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  • Two-step synthesis of niobium doped Na–Ca–(Mg)–P–Si–O glasses
    • Natalia Wójcik
    • S Ali
    • Aleksandra Mielewczyk-Gryń
    • B Jonson
    2021 Pełny tekst JOURNAL OF MATERIALS SCIENCE

    Niobium doped biosolubility glasses in the Na–Ca–(Mg)–P–Si–O system were prepared by using an untypical two-step synthesis route. The parent glass was melted in air atmosphere at 1350 °C followed by re-melting the glass in Nb crucible with the addition of metallic Mg/Ca powder in the nitrogen atmosphere. The second melting step was carried out at 1450–1650 °C, using an induction furnace. The topography and structure of the obtained glasses were characterized by confocal microscopy, X-ray powder diffraction and infrared spectroscopic techniques. The chemical compositions were examined by energy-dispersive X-ray spectroscopy (EDS). The glasses were found to be of grayish color, X-ray amorphous and having network connectivity between * 2.5 and 2.7. The network connectivity of re-melted glasses was lower than the one of the parent glass. The glass structure consists of a highly disrupted silicate network of predominantly Q2 groups as well as isolated orthophosphate tetrahedra. The parent glass contains nanocrystallites consisted of apatitic PO43- groups. The re-melted glasses contain nonapatitic or amorphous calcium phosphates. The obtained glass transition temperatures range from 530 to 568 °C and exhibit higher values for glassed doped with Ca metal. These glasses have improved thermal stability as compared to reference bioglasses. The biosolubility test in phosphate buffered saline solution (PBS) confirms that the glasses have biosolubility properties and HAp formation on the surfaces was observed

  • Twórczość - przekraczanie dyscyplin. Analiza postawy autorskiej
    • Agnieszka Kurkowska
    2021 Pełny tekst Facta Ficta. Journal of Theory, Narrative & Media

    Agnieszka Kurkowska w artykule Twórczość - przekraczanie dyscyplin. Analiza postawy autorskiej odnosi się do zagadnienia poruszania w różnych obszarach wiedzy i umiejętności przez jednostkowego twórcę. Zarysowany jest problem niemożności wąskiego traktowania architektury jako dziedziny stricte inżynieryjnej. Architekt otwarty na otaczające problemy przestrzenne, ich fizyczne i pozafizyczne aspekty sięga w swoich wypowiedziach do obszarów pokrewnych architekturze, aby swoją wypowiedź wzmocnić i wzbogacić. W poniższej pracy podjęto próbę udowodnienia tezy, że przeanalizowana tu postawa autorska ukazuje konieczność przekraczania dyscyplin w projektowaniu architektonicznym. Ukazano, w oparciu o studium przypadku, w jaki sposób poruszanie się poza ścisła inżynierią może wzbogacać projekty architekta i wzmacniać możliwość ich oddziaływania. Na dobrane do prezentowanej analizy projekty składają się projekty obiektów architektonicznych, projekty małej architektury, mebli, przedmiotów użytkowych, wnętrz. To również projekty artystyczne posiłkujące się malarstwem, grafiką, rzeźbą, fotografią czy instalacją przestrzenną, także publikacje książkowe. Kolejną kategorią są projekty edukacyjne skoncentrowane na cyklach działań warsztatowych, materiałach edukacyjnych, wydarzeniach partycypacyjnych. Wszystkie przykłady łączy osoba autora, poruszającego się w swojej pracy w obszarze kilku dyscyplin, co w perspektywie czasowej ukazuje kompletną, wieloelementową postawę wobec przestrzeni, korzystających z niej ludzi i wypełniających ją obiektów. Wspomniana postawa zawiera kilka istotnych komponentów, które przeważając w określonych przypadkach, przenoszą go do poszczególnych zadań i związanych z nimi ról społecznych i zawodowych. Bywa więc architekt twórcą, gdy posługuje się narzędziami wyrazu artystycznego, kreując indywidualne, unikalne obiekty w różnej skali, poruszając się jednocześnie w obszarze sztuki i inżynierii. Może też być naukowcem, czy badaczem analizujący, pogłębiający, poszukującym, weryfikujący przyjęte rozwiązania. Czasami staje się pedagogiem czy edukatorem, gdy swoje działania skupia na przekazaniu wiedzy. Ponad wszystko architekt pozostaje jednakże człowiekiem o określonej strukturze psychicznej i fizycznej, będąc osobowym elementem społeczności. Architekt to autor przekraczający różne dyscypliny w ramach swojej twórczości czego konieczności i celowości mają dowieść przedstawione analizy i wspierające je studium przypadku.

