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Gdańsk University of Technology

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Publications from the year 2021

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  • Stabilizacja podtorza z wykorzystaniem georusztów heksagonalnych
    • Remigiusz Duszyński
    • Michał Gołos
    2021 Inżynier Budownictwa

    Georuszty wielokierunkowe ograniczją przemieszczenia kruszywa, redukują deformacje podsypki tłuczniowej, wydłużają okres pomiędzy zabiegami utrzymaniowymi

  • Stabilizing forces in trapezoidal sheeting used as a part of the bracing system
    • Natalia Korcz-Konkol
    • Piotr Iwicki
    2021

    In the analysis of bracing systems imperfections of the restrained elements should be considered. According to EC3 this effect can be calculated by means of the equivalent stabilizing force, which replaces (in simplified way) initial bow imperfection of the braced element. However, alternative suggestions of the equivalent stabilizing force calculations can be also found in the literature. In this paper segment of the pitched roof with truss girders, purlins and trapezoidal sheeting was analyzed in two variants: with bar bracing and with trapezoidal cladding as a part of the bracing system (resisting in-plane forces). The influence of the imperfections of the truss girder on the axial forces in the purlins in two cases of the bracing systems were observed. Geometrically nonlinear analysis using shell elements was performed in Abaqus. Initial imperfections of the truss girder were implemented in direct way (by importing imperfect geometry using LBA) and compare to the analytical result according to three selected methods. A few aspects that are omitted in analytical procedures were included in numerical analysis, e.g. the eccentricity between structural elements and the stiffness of selected connections. Results showed discrepancies between numerical and analytical outcomes.

  • Stabilizing forces in trapezoidal sheeting used as a part of the bracing system
    • Natalia Korcz-Konkol
    • Piotr Iwicki
    2021 ce/papers

    In the analysis of bracing systems imperfections of the restrained elements should be considered. According to EC3 this effect can be calculated by means of the equivalent stabilizing force, which replaces (in simplified way) initial bow imperfection of the braced element. However, alternative suggestions of the equivalent stabilizing force calculations can be also found in the literature. In this paper segment of the pitched roof with truss girders, purlins and trapezoidal sheeting was analyzed in two variants: with bar bracing and with trapezoidal cladding as a part of the bracing system (resisting in-plane forces). The influence of the imperfections of the truss girder on the axial forces in the purlins in two cases of the bracing systems were observed. Geometrically nonlinear analysis using shell elements was performed in Abaqus. Initial imperfections of the truss girder were implemented in direct way (by importing imperfect geometry using LBA) and compare to the analytical result according to three selected methods. A few aspects that are omitted in analytical procedures were included in numerical analysis, e.g. the eccentricity between structural elements and the stiffness of selected connections. Results showed discrepancies between numerical and analytical outcomes.

  • Stable Field Electron Emission and Plasma Illumination from Boron and Nitrogen Co‐Doped Edge‐Rich Diamond‐Enhanced Carbon Nanowalls
    • Mateusz Ficek
    • Bartłomiej Dec
    • Kamatchi J Sankaran
    • Krzysztof Gajewski
    • Piotr Tatarczak
    • Igor Wlasny
    • Andrzej Wysmolek
    • Ken Haenen
    • Teodor Gotszalk
    • Robert Bogdanowicz
    2021 Full text Advanced Materials Interfaces

    Superior field electron emission (FEE) characteristics are achieved in edge-rich diamond-enhanced carbon nanowalls (D-ECNWs) grown in a single-step chemical vapor deposition process co-doped with boron and nitrogen. The structure consists of sharp, highly conductive graphene edges supplied by a solid, diamond-rich bottom. The Raman and transmission electron microscopy studies reveal a hybrid nature of sp3-diamond and sp2-graphene in these nanowalls. The ab-initio calculations were carried out to support the experimental observations of diamond-graphene hybrid structure. Finally, this hybrid D-ECNWs is employed as a cathode in an FEE device resulting in a low turn-on field of 3.1 V µm−1, a large field enhancement factor, a high FEE Je of 2.6 mA cm−2, and long lifetime stability of 438 min. Such an enhancement in the FEE originates from the unique materials combination, resulting in good electron transport from the graphene phases and efficient FEE of electrons from the sharp edges on the nanowalls. The prospective application of these materials is displayed by employing these hybrids as cathodes in a microplasma device ensuing a low threshold voltage of 160 V and high plasma stability of 140 min, which confirms the role of these hybrid structured nanowalls in the enhancement of electron emission.

