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  • Spatial variability of the hydrochemistry of shallow groundwaters and surface waters of the Rensdyrbekken: A case study of a permafrost catchment in Bellsund (SW Spitsbergen, Svalbard)
    • Sara Lehmann-konera
    • Piotr Zagorski
    • Kamil Nowinski
    • Krzysztof Raczynski
    • Marcin Frankowski
    • Łukasz Franczak
    • Mateusz Dobek
    • Danuta Szumińska
    • Ruman Marek
    • Ramia Bakain Al
    • Żaneta Polkowska
    2024 Pełny tekst LAND DEGRADATION & DEVELOPMENT

    Progressive climate change may have unpredictable consequences for the Arctic environment. Permafrost catchments off the west coast of Svalbard, described as “thin” and “warm,” are particularly sensitive to climate change. The interdisciplinary research on the hydrochemical response of surface and underground water functioning within a small permafrost catchment area focused on the determination of the impact of meteorological conditions (temperature (T), precipitation (P)) on the mean daily discharge (Q), and the lowering of the groundwater table (H). We determined physical and chemical properties (pH and SEC) and concentrations of major elements (Ca, Mg, Na, K) and 23 trace elements (i.a. Cd, Cu, Hg, Pb, Zn) in 280 water samples. The results of the correlation matrix showed that an increase in the average air temperature in the summer of 2021 had a significant impact on the hydrochemistry of both types of waters operating in the catchment. In response to increase in T, the lowering of the H (0.52 < r < 0.66) and a decrease in Q (0.66 < r < 0.68) were observed what in consequence also leads to changes in water chemistry. The principal component analysis (CA) indicates that chemical weathering and binding of elements to DOC are processes influencing water chemistry. Results of statistical analysis showed that the resultant of the hydrometeorological conditions that prevailed in that season and the type of geological formations on which they were located had a significant impact on the water chemistry at individual measurement points. Significant differences in the concentrations of elements between points on the same geological formations were also found.

  • Specification-Oriented Automatic Design of Topologically Agnostic Antenna Structure
    • Adrian Bekasiewicz
    • Mariusz Dzwonkowski
    • Tom Dhaene
    • Ivo Couckuyt
    2024

    Design of antennas for modern applications is a challenging task that combines cognition-driven development of topology intertwined with tuning of its parameters using rigorous numerical optimization. However, the process can be streamlined by neglecting the engineering insight in favor of automatic de-termination of structure geometry. In this work, a specification-oriented design of topologically agnostic antenna is considered. The radiator is developed using a bi-stage algorithm that involves min-max classification of randomly-generated topologies followed by local tuning of the promising designs using a trust-region optimization applied to a feature-based representation of the structure frequency response. The automatically generated antenna is characterized by –10 dB reflection for over 600 MHz around the center frequency of 6.5 GHz and a dual-lobe radiation pattern. The obtained performance figures make the radiator of use for in-door positioning applications. The design method has been favorably compared against the frequency-based trust-region optimization.

  • Spectroscopic studies on physicochemical properties of selected unsymmetrical bisacridine derivatives and NMR analysis of their interactions with the model sequence Pu22 aided by molecular dynamics
    • Michał Kosno
    2024 Pełny tekst

    In recent years, new promising acridine derivatives have appeared, belonging to the unsymmetrical bisacridines (UAs) family with high anticancer activity. Both their physicochemical properties and their mechanism of action at the molecular level have not been thoroughly analyzed so far. Four derivatives were selected for the study, termed as: C-2028, C-2041, C-2045 and C-2053. The first aim of this work was to determine the protonation forms in which the studied compounds exist at different pH. The second aim was the analysis of aggregation process at different conditions. Methods such as UV-Vis and NMR spectroscopy were used for this purpose. The obtained spectral data were subjected to a thorough chemometric analysis, using techniques such as principal components analysis, multiple regression and numerical optimization. Previous studies have shown that a potential molecular target for unsymmetrical bisacridines may be the promoter sequence of the C-Myc proto-oncogene, known as Pu22. Next goal of the presented work was to determine the interactions of the studied compounds with the above mentioned sequence using advanced NMR spectroscopy and molecular dynamics methods. These studies were narrowed down to the two most promising derivatives: C-2045 and C-2053. In order to determine the exact molecular structure of the obtained complexes, a series of one- and two-dimensional NMR spectra of both investigated compounds and their monomeric derivatives (C-1311 and C-1748) were recorded, which allowed to build the initial structures of the studied complexes. In the next step, they were subjected to an equilibrium MD simulation. In the final stage of the research, the nature and strength of the interactions between the studied compounds and the selected G-quadruplex were estimated using the umbrella sampling method, which allowed the determination of the free energy profiles of the obtained complexes. The results obtained allowed to determine the way in which the unsymmetrical bisacridines interact with the C-Myc promoter sequence - their potential molecular target. In addition, their basic physicochemical properties have been determined, which will allow further research on the compounds described above. In this work, a simple and reliable method for the determination of physicochemical constants has been developed and presented, which yields well credible results, even in the case of compounds with a complex structure having many sites capable of protonation.

