Publications Repository - Gdańsk University of Technology

Page settings

polski
Publications Repository
Gdańsk University of Technology

Show publications from the year

Recent items

  • Comparison of the paracetamol electrochemical determination using boron-doped diamond electrode and boron-doped carbon nanowalls
    • Paweł Niedziałkowski
    • Zofia Celuba
    • Natalia Malinowska
    • Wioleta Białobrzeska
    • Michał Sobaszek
    • Mateusz Ficek
    • Robert Bogdanowicz
    • Jacek Sein Anand
    • Tadeusz Ossowski
    2019 Full text BIOSENSORS & BIOELECTRONICS

    Two different type of electrodes, boron-doped diamond electrode (BDD) and boron-doped carbon nanowalls (B:CNW) electrode, were used for the electrochemical determination of paracetamol using the cyclic voltammetry and the differential pulse voltammetry in phosphate buffered saline, pH = 7.0. The main advantage of these electrodes is their utilization without any additional modification of the electrode surface. The peak current was linearly related to the concentration of paracetamol in the range from 0.065 µM to 32 µM for BDD electrode and from 0.032 µM to 32 µM for B:CNW electrode. The limit of detection was 0.430 µM and 0.281 µM for BDD and B:CNW electrode, respectively. Additionally, we studied the effect of pH on the redox reaction of paracetamol at the both electrodes in Britton-Robinson buffer solution in the range of pH 3.0–12.0, indicating the pH 7.0 value as the most suitable for the current experiments. The studies also included the various scan rates in range of 50–500 mV/s. Finally, our team selected the B:CNW electrode for the determination of paracetamol in the artificial urine sample using differential pulse voltammetry method, obtaining the calculated limit of detection on the level of 0.08006 µM.

  • Compensation Topologies in IPT Systems: Standards, Requirements, Classification, Analysis, Comparison and Application
    • Viktor Shevchenko
    • Oleksandr Husev
    • Ryszard Strzelecki
    • Bohdan Pakhaliuk
    • Nikolai Poliakov
    • Natalia Strzelecka
    2019 Full text IEEE Access

    Wireless power transfer devices are becoming more relevant and widespread. Therefore, an article is devoted to a review, analysis and comparison of compensation topologies for an inductive power transfer. A new classification of topologies is developed. A lot of attention is paid to the problems of the physical fundamentals of compensation work, standards, safety, and five main topology requirements. It is determined, that topologies with the series primary compensating are the most effective in the IPT for charging devices among the four classical schemes. The series-parallel solution is recommended in case of the low output voltage, minimum size of a secondary side coil is achievable. The series-series solution does not depend on the magnetic coupling coefficient and the load on the resonance frequency. For the convenience of displaying and understanding the information, the comparison results are listed in the tables, graphs and dependencies. The main suitable topologies for a certain application are defined. The given conclusions provide a “one-stop” information source and a selection guide on the application of compensation topologies both in terms of devices and in terms of power level that is the main value of this paper. During literature analysis and recent trends in the market for wireless power transmission devices, the main possible further ways of developing topologies are underlined. First of all, it concerns increasing the frequency of resonance of compensation topologies, the use of multilevel / multi-pulse / multicoils structures, the study of existing high-frequency semiconductors and the development of the semiconductor and magnetic materials.

  • Compressed Projection Bases for Model-Order Reduction of Multiport Microwave Components Using FEM
    • Martyna Mul
    • Damian Szypulski
    • Grzegorz Fotyga
    • Michał Mrozowski
    2019 Full text

    This paper presents a projection basis compression technique for generating compact reduced-order models (ROM) in the FE analysis of microwave devices. In this approach redundancy is removed from the projection basis by means of the proper orthogonal decomposition technique applied to the projected system of linear equations. Compression allows for keeping the size of a reduced-order model as small as possible without compromising ROM’s accuracy. Effectiveness of the basis compression technique, including memory and time consumption as well as the size of the resultant ROM, are discussed for both global and local model-order reduction schemes.

  • Computational collective intelligence for enterprise information systems
    • Ngoc-Thanh Nguyen
    • Dosam Hwang
    • Edward Szczerbicki
    2019 Enterprise Information Systems

    Collective intelligence is most often understood as a kind of intelligence which arises on the basis of a group (collective) of autonomous unites (people, systems) which is taskoriented. There are two important aspects of an intelligent collective: The cooperation aspect and the competition aspect (Levy 1997). The first of them means the possibility for integrating the decisions made by the collective members for creating the decision of the collective as a whole. The second aspect, on the other hand, states the diversity of the collective members. It has been proved that for prediction market tasks, these two aspects have an important impact on the collective prediction accuracy. This means, in the general case, that owing to manipulating them one can achieve a given level of intelligence for a collective (Maleszka and Nguyen 2015; Nguyen and Nguyen 2018).

  • Computational Fluid Dynamic study on the wind characteristics of a multifunctional building system model in developed coastal cities
    • Mateusz Gerigk
    • Jacek Jachowski
    2019 Full text Zeszyty Naukowe Akademii Morskiej w Szczecinie

    This paper presents an approach for providing innovative technology by applying fluid mechanics to the field of architectural design. The aim is to make a building’s shape profitable and strengthen environmental protection by using the wind force to create an integrated wind absorption definition for a multifunctional building system model. Furthermore, taking control of the wind flow over an object can have an impact on not only the designed object itself but also on its surroundings. In modern coastal cities there are issues associated with the wind and ventilation that need to be solved. The presented system model and the calculations conducted are part of the new definition of a multifunctional object and the wind force as a significant subsystem. Systematizing this scope can be useful in design practice.

  • Computationally Effcient Solution of a 2D Diffusive Wave Equation Used for Flood Inundation Problems
    • Wojciech Artichowicz
    • Dariusz Gąsiorowski
    2019 Full text Water

    This paper presents a study dealing with increasing the computational efficiency in modeling floodplain inundation using a two-dimensional diffusive wave equation. To this end, the domain decomposition technique was used. The resulting one-dimensional diffusion equations were approximated in space with the modified finite element scheme, whereas time integration was carried out using the implicit two-level scheme. The proposed algorithm of the solution minimizes the numerical errors and is unconditionally stable. Consequently, it is possible to perform computations with a significantly greater time step than in the case of the explicit scheme. An additional efficiency improvement was achieved using the symmetry of the tridiagonal matrix of the arising system of nonlinear equations, due to the application of the parallelization strategy. The computational experiments showed that the proposed parallel implementation of the implicit scheme is very effective, at about two orders of magnitude with regard to computational time, in comparison with the explicit one.

  • Concentration levels of selected analytes in the gas phase of an e-cigarette aerosol
    • Justyna Aszyk
    • Mateusz Kacper Woźniak
    • Paweł Kubica
    • Agata Kot-Wasik
    • Andrzej Wasik
    2019 Full text MICROCHEMICAL JOURNAL

    The aerosols generated from e-cigarettes are composed of liquid and gas phases resulting from vapourized e-liquid. The apportioning of substances from e-liquid into the liquid and gas phases during e-cigarette use has not been extensively studied. Partitioning of e-liquid components between the gas and the liquid phase of the aerosol influences the substances inhaled and exhaled by the users, leading to second-hand exposure. It seems important to determine which compounds and how much of them are transferred into the gas phase and may immediately enter the bloodstream. For this purpose, a method based on thermal desorption followed by gas chromatography coupled with tandem mass spectrometry (GC–MS/MS) in electron ionization mode was developed. As in a previous study, an automatic generator of an aerosol from an e-cigarette with a collection tube filled with melt-blown non-woven fabric discs and equipped with Tenax TA sorption tubes was used. The melt-blown non-woven fabric is designed to capture liquid phase compounds, while sorption tubes are meant to sorb compounds in the gas phase of the aerosol. To control the e-liquid mass changes before and after a puff session, quantitation based on the mass change tracking approach (MCT) was applied. Accuracy of the developed method ranged between 91% and 110% regardless of the spiking level, with precision and reproducibility better than 10%. The limits of detection (LODs) ranged from 0.015 to 0.076 ng of substance emitted/mg of consumed e-liquid, while limits of quantitation (LOQs) ranged from 0.045 to 0.23 ng of substance emitted/mg of consumed e-liquid. Most of the compounds are deposited in the liquid phase of the aerosol, while only trace levels of some substances may be observed in an actual, non-condensed gas phase.

