiej Grupy Użytkowników systemu VIRTUA (od czerwca 2021 r.)

  • DWDM Network Laboratory Solution for Telecommunication Education Engineering
    • Sylwester Kaczmarek
    • Magdalena Młynarczuk
    2021

    Development of network architectures in the field of optical telecommunications technologies is an indicator of changes in telecommunication education engineering. Conducting didactic classes requires hardware infrastructure and research in terms of teaching needs. In the paper we present DWDM network laboratory solution for telecommunication education engineering on the basis of the ADVA Optical Networking equipment. We have to adjust and configure telecommunication equipment for a didactic purpose. We present the core optical equipment, network structure, its configuration and laboratory exercises.

  • Dynamic mechanical properties and flexing fatigue resistance of tire sidewall rubber as function of waste tire rubber reclaiming degree
    • Zhen Zhang
    • Zonglin Peng
    • Krzysztof Formela
    • Shifeng Wang
    2021 JOURNAL OF APPLIED POLYMER SCIENCE

    A stepwise downsizing method of gel particles in reclaimed rubber to a micro-nano scale and its excellent dynamic performance in tire sidewall were introduced by this work. The results showed that the size of gel particles decreased from several micrometers to micro-nanometers with the increase of reclaiming degree, accompanied by reduced molecular weight and widened molecular weight distribution of sol fraction. The addition of reclaimed rubber with low Mooney viscosity improved the dynamic mechanical properties of the natural rubber/butadiene rubber blends effectively, including wet resistance and rolling resistance. Moreover, the flexing fatigue resistance has also been improved dozens of times compared to traditional tire sidewall.

  • Dynamic Route Discovery Using Modified Grasshopper Optimization Algorithm in Wireless Ad-Hoc Visible Light Communication Network
    • Sharmila Vadivel
    • Srinivas Konda
    • Kavitha Rani Balmuri
    • Andrzej Stateczny
    • B. D. Parameshachari
    2021 Full text Electronics

    In recent times, visible light communication is an emerging technology that supports high speed data communication for wireless communication systems. However, the performance of the visible light communication system is impaired by inter symbol interference, the time dispersive nature of the channel, and nonlinear features of the light emitting diode that significantly reduces the bit error rate performance. To address these problems, many environments offer a rich infrastructure of light sources for end-to-end communication. In this research paper, an effective routing protocol named the modified grasshopper optimization algorithm is proposed to reduce communication interruptions, and to provide alternative routes in the network without the need of previous topology knowledge. In this research paper, the proposed routing protocol is implemented and analyzed using the MATLAB environment. The experimental result showed that the proposed routing protocol adapts to dynamic changes in the communication networks, like obstacles and shadows. Hence, the proposed protocol achieved better performance in data transmission in terms of throughput, packet delivery ratio, end-to-end delay, and routing overhead. In addition, the performance is analyzed by varying the number of nodes like 50, 100, 250, and 500. From the experimental analysis, the proposed routing protocol achieved maximum of 16.69% and minimum of 2.20% improvement in packet delivery ratio, and minimized 0.80 milliseconds of end-to-end delay compared to the existing optimization algorithms.

  • Dynamic Signature Vertical Partitioning Using Selected Population-Based Algorithms
    • Marcin Zalasiński
    • Tacjana Niksa-Rynkiewicz
    • Krzysztof Cpałka
    2021 LECTURE NOTES IN COMPUTER SCIENCE

    The dynamic signature is a biometric attribute used for identity verification. It contains information on dynamics of the signing process. There are many approaches to the dynamic signature verification, including the one based on signature partitioning. Partitions are the regions created on the basis of signals describing the dynamics of the signature. They contain information on the shape of the signature characteristic of a given individual. In this paper, we focus on so-called vertical partitioning and different population-based algorithms which are used to determine partition division points. In the verification process we use an authorial one-class classifier.

  • Dynamics of Chains as a Tool to Study Thermomechanical Properties of Proteins.
    • Piotr Weber
    2021

    Polymer dynamics can be formulated on different levels of detail. One approach eliminates microscopic degrees of freedom and a polymer molecule is represented by a simplified structure—a chain. In the simplest case monomers of ideal chain have fixed length, and their orientation is independent of the orientations and positions of neighbouring monomers. This is reason that two monomers can co-exist at the same place. Ideal chain model doesn’t describe correctly the local structure of polymer, but correctly describe the property on large-scale. In this scale chain can be treated as a thermodynamical system, which their dynamic have to fulfill laws of nonequilibrium thermodynamics. In a living systems there are a special polymers-proteins, that can operate under non-equilibrium conditions. During biochemical processes, they changes its states and are treated as free energy transducers. I will present a certain formalism of non-equilibrium thermodynamic when non-Markovian processes appear.

  • Działania antykryzysowe w obszarze kultury w trakcie pandemii SARS-CoV-2. Stan obecny i wnioski de lege ferenda w zakresie zwiększenia partycypacji obywatelskiej oraz instytucjonalnej
    • Sebastian Skuza
    • Anna Modzelewska
    • Marta Szeluga-Romańska
    • Marta Materska-Samek
    2021 Full text Przegląd Sejmowy

    Celem artykułu jest analiza różnych rozwiązań prawnych w zakresie wsparcia instytucji kultury w trakcie stanu epidemii. Przeprowadzono przegląd działań Ministerstwa Kultury i Dziedzictwa Narodowego wspierających instytucje kultury w Polsce w czasie epidemii według stanu na maj 2020 r. Na podstawie analizy wskazano wnioski de lege ferenda co do nowych możliwości finansowania działań takich instytucji. Autorzy prezentują rozwiązania prawne dotyczące przekazywania 1% PIT, odliczania darowizn, emisji obligacji przychodowych i dofinansowania w formie skarbowych papierów wartościowych. Wnioski z badań prowadzonych przez autorów osadzone są w obszarze ekonomicznej analizy prawa (Law&Economics).