  • Społeczna opieka nad zabytkami - doświadczenia z ostatnich kilkunastu lat z Gdyni
    • Robert Hirsch
    • Celina Łozowska
    2024 Pełny tekst Ochrona Dziedzictwa Kulturowego

    W artykule przedstawiono analizę funkcjonowania społecznej opieki nad zabytkami w Gdyni po 2003 r. Kilkanaście lat doświadczenia samorządu lokalnego oraz czas jaki upłynął od wejścia w życie obowiązujących regulacji związanych z instytucją społecznych opiekunów zabytków pozwalają na sformułowanie wniosków i pokazanie wad oraz zalet różnych rozwiązań. W artykule przedstawiono doświadczenia Biura Miejskiego Konserwatora Zabytków w Gdyni ze współpracy zarówno ze społecznymi opiekunami zabytków jak i z lokalnymi stowarzyszeniami zajmującymi się ochroną dziedzictwa. Z doświadczeń autorów wynika jednoznacznie, że przepisy ustawy o ochronie zabytków i opiece nad zabytkami, regulujące działalność społecznych opiekunów zabytków są anachroniczne i w praktyce mają minimalny wpływ na ochronę zabytków. Natomiast rozwinęła i rozwija się działalność społeczna aktywnych mieszkańców z wykorzystaniem stowarzyszeń i innych form kolektywnego współdziałania. Dużą rolę odgrywają obecnie portale internetowe a zwłaszcza media społecznościowe, które ułatwiają komunikację i pozwalają szybko reagować. Widoczne jest ogromne zainteresowanie społeczne ochroną zabytków i spora aktywność mieszkańców w tym zakresie. W ocenie autorów należy skorzystać z nowych doświadczeń i całkowicie przeformułować zasady współpracy organów ochrony zabytków ze społeczeństwem. Taka współpraca może przynieść korzystne efekty.

  • Sport as a Tool for the Development of Healthy and Sustainable Cities: A Strategic Documentation Review
    • Aleksander Orłowski
    • Narek Parsamyan
    2024

    The rapidly changing cities and their environment are causing new challenges for which actions and solutions must be sought. Most of all, a major challenges facing cities are adverse environmental changes and issues related to public health and citizens well-being. Sport is present in the lives of most of us and is an essential component of urban infrastructure, while in relation to this, to what extent is it being used to support health and sustainable goals, shaping cities of tomorrow. The area of relevance of sport for healthy and sustainable cities has not been explored in depth so far. The study aims to examine the sport dimensions and sport factors that contribute to healthy and sustainable city frameworks, through a literature review and analysis of international institutions' policy documents and metrics. The study will contribute to broader understanding of the role of sport within the framework of healthy and sustainable cities and creates the paradigm of future considerations of the relevance of sport from the perspective of city management and policy maker. The novelty of this study is the use of primary sources (strategic documents) for analysis, being a relevant step for the further process of identifying the sport role towards healthy and sustainable cities.