  • Concentrations and loads of DOC, phenols and aldehydes in a proglacial arctic river in relation to hydro-meteorological conditions. A case study from the southern margin of the Bellsund Fjord – SW Spitsbergen
    • Sara Lehmann-Konera
    • Waldemar Kociuba
    • Stanisław Chmiel
    • Łukasz Franczak
    • Żaneta Polkowska
    2019 CATENA

    Climate warming accelerates the melting and thawing of cryosphere components. Therefore, it favours the release of contaminants stored in High-Arctic glaciers for many years. The rate of land-based glacier retreat is of particular importance for the hydrological regime of glacial rivers, but also for the chemical composition of their waters. In this study, we examined 84 surface water samples collected during a period of 42 days (melt season 2012) from the Scott River of glacial-hydrological regime (NW Wedel-Jarlsberg Land). The studies of Scott River hydro-meteorological conditions provided indication on the relation between mean air temperatures (T) and mean daily discharge (Q) (r = 0.67). Moreover, they confirmed the role of short-term meteorological events (increasing of air temperature and heavy precipitation) on the acceleration of glacier melt. In this context, the study also demonstrated incidents of the release of a more concentrated pulse of chemical compounds delivered by the Scottbreen valley glacier. The analysis covered fluctuations of physicochemical parameters, and presence of selected organic pollutants (∑phenols, formaldehyde (HCHO)). Based on the correlation matrix analysis, it was found that fluctuations of physicochemical indices (pH, specific electrolytic conductivity (SEC) and dissolved organic carbon (DOC)) were related to changes in T and Q. Principal components analysis (PCA)permitted us to distinguish two principal components (hydro-meteorological and biogeochemical conditions) responsible for 71.1% of the total hydrochemical variation. In terms of the first principal component, it was found that there was a relationship with the intensified ablation of glacier ice and with the second one, the influence of geological and biological conditions of the environment on the chemistry of the river. The combination of these factors directly shaped the hydrochemistry of the proglacial river during the melt season of 2012. The results of organic compound loads, which are presented in this paper provide unique information about the transport of contaminants such as: (DOC) (9.41–579 mgC s−1), ∑phenols (19.7–534 mg s−1), HCHO (34.0–82.3 mg s−1)) in the Scott River. It is worth noting that the differentiation of concentration and mean daily loads of DOC, between the gorge (96.0 mgC s−1) and mouth (99.6 mgC s−1) sections of the river, were related with the activity of a herring gull (Larus argentatus) colony at the river mouth.

  • Concrete mix design using machine learning
    • Patryk Ziółkowski
    • Maciej Niedostatkiewicz
    2019

    Designing a concrete mix is a process of synthesizing many components, it is not a simple process and requires extensive technical knowledge. The design process itself focuses on obtaining the required strength of concrete. Very often designing a concrete mix takes into account the need to maintain the proper water-demand and frost-resistance features. The parameters that influence the concrete class most significantly are the water-cement ratio along with the type and amount of cement and aggregate (crumb pile composition). However, in practice, the design of a concrete mix is done using additives, the so-called plasticizers, which are workability improving agents, as well as increasing frost resistance and aeration. Nowadays, the most widely used concrete mix design approaches are computational-experimental methods based on three-equations method, which allow estimating the amount of aggregate, cement and water. The results obtained in such a way requires laboratory verification. An entirely new approach is a prediction of concrete strength using extensive databases and machine learning algorithms, which can bring some potential benefits, the most important of which is the automation of the concrete mix design process. This paper aims to present preliminary work on the application of data mining in a concrete mix designing process. The primary parameter of concern is concrete compressive strength. The analysis is base on ready-made formulas of concrete mixes from personal resources, prepared for structural concretes of various classes. Furthermore, recently many researchers work on developing perfect concrete compressive strength prediction formula, which makes it an active field of research. © Federation Internationale du Beton (fib) - International Federation for Structural Concrete, 2019.

  • Condition of Reinforced Concrete Structures and Their Degradation Mechanism at the Former Auschwitz Concentration and Extermination Camp
    • Michał Szociński
    • Andrzej Miszczyk
    • Kazimierz Darowicki
    2019 Full text STUDIES IN CONSERVATION

    This paper presents the results of investigations on reinforced concrete structures present in the former Auschwitz I and Auschwitz II-Birkenau concentration and extermination camp. Field inspection employing the non-destructive method of reinforcement potential measurement according to the ASTM-C 876–15 standard, followed by laboratory investigations performed on genuine historic reinforced concrete samples collected from the former Auschwitz camp, allowed assessment of the actual condition of this 70-year-old construction material. Electrochemical potential measurements allowed mapping of the regions characterized by enhanced reinforcement corrosion risk and the regions of its immunity. The composition of concrete, water absorbency, content of detrimental salts, and degree and profile of carbonation as well as mechanical properties were evaluated. Results revealed the most common and probable mechanism responsible for degradation of the reinforced concrete structures in the former Auschwitz camp.

  • CONDITIONS, STREAM AND OUTLOOK FOR ECONOMIC MIGRATION FROM ASIA TO POLAND
    • Robert Sterniński
    2019

    The aim of the article is to present the data about the conditions and perspectives of economic migration from Asia to Poland and data on the stream of this phenomenon in recent years based on work permission documents. The first part presents an introduction on the general migration situation to Poland in recent years and describes the theoretical approach to the aspect of migration. Then the legal conditions of migrants' work in Poland and the method of obtaining data for the purposes of the survey were presented. The study was conducted on the basis of issued work permits and declarations of entrustment of work for migrants from Asia. The last part summarizes and presents the conclusions.

  • Constant vs. Variable Efficiency of Electric Drive in Train Run Simulations
    • Aleksander Jakubowski
    • Leszek Jarzębowicz
    2019 Full text

    Train run simulations, which focus on various power- and energy-oriented aspects, should reflect the losses in the electric powertrain. In general, the powertrain efficiency varies with respect to load and speed. Including this relation in simulation requires knowledge about detailed drivetrain parameters, which are often unavailable. This paper verifies the possibility to approximate the drivetrain efficiency in train run simulations by an equivalent constant that provides the same results of total energy usage. A case study of a suburban electric traction unit was selected to compare results of simulations carried out for different operating conditions including: route length, cruising speed and route inclination. The impact of replacing the variable efficiency with the equivalent constant on various outcomes of train run simulations was discussed and the limitations were formulated.