  • Type III Responses to Transient Inputs in Hybrid Nonlinear Neuron Models
    • Jonathan E. Rubin
    • Justyna Signerska-Rynkowska
    • Jonathan D. Touboul
    2021 Pełny tekst SIAM JOURNAL ON APPLIED DYNAMICAL SYSTEMS

    Experimental characterization of neuronal dynamics involves recording both of spontaneous activity patterns and of responses to transient and sustained inputs. While much theoretical attention has been devoted to the spontaneous activity of neurons, less is known about the dynamic mechanisms shaping their responses to transient inputs, although these bear significant physiological relevance. Here, we study responses to transient inputs in a widely used class of neuron models (nonlinear adaptive hybrid models) well-known to reproduce a number of biologically realistic behaviors. We focus on responses to transient inputs that have been previously associated with Type III neurons, arguably the least studied category in Hodgkin's classification, which are those neurons that never exhibit continuous firing in response to sustained excitatory currents. The two phenomena that we study are postinhibitory facilitation, in which an otherwise subthreshold excitatory input can induce a spike if it is applied with proper timing after an inhibitory pulse, and slope detection, in which a neuron spikes to a transient input only when the input's rate of change is in a specific, bounded range. Using dynamical systems theory, we analyze the origin of these phenomena in nonlinear hybrid models. We provide a geometric characterization of dynamical structures associated with postinhibitory facilitation in the system and an analytical study of slope detection for tent inputs. While the necessary and sufficient conditions for these behaviors are easily satisfied in neurons with Type III excitability, our proofs are quite general and valid for neurons that do not exhibit Type III excitability as well. This study therefore provides a framework for the mathematical analysis of these responses to transient inputs associated with Type III neurons in other systems and for advancing our understanding of these systems' computational properties.

  • Typology and comparative analysis of black tents built in tradition of iranian tribes
    • Najmeh Hassas
    2021 Pełny tekst

    This study focused on the habits and way of life of nomads in the Iranian Highlands, but their homes, called Black Tents, were of the main interest. The research explored the construction of the Black Tents and the way of shaping the space in which family life takes place. It concerned the architectural forms of tents, structures and materials from which they are erected, as well as interior furnishings and objects that determine their character. The methods used in the research include descriptive analysis and graphical presentation of the test results. The inquiry was conducted in libraries, archives and institutions and using official websites. The author also conducted drawing and photographic inventories of tents and everyday life of nomads. Laboratory tests of the next phase of work have been documented with printouts and presentations of the sets of devices used in the research. Further analysis was carried out using advanced software computer programmes, such as 3DMax, ABAQUS and other professional civil engineering digital tools allowing to obtain comparable results. The research results and summaries of their individual phases are presented in the form of maps, charts and tables. As a result of macroscopic studies, it turned out that the fabric, made of cloth woven from long black goat hair, with which the structures are covered (Chador), which is woven by women, is the same for all tribes. Women also erect and dismantle tents before and after the journey and so have an influence on their construction. The analysis of the dimensions and forms of the discussed seven types of tents from different parts of the country showed large differences, which is evidence of creativity and engineering thinking. The next step of the research was to check to what extent the stability of each tent is adjusted to the climatic situation in which it is used. For this purpose, models were created in the ABACUS program. Their responses to wind and rain loads have been studied. It has been confirmed that the tents are strictly adapted to the conditions in which they are used. Their diversification is the result of the experience of many generations of nomads: observing the routes they traveled and the materials they could use. Tests of tent models covered with hand-made goat hair fabric showed that it is more useful for strengthening the structure of the tent and protecting its interior than fabrics used today for a similar purpose.