  • Dzieje latarni w Twierdzy Wisłoujście w świetle badań architektonicznych z roku 2018 History of the Lighthouse of the Wisłoujście Fortress in Light of a 2018 Architectural Study
    • Piotr Samól
    • Robert Hirsch
    • Arkadiusz Woźniakowski
    2021 Full text Wiadomości Konserwatorskie

    W roku 2018 zespół autorski wykonał badania architektoniczne wieży w Twierdzy Wisłoujście w Gdańsku w związku z planowanymi pracami konserwatorskimi. Pierwszy raz podjęto metodologiczne badania architektoniczne najstarszej struktury zespołu – wieży-latarni morskiej wzniesionej w 1482, a następnie rozbudowywanej w wiekach XVI–XX. Wyniki badań oraz weryfikacja źródeł historycznych i archeologicznych pozwoliły zrekonstruować 6 głównych etapów budowy. Ustalono, że obecne wejście do wieży jest wtórne, a forma jej zwieńczenia (krenelaż) jest ahistoryczną kreacją zrealizowaną pod koniec lat pięćdziesiątych XX stulecia, nieznajdującą historycznego uzasadnienia. Wyniki badań – pomimo nowych ustaleń – wskazują na wiele dalszych wątpliwości na temat historii, a zwłaszcza przekształceń twierdzy, które do tej pory nie zostały rozpoznane. Dowodzą też konieczności kontynuowania analiz twierdzy poprzez badania architektoniczne i archeologiczne w powiązaniu z badaniami archiwalnymi.

  • Eco-Friendly Ether and Ester-Urethane Prepolymer: Structure, Processing and Properties
    • Joanna Niesiobędzka
    • Ewa Głowińska
    • Janusz Datta
    2021 Full text INTERNATIONAL JOURNAL OF MOLECULAR SCIENCES

    This study concerns bio-based urethane prepolymers. The relationship between the chemical structure and the thermal and processing parameters of bio-based isocyanate-terminated ether and ester-urethane prepolymers was investigated. Bio-based prepolymers were obtained with the use of bio-monomers such as bio-based diisocyanate, bio-based polyether polyol or polyester polyols. In addition to their composition, the bio-based prepolymers were different in the content of iso-cyanate groups content (ca. 6 and 8%). The process of pre-polymerization and the obtained bio-based prepolymers were analyzed by determining the content of unreacted NCO groups, Fourier transform infrared spectroscopy, proton nuclear magnetic resonance, thermogravimetry, and rheological measurements. The research conducted facilitated the evaluation of the properties and processability of urethane prepolymers based on natural components. The results indicate that a significant impact on the processability has the origin the polyol ingredient as well as the NCO content. The thermal stability of all of the prepolymers is similar. A prepolymer based on a poly-ether polyol is characterized by a lower viscosity at a lower temperature than the prepolymer based on a polyester polyol. The viscosity value depends on the NCO content.

  • Eco-friendly Route for Thermoplastic Polyurethane Elastomers with Bio-based Hard Segments Composed of Bio-glycol and Mixtures of Aromatic–Aliphatic and Aliphatic–Aliphatic Diisocyanate
    • Ewa Głowińska
    • Wojciech Wolak
    • Janusz Datta
    2021 JOURNAL OF POLYMERS AND THE ENVIRONMENT

    Application of bio-based diisocyanates with low volatility instead petrochemical diisocyanates has positive impact on environment by reduction of hazardous effects on living organisms and lead to bio-based polyurethanes (bio-PUs) with good usage properties. This work was focused on the synthesis and chosen properties examination of partially bio-based thermoplastic polyurethane elastomers (bio-PUs) obtained using diisocyanate mixtures, polytetrahydrofurane (PolyTHF) and bio-1,3-propanediol (bio-PDO). Two types of diisocyanate mixtures were prepared as follows: aliphatic–aliphatic based on hexamethylene diisocyanate with partially bio-based aliphatic diisocyanate Tolonate™ X FLO 100 (HDI-FLO) and aromatic–aliphatic based on diphenylmethane diisocyanate with partially bio-based diisocyanate (MDI-FLO) with reduction of 25 mass% of petrochemical diisocyanate. Bio-PUs were obtained via prepolymer method. Thermoplastic polyurethane elastomers have been examined in the terms of chemical structure and thermal, thermomechanical, mechanical and physicochemical properties. Bio-PU based on HDI-FLO diisocyanate mixture exhibited higher thermal stability. The beginning of thermal decomposition took a place at lower temperature ca. 30 ºC) and lower rate than the MDI-PU based materials. DMA analysis showed that HDI-FLO based polyurethanes exhibited greater capacity to accumulate energy and higher stiffness. Both materials characterized similar tensile strength and hardness, but with difference that TPU based on HDI-FLO relieved greater elongation at break about 360% reached 813%. Taking into account versatile properties of bio-TPU, these material can find application in many branches of industry.