  • Constrained optimization for generating gain-bandwidth design trade-offs of wideband unidirectional antennas
    • Sławomir Kozieł
    • Adrian Bekasiewicz
    2019 IET Microwaves Antennas & Propagation

    Broadband unidirectional antennas realised in microstrip technology find applications in many wireless communication systems. One of their design challenges is the necessity of handling multiple performance figures which is difficult when using traditional design methods, largely based on parameter sweeping. This work presents a simple optimisation-based framework that permits generation of gain-bandwidth trade-off designs for this class of antenna structures. The proposed methodology exploits sequentially executed constrained optimisation runs which produce maximum-gain designs across the range of prescribed target impedance bandwidths. To control the latter, design constraints are imposed on the reflection response but also on gain variability to ensure flat in-band characteristics. For the sake of demonstration, an example compact wideband quasi-Yagi antenna is considered for which a set of trade-off designs is obtained with the impedance bandwidth varied from 9 to over 54%, and corresponding gain levels from 7.4 dB to around 5.5 dB, which determines the antenna capabilities in terms of these performance figures. The approach proposed in this work can be utilised as a design aid as well as a tool for quantitative performance comparison of different (alternative) antenna topologies.

  • CONSUMERS’ APPROACH TO THE CREDIBILITY OF THE INFLATION FORECASTS PUBLISHED BY CENTRAL BANKS: A NEW METHODOLOGICAL SOLUTION
    • Karolina Tura-Gawron
    2019 Full text JOURNAL OF MACROECONOMICS

    Modern monetary policy focuses on credibility and shaping inflation expectations. In keeping with the concept of inflation forecast targeting, the inflation forecasts published by central banks play a crucial role in the instrument rate decision-making process and may be treated as a specific intermediate target. This study proposes an inflation forecast credibility index, the scope of which is narrowed to non-specialists’ approach to inflation forecasts. The credibility of the forecast is defined as the ability to shape consumers’ inflation expectations. This ability is measured as the absolute difference between the central paths of inflation forecasts (the mode values) in the one-year forecast horizon and one-year consumers’ inflation expectations. The inflation forecast is represented in the study as a function of forecast attributes (accuracy, similarity, and deviation from the inflation target). The credibility function of the forecast is derived from belief function theory, normally distributed, and determined by the linear function of the chosen forecast attributes. The importance of these attributes depends on whether monetary policy was conducted before or after reaching the zero lower bound on the policy rate. The credibility index is calculated for the inflation forecasts published by the central banks of the United Kingdom and Sweden. The main conclusion of the study is that the deviations of the forecast in the last year of the forecast horizon and similarity between consecutive forecasts are important forecast attributes for shaping the inflation expectations of consumers before and after reaching the zero lower bound on the policy rate, and may determine the inflation forecast’s credibility. However, the similarity to consecutive forecasts affects the forecast’s credibility in opposite ways before and after reaching the zero lower bound on the policy rate.

  • Container port expansion towards the sea in the context of maritime spatial planning
    • Karolina Krośnicka
    2019 Full text EUROPA XXI

    The growth of ships causes a significant increase in demand for new port surfaces and demands for the depths of water bodies in the ports. Due to technological changes in the transshipment and development pressure ports lacks space and they move towards the sea with their activities. The paper discusses the reasons for the phenomenon of expansion of ports towards the sea and its effects on maritime spatial planning.

  • Context-Aware Indexing and Retrieval for Cognitive Systems Using SOEKS and DDNA
    • Caterine De Silva Oliveira
    • Cesar Sanin
    • Edward Szczerbicki
    2019 Full text Advances in Intelligent Systems and Computing

    Visual content searching, browsing and retrieval tools have been a focus area of interest as they are required by systems from many different domains. Context-based, Content-Based, and Semantic-based are different approaches utilized for indexing/retrieving, but have their drawbacks when applied to systems that aim to mimic the human capabilities. Such systems, also known as Cognitive Systems, are still limited in terms of processing different sources of information (especially when structured in different ways) for decision making purposes. This issue becomes significantly greater when past information is retrieved and taken in account. We address this issue by proposing a Structuralized Context-Aware Indexing and Retrieval using Set of Experience Knowledge Structure (SOEKS) and Decisional DNA (DDNA). SOEKS and DDNA allow the creation of a multi-modal space composed of information from different sources, such as contextual, visual, auditory etc., in a form of a structure and explicit experiential knowledge. SOKES is composed by fields that allow this experiences to participate in the processes of similarity, uncertainty, impreciseness, or incompleteness measures and facilitate the indexing and retrieval of knowledge in Cognitive Systems.

  • Continuum wave functions for estimating the electric dipole moment: Calculation based on a multiconfiguration Dirac-Hartree-Fock approximation
    • Paweł Syty
    • Józef Eugeniusz Sienkiewicz
    • Laima Radžiūtė
    • Gediminas Gaigalas
    • Pavel Rynkun
    • Jacek Bieroń
    2019 Full text PHYSICAL REVIEW A

    The multiconfiguration Dirac-Hartree-Fock method is employed to calculate the continuum electron wave functions, which are then used to estimate their contribution to the atomic electric dipole moment (EDM) of 129Xe. The EDM arises from (P,T)-odd electron-nucleon tensor-pseudotensor and pseudoscalar-scalar interactions, the nuclear Schiff moment, the interaction of the electron electric dipole moment with nuclear magnetic moments, and atomic electric dipole matrix elements. In addition to being estimated in the continuum states, all of these interactions are also estimated in the ground state, as well as in the Rydberg states of 129Xe. Calculations of one-electron atomic orbitals include the interelectronic interactions, through valence and core-valence electron correlation effects. The contribution to the EDM from continuum states is found to be of the same order of magnitude as the contribution from discrete states.

  • Control of a vapour microturbine set in cogeneration applications
    • Wojciech Włodarski
    2019 Full text ISA TRANSACTIONS

    Systems with microturbines are implemented for local generation of heat and electricity. This paper presents the analysis of control concepts for a vapour microturbine set with a generator with permanent magnets, intended to work in small heat and power plants. Control system variants differed by the selection of controlled signals and set parameters. Possible ways of control were discussed and compared with experimentally determined static characteristics of the microturbine set. The simulation calculations were performed to check the control systems operation in various expected operating conditions.

  • Co-operation with local stakeholders: a crucial element of urban design
    • Anna Golędzinowska
    • Małgorzata Kostrzewska
    2019 Full text World Transactions on Engineering and Technology Education

    In this article,the authors endeavour to illustratethe evolution of the role of local stakeholder in teaching urban planning by example of selected experiences in the Faculty of Architecture atGdańsk University of Technology(FA-GUT), Gdańsk, Poland. The timeframe covers the period from the political breakthrough in 1989 to the present. The background is composed of the social, economic and legal changes that have taken place over the years in Poland. The authors also attempt to identify the present local stakeholders; the value of co-operation for the education process; and the added value each can bring.

  • Copper and cobalt co-doped ceria as an anode catalyst for DIR-SOFCs fueled by biogas
    • Beata Bochentyn
    • Mikołaj Chlipała
    • Maria Gazda
    • Sea-Fue Wang
    • Piotr Jasiński
    2019 Full text SOLID STATE IONICS

    The nanocrystalline compounds of Co and Cu co-doped ceria (with up to 20 mol.% of dopants) were fabricated by the reverse microemulsion synthesis method. They were deposited in a form of layers on the surface of SOFC anode in an aim to act as electrochemically active materials for biogas reforming process. Fourier Transformed Infrared Spectroscopy was used to analyze a composition of outlet gases simultaneously with the tests of electrical parameters of a fuel cell. It allowed comparing a catalytic activity of fabricated materials towards internal biogas reforming. It was found that Cu and Co ceria co-doping improves electrical parameters of a fuel cell and enhances its long-term stability when compared with mono-doped ceria. This type of a material gives also the highest conversion rate of methane and the highest yield of carbon monoxide.