  • Standard and modified falling mass impact tests on preplaced aggregatefibrous concrete and slurry infiltrated fibrous concrete
    • K. Ramakrishnan
    • S.r. Depak
    • K.r. Hariharan
    • Sallal R. Abid
    • G. Murali
    • Daiane Cecchin
    • Roman Fediuk
    • Y.h. Mugahed Amran
    • Hakim Abdelgader
    • Jamal M. Khatibi
    2021 CONSTRUCTION AND BUILDING MATERIALS

    Although several studies have been conducted to evaluate the impact response of concrete using theAmerican Concrete Institute (ACI) 544-2R falling mass impact test, the variations in test results are themain drawback of this testing method. This study aims to reduce the variations in experimental impacttest results by introducing two simple test setup modifications; (1) using coarse or fine aggregate bed-ding as an alternative to the steel base plate, (2) the use of line or cross-notched specimens with a lineor cross-load distributing steel plate. One hundred thirty-five cylindrical discs were prepared withPreplaced Aggregate Fibrous Concrete (PAFC) and Slurry Infiltrated Fibrous Concrete (SIFCON), testedin nine groups to assess the proposed modified techniques. Steel hooked-end (2.5%) and macropolypropylene (8.0%) fibers were used to develop PAFC and SIFCON, respectively. The research findingsrevealed that using aggregate bedding increased the impact resistance by 38 to 429% for no-notch spec-imens and up to 283% for notched specimens. The presence of notches reduced the total energy absorbedby the bedding material. For instance, the specimens with a line notch and sand bedding exhibited 15 to51% lower failure impact numbers than their corresponding no-notch specimens. Considering surface-notched specimens and aggregate bedding led to a lower scattering of the impact test results, whilethe line-notched specimens exhibited lower average scattering than the cross and no-notched specimens.In general, a percentage decrease in the coefficient of variation of 30 to 74% was attained for specimenswith bedding and/or surface notch compared to reference specimens.

  • Stannates, titanates and tantalates modified with carbon and graphene quantum dots for enhancement of visible-light photocatalytic activity
    • Marta Paszkiewicz-Gawron
    • Kowalska Ewa
    • Maya Endo-Kimura
    • Julia Zwara
    • Anna Pancielejko
    • Kunlei Wang
    • Wojciech Lisowski
    • Justyna Łuczak
    • Adriana Zaleska-Medynska
    • Ewelina Grabowska-Musiał
    2021 Full text APPLIED SURFACE SCIENCE

    Most efforts in heterogeneous photocatalysis are focused on development of new and stable photoactive materials efficient in degradation of various pollutants under visible-light irradiation. In this regard, the wide-bandgap perovskite semiconductors, i.e., SrTiO3 (titanate), SrSnO3 (stannate) and AgTaO3 (tantalate), were prepared by a solvothermal method, and then modified with carbon quantum dots (CQDs) or graphene quantum dots (GQDs) co-modified with erbium. The photocactivity was investigated for: (i) toluene degradation (gas phase), (ii) phenol decomposition (aqueous phase), and (iii) inactivation of Escherichia coli K12 bacteria. It has been found that the morphology of semiconductors depends on the synthesis conditions, resulting in the formation of spherical particles, rods and faceted particles for SrTiO3, SnSrO3 and AgTaO3, respectively. Additionally, deposition of CQDs and GQDs/erbium has resulted in an enhancement of light harvesting, thus improved photoactivity under visible-light irradiation. Samples modified with both erbium and GQDs revealed much higher photoactivity than corresponding pristine and CQDs-modified samples. Moreover, all photocatalyst modified with GQDs and Er exhibited a significant antibacterial properties under visible light irradiation (λ>420 nm). Accordingly, it has been proposed that obtained semiconductors modified with QDs and Er are promising candidates as sustainable, clean and cheap materials for environmental purification under solar radiation.