  • Sport-related concussion alters cerebral hemodynamic activity during controlled respiration
    • Cody A. Ellingson
    • Jyotpal Singh
    • Chase J. Ellingson
    • M. Abdullah Shafiq
    • Luke W. Sirant
    • Kim D. Dorsch
    • Marcin Gruszecki
    • Gregory Kratzig
    • J Neary
    2024 JOURNAL OF NEUROPHYSIOLOGY

    This study investigated cerebral hemodynamic activity following sport-related concussion. Prefrontal cortex oxygenation was assessed by near-infrared spectroscopy (NIRS) during a controlled breathing protocol. Wavelet transformation of the NIRS signals showed significant decreases in HbO2 and HbD amplitude at the respiratory frequency interval (0.10–0.6 HZ) from preseason baseline to acute concussion. These results suggest a decreased respiratory contribution to cerebral hemodynamic activity following acute concussion.

  • Standardy dostępności do Zintegrowanych Węzłów Przesiadkowych
    • Kazimierz Jamroz
    • Marek Wysocki
    • Jacek Szmagliński
    • Romanika Okraszewska
    • Łukasz Jeliński
    • Anna Gobis
    2024

    Wiele z istniejących węzłów wymaga integracji pomiędzy poszczególnymi rodzajami transportu pasażerskiego i dostosowania do wymagań osób ze szczególnymi potrzebami, co jest związane z opracowaniem jednolitych standardów dostępności, jednolitej procedury i narzędzi przeprowadzenia oceny dostępności tych węzłów dla OzSP i zaproponowania skutecznych i efektywnych usprawnień. Problemy z samodzielnym i bezproblemowym przemieszczaniem się uwidaczniają się w zależności od klasy i wielkości węzła przesiadkowego (międzynarodowy, krajowy, regionalny, lokalny), jego dostępności, jakości infrastruktury i systemu obsługi. Różnice między przyjętymi rozwiązaniami i stosowanymi udogodnieniami występować mogą nie tylko między węzłami, ale również w obszarze jednego węzła, w zależności od obszaru lub elementu węzła. Sytuacja ta wynika z braku spójnych zasad projektowania obszarów węzłów transportowych traktowanych jako całość, niezależnie od rodzaju podsystemu i odpowiedzialnej jednostki. Nawet w sytuacji stosowania rozwiązań uwzględniających potrzeby poszczególnych grup OzSP, w przypadku braku spójnego podejścia dla niektórych grup – jak np. osoby niewidome – wielość rozwiązań i brak standaryzacji może również stanowić barierę. Dlatego w ramach projektu „Przesiadka bez Barier” podjęto wyzwanie zwiększenia dostępności węzłów przesiadkowych poprzez opracowanie spójnych zasad dla wszystkich elementów Zintegrowanego Węzła Przesiadkowego (budynków, ciągów pieszych, przystanków). Zasady te zebrano i przedstawiono w dokumencie zatytułowanym „Zintegrowane Węzły Przesiadkowe. Standardy Dostępności” (dalej zwanym Standardami Dostępności). Opracowany dokument z jednej strony integruje już istniejące standardy, a dodatkowo rozszerza je o zasady dla miejsc styku infrastruktury poszczególnych rodzajów transportu. Holistyczne podejście, zestawienie zbioru zasad i wytycznych odnoszących się do całego obszaru i wszystkich elementów węzła są podstawą spójnej w skali kraju oceny dostępności ZWP.

  • Static and dynamic concrete calculations: Breakable aggregates in DEM model
    • Michał Nitka
    2024 Journal of Building Engineering

    The paper deals with the calculations of a 3-point bending beam under static and dynamic loads. The real microstructure was obtained from laboratory tests using micro-tomography images. The quasi-static results were compared directly with experimental data at both macro and micro levels. Subsequently, higher strain rates were applied to investigate dynamic effects. The study focused on the influence of dynamic loading on the macroscopic stress-strain curve, crack propagation, the number of broken contacts, and the distribution of forces and stresses. Special attention was given to micro-fracture and cracking. The calculations were performed using the discrete element method (DEM) and were limited to a 2D problem. The proposed model introduced the consideration of aggregate breakages, which is a novel aspect compared to our previous computations. Fragmentation of the aggregate is particularly important in dynamic tests due to the release of higher energy. Finally, a beam with weak aggregate was used to validate the effectiveness of the model.