  • Economic benefits of dynamic charging of electric buses
    • Mikołaj Bartłomiejczyk
    • Marcin Połom
    • Leszek Jarzębowicz
    • Kristina Jakimovska
    2021 Full text

    Diesel engines buses are still the most used type of buses. Electric buses provide promising green alternatives and a lot of advantages, but their main disadvantages are limited travel range and long charging time. This article is a presentation of innovative solution for charging of electric busses - Dynamic Charging (IMC). The modern IMC system in Solingen was presented. At the end of the article, a proposal was made to introduce a similar solution in Skopje, which would allow the electric vehicles operation on bus line no 9. This, in turn, would create score of electric Bus Rapid Transit system.

  • ECONOMIC MEASURES AGAINST A PANDEMICS
    • Oleksandr Melnychenko
    2021 Full text BULLETIN OF THE CHERKASY BOHDAN KHMELNYTSKY NATIONAL UNIVERSITY. ECONOMIC SCIENCES

    The appropriate level of treatment during periods of increasing workload in the health care system or a particular hospital is ensured either by changing the organization of the system and the principles of use of resources such as space, staff and consumables or their redistribution, or by financial resources such resources are increased or replenished. This article contributes to improve the concept of resource allocation as an economic means to increase the capacity of the health care system during medical emergencies. Initiating the purchase of equipment or other materials will cause demand for them and, accordingly, supply in the market, provided a balanced policy, physical and organizational access to markets.

  • Edgewise Compressive Behavior of Composite Structural Insulated Panels with Magnesium Oxide Board Facings
    • Łukasz Smakosz
    • Ireneusz Kreja
    • Zbigniew Pozorski
    2021 Full text Materials

    Edgewise compression response of a composite structural insulated panel (CSIP) with magnesium oxide board facings was investigated. The discussed CSIP is a novel multifunctional sandwich panel introduced to the housing industry as a part of the wall, floor, and roof assemblies. The study aims to propose a computational tool for reliable prediction of failure modes of CSIPs subjected to concentric and eccentric axial loads. An advanced numerical model was proposed that includes geometrical and material nonlinearity as well as incorporates the material bimodularity effect to achieve accurate and versatile failure mode prediction capability. Laboratory tests on small-scale CSIP samples of three different slenderness ratios and full-scale panels loaded with three different eccentricity values were carried out, and the test data were compared with numerical results for validation. The finite element (FE) model successfully captured CSIP’s inelastic response in uniaxial compression and when flexural action was introduced by eccentric loads or buckling and predicted all failure modes correctly. The comprehensive validation showed that the proposed approach could be considered a robust and versatile aid in CSIP design.

  • Edward Kajdański - wspomnienie
    • Adam Barylski
    2021 Przemysł Spożywczy

    Przedstawiono pokrótce życiorys i dokonania Edwarda Kajdańskiego, absolwenta Wydziału Technologii Maszyn Politechniki Gdańskiej z roku 1960. Edward Kajdański był dyplomatą, wybitnym znawcą historii, medycyny i sztuki Chin oraz autorem wielu fascynujących książek. Przez kilka lat po studiach pracował również w kilku zakładach przemysłu spożywczego w trójmieście. Zmarł 10 września 2020 roku w Gdańsku.

  • Edward Kajdański (1925-2020)
    • Adam Barylski
    2021 Przegląd Techniczny

    Przedstawiono w dużym skrócie działalność zawodową i dorobek mgra inż. Edwarda Kajdańskiego, absolwenta Wydziału Technologii Maszyn Politechniki Gdańskiej, wybitnego znawcy historii, medycyny i sztuki Chin, autora fascynujacych książek i obrazów.

  • Efektywność energetyczna systemów chłodniczych pracujących z dwutlenkiem węgla jako czynnikiem roboczym
    • Paulina Boroń
    • Blanka Jakubowska
    2021 Full text Chłodnictwo : organ Naczelnej Organizacji Technicznej

    Artykuł dotyczy zagadnienia efektywności energetycznej układów chłodniczych pracujących z dwutlenkiem węgla jako czynnikiem roboczym. W celu szczegółowego przeanalizowania potencjału zastosowania dwutlenku węgla, jako czynnika roboczego w urządzeniach chłodniczych, przeprowadzone zostały obliczenia dla kilku modeli układów chłodniczych. Do przeprowadzenia analizy wybrano trzy układy chłodnicze, tj. układ transkrytyczny, układ kaskadowy oraz typu booster. W ramach prowadzonej analizy zbadano i omówiono wpływ temperatury skraplania i parowania na efektywność energetyczną analizowanych układów.

  • Effect of annealing temperature on slurry erosion resistance of ferritic X10CrAlSi18 steel
    • Marta Buszko
    • Alicja Krella
    • Artur Marchewicz
    • Grzegorz Gajowiec
    2021 TRIBOLOGY INTERNATIONAL

    In the present work, the slurry erosion tests were carried out to investigate the influence of heat treatment on slurry erosion process of ferritic X10CrAlSi18 stainless steel using a slurry pot test rig. X10CrAlSi18 stainless steel was tested in as-received condition and after annealing at three different temperatures: 600°C, 800°C and 1000°C. Degradation of materials due to slurry erosion depends on many factors connected with fluid flow conditions, properties of target material and erodent characteristics. In this case, factors related to the properties of the eroded material such as microstructure, grain size, work hardening, hardness played an important role. The heat treatment decreased hardness of this steel and increased erosion resistance. Microstructure was one of the most important parameters influencing the slurry erosion process of tested materials. X10CrAlSi18 stainless steel after annealing at 600 °C with fine-grained microstructure and the deepest of work hardening layer obtained the best resistance to slurry erosion. Heat treatment contributed to approximately 55%, 23% and 41% decrease in mass loss compared to steel in as-received condition. After slurry erosion tests craters, fracture, ridges and flakes were observed on the eroded surface. Furthermore, to identify the dominant mechanism of erosion, the erosion efficiency parameter was used, η.