  • Stanowisko badawcze do automatycznej analizy jakości transmisji koncentratora KODEŚ z interfejsami LTE, NB-IoT oraz ISM
    • Olga Błaszkiewicz
    • Robert Burczyk
    • Agnieszka Czapiewska
    • Małgorzata Gajewska
    • Sławomir Gajewski
    • Andrzej Marczak
    • Mariusz Miszewski
    • Jarosław Sadowski
    • Jacek Stefański
    2021 Przegląd Telekomunikacyjny + Wiadomości Telekomunikacyjne

    Zaprezentowano podstawowe właściwości projektowanego koncentratora danych elektroenergetycznych KODEŚ oraz stanowisko badawcze do automatycznych pomiarów jakości transmisji w sieci LTE (Long Term Evolution), opracowane na potrzeby projektu badawczego. Głównym elementem stanowiska jest autorskie oprogramowanie, które umożliwia konfigurowanie urządzeń pomiarowych oraz definiowanie scenariuszy pomiarowych. Dopełnieniem tego jest dodatkowe oprogramowanie zastosowane do graficznej prezentacji otrzymanych wyników badań pomiarowych. W artykule opisano również stanowisko, wykorzystujące technikę radia programowalnego i otwarte oprogramowanie, emulujące funkcje stacji bazowej oraz terminala ruchomego sieci LTE.

  • Starter for Voltage Boost Converter to Harvest Thermoelectric Energy for Body-Worn Sensors
    • Grzegorz Blakiewicz
    • Jacek Jakusz
    • Waldemar Jendernalik
    2021 Full text ENERGIES

    This paper examines the suitability of selected configurations of ultra-low voltage (ULV) oscilla-tors as starters for a voltage boost converter to harvest energy from a thermoelectric generator (TEG). Important properties of particularly promising configurations, suitable for on-chip imple-mentation are compared. On this basis, an improved oscillator with a low startup voltage and a high output voltage swing is proposed. The applicability of n-channel native MOS transistors with negative or near-zero threshold voltage in ULV oscillators is analyzed. The results demonstrate that a near-zero threshold voltage transistor operating in the weak inversion region is most ad-vantageous for the considered application. The obtained results were used as a reference for de-sign of a boost converter starter intended for integration in 180-nm CMOS X-FAB technology. In the selected technology, the most suitable transistor available with a negative threshold voltage was used. Despite using a transistor with a negative threshold voltage, a low startup voltage of 29 mV, a power consumption of 70 µW, and power conversion efficiency of about 1.5% were achieved. A great advantage of the proposed starter is that it eliminates a multistage charge pump necessary to obtain a voltage of sufficient value to supply the boost converter control circuit.

  • State of the Art in Open Platforms for Collaborative Urban Design and Sharing of Resources in Districts and Cities
    • Barry Hayes
    • Dorota Kamrowska-Załuska
    • Aleksandar Petrovski
    • Cristina Jiménez-pulido
    2021 Full text Sustainability

    This work discusses recent developments in sharing economy concepts and collaborative co-design technology platforms applied in districts and cities. These developments are being driven both by new technological advances and by increased environmental awareness. The paper begins by outlining the state of the art in smart technology platforms for collaborative urban design, highlighting a number of recent examples. The case of peer-to-peer trading platforms applied in the energy sector is then used to illustrate how sharing economy concepts and their enabling technologies can accelerate efforts towards more sustainable urban environments. It was found that smart technology platforms can encourage peer-to-peer and collaborative activity, and may have a profound influence on the future development of cities. Many of the research and development projects in this area to date have focused on demonstrations at the building, neighbourhood, and local community scales. Scaling these sharing economy platforms up to the city scale and beyond has the potential to provide a number of positive environment impacts. However, significant technical and regulatory barriers to wider implementation exist, and realising this potential will require radical new approaches to the ownership and governance of urban infrastructure. This paper provides a concise overview of the state of the art in this emerging field, with the aim of identifying the most promising areas for further research.

  • Stateczność kratownic ze sprężystymi podporami bocznymi
    • Marcin Krajewski
    2021 Full text

    W rozprawie doktorskiej podjęto temat stateczności kratownic płaskich, które często stanowią zadaszenie stalowych budynków halowych i innych obiektów budowlanych. Głównym celem pracy było badanie zależności pomiędzy sztywnością na przesuw i obrót, sprężystych podpór bocznych a obciążeniem krytycznym i granicznym kratownic. W pracy przedstawiono rezultaty analiz numerycznych stateczności i nośności rzeczywistych kratownic poddanych obciążeniu grawitacyjnemu i obciążeniu od wiatru. Obliczenia przeprowadzono dla modeli prętowych i powłokowych badanych konstrukcji, metodą elementów skończonych, wykorzystując programy Femap i Autodesk Robot Structural Analysis. Na podstawie liniowych analiz stateczności (LBA) oraz analiz statycznych geometrycznie i fizycznie nieliniowych (GMNIA) wykazano, że w każdym przypadku istniała pewna progowa (minimalna) sztywność sprężystych podpór bocznych kratownicy zapewniająca, że nośność konstrukcji wynosiła 90% lub 95% nośności uzyskanej przy sztywnych stężeniach. W pracy analizowano wpływ kształtu i amplitudy globalnych imperfekcji geometrycznych kratownic, w postaci łukowej krzywizny ściskanych pasów oraz w formie pierwszej postaci wyboczenia, na progowe sztywności stężeń. Analizie poddano również wpływ liczby i wymiarów przewiązek, stosowanych między gałęziami pasów kratownic na nośność prętów o przekrojach złożonych. Ponadto, przeprowadzono badania doświadczalne nośności modelu kratownicy (podpartej sprężyście), poddanej obciążeniu pionowemu skierowanemu ku górze i obciążeniu grawitacyjnemu.