  • UAV Photogrammetry under Poor Lighting Conditions—Accuracy Considerations
    • Paweł Burdziakowski
    • Katarzyna Bobkowska
    2021 Pełny tekst SENSORS

    The use of low-level photogrammetry is very broad, and studies in this field are conducted in many aspects. Most research and applications are based on image data acquired during the day, which seems natural and obvious. However, the authors of this paper draw attention to the potential and possible use of UAV photogrammetry during the darker time of the day. The potential of night-time images has not been yet widely recognized, since correct scenery lighting or lack of scenery light sources is an obvious issue. The authors have developed typical day- and night-time photogrammetric models. They have also presented an extensive analysis of the geometry, indicated which process element had the greatest impact on degrading night-time photogrammetric product, as well as which measurable factor directly correlated with image accuracy. The reduction in geometry during night-time tests was greatly impacted by the non-uniform distribution of GCPs within the study area. The calibration of non-metric cameras is sensitive to poor lighting conditions, which leads to the generation of a higher determination error for each intrinsic orientation and distortion parameter. As evidenced, uniformly illuminated photos can be used to construct a model with lower reprojection error, and each tie point exhibits greater precision. Furthermore, they have evaluated whether commercial photogrammetric software enabled reaching acceptable image quality and whether the digital camera type impacted interpretative quality. The research paper is concluded with an extended discussion, conclusions, and recommendation on night-time studies.

  • Uczelnia organizacją z domieszka turkusu - sznasa czy iluzja?
    • Krzysztof Leja
    • Aleksandra Pawlak
    2021 Pełny tekst e-mentor

    Po kilkuletnich dyskusjach nad przyszłym kształtem szkolnictwa wyższego w Polsce, zarówno na poziomie systemowym, jak i instytucjonalnym, w 2018 r. uchwalono ustawę Prawo o szkolnictwie wyższym i nauce, zwaną dalej Ustawą (2018). Regulacja ta wraz z pakietem rozporządzeń poszerzyła autonomię uczelni w zakresie organizacyjno-zarządczym, jednocześnie potęgując znaczenie ich rozliczalności. Wzmocnienie władzy rektora spowodowało zmianę postrzegania uczelni jako organizacji rozproszonych (Weick, 1976) w kierunku organizacji zwartych (Brunsson i Sahlin-Andersson, 2000) Autorzy opracowania dostrzegli, że koncepcja uczelni, zgodnie z literą i duchem Ustawy, nie zwraca należytej uwagi na relacje między pracownikami. Dlatego za cel artykułu uznano przedstawienie propozycji wdrożenia do instytucji akademickiej elementów coraz częściej opisywanej w literaturze naukowej – a równocześnie budzącej skrajne emocje – koncepcji organizacji turkusowej (Laloux, 2015). W artykule wskazano niewykorzystane, zdaniem autorów, możliwości zmian organizacyjno-zarządczych, jakie stworzyła Ustawa, a także opisano wybrane cechy organizacji turkusowej, odnosząc je do instytucji akademickiej. Ponadto zestawiono cechy uniwersytetu tradycyjnego, przedsiębiorczego oraz uniwersytetu z domieszką turkusu. W części badawczej przeanalizowano wywiady przeprowadzone z celowo wybranymi pracownikami Politechniki Gdańskiej, którzy wyrażali opinie dotyczące nowych rozwiązań organizacyjno-zarządczych zaproponowanych przez współautorkę artykułu podczas wywiadów. W podsumowaniu starano się odpowiedzieć na pytanie sformułowane w tytule.

  • Uczelnie kształcące polskich inżynierów elektryków do II wojny światowej
    • Dariusz Świsulski
    2021 Pełny tekst Przegląd Elektrotechniczny

    Na podstawie notek biograficznych ponad 1000 osób przedstawiono uczelnie, w których wykształcenie w latach 1891-1935 zdobywali polscy inżynierowie elektrycy. Do I wojny światowej były to uczelnie zagraniczne: niemieckie, rosyjskie, francuskie, belgijskie. Później Polacy kształcili się w polskich uczelniach: Politechnice Lwowskiej oraz w utworzonej w 1915 roku i szybko rozwijającej się Politechnice Warszawskiej.