  • Statistical Data Pre-Processing and Time Series Incorporation for High-Efficacy Calibration of Low-Cost NO2 Sensor Using Machine Learning
    • Sławomir Kozieł
    • Anna Pietrenko-Dąbrowska
    • Marek Wójcikowski
    • Bogdan Pankiewicz
    2024 Pełny tekst Scientific Reports

    Air pollution stands as a significant modern-day challenge impacting life quality, the environment, and the economy. It comprises various pollutants like gases, particulate matter, biological molecules, and more, stemming from sources such as vehicle emissions, industrial operations, agriculture, and natural events. Nitrogen dioxide (NO2), among these harmful gases, is notably prevalent in densely populated urban regions. Given its adverse effects on health and the environment, accurate monitoring of NO2 levels becomes imperative for devising effective risk mitigation strategies. However, the precise measurement of NO2 poses challenges as it traditionally relies on costly and bulky equipment. This has prompted the development of more affordable alternatives, although their reliability is often questionable. The aim of this article is to introduce a groundbreaking method for precisely calibrating cost-effective NO2 sensors. This technique involves statistical preprocessing of low-cost sensor readings, aligning their distribution with reference data. Central to this calibration is an artificial neural network (ANN) surrogate designed to predict sensor correction coefficients. It utilizes environmental variables (temperature, humidity, atmospheric pressure), cross-references auxiliary NO2 sensors, and incorporates short time series of previous readings from the primary sensor. These methods are complemented by global data scaling. Demonstrated using a custom-designed cost-effective monitoring platform and high-precision public reference station data collected over five months, every component of our calibration framework proves crucial, contributing to its exceptional accuracy (with a correlation coefficient near 0.95 concerning the reference data and an RMSE below 2.4 µg/m3). This level of performance positions the calibrated sensor as a viable, cost-effective alternative to traditional monitoring approaches.

  • Statistical Method for Analysis of Interactions Between Chosen Protein and Chondroitin Sulfate in an Aqueous Environment
    • Piotr Weber
    • Piotr Bełdowski
    • Adam Gadomski
    • Krzysztof Domino
    • Piotr Sionkowski
    • Damian Ledziński
    2024

    We present the statistical method to study the interaction between a chosen protein and another molecule (e.g., both being components of lubricin found in synovial fluid) in a water environment. The research is performed on the example of univariate time series of chosen features of the dynamics of mucin, which interact with chondroitin sulfate (4 and 6) in four different saline solutions. Our statistical approach is based on recurrence methods to analyze chosen features of molecular dynamics. Such recurrence methods are usually applied to reconstruct the evolution of a molecular system in its reduced phase space, where the most important variables in the process are taken into account. In detail, the analyzed time-series are spitted onto sub-series of records that are expected to carry meaningful information about the system of molecules. Elements of sub-series are splinted by the constant delay-time lag (that is the parameter determined by statistical testing in our case), and the length of sub-series is the embedded dimension parameter (using the Cao method). We use the recurrent plots approach combined with the Shannon entropy approach to analyze the robustness of the sub-series determination. We hypothesize that the robustness of the sub-series determines some specifics of the dynamics of the system of molecules. We analyze rather highly noised features to demonstrate that such features lead to recurrence plots that graphically look similar. From the recurrence plots, the Shannon entropy has been computed. We have, however, demonstrated that the Shannon entropy value is highly dependent on the delay time value for analyzed features. Hence, elaboration of a more precise method of the recurrence plot analysis is required. For this reason, we suggest the random walk method that can be applied to analyze the recurrence plots automatically.

  • Sterowanie napięciem pracy kabli eksportowych morskich farm wiatrowych
    • Jacek Klucznik
    2024 Pełny tekst Przegląd Elektrotechniczny

    Referat przestawia problematykę doboru napięcia pracy kabli eksportowych morskich farm wiatrowych. Wskazano, że praca przy napięciu odbiegającym od napięcia znamionowego kabli może skutecznie ograniczyć straty energii jakie występują w sieci farmy. Zaproponowano uzależnienie napięcia pracy kabla od generowanej przez farmę mocy czynnej, na wzór stosowanych w przeszłości w regulatorach napięcia transformatorów układów kompensacji prądowej. Dla przykładowej farmy morskiej o mocy zainstalowanej 510 MW uzyskano zmniejszenie rocznych strat energii o około 3%.