  • Cops, a fast robber and defensive domination on interval graphs
    • Dariusz Dereniowski
    • Tomáš Gavenčiak
    • Jan Kratochvíl
    2019 Full text THEORETICAL COMPUTER SCIENCE

    The game of Cops and ∞-fast Robber is played by two players, one controlling c cops, the other one robber. The players alternate in turns: all the cops move at once to distance at most one each, the robber moves along any cop-free path. Cops win by sharing a vertex with the robber, the robber by avoiding capture indefinitely. The game was proposed with bounded robber speed by Fomin et al. in “Pursuing a fast robber on a graph”, generalizing a well-known game of Cops and Robber which has robber speed 1. We answer their open question about the computational complexity of the game on interval graphs with ∞-fast robber, showing it to be polynomially decidable. We also generalize the concept of k-defensive domination introduced by Farley and Proskurowski in “Defensive Domination” to A--defensive domination and use it as a main tool in our proof. The generalization allows specifying arbitrary attacks and limiting the number of defenders of each vertex. While this problem is NP-complete even for split graphs, we show that A-defensive domination is decidable in polynomial time on interval graphs.

  • CORPORATE BANKRUPTCY PREDICTION IN POLAND AGAINST THE BACKGROUND OF FOREIGN EXPERIENCE
    • Błażej Prusak
    2019 Full text Financial Internet Quarterly

    In highly developed countries, research in the field of bankruptcy risk prediction has been conducted for many years. For example, in the United States, which can be considered a pioneering country, the first publications appeared in the early twentieth century. In Poland, due to political and economic reasons, the interest in this issue dates back to the early 1990s. For this reason, this publication attempts to answer the following questions: 1) What is the level of advancement of the research into predicting bankruptcies of enterprises in Poland? 2) How does it compare to worldwide trends? Therefore, the main aim of this study is to present and evaluate the scientific achievements of Polish authors in the field of corporate bankruptcy prediction and compare them to global trends. Literature analysis was adopted as the research method and shows that initially in Poland only very simple tools were used to assess the risk of bankruptcy of enterprises. With time, however, advanced methods began to be introduced and new models included non-financial variables. Also, research on the selection of the samples was conducted. Currently, the level of research and applied tools do not differ from those used in highly developed countries.

  • CORPORATE BANKRUPTCY PREDICTION IN POLAND AGAINST THE BACKGROUND OF FOREIGN EXPERIENCE
    • Błażej Prusak
    2019 Full text Financial Internet Quarterly

    In highly developed countries, research in the field of bankruptcy risk prediction has been conducted for many years. For example, in the United States, which can be considered a pioneering country, the first publications appeared in the early twentieth century. In Poland, due to political and economic reasons, the interest in this issue dates back to the early 1990s. For this reason, this publication attempts to answer the following questions: 1) What is the level of advancement of the research into predicting bankruptcies of enterprises in Poland? 2) How does it compare to worldwide trends? Therefore, the main aim of this study is to present and evaluate the scientific achievements of Polish authors in the field of corporate bankruptcy prediction and compare them to global trends. Literature analysis was adopted as the research method and shows that initially in Poland only very simple tools were used to assess the risk of bankruptcy of enterprises. With time, however, advanced methods began to be introduced and new models included non-financial variables. Also, research on the selection of the samples was conducted. Currently, the level of research and applied tools do not differ from those used in highly developed countries.

  • Corrosion Inhibition Mechanism and Efficiency Differentiation of Dihydroxybenzene Isomers Towards Aluminum Alloy 5754 in Alkaline Media
    • Jacek Ryl
    • Mateusz Brodowski
    • Marcin Kowalski
    • Wiktoria Lipińska
    • Paweł Niedziałkowski
    • Joanna Wysocka
    2019 Full text Materials

    The selection of efficient corrosion inhibitors requires detailed knowledge regarding the interaction mechanism, which depends on the type and amount of functional groups within the inhibitor molecule. The position of functional groups between different isomers is often overlooked, but is no less important, since factors like steric hinderance may significantly affect the adsorption mechanism. In this study, we have presented how different dihydroxybenzene isomers interact with aluminum alloy 5754 surface, reducing its corrosion rate in bicarbonate buffer (pH = 11). We show that the highest inhibition efficiency among tested compounds belongs to catechol at 10 mM concentration, although the differences were moderate. Utilization of novel impedance approach to adsorption isotherm determination made it possible to confirm that while resorcinol chemisorbs on aluminum surface, catechol and quinol follows the ligand exchange model of adsorption. Unlike catechol and quinol, the protection mechanism of resorcinol is bound to interaction with insoluble aluminum corrosion products layer and was only found efficient at concentration of 100 mM (98.7%). The aforementioned studies were confirmed with Scanning Electron Microscopy and X-ray Photoelectron Spectroscopy analyses. There is a significant increase in the corrosion resistance offered by catechol at 10 mM after 24 h exposure in electrolyte: from 63 to 98%, with only negligible changes in inhibitor efficiency observed for resorcinol at the same time. However, in the case of resorcinol a change in electrolyte color was observed. We have revealed that the differentiating factor is the keto-enol tautomerism. The Nuclear Magnetic Resonance (NMR) studies of resorcinol indicate the keto form in structure in presence of NaOH, while the chemical structure of catechol does not change significantly in alkaline environment.

  • Corrosion Inhibition of Aluminium Alloy AA6063-T5 by Vanadates: Local Surface Chemical Events Elucidated by Confocal Raman Micro-Spectroscopy
    • Dmitry Kharitonov
    • Jens Sommertune
    • Cem Örnek
    • Jacek Ryl
    • Irina Kurilo
    • Per Claesson
    • Jinshan Pan
    2019 Full text CORROSION SCIENCE

    Chemical interactions between aqueous vanadium species and aluminium alloy AA6063-T5 were investigated in vanadate-containing NaCl solutions. Confocal Raman and X-ray photoelectron spectroscopy experiments were utilised to gain insight into the mechanism of corrosion inhibition by vanadates. A greenish-grey coloured surface layer, consisting of V+4 and V+5 polymerized species, was seen to form on the alloy surface, especially on top of cathodic micrometre-sized IMPs, whereby suppressing oxygen reduction kinetics. The results suggest a two-step mechanism of corrosion inhibition in which V+5 species are first reduced to V+4 or V+3 species above cathodic IMPs, and then oxidized to mixed-valence V+5/V+4 polymerized compounds.

  • Cost Analysis of Prefabricated Elements of the Ordinary and Lightweight Concrete Walls in Residential Construction
    • Marzena Kurpińska
    • Beata Grzyl
    • Adam Kristowski
    2019 Full text Materials

    Global economic growth causes an increase in natural resources exploitation, particularly in construction branch. The growing use of electricity contributes to climate change. Therefore, it is necessary to search the solutions, which will allow for reducing natural resources exploitation. One of the many opportunities to do that is the application of the recycled materials. The authors of the given article have analyzed three variants of construction solutions. One of them was the production of the walls of a building from reinforced concrete prefabricates with styrofoam insulation layer. The second variant for analysis were prefabricated walls from lightweight concrete, made of sintered clay aggregate with a foam core. The third proposed variant was a system of multi-layered walls, which was made of lightweight concrete with granulated expanded glass aggregate (GEGA). The main objective of the research was to assess the use of lightweight GEGA prefabricates, focusing on economic and technological aspects of the solution. The authors have analyzed the entire construction costs; ceilings and stairs were assumed as reinforced concrete elements. In calculations, the weight of the elements was taken into account, as well as transportation and mounting costs. On the basis of this cost analysis, it was concluded that the use of prefabricated element, made of lightweight concrete with GEGA, could be a replacement for the solutions, widely applied until these days. The analysis has also shown that the use of prefabricates with GEGA is sensible from the economic viewpoint, as it allows for saving construction time. Moreover, the solutions, proposed here, allow for saving natural resources and assuming a more environmentally friendly and caring attitude.