  • Effect of choline chloride based natural deep eutectic solvents on aqueous solubility and thermodynamic properties of acetaminophen
    • Dorota Warmińska
    • Bartosz Nowosielski
    • Adrian Szewczyk
    • Jakub Ruszkowski
    • Magdalena Prokopowicz
    2021 JOURNAL OF MOLECULAR LIQUIDS

    In this work, natural deep eutectic solvents (NADESs) containing choline chloride as hydrogen bond acceptor and 1,2-propanediol, malic acid and tartaric acid as hydrogen bond donors have been synthesized and applied to enhance the aqueous solubility of model sparingly water-soluble drug – acetaminophen. The results indicate that the greatest impact on the solubility of acetaminophen have deep eutectic solvents based on 1,2-propanediol or malic acid and the solubility of acetaminophen increases with both the concentration of NADES and temperature. Among the Apelblat, λh (Buchowski-Ksiazczak), Yalkowsky and combined Jouyban–Acree and van ‘t Hoff models correlating the solubility data, the Apelblat model is more consistent with the experimental data. Moreover, densities and sound velocities of acetaminophen in aqueous NADESs were measured at T = (298.15–313.15) K and these data were used to derive the limiting apparent molar volumes and the apparent molar compressibilities of the transfer. The thermodynamic properties show that the hydrophilic-ionic and hydrophilic-hydrophilic interactions in solutions of acetaminophen are predominant and this effect is the strongest for acetaminophen in aqueous choline chloride:malic acid solution.

  • Effect of double thermal and electrochemical oxidation on titanium alloys for medical applications
    • Agnieszka Ossowska
    • Jean-marc Olive
    • Andrzej Zieliński
    • Andrzej Wojtowicz
    2021 Full text APPLIED SURFACE SCIENCE

    The research focuses on the development and characterization of innovative thin hybrid oxide coatings obtained in subsequent processes of thermal (TO) and electrochemical (EO) oxidation. Four different surface modifications were investigated and the microstructure was determined, the mechanical, chemical and biological properties of the Ti-13Nb-13Zr alloy were assessed using scanning electron microscopy, X-ray dispersion analysis, glow discharge emission spectroscopy, Raman spectroscopy, nanoindentation and corrosion resistance measurements. The composite layers were evaluated for antimicrobial activity, cytotoxicity bioassays and wettability tests were performed. The conducted studies of two-stage oxidation (TO + EO) have shown that it is possible to obtain layers with a different structure - crystalline and nanotubular. The formation of a nanotube layer on the surface of the crystalline layer is dependent on the thickness of the crystalline layer. The produced double titanium oxide coatings show high surface roughness, high corrosion resistance, are hydrophilic, slightly antibacterial, and not cytotoxic, which has a huge impact on the process of connecting the tissue with the implant.

  • Effect of excitation intensity on slope stability assessed by a simplified approach
    • Aleksandra Korzec
    • Robert Jankowski
    2021 Full text Earthquakes and Structures

    The paper concerns the selection of a design accelerograms used for the slope stability assessment under earthquake excitation. The aim is to experimentally verify the Arias Intensity as an indicator of the excitation threat to the slope stability. A simple dynamic system consisting of a rigid block on a rigid inclined plane subjected to horizontal excitation is adopted as a slope model. Strong ground motions recorded during earthquakes are reproduced on a shaking table. The permanent displacement of the block serves as a slope stability indicator. Original research stand allows us to analyse not only the relative displacement but also the acceleration time history of the block. The experiments demonstrate that the Arias Intensity of the accelerogram is a good indicator of excitation threat to the stability of the slope. The numerical analyses conducted using the experimentally verified extended Newmark’s method indicate that both the Arias Intensity and the peak velocity of the excitation are good indicators of the impact of dynamic excitation on the dam's stability. The selection can be refined using complementary information, which is the dominant frequency and duration of the strong motion phase of the excitation, respectively.

  • Effect of Functionalization of Reduced Graphene Oxide Coatings with Nitrogen and Sulfur Groups on Their Anti-Corrosion Properties
    • Karolina Grajewska
    • Jakub Karczewski
    • Marek Lieder
    2021 Full text Materials

    Electrophoretic production of anticorrosion carbonaceous coatings on copper could be successfully performed by anodic oxidation of negatively charged graphene platelets suspended in an aqueous solution. The various platelets were synthesized by Hummer’s method followed by a hydrothermal reduction in the presence of NH4SCN which was expected to substitute some parts of graphene structure with nitrogen and sulfur groups. X-ray photoelectron spectroscopy analysis confirmed that the graphene precursors, as well as the coatings, contained typical nitrogen groups, such as pyridinic and pyrrolic, and sulfur groups, such as thiol, thiophene, or C-SO2 . However, due to oxidation during deposition, the qualitative and quantitative composition of the graphene coatings changed relative to the composition of the precursors. In particular, the concentration of nitrogen and sulfur dropped and some thiophene groups were oxidized to C-SO2 . Studies showed the functionalized coatings had a uniform, defect-free, hydrophobic, more adhesive surface than nonmodified films. The corrosion measurements demonstrated that these coatings had better protective properties than the ones without these heteroatoms. This behavior can be assigned to the catalytic activity of nitrogen towards oxidation of C-SO2 groups to C-SO3H with oxygen.