  • Ukrainian Market of Electrical Energy: Reforming, Financing, Innovative Investment, Efficiency Analysis, and Audit
    • Ruslan Kostyrko
    • Tetiana Kosova
    • Lidiia Kostyrko
    • Liudmyla Zaitseva
    • Oleksandr Melnychenko
    2021 Pełny tekst ENERGIES

    The aim of this research is to determine the influence of electrical energy market regulation reform in Ukraine on the competitive environment, the reproduction processes of financial and innovative support, and the energy efficiency of the national economy. The authors have put forward and verified the hypothesis that, under conditions of institutional maturity of the Ukrainian electrical energy market, its liberalization and separation of the kinds of activity related to generation, transmission, and distribution leads to a decrease in prices, and the level of economic concentration stimulates implementation of innovations and the formation of reports on sustainable development. Over the thirteen-year time interval, a steady trend of decreasing energy intensity of the Ukrainian economy was established, and the appropriateness of energy efficiency management based on strategic targets was substantiated. The electricity market model in Ukraine is defined as a hybrid one, with an emphasis on trade under bilateral agreements. It was statistically found that liberalization of the electrical energy market in Ukraine contributed to a decrease in prices, with the exception of the areas of largest household and non-household consumers. The high level of asset concentration in the accounts of large enterprises was revealed, and the conclusion concerning the improvement of the competitive environment in the electricity production sector and the existence of the features of natural monopolies in the areas of transmission and distribution of electricity was made. The assessment of the financial competitive ability and profitability of electrical energy market entities was made, the main entities of the investment activity and the sources of their financing were characterized, and innovations were emphasized. The role of the standards of the audit of integrated reporting of the Ukrainian energy holdings and their role in ensuring sustainable development was determined.

  • Ulepszanie podłoża gruntowego i podtorza z użyciem środków strzałowych
    • Eligiusz Mieloszyk
    • Anita Milewska
    • Mariusz Wyroślak
    2021

    Szybka i skuteczna metoda wzmacniania podłoża gruntowego i podtorza z wykorzystaniem środków strzałowych (zastrzeżona nazwa handlowa: metoda mikrowybuchów) pozwala projektować i budować drogi kolejowe na gruntach o obniżonej nośności (np. tereny podmokłe, bagna, odpady przemysłowe, komunalne, zdegradowane nasypy antropogeniczne). Jest przydatna i godna polecenia przy budowie nowych linii kolejowych, modernizacji istniejących oraz naprawach bieżących i głównych (często powiązanych z modernizacją). Prawidłowo wzmocnione podłoże gruntowe i podtorze jest gwarantem niezawodności danej linii kolejowej. Zwiększa żywotność trasy i bezpieczeństwo prowadzonego ruchu kolejowego.

  • Ultimate compressive strength assessment of uncleaned and cleaned corroded plates with locked crack
    • Krzysztof Wołoszyk
    • Yordan Garbatov
    2021 Pełny tekst Polish Maritime Research

    The work presented here investigates the structural response of cleaned corroded plates, subjected to compressive load in the presence of a locked crack, where the change of mechanical properties as a result of corrosion development and the cleaning process is also accounted for. A Finite Element model for assessing the compressive strength, considering geometric and material nonlinearities, is developed, and the analysed plates are compared with the available experimental data. An experimental design plan is generated using the Design of Experiments techniques, which quantifies the influence of the governing variables and their interactions with respect to the plate's ultimate compressive strength. With a limited number of observations, the most significant effects are identified. The corrosion degradation is revealed to be the most crucial effect leading to an effective strength reduction. It was found that, in the case of a corroded plate with a locked crack subjected to a compressive load, the most severe case is when the crack is transversely oriented. The strength reduction is slightly lower than when the corrosion degradation and the presence of a crack are considered to be a simple summation of these two effects but acting separately. The outcome of the analysis is the development of several empirical formulations that allow a fast estimation of the ultimate strength of a corroded plate, subjected to compressive load in the presence of a locked crack, accounting for different cleaning.

  • Ultimate strength of stiffened plates subjected to compressive load and spatially distributed mechanical properties
    • Krzysztof Wołoszyk
    • Yordan Garbatov
    2021

    The present study deals with the ultimate strength of stiffened plates subjected to spatially distributed mechanical properties and compressive load. Normally, mean values of mechanical properties based on tensile tests are used to validate the numerical assessment with experimental results. However, mechanical properties may vary within a single specimen. To investigate the impact of that, random fields of yield stress and Young modulus are employed together with the FE method. The variations of mechanical properties are estimated based on tensile tests. Different parameters of the random field are analysed, showing that the structural response will be different when compared with the stiffened plate with constant mechanical properties. Finally, it was revealed that the variation of yield stress has a significant impact, and Young modulus uncertainties play a secondary role. It is concluded, that the spatial variation of mechanical properties need to be considered when validating the numerical assessment with experimental measurements.