  • Stiffness assessment of the laminate recovered from end-of-life wind turbine blade
    • Łukasz Pyrzowski
    • Agnieszka Sabik
    • Jacek Kluska
    • Jakub Zembrzuski
    2024 COMPOSITE STRUCTURES

    In the paper the stiffness parameters of the laminate recovered from an aerodynamic shell of a decommissioned wind turbine blade are evaluated. The aim of the work is to assess selected methods for identifying material data, as well as to estimate the level of stiffness degradation during turbine operation. Several practical identification methods are presented and compared. Two concepts of a single laminate layer are considered, global and local. The global concept assumes that the equivalent layer of the laminate is a system of three physical layers of a single triaxial fabric. The local concept takes into account all physical layers of the laminate. The material parameters of the global layer are identified and validated in experimental tests. Data for individual physical layers are determined by inverse analysis and the rule of mixtures. The compliance of the results obtained allows one to conclude that the stiffness of the material did not degrade significantly during the operation period. The stiffness parameters of the laminate have shown that the tested material is still very attractive for structural purposes.

  • Storage of High-Strength Steel Flux-Cored Welding Wires in Urbanized Areas
    • Adrian Wolski
    • Aleksandra Świerczyńska
    • Grzegorz Lentka
    • Dariusz Fydrych
    2024 Pełny tekst International Journal of Precision Engineering and Manufacturing-Green Technology

    The condition of the consumables is a key factor determining the waste reduction in the welding processes and the quality of the welded joint. The paper presents the results of tests of four types of fux-cored wires dedicated for welding high-strength steels, stored for 1 month and 6 months in Poland in two urbanized areas: in a large seaside city (Gdańsk) and in Warsaw, located in the center of the country. The wires were subjected to macroscopic and microscopic (stereoscopic, SEM) observations, EDS analysis, technological tests assessing elastic properties and targetability. The degree of degradation of the wires was also tested using resistance measurements. In order to assess the efect of storing wires on the weldability of steel, the difusible hydrogen content in deposited metal was determined by high-temperature extraction. It was found that the storage caused changes in the surface condition of the wires, afected their elasticity and electrical properties, which afects the behavior of the wires during welding. A signifcant infuence of storage conditions on the hydrogenation of deposited metal was found: in the case of three types of wires, the level of low hydrogen processes was exceeded and the maximum result was 15.18 ml/100 g of deposited metal. It was also found that copper-plated wire showed a signifcantly increased resistance to storage conditions compared to non-copper-plated wires.

  • Strain energy density and entire fracture surface parameters relationship for LCF life prediction of additively manufactured 18Ni300 steel
    • Wojciech Macek
    • Ricardo Branco
    • Joel de Jesus
    • José Domingos Costa
    • Shun-Peng Zhu
    • Reza Masoudi Nejad
    • Andrew Gryguć
    2024 Pełny tekst INTERNATIONAL JOURNAL OF DAMAGE MECHANICS

    In this study, the connection between total strain energy density and fracture surface topography is investigated in additively manufactured maraging steel exposed to low-cycle fatigue loading. The specimens were fabricated using laser beam powder bed fusion (LB-PBF) and examined under fully-reversed strain-controlled setup at strain amplitudes scale from 0.3% to 1.0%. The post-mortem fracture surfaces were explored using a non-contact 3D surface topography measuring system and the entire fracture surface method. The focus is on the relationship between fatigue characteristics, expressed by the total strain energy density, and the fracture surface topography features, represented by areal, volume, and fractal dimension factors. A fatigue life prediction model based on total strain energy density and fracture surface topography parameters is proposed. The presented model shows good accordance with fatigue test results and outperforms other existing models based on the strain energy density. This model can be useful for post-failure analysis of engineering elements under low-cycle fatigue, especially for materials produced by additive manufacturing (AM).