  • Coupling of Blood Pressure and Subarachnoid Space Oscillations at Cardiac Frequency Evoked by Handgrip and Cold Tests: A Bispectral Analysis
    • Marcin Gruszecki
    • Yurii Tkachenko
    • Jacek Kot
    • Marek Radkowski
    • Agnieszka Gruszecka
    • Krzysztof Basiński
    • Monika Waskow
    • Wojciech Gumiński
    • Jacek Anand
    • Jerzy Wtorek
    • Andrzej F. Frydrychowski
    • Urszula Demkow
    • Pawel Winklewski
    2019 Advances in Experimental Medicine and Biology

    The aim of the study was to assess blood pressure–subarachnoid space (BP–SAS) width coupling properties using time–frequency bispectral analysis based on wavelet transforms during handgrip and cold tests. The experiments were performed on a group of 16 healthy subjects (F/M; 7/9) of the mean age 27.2 ± 6.8 years and body mass index of 23.8 ± 4.1 kg/m². The sequence of challenges was first handgrip and then cold test. The handgrip challenge consisted of a 2-min strain, indicated by oral communication from the investigator, at 30% of maximum strength. The cold test consisted of 2 min of hand immersion to approximately wrist level in cold water of 4 °C, verified by a digital thermometer. Each test was preceded by 10 min at baseline and was followed by 10-min recovery recordings. BP and SAS were recorded simultaneously. Three 2-min stages of the procedure, baseline, test, and recovery, were analyzed. We found that BP–SAS coupling was present only at cardiac frequency, while at respiratory frequency both oscillators were uncoupled. Handgrip and cold test failed to affect BP–SAS cardiac–respiratory coupling. We showed similar handgrip and cold test cardiac bispectral coupling for individual subjects. Further studies are required to establish whether the observed intersubject variability concerning the BP–SAS coupling at cardiac frequency has any potential clinical predictive value.

  • Criteria for evaluation and selection of the best offer for the Contract Engineer service
    • Beata Grzyl
    • Magdalena Apollo
    • Heyducki Igor
    2019 Full text IOP Conference Series: Materials Science and Engineering

    The purpose of the legal regulations regarding public procurement in EU countries is to ensure effective funds' spending. When assessing and selecting the best offer, the contracting entities have at their disposal many different criteria, including non-price criteria. Their proper selection and application is necessary to ensure the high quality of the ordered product, delivery or service. Making an order for intellectual services, including performed by the Contract Engineer (CE), should be based primarily on the criterion of qualifications and experience. The actions and decisions taken by CE are particularly important for the quality and timeliness of the contract. The purpose of the research is to indicate to what scope and extent the awarding entities in Poland use the possibility of a wide selection of different criteria for the evaluation of intellectual services, consisting of performing the CE function. On the basis of selected proceedings, the authors discuss the criteria for evaluation and selection of the best offer applied in practice, classify them, analyze and evaluate them. The results of the conducted research indicate that the price and experience are often used in practice as the CE selection criteria. The authors, however, give numerous examples of other criteria. In many cases, these criteria are difficult to verify at the stage of evaluating offers and enforcing them in practice in course of works, raising doubts as to their effectiveness, sometimes making it impossible to make a reliable assessment and select the most advantageous offer. The authors indicate that despite many possibilities offered by the legal status in force in Poland, in practice, in some cases, criteria that have a large impact on the increase of the proposed service price, but not reflected in its quality, apply. As a consequence, it results in the lack of effective spending of public funds.

  • Critical review of electronic nose and tongue instruments prospects in pharmaceutical analysis
    • Wasilewski Tomasz
    • Dorian Migoń
    • Jacek Gębicki
    • Wojciech Kamysz
    2019 ANALYTICA CHIMICA ACTA

    Electronic nose (enose, EN) and electronic tongue (etongue, ET) have been designed to simulate human senses of smell and taste in the best possible way. The signals acquired from a sensor array, combined with suitable data analysis system, are the basis for holistic analysis of samples. The efficiency of these instruments, regarding classification, discrimination, detection, monitoring and analytics of samples in different types of matrices, is utilized in many fields of science and industry, offering numerous practical applications. Popularity of both types of devices significantly increased during the last decade, mainly due to improvement of their sensitivity and selectivity. The electronic senses have been employed in pharmaceutical sciences for, among others, formulation development and quality assurance. This paper contains a review of some particular applications of EN and ET based instruments in pharmaceutical industry. In addition, development prospects and a critical summary of the state of art in the field were also surveyed.

  • Cross sections for electron collision with pyridine [C5H5N] molecule
    • Czesław Szmytkowski
    • Sylwia Stefanowska-Tur
    • Natalia Tańska
    • Bożena Żywicka
    • Elżbieta Ptasińska-Denga
    • Paweł Możejko
    2019 MOLECULAR PHYSICS

    The absolute grand -total cross section (TCS) for electron scattering from pyridine, C5H5N, molecules has been measured at impact energies from 0.6 to 300 eV in the linear electron-transmission experiment. The obtained TCS energy dependence appears to be typical for targets of high electric-dipole moment; the cross section generally decreases with rising energy, except for the 3–20 eV range, where a broad enhancement peaked near 8.5 eV is clearly visible. Below 10 eV, some weak structures which can be attributed to resonant scattering processes are also discernible. The present TCS energy dependence is compared with TCS experimental data reported very recently. Comparison with TCS for benzene is also made to search how the replacement of the CH group in the benzene ring with the nitrogen atom influences the electron-scattering process. In addition, for pyridine and its halogenated derivatives: 2-chloropyridine [2-C5H4ClN] and 2-bromopyridine [2-C5H4BrN], integral elastic (ECS) and ionisation (ICS) cross sections have been calculated at intermediate and high electron-impact energies within semiempirical approaches. For pyridine the sum of ECS and ICS is in reasonable agreement with the measured TCS above 40 eV.

  • Cross-Bonding of MV Cable Lines for Energy Losses Decrease
    • Krzysztof Dobrzyński
    • Zbigniew Lubośny
    • Jacek Klucznik
    • Dominik Falkowski
    • Janusz Grala
    • Sławomir Noske
    2019 Full text Acta Energetica

    Currently, almost all medium voltage cable lines (MV) operate with the return wires earthed at both ends of the cable. Such a way of operation causes that during normal states of operation as well as during disturbances, e.g. short-circuits, in the return wires induce currents whose values mainly depend on the currents flowing in the phase wires. These currents in normal operating states are a source of additional energy losses incurred in the MV cables. The effect can be decreased by the return wires cross-bonding or the phase wires transposition. The paper discusses the potential effects that can be achieved by use of the return wires cross-bonding or the phase wires transposition in the domestic grids.