  • Ultrafiltration Process in Disinfection and Advanced Treatment of Tertiary Treated Wastewater
    • Rafał Bray
    • Katarzyna Jankowska
    • Eliza Kulbat
    • Aneta Łuczkiewicz
    • Aleksandra Sokołowska
    2021 Pełny tekst Membranes

    The paper presents the results of research on the use of ultrafiltration, using membranes of 200 and 400 kDa separation, for disinfection of municipal treated wastewater. The research was conducted on a fractional technical scale using real municipal treated wastewater from two large wastewater treatment plants treating most of the wastewater over the one-million polycentric Gdańsk agglomeration (1.2 million inhabitants). UF 200 kDa and UF 400 kDa processes enabled further improvement of the physical and chemical parameters of treated wastewater. Total phosphorus (to below 0.2 mg/L–UF 200 kDa, 0.13 mg/L–UF 400 kDa) and turbid substances (to below 0.2 mg/L, both membranes) were removed in the highest degree. COD was reduced efficiently (to below 25.6 mgO2/L–UF 200 kDa, 26.8 mgO2/L–UF 400 kDa), while total nitrogen was removed to a small extent (to 7.12 mg/L–UF 200 kDa and 5.7 mg/L–UF 400 kDa. Based on the reduction of indicator bacteria; fecal coliforms including E. coli (FC) and fecal enterococci (FE) it was found that the ultrafiltration is an effective method of disinfection. Not much indicator bacterial were observed in the permeate after processes (UF 200 kDa; FC—5 CFU/L; FE—1 CFU/L and UF 400 kDa; FC—70 CFU/L; FE—10 CFU/L. However, microscopic analysis of prokaryotic cells and virus particles showed their presence after the application of both membrane types; TCN 3.0 × 102 cells/mL–UF 200 kDa, 5.0 × 103 cells/mL–UF 400 kDa, VP 1.0 × 105/mL. The presence of potentially pathogenic, highly infectious virus particles means that ultrafiltration cannot be considered a sufficient disinfection method for treated wastewater diverted for reuse or discharged from high load wastewater treatment plants to recreational areas. For full microbiological safety it would be advisable to apply an additional disinfection method (e.g., ozonation)

  • Ultrasensitive electrochemical determination of the cancer biomarker protein sPD-L1 based on a BMS-8-modified gold electrode
    • Paweł Niedziałkowski
    • Magdalena Bojko
    • Jacek Ryl
    • Anna Wcisło
    • Marta Spodzieja
    • Katarzyna Magiera Mularz
    • Katarzyna Guzik
    • Grzegorz Dubin
    • Tad A. Holak
    • Tadeusz Ossowski
    • Sylwia Rodziewicz-Motowidło
    2021 Pełny tekst BIOELECTROCHEMISTRY

    This work describes the modification of a gold electrode with the BMS-8 compound that interacts with the Programmed Death-Ligand 1 (PD-L1), an immune checkpoint protein. The results show that we can confirm the presence of the sPD-L1 in the concentration range of 10−18 to 10−8 M using electrochemical impedance spectroscopy (EIS) with a limit of detection (LOD) of 1.87 × 10−14 M for PD-L1 (S/N = 3.3) and at a concentration of 10−14 M via cyclic voltammetry (CV). Additionally, high-resolution X-ray photoelectron spectroscopy (XPS), contact angle, and surface free energy measurements were applied to confirm the functionalization of the electrode. We investigated the selectivity of the electrode for other proteins: Programmed Death-1 (PD-1), cluster of differentiation 160 (CD160), and B- and T-lymphocyte attenuator (BTLA) at concentrations of 10−8 M. Differentiation between PD-L1 and PD-1 was achieved based on the analysis of the capacitance effect frequency dispersion at the surface of the modified Au electrode with BMS-8 after incubation at various concentrations of PD-L1 and PD-1 proteins in the range of 10−18 to 10−8 M. Significant differences were observed in the heterogeneity of PD-L1 and PD-1. The results of the quasi-capacitance studies demonstrate that BMS-8 strongly and specifically interacts with the PD-L1 protein.