  • Effect of gas content in macropores on hydraulic fracturing in rocks using a fully coupled DEM/CFD approach
    • Marek Krzaczek
    • Michał Nitka
    • Andrzej Tejchman-Konarzewski
    2021 INTERNATIONAL JOURNAL FOR NUMERICAL AND ANALYTICAL METHODS IN GEOMECHANICS

    W pracy skupiono się na wpływie zawartości gazu w makroporach skał na proces szczelinowania hydraulicznego. Proces został zasymulowany przez połączenie metody elementów dyskretnych (DEM) z obliczeniową dynamiką płynów (CFD) w ramach dwuwymiarowych (2D) warunków izotermicznych. Mechaniczne zachowanie skały zostało zasymulowane za pomocą DEM, a CFD została wykorzystana do opisu zachowanie przepływu laminarnego, dwufazowego płynu szczelinującego (cieczy i gazu) we wcześniej istniejących i nowo powstałych szczelinach. Zmiany geometrii porów i pęknięć w matrycy skalnej zostały precyzyjnie odtworzone. W pełni sprzężone hydro-mechaniczne symulacje przeprowadzono na segmencie skalnym o uproszczonej mezostrukturze cząstek stałych pod wpływem odkształcenia płaskiego. Segment skalny zawierał jedno lub dwa gniazda wtryskowe. Wpływ początkowej zawartości fazy gazowej w makroporach na rozprzestrzenianie się szczelin hydraulicznych okreslono liczbowo dla różnych początkowych porowatości skał. Ponadto zbadano wpływ obecności różnych wcześniejszych nieciągłości w segmencie skalnym. Główne cechy pęknięcia segmentu skały w wyniku wtrysku płynu pod wysokim ciśnieniem zostały realistycznie odtworzone stosując proponowane podejście. Stwierdzono, że początkowa frakcja fazy gazowej w makroporach i istniejące wcześniej nieciągłości mają silny wpływ na przebieg szczelinowania hydraulicznego.

  • Effect of heat treatment on the diffusion intermixing and structure of the Cu thin film on Si (111) substrate: a molecular dynamics simulation study
    • Walery Pleczysty
    • Ihor Shtablavyi
    • Szymon Winczewski
    • Kamil Rybacki
    • B. Tsizh
    • Stepan Mudry
    • Jarosław Rybicki
    2021 MOLECULAR SIMULATION

    This work is devoted to the study of the diffusion process at the interface between copper films with a thickness of 2, 3, 4, 7 and 10 atomic monolayers and silicon substrate by molecular dynamics simulation method. For this purpose, the variation of the concentration of copper and silicon along the perpendicular direction to the interface was investigated. An analysis of the density profile along this direction made it possible to determine the melting point of the interface between copper and silicon. The atomic structure of the diffusion layer was compared with that of the bulk Cu3Si compound. Using the formalism pair correlation functions find partial coordination numbers distribution it was revealed the possibility of nucleation centres formation with the structure of the compound in the liquid state. This work will allow expanding knowledge about the process of atomic diffusion at the metal–semiconductor interface.

  • Effect of MAO coatings on cavitation erosion and tribological properties of 5056 and 7075 aluminum alloys
    • Marek Szkodo
    • Alicja Stanisławska
    • Aleksandr Komarov
    • Łukasz Bolewski
    2021 Full text WEAR

    Two ceramic coatings have been applied on 5056 and 7075 aluminum alloy by microarc oxidation (MAO) technology. The mass losses, surface morphologies and the phase constituents of the MAO coatings before and after cavitation tests were examined by means of digital scales, scanning electron microscopy (SEM) and X-ray diffraction (XRD), respectively. In order to assess the impact of the mechanical properties of the surface layer on cavitation erosion resistance, hardness (H), reduced Young's modulus (E), surface elastic properties (Wel), surface toughness (KIC), structure continuity and resistance to delamination and cohesion forces were determined using nanoindentation and scratch tests. The results indicate that there is a correlation between cavitation erosion resistance and hardness, H/E ratio and surface elasticity.

  • Effect of pH on optical sensing with poly-L-lysine-modified nanodiamonds
    • Maciej Jerzy Głowacki
    • Monika Janik
    • Mirosław Sawczak
    • Anna Wcisło
    • Paweł Niedziałkowski
    • Mateusz Ficek
    • Robert Bogdanowicz
    2021

    Nitrogen-vacancy (NV) centers are crystallographic defects which provide diamonds with unique physical properties. The centers are known for their intensive, time-stable fluorescence, and an electron spin, which exhibits long coherence time and may be manipulated using external stimuli. Nanodiamonds containing the NV centers are promising tools in biolabeling, biosensing, and drug delivery due to the aforementioned properties of the defects combined with a chemical inertness of a core and an easily functionalized surface of the diamond. Many biochemical reactions are pH-sensitive, therefore, in order to utilize the NV centers for monitoring of such processes, the pH-dependency of the properties of the nanodiamonds needs to be well-understood. Functionalization of the nanodiamonds’ surfaces with biological molecules undergoing pH-triggered changes of conformation, e.g. poly-L-lysine, could not only increase the particles’ biocompatibility and promote cell adhesion, but also possibly enhance pH-sensitivity. In the present study, an impact of pH on the fluorescence, a zeta potential, and a contact angle of the NV centers-containing nanodiamonds dispersed in liquid media is examined. The suspensions were made of commercially available, fluorescent diamond particles in an as-received, unmodified state, and after the poly-L-lysine had been attached to their surfaces via two different procedures – in aqueous, and anhydrous environment. Values of pH of dispersion media were specifically chosen to induce diverse conformation of the poly-L-lysine: from a fully relaxed conformation, through a state of being neither wholly extended, nor helical, to a complete α-helix conformation. The intensity of the photoluminescence emitted by the NV centers has been found to depend on the pH-triggered conformation of the poly-L-lysine attached to the surfaces of the nanodiamonds. The impact of the conformation of the poly-L-lysine on the electric charge of the nanoparticles has also been analyzed. This study confirms the potential of the nitrogen-vacancy centers for optical sensing of pH-triggered processes.