  • Crossover from charge density wave stabilized antiferromagnetism to superconductivity in Nd1−xLaxNiC2 compounds
    • Marta Roman
    • Leszek Litzbarski
    • Tomasz Klimczuk
    • Kamil Kolincio
    2019 Full text PHYSICAL REVIEW B

    The path from the charge density wave antiferromagnet NdNiC2 to the noncentrosymmetric superconductor LaNiC2 is studied by gradual replacement of Nd by La ions. The evolution of physical properties is explored by structural, magnetic, transport, magnetoresistance, and specific heat measurements. With the substitution of La for Nd, the Peierls temperature is gradually suppressed, which falls within the BCS mean-field relation for chemical pressure with a critical concentration of xc=0.38. As long as the charge density wave (CDW) is maintained, the antiferromagnetic (AFM) ground state remains robust against doping and, despite a Néel temperature reduction, shows a rapid and sharp magnetic transition. Once the CDW is completely suppressed, intermediate compounds of the Nd1−xLaxNiC2 series reveal symptoms of a gradual softening of the features associated with the AFM transition and an increase of the spin disorder. Immediately after the antiferromagnetic transition is depressed to zero temperature, the further incorporation of La ions results in the emergence of superconductivity. This crossover in Nd1−xLaxNiC2 is discussed in terms of the possible quantum critical point.

  • Cross-talk Between the Heart and Arteries in Older 65+ Adults
    • Tomasz Wierzba
    • Stanisław Zajączkowski
    • Paweł Figarski
    • Robert Olek
    • Artur Poliński
    2019

    Regulatory synchronization between the heart and the arterial walls is essential for optimal blood delivery to tissues. We investigated functional coherence between heart rhythm and aortic wall compliance in 30 volunteers aged 65 – 74. ECG and carotid and iliac pulse-wave were recorded and digitized at 2 kHz. Carotid-femoral pulse-wave transit time (cfTT) which reflex aortic compliance was assessed using the intersecting tangent algorithm at time-point of the maximal upstroke of the second derivative of the filtered pulse signal. Time-series of 256 heart cycles were used for heart rate variability (HRV) and cfTT variability analysis. Averaged power spectral density (aPSD) was estimated within selected frequency ranges by fast Fourier transform (FFT) approach. Magnitude squared coherence (MSC) between the both spectra was estimated. All volunteers exhibited variable temporal patterns of both HRV and cfTT variability. aPSD was reduced along with decreasing of time-window from 60 to 240 s. High coherent states between HRV and cfTT variability were observed as a short time prominent MSC peaks in almost all participants. Individual patterns of irregular MSC changes in time but not a generalized model of its fluctuations seem to reflect dynamic functional interaction between the heart and aortic compliance at an advanced age.

  • Crowdsourcing-Based Evaluation of Automatic References Between WordNet and Wikipedia
    • Julian Szymański
    • Tomasz Maria Boiński
    2019 Full text INTERNATIONAL JOURNAL OF SOFTWARE ENGINEERING AND KNOWLEDGE ENGINEERING

    The paper presents an approach to build references (also called mappings) between WordNet and Wikipedia. We propose four algorithms used for automatic construction of the references. Then, based on an aggregation algorithm, we produce an initial set of mappings that has been evaluated in a cooperative way. For that purpose, we implement a system for the distribution of evaluation tasks, that have been solved by the user community. To make the tasks more attractive, we embed them into a game. Results show the initial mappings have good quality, and they have also been improved by the community. As a result, we deliver a high quality dataset of the mappings between two lexical repositories: WordNet and Wikipedia, that can be used in a wide range of NLP tasks. We also show that the framework for collaborative validation can be used in other tasks that require human judgments.

  • Crystal structure and physical properties of a novel ternary compound La15MoxGe9
    • Joanna Blawat
    • Weiwei Xie
    • Robert J. Cava
    • Tomasz Klimczuk
    2019 CHEMICAL PHYSICS LETTERS

    We present the synthesis, structural characterization and physical properties measurements of a new compound, La15MoxGe9 in Mn5Si3-type derived structure with interstitial Mo. The sample was synthesized by arc-melting method. La15MoxGe9 crystallizes in non-centrosymmetric hexagonal structure P63mc (#186) with lattice parameters a = b = 15.495(5) Å and c = 6.917(2) Å. The refinement on single X-ray diffraction data show that interstitial atom Mo occupies two different Wyckoff positions (2a, 2b) with 0.19(2) Mo/per f.u. The specific heat properties were well studied. The obtained Sommerfeld coefficient and Debye temperature are: γ = 89.2(9) mJ/(mol K2) and ΘD = 190(5) K, respectively. La15MoxGe9 is the first compound in the ternary system La-Mo-Ge

  • Crystal structure, chemical bonding, and physical properties of layered AIrSn2 (A = Sr and Ba)
    • Madalynn Marshall
    • Lingyi Xing
    • Zuzanna Sobczak
    • Joanna Blawat
    • Tomasz Klimczuk
    • Rongying Jin
    • Weiwei Xie
    2019 JOURNAL OF MATERIALS SCIENCE

    We report the experimental and theoretical investigation of structure, chemical bonding interactions, and physical properties of new ternary stannides AIrSn2 (A = Sr and Ba). AIrSn2 (A = Sr and Ba) crystallizes in the orthorhombic Re3B-type structure with the space group Cmcm (No. 64). According to single-crystal X-ray diffraction results, the structure of AIrSn2 (A = Sr and Ba) can be considered as a Zintl-type compound with heterogeneous polyanionic [IrSn2]2− and A2+. The specific heat down to 1.8 K shows no evidence for bulk superconductivity in either SrIrSn2 or BaIrSn2. Electronic structure calculations, especially chemical bonding interactions in SrIrSn2 and BaIrSn2, match well with the observed structural stability and metallic nature.

  • Crystal structures of aminotransferases Aro8 and Aro9 from Candida albicans and structural insights into their properties
    • Agnieszka Kiliszek
    • Wojciech Rypniewski
    • Kamila Rząd
    • Sławomir Milewski
    • Iwona Gabriel
    2019 Full text JOURNAL OF STRUCTURAL BIOLOGY

    Aminotransferases catalyze reversibly the transamination reaction by a ping-pong bi-bi mechanism with pyridoxal 5′-phosphate (PLP) as a cofactor. Various aminotransferases acting on a range of substrates have been reported. Aromatic transaminases are able to catalyze the transamination reaction with both aromatic and acidic substrates. Two aminotransferases from C. albicans, Aro8p and Aro9p, have been identified recently, exhibiting different catalytic properties. To elucidate the multiple substrate recognition of the two enzymes we determined the crystal structures of an unliganded CaAro8p, a complex of CaAro8p with the PLP cofactor bound to a substrate, forming an external aldimine, CaAro9p with PLP in the form of internal aldimine, and CaAro9p with a mixture of ligands that have been interpreted as results of the enzymatic reaction. The crystal structures of both enzymes contains in the asymmetric unit a biologically relevant dimer of 55 kDa for CaAro8 and 59 kDa for CaAro9p protein subunits. The ability of the enzymes to process multiple substrates could be related to a feature of their architecture in which the active site resides on one subunit while the substrate-binding site is formed by a long loop extending from the other subunit of the dimeric molecule. The separation of the two functions to different chemical entities could facilitate the evolution of the substrate-binding part and allow it to be flexible without destabilizing the conservative catalytic mechanism.