  • Ultrasonic-assisted Electrodeposition of Cu-Sn-TiO2 Nanocomposite Coatings with Enhanced Antibacterial Activity
    • Dmitry Kharitonov
    • Aliaksandr Kasach
    • Denis Sergievich
    • Angelika Wrzesińska
    • Izabela Bobowska
    • Kazimierz Darowicki
    • Artur Zieliński
    • Jacek Ryl
    • Irina Kurilo
    2021 Pełny tekst ULTRASONICS SONOCHEMISTRY

    Copper-based coatings are known for their high antibacterial activity. In this study, nanocomposite Cu–Sn–TiO2 coatings were obtained by electrodeposition from an oxalic acid bath additionally containing 4 g/dm3 TiO2 with mechanical and ultrasonic agitation. Ultrasound treatment was performed at 26 kHz frequency and 32 W/dm3 power. The influence of agitation mode and the current load on the inclusion and distribution of the TiO2 phase in the Cu–Sn metallic matrix were evaluated. Results indicated that ultrasonic agitation decreases agglomeration of TiO2 particles and allows for the deposition of dense Cu–Sn–TiO2 nanocomposites. It is shown that nanocomposite Cu–Sn–TiO2 coatings formed by ultrasonic-assisted electrodeposition exhibit excellent antimicrobial properties against E. coli bacteria.

  • Ultrasound-assisted wet-impregnation of Ag–Co nanoparticles on cellulose nanofibers: Enhanced catalytic hydrogenation of 4-nitrophenol
    • Vividha K. Landge
    • Shirish H. Sonawane
    • Sivakumar Manickam
    • G.Uday Bhaskar Babu
    • Grzegorz Boczkaj
    2021 Journal of Environmental Chemical Engineering

    In this study, a novel nanocomposite of bimetallic Ag–Co nanoparticles supported on cellulose nanofibers (CNFs) was synthesised using the ultrasound-assisted wet-impregnation method for catalytic applications. CNFs were prepared from cellulose acetate using the electrospinning technique. Fourier transform infrared spectroscopy (FTIR) analysis confirmed the successful synthesis of CNFs. Further, scanning electron microscopy (SEM) with energy dispersive X-ray analysis (EDX) revealed a uniform dispersion of Ag and Co metals on the CNFs. At the same time, X-Ray diffraction (XRD) spectra indicated the highly crystalline nature of the as-produced composite. The hydrogenation of 4-nitrophenol (4-NP) was used to study the efficiency of the synthesised nanocomposite. The progress of the reaction was examined via UV–visible spectroscopy. It was noted that Ag-Co nanoparticles supported on CNFs catalysed the hydrogenation of 4-NP (0.1 mM) to 4-aminophenol within just 110 s with an apparent rate constant of 0.0172 s−1. This study proved that the obtained catalysts have superior stability and reusability with about 100% conversion up to 5 cycles. The excellent activity of the as-synthesised Ag-Co/CNFs nanocomposites makes it a promising nanocatalyst for catalytic applications.

  • Understanding Knowledge-Intensive Business Services. Identification, Systematization, and Characterization of Knowledge Flows
    • Małgorzata Zięba
    2021 Pełny tekst

    This book contributes to an improved understanding of knowledge-intensive business services and knowledge management issues. It offers a complex overview of literature devoted to these topics and introduces the concept of ‘knowledge flows’, which constitutes a missing link in the previous knowledge management theories. The book provides a detailed analysis of knowledge flows, with their types, relations and factors influencing them. It offers a novel approach to understand the aspects of knowledge and its management not only inside the organization, but also outside, in its environment.

  • Understanding the capacitance of thin composite films based on conducting polymer and carbon nanostructures in aqueous electrolytes
    • Anita Cymann-Sachajdak
    • Magdalena Graczyk-Zajac
    • Grzegorz Trykowski
    • Monika Wilamowska-Zawłocka
    2021 Pełny tekst ELECTROCHIMICA ACTA

    In this work electrochemical performance of thin composite films consisted of poly(3,4-ethylenedioxythiophene) (PEDOT), graphene oxide (GOx) and oxidized multiwalled carbon nanotubes (oxMWCNTs) is investigated in various sulphates (Li2SO4, Na2SO4, K2SO4, MgSO4) and acidic (H2SO4) electrolytes. Capacitance values, rate capability and cycling stability achieved for the composite layers are correlated with the electrolytes’ properties such as the conductivity, viscosity, cation size and pH. The highest capacitance values are achieved in acidic solution (98.6 mF cm−2 at 1 mA cm−2), whereas cycling stability is better in neutral electrolytes (88.4% of initial capacitance value after 10’000 cycles recorded for symmetric supercapacitor in 0.5 M MgSO4 solution). Diffusion controlled and non-diffusion controlled capacitance contributions are calculated and the results are discussed considering various ranges of sweep rates taken into account in the linear fitting and extrapolation of parameters.