  • Effect of Pin Shape on Thermal History of Aluminum-Steel Friction Stir Welded Joint: Computational Fluid Dynamic Modeling and Validation
    • Dmitry Olegovich Bokov
    • Mohammed Abed Jawad
    • Wanich Suksatan
    • Mahmoud E. Abdullah
    • Aleksandra Świerczyńska
    • Dariusz Fydrych
    • Hamed Aghajani Derazkola
    2021 Full text Materials

    This article studied the effects of pin angle on heat generation and temperature distribution during friction stir welding (FSW) of AA1100 aluminum alloy and St-14 low carbon steel. A validated computational fluid dynamics (CFD) model was implemented to simulate the FSW process. Scanning electron microscopy (SEM) was employed in order to investigate internal materials’ flow. Simulation results revealed that the mechanical work on the joint line increased with the pin angle and larger stir zone forms. The simulation results show that in the angled pin tool, more than 26% of the total heat is produced by the pin. Meanwhile, in other cases, the total heat produced by the pin was near 15% of the total generated heat. The thermo-mechanical cycle in the steel zone increased, and consequently, mechanical interlock between base metals increased. The simulation output demonstrated that the frictional heat generation with a tool without a pin angle is higher than an angled pin. The calculation result also shows that the maximum heat was generated on the steel side.

  • Effect of small quantities of potassium promoter and steam on the catalytic properties of nickel catalysts in dry/combined methane reforming
    • Izabela Wysocka
    • Aleksandra Mielewczyk-Gryń
    • Marcin Łapiński
    • Bartłomiej Cieślik
    • Andrzej Rogala
    2021 INTERNATIONAL JOURNAL OF HYDROGEN ENERGY

    Carbon dioxide and methane are two of the principal greenhouse gases. Reduction of their content in the atmosphere is currently the subject of much worldwide research. Dry and combined reforming of methane are effective methods of CO2 and CH4 utilization and production of synthesis gas (syngas) in chemical technology. Testing of catalysts that provide the desired H2/CO ratio and long operation time is one of the critical aspects of syngas production and the focus of much study. In this study, K-promoted Ni/MgAl2O4 catalysts prepared using a co-precipitation-impregnation method with different K/Ni ratios (range of 0–0.15) were examined in dry reforming of methane (DRM). The obtained catalysts were characterized using X-ray diffractometry (XRD), atomic emission spectrometry (MP-AES), Brunauer–Emmett–Teller (BET) specific surface area, BJH pore size distribution, TEM imaging, analysis of reducibility H2-TPR, infrared spectroscopy (FTIR), X-ray photoelectron spectroscopy (XPS), Hammet basicity analysis, thermogravimetric analysis (TG) and elemental carbon-hydrogen-nitrogen analysis (CHN). Promotion of nickel catalysts with potassium led to changes in nickel distribution, metal-support interactions and deceleration of carbon deposition while enhancing sorption of carbon dioxide and reduction of nH2:CO to 0.5 for 0.7 K–Ni/MgAl2O4 catalyst. To obtain the required H2:CO ratio close to unity a study on the effect of steam in inlet stream was performed. It was found that maintaining inlet stream composition equal CH4:CO2:H2O = 1.0:1.0:0.1 obtained an H2:CO ratio close to unity.

  • Effect of surface on the flexomagnetic response of ferroic composite nanostructures; nonlinear bending analysis
    • Mohammad Malikan
    • Victor Eremeev
    2021 Full text COMPOSITE STRUCTURES

    Our analysis incorporates the geometrically nonlinear bending of the Euler-Bernoulli ferromagnetic nanobeam accounting for a size-dependent model through assuming surface effects. In the framework of the flexomagnetic phenomenon, the large deflections are investigated referring to von-Kármán nonlinearity. Employing the nonlocal effects of stress coupled to the gradient of strain generates a scale-dependent Hookean stress-strain scheme related to the small scale. Taking into account the supports of the nanobeam in two cases, that is, totally fixed and hinged, the deformations are predicted. A constant static lateral load is postulated uniformly along the length of the beam, which forces the deformation. As the analysis is based on the one-dimensional media, the electrodes are embedded so that they give off a transverse magnetic field creating a longitudinal force. The newly developed mathematical model is computed by means of the differential quadrature method together with the Newton-Raphson technique. The computational section discusses and reveals the numerical results in detail for the characteristics and parameters involved in the design of beam-like magnetic nanosensors. As shown later, the conducted research presents that there is a strong linkage between the surface effect and the flexomagneticity behavior of the bulk.