  • Strain-dependent behaviour of cold recycled material mixtures in cyclic compression tests
    • Mariusz Jaczewski
    • Andrea Graziani
    2024 Pełny tekst MATERIALS AND STRUCTURES

    The purpose of the study is to evaluate strain-dependent behaviour of Cold Recycled Material (CRM) mixtures using three frameworks typically applied for Hot Mix Asphalt (HMA): linear viscoelastic (LVE) limits; non-linearity directions; changes in rheological model parameters. To this aim, the complex modulus of three CRM mixtures with different bitumen-to-cement ratio (0.2, 0.6 and 1.8) was measured in cyclic compression mode, at increasing level of axial deformation (from 35 to 195 μstrain) and at three temperatures (4, 20 and 40 °C). CRM mixtures showed strong strain dependent behaviour, which does not fully comply with the LVE hypothesis. LVE limit framework is applicable, but strain limits for CRM are different from HMA. Linearity direction framework does not give unique trend, hence it is not applicable in the same way as it was developed for HMA. The most promising framework for further analysis is the change in rheological model parameters, but it requires high number of performed tests.

  • STRATEGIC PARTNERSHIPS IN THE DEVELOPMENT OF THE POLISH BIOTECHNOLOGY INDUSTRY
    • Piotr Grudowski
    • Sylwia Sieracka
    2024 Zeszyty Naukowe Politechniki Śląskiej. Seria Organizacja i Zarządzanie

    Purpose: Identification of causative factors and the resulting benefits regarding strategic partnerships in developing biotechnology enterprises in Poland. Design/methodology/approach: Analysis of the literature on the subject, in-depth interviews, case studies and participant observations. Findings: Effective strategic partnerships in Poland are few. They intertwine with other forms of cooperation, striving to create an innovation ecosystem that can increase the commercialisation of the work being carried out. Research limitations/implications: The biotechnology enterprise sector does not maintain a register of strategic partnerships. Enterprises do not willingly disclose newly developed technologies. The research is of a pilot nature and requires continuation. Practical implications: No register of strategic partnerships could guide the government in developing cooperation. Identify the sector's needs and measure the effectiveness of concluded partnerships (evaluation) and the directions of collaboration undertaken. Originality/value: Identification of strategic partnerships in the biotechnology industry in Poland compared to other countries.

  • Stress Assessment of a Steel Bullet LPG Tank Under Differential Settlement Based on Geodetic Measurements and Sensitivity Analysis
    • Tomasz Ferenc
    • Rafał Gierasimczyk
    • Tomasz Mikulski
    2024 Pełny tekst Polish Maritime Research

    This paper presents an analysis of a steel bullet LPG tank in operation at a base in Poland. The structure was set on a sand-gravel pillow and rigid concrete slab, and its settlement was periodically measured at five measuring points along the structure. After a few years, differential settlement was observed. Based on geodetic data, we attempt to assess the current stress level in the structure. The proposed methodology uses a sensitivity analysis apparatus. A numerical model of the structure and sand-gravel pillow is analysed using the finite element method, and the impact of variation in the stiffness of the sand-gravel pillow on the vertical displacement of the tank is determined. The algorithm involves six iterations of calculations, and after each iteration, the stiffness modified sand-gravel pillow is determined. After the sixth iteration, the vertical displacement in the FEM model is found to be similar to the measured values in the real structure. The results obtained after the last iteration are used to assess the stress state in the bullet tank’s shell structure.

  • Structural phase transitions in multicomponent La0.2Nd0.2Sm0.2Gd0.2RE50.2NbO4 (RE5 = Ho, Y, Tb, Eu, Pr) oxides
    • Arkadiusz Dawczak
    • Aleksandra Mielewczyk-Gryń
    • Maria Gazda
    2024 Pełny tekst JOURNAL OF THE AMERICAN CERAMIC SOCIETY

    In this work, the influence of compositional complexity on the structural and thermal properties of multicomponent rare-earth ortho-niobates from the La0.2Nd0.2Sm0.2Gd0.2RE50.2NbO4 (RE5 = Ho, Y, Tb, Eu, Pr) series have been investigated. Based on X-ray powder diffraction studies using synchrotron radiation, it was found that all tested materials were pure single-phase compositions and showed stability in the monoclinic I2/c crystal structure at room temperature. High-temperature X-ray powder diffraction studies and dilatometry studies confirmed the presence of a structural phase transition between low- (I2/c ) and high-temperature (I41/a) polymorphs. The structural phase transition temperatures are between 676 °C and 701 °C. Interestingly, despite their compositional complexity, the structural phase transition temperature behaves similarly to conventional ortho-niobates, i.e. it depends on the radius of the A-cation, that is, as the ionic radius increases, the phase transition temperature decreases. The transition has been categorized as a second-order phase transition based on the observed relationship between the Landau order parameter and spontaneous strain. The coexistence of the tetragonal and monoclinic phases has been seen in all compositions around the temperature of the structural phase transition. The presence of two orientation states in the monoclinic structure leads to the so-called spontaneous strain, which consists of longitudinal (u) and shear (v) strain components. The values of these strains at 300 °C range between 2.42 – 2.58·10-2 for longitudinal, 2.98 – 3.04·10-2 for shear, and 5.46 – 5.57·10-2 for scalar spontaneous strain. It was found that the spontaneous strain in each of the materials under test was very little impacted by the variation in the complexity of the A sublattice's composition. In addition, thermal expansion coefficients of both polymorphs were determined, which range from 12.7·10-6 1/K to 13.2·10-6 1/K for the monoclinic structure and 9.7·10-6 1/K to 9.9·10-6 1/K for the tetragonal one.