  • Crystal structures of (E)-3-(4-hydroxybenzylidene)chroman-4-one and (E)-3-(3-hydroxybenzylidene)-2-phenylchroman-4-one
    • Kamil Suchojad
    • Anna Dołęga
    • Angelika Adamus-Grabicka
    • Elżbieta Budzisz
    • Magdalena Małecka
    2019 Full text Acta Crystallographica Section E CRYSTALLOGRAPHIC COMMUNICATIONS

    The synthesis and crystal structures of (E)-3-(4-hydroxybenzylidene)chroman-4-one, C16H12O3,I, and (E)-3-(3-hydroxybenzylidene)-2-phenylchroman-4-one,C22H16O3,II, are reported. These compounds are of interest with respect to biological activity. Both structures display intermolecular C—H---O and O—H---O hydrogen bonding, forming layers in the crystal lattice. The crystal structure of compound I is consolidated by pi–pi interactions. The lipophilicity (logP) was determined as it is one of the parameters qualifying compounds as potential drugs. The logP value for compound I is associated with a larger contribution of C---H interaction in the Hirshfeld surface.

  • (CsX)Cu5O2(PO4)2 (X = Cl, Br, I): A Family of Cu2+ S = 1/2 Compounds with Capped-Kagomé Networks Composed of OCu4 Units
    • Michał Jerzy Winiarski
    • Thao Tran
    • Juan Chamorro
    • Tyrel McQueen
    2019 Full text INORGANIC CHEMISTRY

    Three new salt inclusion compounds (CsX)Cu5O2(PO4)2 (X = Cl, Br, I), phosphate analogues of the kagomé mineral averievite, are reported. Their crystal structures are composed of trigonal networks of corner-sharing OCu4 anion-centered tetrahedra, forming capped-kagomé planes, which can also be regarded as two-dimensional slices along the [111] direction of a pyrochlore lattice. Magnetization and heat capacity measurements reveal strong geometric frustration of this network and complex magnetic behavior. X-ray and neutron diffraction studies show that all three compounds undergo a trigonal-to-monoclinic phase transition upon cooling, with a first-order phase transition seen in CsBr and CsI analogues. Along with the previously reported (CsCl)Cu5O2(VO4)2, these three new compounds belong to a large family of OCu4-based networks, which are a playground for studying frustrated quantum magnetism.

  • Cure Index demonstrates curing of epoxy composites containing silica nanoparticles of variable morphology and porosity
    • Farimah Tikhani
    • Maryam Jouyandeh
    • Seyed Jafari
    • Sara Chabokrow
    • Mehdi Ghahari
    • Kamaladin Gharanjig
    • Felix Klein
    • Norbert Hampp
    • Mohammad Ganjali
    • Krzysztof Formela
    • Mohammad Saeb
    2019 PROGRESS IN ORGANIC COATINGS

    An image was taken by Cure Index on curability of epoxy with silica nanoparticles having variable morphology and porosity. Three kinds of silica nanoparticles with non-porous curved-rod, non-porous spherical, and mesoporous spherical microstructures were synthesized and characterized by Fourier-transform infrared spectroscopy, scanning electron microscopy (SEM) and Brunauer–Emmett–Teller analyses. Epoxy nanocomposites containing 0.1, 0.3, 0.5 wt.% of nanoparticles cured nonisothermally in differential scanning calorimetry (DSC) at different heating rates and the glass transition temperature (Tg) for fully-cured samples was estimated. Cure Index unravelled the effect of nanoparticle morphology and porosity on epoxy crosslinking. Good cure was unconditionally the case for systems containing 0.3 wt.% of mesoporous spherical nanoparticles due to appropriate dispersion of porous nanoparticles, as captured by SEM. By contrast, dependency of curing on heating rate and nanoparticle loading in the case of non-porous spherical and curved-rod particles was evidenced by partially agglomerated domains. The state of nanoparticle-polymer interaction was also inferred in view of network formation in the presence of nanosilica particles of various morphology and porosity, which was nicely monitored by the use of Cure Index.

  • Curing epoxy resin with anhydride in the presence of halloysite nanotubes: the contradictory effects of filler concentration
    • Maryam Jouyandeh
    • Zohre Karami
    • Omid Moini
    • Krzysztof Formela
    • Seyed Paran
    • Ali Jannesari
    • Mohammad Saeb
    2019 PROGRESS IN ORGANIC COATINGS

    Epoxy resins can be cured with a wide variety of curing agents such as amines and anhydrides, but anhydride curing would be more favorable for research purpose because of epoxy-anhydride curing taking place slowly at room temperature. Incorporation of natural nanosized minerals into epoxy is of environmental importance. Halloysite nanotubes (HNTs) display chemical properties similar to those of silica and alumina, and hydroxyl groups positioned somewhere in between or at the edge of HNTs layers give them potential to participate in epoxy ring-opening. Curing epoxy/anhydride systems containing HNTs at various concentrations (0.5, 1 and 2 wt.% based on 100 parts by weight of epoxy) via nonisothermal differential scanning calorimetry at three heating rates (5, 10 and 15 °C.min−1) is discussed here to study the effect of HNTs concentration on epoxy-anhydride curing reactions. The extent of crosslinking reaction was promoted at 0.5 and 1 wt.% of HNTs as a result of participation of hydroxyl groups of HNTs in epoxide ring-opening, while at 2 wt.% of HNTs a hindered curing was the case, which has been speculated on account of probable deactivation of anhydride curing agent by the internal surface of HNTs pursued by anhydride molecules diffusion into the lumen of HNTs.

  • Curing epoxy with electrochemically synthesized Zn Fe3-O4 magnetic nanoparticles
    • Maryam Jouyandeh
    • Jagar A. Ali
    • Mustafa Aghazadeh
    • Krzysztof Formela
    • Mohammad Saeb
    • Zahra Ranjbar
    • Mohammad Ganjali
    2019 PROGRESS IN ORGANIC COATINGS

    Cathodic electrodeposition (CED) was applied in synthesis of undoped and zinc (Zn) doped Fe3O4 nanoparticles. Changes in the lattice structure of nanoparticles were monitored using X-ray diffraction (XRD), field-emission scanning electron microscopy (FE-SEM) supported by dispersive X-ray spectrometry (EDS), and vibrating sample magnetometry (VSM). Detailed analyses explored the formation of ZnxFe3–xO4 nanoparticles with x ≈ 0.1, and relatively low coercivity and remanence of 11.71 Oe and 0.36 emu/g, respectively, demonstrating adequate superparamagnetic degree of Zn2+-doped Fe3O4 nanoparticles. Epoxy nanocomposites containing undoped and Zn2+-doped Fe3O4 were prepared at very low amount of nanoparticles (0.1 wt.% based on 100 parts by weight of epoxy) and subjected to nonisothermal differential scanning calorimetry (DSC) at different heating rates of 5, 10, 15, and 20 °C/min. Analyses based on Cure Index criterion were edivent that curability behavior of epoxy/amine systems was changed from Poor to Good state of cure by substitution of Zn2+ cations in Fe2+ sites in the Fe3O4 lattice. Nevertheless, curing state of epoxy nanocomposite was Poor at 20 °C/min regardless of nanoparticle type, which was inferred on account of progressive curing reaction of epoxy that expedited gelation and made crosslinking pertinent to diffusion.