  • Understanding the interactions between protein stabilizers and the peptide bond through the analysis of the volumetric and compressibility properties for the model systems
    • Emilia Kaczkowska
    • Jarosław Wawer
    • Magdalena Tyczyńska
    • Małgorzata Jóźwiak
    • Joanna Krakowiak
    2021 Pełny tekst JOURNAL OF CHEMICAL THERMODYNAMICS

    This work confirms our earlier supposition, that volumetric and acoustic parameters for simple model proposed by us are directly related to stabilizing/destabilizing effect of osmolytes on proteins structure. The apparent molar volumes, V and the apparent molar isentropic compressions, KS,, of glycine and N,N,N –trimethylglycine (betaine) were determined from densities and speed of sound measurements in aqueous solution of N-methylacetamide (as a model of peptide bond of protein). The standard molar parameters for osmolytes were obtained from concentration dependence of the calculated quantities at NMA concentration equal 2, 4, 6 and 8 (mol/kg) and at temperature T = (288.15, 298.15 and 308.15) K. The standard values were combined with volumetric and compressibility data for amino acids in pure water to obtain transfer properties from water to aqueous N-methylacetamide solutions. The standard partial molar volume of transfer of studied osmolytes, 〖Δ_t V〗_Φ^0, seems to be related mainly to hydrophilic/hydrophobic features of molecules. The stabilizing/destabilizing effect of solute on protein structure is reflected in temperature influence on the limiting partial molar quantities.

  • Underwater acoustic communication system using broadband signal with hyperbolically modulated frequency
    • Jan Schmidt
    • Aleksander Schmidt
    2021 Pełny tekst Vibrations in Physical Systems

    The implementation of reliable acoustic underwater communication in shallow waters is a scientific and engineering challenge, mainly due to the permanent occurrence of the multipath phenomenon. The article presents the concept of a transmission system using a broadband signal with hyperbolically modulated frequency (HFM) to transmit data symbols and synchronize data frames. The simulation tests were carried out in channels with Rician fading, reflecting the short- and mediumrange shallow water channels. The simulation also took into account the presence of additive Gaussian noise in the channel on the functioning of the receiver. The obtained results prove the high reliability of the underwater communication system based on broadband HFM signals.

  • Unexpected Z/E isomerism of N-methyl-O-phosphothioyl benzohydroxamic acids, their oxyphilic reactivity and inertness to amines
    • Arkadiusz Majewski
    • Jarosław Chojnacki
    • Witold Przychodzeń
    2021 Pełny tekst STRUCTURAL CHEMISTRY

    Thiophosphinoylation of N-methyl p-substituted benzohydroxamic acids using disulfanes (method A) or diphenylphosphinothioyl chloride (method B) provides only one conformer of the respective O-phosphothioyl derivative (Xray and NMR analysis). Undergoing the P-transamidoxylation reaction is an evidence of the reversibility of thiophosphinoylation. Only those products containing strong EWG substituents in the aroyl residue or bulky substituents at the phosphorus atom possess E conformation. DFT calculations confirmed the energetic domination of each isomer. The Z-isomers are distorted amides having both high degree of nitrogen pyramidalization (38–55°) and amide twist (12–30°). In solution they exist in a defined conformation that is evidenced by the presence of a sharp signal of N-methyl protons at low temperature. They do not isomerize in solutions. Some of them slowly undergo the N-O bond scission above 100 °C. Both isomers are not as sensitive to neutral hydrolysis as twisted amides can be and are inert toward amines. The rate of alkaline hydrolysis can be correlated with pKa of hydroxamic acid. Because of their outstanding oxyphilicity, these compounds can be defined as nerve agent surrogates and safer alternatives of phosphorus fluorides for serine-active enzyme inhibition studies