  • Structure versus hydrolytic and thermal stability of bio-based thermoplastic polyurethane elastomers composed of hard and soft building blocks with high content of green carbon
    • Ewa Głowińska
    • Joanna Smorawska
    • Joanna Niesiobędzka
    • Janusz Datta
    2024 Pełny tekst JOURNAL OF THERMAL ANALYSIS AND CALORIMETRY

    Nowadays, sustainability plays a key role in the design and synthesis of new materials. One of the methods for the preparation of green materials is incorporation into their structure the monomers with a high content of green carbon. Therefore, the aim of this work was to investigate the influence of the type and molecular mass of two bio-based polyester polyols and bio-glycol on the properties of aliphatic partially bio-based thermoplastic polyurethane elastomers (bio-TPU). Two series of bio-TPUs materials composed of hard and soft building blocks with high green carbon content were prepared via the two-step method (prepolymer method). Two amorphous bio-based polyester polyols with the molecular mass ~ 2000 (P1) and ~ 3000 (P2) were used. Bio-TPUs were prepared at three different molar ratio of [NCO]/[OH]: 0.9, 0.95, and 1.0. In order to determine the influence of bio-based polyols and the content of hard segments on the properties of bio-TPU, relevant test methods were used. The Fourier transform infrared spectroscopy (FTIR), differential scanning calorimetry (DSC), and thermogravimetry (TG) revealed hydrolytic and thermal stability of bio-TPUs. Viscoelastic behavior, mechanical and physical properties were examined in terms of dynamic mechanical thermal analysis (DMTA), tensile test, hardness, and density. Analysis of the measurement results confirmed the significant influence of the molecular mass of the bio-based polyols and the molar ratio of [NCO]/[OH] on the bio-TPUs properties. Due to good mechanical properties, low density, and thermal stability up to 300 °C, the obtained materials can find many useful applications. This issue is essential in terms of sustainable development and reduction in the CO 2 emissions to the atmosphere.

  • Studies of the Interaction Dynamics in Albumin-Chondroitin Sulfate Systems by Recurrence Method
    • Piotr Bełdowski
    • Piotr Weber
    • Adam Gadomski
    • Piotr Sionkowski
    • Natalia Kruszewska
    • Krzysztof Domino
    2024

    The physicochemical basis of lubrication of articular cartilage is still not fully understood. However, the synergy between components of the synovial fluid can be a crucial factor that could explain this phenomenon. This work presents a nonlinear data analysis technique named the recurrence method, applied to the system involving two components of synovial fluid: albumin and chondroitin sulfate (CS) immersed in a water environment. This analysis is performed in order to obtain the ”statistical fingerprint” of the dynamics of the interaction between the molecules and to answer whether the variables are more deterministic or more random. The system simulation has been prepared by molecular docking method followed by molecular dynamics simulations. The already mentioned recurrence method has been applied to the time series of the energy of binding, and the time series of the number of intermolecular hydrogen bonds, as these features describe well binding between the two molecules. In detail, the time delay approach and embedded dimension approach have been applied to extract meaningful records from time series. Then, by means of recurrence plots and entropy approach, we discuss the similarities and differences between the molecular systems consisting of CS-4 and CS-6 molecules. Our main finding is a higher affinity of chondroitin sulfate IV to albumin as compared with chondroitin sulfate VI.