  • Effect of synthesis method parameters on properties and photoelectrocatalytic activity under solar irradiation of TiO2 nanotubes decorated with CdS quantum dots
    • Aleksandra Pieczyńska
    • Paweł Mazierski
    • Wojciech Lisowski
    • Tomasz Klimczuk
    • Adriana Zaleska-Medynska
    • Ewa Siedlecka
    2021 Journal of Environmental Chemical Engineering

    The growing research interest on photoelectrocatalysis has encouraged the search for new materials with high activity and the development of methods for their synthesis. The successive ionic layer adsorption and reaction (SILAR) method is an effective way to synthesize materials with photoelectrocatalytic (PEC) properties that are active under visible radiation. Therefore, studies on the impact of the parameters of the SILAR method on the properties and PEC activity of TiO2 nanotubes sensitized with CdS quantum dots (QDs) were conducted. PEC activity was determined based on the efficiency of ifosfamide (IF) degradation, which is currently one of the most commonly detectable anticancer drugs in aquatic environment. The highest IF PEC degradation rate (0.0184 min 1) and the highest TOC removal (48%) was achieved with the CdS-Ti/TiO2_NO3 _0.1M_3c_60s photoelectrode. Among the SILAR parameters, the highest impact on the PEC IF degradation efficiency had the concentration of the Cd precursor, as well as the number and time of the cycles. Our studies showed that CdS-Ti/TiO2 nanocomposites exhibited more than twice higher photocatalytic and PEC IF degradation efficiency than pristine Ti/TiO2 under UV–Vis irradiation. In addition, the PEC mechanism of IF degradation using pristine Ti/TiO2 and CdS-Ti/TiO2 was compared, from which it was concluded that the higher PEC activity of the nanocomposites is due to the greater contribution of h+ and the generation of other oxidants caused by the presence of CdS QDs. Based on the identified degradation products, a pathway for PEC IF degradation was also proposed.

  • Effect of Temperature and Nanoparticle Concentration on Free Convective Heat Transfer of Nanofluids
    • Janusz Cieśliński
    • Sławomir Smoleń
    • Dorota Sawicka
    2021 Full text ENERGIES

    A theoretical analysis of the influence of temperature and nanoparticle concentration on free convection heat transfer from a horizontal tube immersed in an unbounded nanofluid was presented. The Nusselt (Nu) number and heat transfer coefficient were parameters of the intensity of the convective heat transfer. For free convection, the Nu number was a function of the Rayleigh (Ra) number and Prandtl (Pr) number. The Rayleigh (Ra) number and Prandtl (Pr) number were functions of the thermophysical properties of nanofluids. The thermophysical properties of nanofluids varied with temperature and nanoparticle concentration. Therefore, an analysis was conducted to evaluate the effects on the performance of nanofluids due to variations of thermal conductivity, viscosity, thermal expansion, density, and specific heat, which are functions of nanoparticle concentration and temperature. Water- and ethylene glycol (EG)-based nanofluids with dispersed alumina (Al2O3) nanoparticles at mass concentrations of 0.01%, 0.1%, and 1% were considered. Calculated Nu numbers and heat transfer coefficients were compared with experimental values taken from the published literature.

  • Effect of the Cavitation Generation Unit Structure on the Performance of an Advanced Hydrodynamic Cavitation Reactor for Process Intensifications
    • Xun Sun
    • Weibin You
    • Xiaoxu Xuan
    • Li Ji
    • Xingtao Xu
    • Guichao Wang
    • Shan Zhao
    • Grzegorz Boczkaj
    • Joon Yong Yoon
    • Songying Chen
    2021 Full text CHEMICAL ENGINEERING JOURNAL

    The advanced rotational hydrodynamic cavitation reactors (ARHCRs) that appeared recently have shown obvious advantages compared with conventional devices in process intensifications. In ARHCRs, the cavitation generation unit (CGU) located on the rotor and stator basically determines their performance. For the first time, the present study investigated the effect of the CGU structure on the performance of a representative ARHCR by utilizing computational fluid dynamics. The amount of generated cavitation and required torque of the axis for various shapes, diameters, interaction distances, heights, and inclination angles of the CGU were analyzed. The results indicate that the interaction-type ARHCR (cavitation is generated by stator-rotor interaction) was far superior to the non-interaction type one. In addition, the hemisphere-shaped CGU demonstrates the best performance compared with that with cone-cylinder, cone, and cylinder shapes. Moreover, by evaluating the effects of various geometrical factors, the hemisphere-shaped CGU with a diameter of 12 mm, interaction distance of 1 mm, height of 1 mm, and inclination angle of 10° achieved the highest performance. The reasons leading to different performance were elaborated in accordance with the flow and pressure field distributions, as well as the generated cavitation patterns. The findings of this work can strongly support the fundamental understanding, design, and application of ARHCRs for process intensifications.

  • Effect of the let-through energy of overcurrent protective devices on the temperature of conductors during short-circuits
    • Stanisław Czapp
    • Daniel Kowalak
    2021 Full text Przegląd Elektrotechniczny

    The scope of the verification of low-voltage systems covers the earth fault loop impedance measurement. This measurement is usually performed with the use of low-value current meters, which force a current many times lower than the one occurring during a real short-circuit. Therefore, the international standard recommends consideration of the increase of resistance of conductors with the increase of temperature, which may occur during short-circuits. This paper analyses the temperature rise of the conductors during short-circuits, taking into account the let-through energy of protection devices. The analysis has shown that in typical circuits the temperature rise of conductors is not significant.