  • Curing epoxy with ethylenediaminetetraacetic acid (EDTA) surface-functionalized Co Fe3-O4 magnetic nanoparticles
    • Maryam Jouyandeh
    • Mohammad Ganjali
    • Jagar A. Ali
    • Mustafa Aghazadeh
    • Isa Karimzadeh
    • Krzysztof Formela
    • Xavier Colom
    • Javier Cañavate
    • Mohammad Saeb
    2019 PROGRESS IN ORGANIC COATINGS

    In this work, the bulk and surface composition of Fe3O4 supermagnetic nanoparticles were modified for efficient epoxy curing. The bare, ethylenediaminetetraacetic acid (EDTA) capped, and cobalt (Co)-doped EDTA capped Fe3O4 nanoparticles were synthesized electrochemically. The crystalline structure and phase information, surface capping, morphology and magnetization behavior of nanoparticles were studied by X-Ray diffraction (XRD), Fourier-transform infrared spectroscopy (FTIR), field-emission scanning electron microscopy (FE-SEM) and vibrating sample magnetometer (VSM), respectively. A low amount of the prepared nanoparticle (0.1 wt.%) was used in preparation of epoxy nanocomposites. Nonisothermal differential scanning calorimetry (DSC) under different heating rates was performed to study the potential of nanoparticles in curing epoxy resin with an aliphatic amine. The heat release data on nanocomposites suggest that EDTA capped Co-doped Fe3O4 considerably improved the curing reaction between epoxy resin and the curing agent. Calculations based on Cure Index approved qualitatively a shift from Poor to Good cure by concurrent lattice and surface modifications of magnetic nanoparticles. It is bielived that the approach used in this work can pave the way to enhance curability of epoxy nanocomposites by the combined modification of bulk and surface of nanoparticles.

  • Current issues of functional safety and cybersecurity analysis of the industrial and critical infrastructures
    • Marcin Śliwiński
    • Kazimierz Kosmowski
    • Emilian Piesik
    2019 Full text TASK Quarterly

    This article addresses some functional safety assessment procedures with cybersecurity aspects in critical industrial installations with regard to the functional safety requirements specified in standards IEC 61508 and IEC 61511. The functional safety management includes hazard identification, risk analysis and assessment, specification of overall safety requirements and definition of safety functions. Based on the risk assessment results, the safety integrity level (SIL) is determined for consecutive safety functions. These functions are implemented within the industrial control system (ICS) and/or the distributed control system (DCS) that consists of the basic process control system (BPCS) and/or the safety instrumented system (SIS). The determination of the required SIL related to the required risk mitigation is based on the semi-quantitative evaluation method. Verification of the SIL for the considered architectures of the BPCS and/or the SIS is supported by probabilistic models with appropriate data and model parameters including cybersecurity related aspects. The proposed approach is illustrated on the example of critical industrial installations.

  • Customer Engagement Consequences for Firms
    • Katarzyna Żyminkowska
    • Nagaraj Samala
    • Edyta Gołąb-Andrzejak
    2019 Full text Journal of Emerging Trends in Marketing and Management

    Purpose: Customer engagement (CE) is a customers’ voluntary resource contribution to firms’ functions, and it goes beyond transactions during customers’ behavioral manifestations toward the brand or firm’s offerings or activities. The effective CE management requires to understand the potential CE effects, and leverage the potential benefit and threat of CE, however negative consequences or risks of CE have remained unexplored in existing literature. Therefore, this paper explores both negative and positive consequences of customer engagement for firms. Methodology: Based on computer-assisted telephone interviews with 402 firms operating in the field of consumer goods and services, descriptive statistics and structural equation modelling were used in this study. Findings: This study recognizes firm-level risks of CE associated with customer resource integration and reveals the linkages between those risks and firm-level benefits of engaging customers by firms. Originality/value: The paper proposes realistic view on firm-level consequences of CE and provides insights into how firms should manage CE by understanding the dark-side of CE resulting from integrating customers’ resources in business processes.

  • Cybersecurity in the Electricity Sector
    • Rafał Leszczyna
    2019

    This book offers a systematic explanation of cybersecurity protection of electricity supply facilities, including discussion of related costs, relevant standards, and recent solutions. The author explains the current state of cybersecurity in the electricity market, and cybersecurity standards that apply in that sector. He then offers a systematic approach to cybersecurity management, including new methods of cybersecurity assessment, cost evaluation and comprehensive defence.

  • Cyfryzacja przedsiębiorstw świadczących usługi komunalne - ocena przypadku
    • Marek Wirkus
    • Waldemar Kosiedowski
    2019

    Analizie poddano cyfryzację przedsiębiorstwa świadczącego usługi komunalne - Gdańskie Nieruchomości. W artykule zidentyfikowano obszary cyfryzacji przedsiębiorstwa, ich aktualny poziom cyfryzacji oraz potrzeby i kierunki dalszych działań. Omówiono czynniki zagrażające wdrażaniu cyfryzacji oraz sposoby przeciwdziałania. Jako metodę badawczą zastosowano obserwację uczestniczącą, ocenę przeprowadzono wg stanu na koniec roku 2018.

  • Cykl trzech performance 1. O byciu bratem, 2. O emanowaniu miłością, 3. O byciu ptakiem
    • Patryk Różycki
    2019

    Nie jestem „najlepszym” bratem, jestem słaby w byciu bratem, to mnie zasmuca. Zobaczyłem go z bliska, z bliska przez kilka dni: jego uśmiech, łzy, otwarte usta, dołeczki w policzkach i łyżeczkę, która tam przyciskała, widziałem jak pali papierosa, jak się garbi, zakrzywioną linię pleców, wobec względnie prostej krawędzi balkonowych drzwi i wobec jeszcze dalszych, prostych linii tyłu budowli sakralnej, widziałem jak zakrywa twarz kocem, jak mlaszcze przez sen, linię jego stóp, jak chodzi i podbiega, by iść równie szybko, jak ja, kiedy gdzieś się śpieszyliśmy, przypomniałem sobie kolano jego kiedyś kontuzjowane z blizną, ale to kiedyś, patrzyłem na jego nos, odrastające włosy na głowie, zakola, linie na czole, dłonie, byłem szczęśliwy, kiedy staliśmy obok siebie, paląc papierosa, może to jedyna czynność, którą mogliśmy wykonywać wspólnie, może to jedyna w życiu, i jeszcze prowadzenie auta, słuchałem jego głosu, widziałem, jak przygląda się ze zdziwieniem pistacjom, próbując się do nich dobrać, widziałem, jak robi nam frytki. Teraz, jedynie chwilę po jego odjeździe, przypominam go sobie w całości, czuję smutek, chcę płakać, chyba tęsknię za nim, pierwszy raz. Chciałbym być lepszym bratem, nie wiem, jak to się robi, pytałem go o to, podpowiedział mi, jakim być wobec niego, co robić. Zrobiliśmy razem mój nowy pokój, on zrobił najwięcej, będę tutaj z nim: z zagipsowanymi przez niego ścianami, z pomalowanym na biało sufitem, całą łazienką, z podłączoną pralką, z uszczelnionymi oknami i drzwiami, z jego ogromną pomocą, z tym całym wzruszeniem i echem piszczącej wersalki, którą rozkładał sobie do spania. Chciałbym być lepszym bratem, nie wiem, jak to się robi, mogę do niego zadzwonić i zapytać, chcę to robić! (Ten pierwszy skok w nowym miejscu dedykuję mojemu bratu)

  • Cztery algorytmy, które wstrząsnęły światem. Część II: Od czasu wykładniczego do wielomianowego
    • Marek Kubale
    2019 Pismo PG

    Odcinek ten poświęcony jest problemowi programowania liniowego oraz problemowi badania liczb pierwszych.

  • Cztery algorytmy, które wstrząsnęły światem. Część III: Sprzęt czy oprogramowanie
    • Marek Kubale
    2019 Pismo PG

    W ostatniej części tryptyku poruszamy problem przyjaznego rysowania grafów oraz prezentujemy algorytmy dla szybkiego mnożenia macierzy. Nasze rozważania kończymy ilustracją postępu w dziedzinie sprzętu i oprogramowania