  • Effect of Thermal Treatment and Erosion Aggressiveness on Resistance of S235JR Steel to Cavitation and Slurry
    • Alicja Krella
    • Dominika Zakrzewska
    • Marta Buszko
    • Artur Marchewicz
    2021 Full text Materials

    S235JR steel is used in many applications, but its resistance to the erosion processes has been poorly studied. To investigate this resistance, cavitation, and slurry erosion tests were conducted. These tests were carried out at different erosion intensities, i.e., different flow rates in the cavitation tunnel with a system of barricades and different rotational speeds in the slurry pot. The steel was tested as-received and after thermal treatment at 930 °C, which lowered the hardness of the steel. To better understand the degradation processes, in addition to mass loss measurements, surface roughness and hardness were measured. Along with increasing erosion intensity, the mass loss increased as well. However, the nature of the increase in mass loss, as well as the effect of steel hardness on this mass loss, was different for each of the erosion processes. In the cavitation erosion tests, the mass loss increased linearly with the increase in flow velocity, while in the slurry tests this relationship was polynomial, indicating a strong increase in mass losses with an increase in rotational speed. Cavitation erosion resulted in stronger and deeper strain hardening than slurry. Surface damage from cavitation erosion tests was mainly deep pits, voids, and cracks during the slurry tests, while flaking was the most significant damage.

  • Effect of TiO2 Concentration on Microstructure and Properties of Composite Cu–Sn–TiO2 Coatings Obtained by Electrodeposition
    • Aliaksandr Kasach
    • Dmitry Kharitonov
    • Andrei Paspelau
    • Jacek Ryl
    • Denis Sergievich
    • Ivan Zharskii
    • Irina Kurilo
    2021 Full text Materials

    In this work, Cu–Sn–TiO2 composite coatings were electrochemically obtained from a sulfate bath containing 0–10 g/L of TiO2 nanoparticles. The effect of TiO2 particles on kinetics of cathodic electrodeposition has been studied by linear sweep voltammetry and chronopotentiometry. As compared to the Cu–Sn alloy, the Cu–Sn–TiO2 composite coatings show rougher surfaces with TiO2 agglomerates embedded in the metal matrix. The highest average amount of included TiO2 is 1.7 wt.%, in the case of the bath containing 5 g/L thereof. Composite coatings showed significantly improved antibacterial properties towards E. coli ATCC 8739 bacteria as compared to the Cu–Sn coatings of the same composition. Such improvement has been connected with the corrosion resistance of the composites studied by linear polarization and electrochemical impedance spectroscopy. In the bacterial media and 3% NaCl solutions, Cu–Sn–TiO2 composite coatings have lower corrosion resistance as compared to Cu–Sn alloys, which is caused by the nonuniformity of the surface.

  • Effect of urea and glycine betaine on the hydration sphere of model molecules for the surface features of proteins
    • Marcin Stasiulewicz
    • Aneta Panuszko
    • Maciej Śmiechowski
    • Piotr Bruździak
    • Paweł Maszota
    • Janusz Stangret
    2021 JOURNAL OF MOLECULAR LIQUIDS

    Water properties may significantly affect protein stability. Osmolytes are compounds that intrinsically affect water in many different ways and thus can influence proteins with this type of indirect mechanism. In this study, we characterize water properties in ternary solutions: model–water–osmolyte, with two model molecules: N-methylacetamide (NMA) and dimethyl sulfoxide (DMSO) and two osmolytes: glycine betaine (TMG)and urea. We focus primarily on the water affected simultaneously by two solutes and propose a new FTIR-based experimental approach to study their properties. Our findings, supported by DFT and AIMD calculations, indicate that TMG promotes hydration cage enhancement around both model molecules. However, direct model–TMG interactions are rare. Simultaneously, urea interacts with them directly, displacing water molecules and weakening the hydrogen bonds in overlapped hydration spheres. The latter behavior results from the cooperativity loss between hydrophobic and hydrophilic-type hydration exhibited by the model molecules in the absence of urea. Relating the obtained results to protein systems, in the case of both osmolytes, the potential mechanism of stabilization–destabilization of these biomolecules is enthalpy-driven

  • Effective Drug Concentration and Selectivity Depends on Fraction of Primitive Cells
    • Jan Lica
    • Miłosz Wieczór
    • Grzegorz Jan Grabe
    • Mateusz Heldt
    • Marta Jancz
    • Majus Misiak
    • Katarzyna Gucwa
    • Wioletta Brankiewicz
    • Natalia Maciejewska
    • Anna Stupak
    • Maciej Bagiński
    • Krzysztof Rolka
    • Andrzej Hellmann
    • Andrzej Składanowski
    2021 Full text INTERNATIONAL JOURNAL OF MOLECULAR SCIENCES

    Poor efficiency of chemotherapeutics in the eradication of Cancer Stem Cells (CSCs) has been driving the search for more active and specific compounds. In this work, we show how cell density-dependent stage culture profiles can be used in drug development workflows to achieve more robust drug activity (IC50 and EC50) results. Using flow cytometry and light microscopy, we characterized the cytological stage profiles of the HL-60-, A-549-, and HEK-293-derived sublines with a focus on their primitive cell content. We then used a range of cytotoxic substances—C-123, bortezomib, idarubicin, C-1305, doxorubicin, DMSO, and ethanol—to highlight typical densityrelated issues accompanying drug activity determination. We also showed that drug EC50 and selectivity indices normalized to primitive cell content are more accurate activity measurements. We tested our approach by calculating the corrected selectivity index of a novel chemotherapeutic candidate, C-123. Overall, our study highlights the usefulness of accounting for primitive cell fractions in the assessment of drug efficiency.