  • Statistical evaluation of physical and index properties of Vistula Marshlands deltaic soft soils
    • Jakub Konkol
    • Lech Bałachowski
    2021 Full text IOP Conference Series: Earth and Environmental Science

    This paper provides statistical evaluation of physical and index parameters of the Vistula Marshlands deltaic soft soils using three datasets. Soft soils from the Vistula Marshlands are grouped into the four categories: (1) silty/sandy loams, (2) organic clays, (3) organic silts and (4) peats. Variability of basic and derivative physical properties as well as Atterberg's limits and plasticity index is studied. It is found that index properties for all soil groups are characterized by large scatter (COV about 50%). The most reliable parameters for silty loams, organic clays and silts are soil density (COV<10%) and specific gravity (COV about 2%). Physical/index parameters of peats are characterized by large scatter, which indicates very local properties and individual formation process. Most of the data points for physical/index quantity are within 1SD range regardless normality of data distribution. In the main body of this paper, the quantitative physical/index properties variability is evaluated and some practical design guidelines concerning variability of deltaic soil in the Vistula Marshlands are given.

  • Sterownik PLC jako urządzenie IED zgodne ze standardem IEC 61850
    • Andrzej Augusiak
    • Mateusz Breza
    • Filip Grabowski
    2021 Full text

    Wraz z rozwojem elektroenergetyki, w stacjach i sieciach elektroenerge- tycznych instalowanych jest coraz więcej cyfrowych urządzeń i układów realizujących złożone funkcje sterowni- cze, nadzorujące i zabezpieczeniowe [1] [2]. Obecnie, większość z tych urządzeń standardowo umożliwia również zdal- ne sterowanie, monitoring i akwizycję danych, wykorzystując jeden z wielu protokołów opracowanych dla prze- mysłowych sieci komunikacyjnych. Jednym z dynamicznie rozwijających się standardów w tym zakresie jest norma IEC 61850 [3], dedykowana dla systemów automatyki w stacjach elek- troenergetycznych. Standaryzuje ona struktury danych opisujących wielo- rakie funkcje w urządzeniach elektro- energetycznych, a także wprowadza jednolite protokoły komunikacji po- między tymi urządzeniami, z wykorzy- staniem przemysłowej sieci ethernet [4]. Dzięki temu możliwa jest stosun- kowo łatwa integracja cyfrowych urzą- dzeń różnych producentów w jednej sieci komunikacyjnej, bez konieczności stosowania urządzeń pośredniczących lub tłumaczących. Wśród dostępnych na rynku urządzeń wykorzystujących standard IEC 61850 (urządzeń IED) na szczególną uwagę zasługują swobodnie programowal- ne sterowniki logiczne (PLC), które umożliwiają oprogramowanie różnych, często bardzo złożonych, funkcji użyt- kowych, a jednocześnie zapewniają zgodność tych funkcji z modelami danych IEC 61850 oraz wymianę in- formacji z innymi urządzeniami i sys- temami obsługującymi komunikację w tym standardzie (w tym z systemami SCADA). Jednym z takich bardzo wszechstron- nych urządzeń IED jest sterownik lo- giczny WAGO PFC200 (750-8212/025- 001) [5], który został udostępniony Politechnice Gdańskiej przez przedsię- biorstwo WAGO ELWAG Sp. z o.o. [6] na potrzeby realizacji projektu Cyfrowego sterownika polowego przeznaczonego do stacji DC [7].

  • STORMWATER AS AN ALTERNATIVE WATER SOURCE: QUALITY CHANGES WITH RAINFALL DURATION AND IMPLICATIONS FOR TREATMENT APPROACHES
    • Aleksandra Pieniaszek
    • Ewa Wojciechowska
    • Eliza Kulbat
    • Nicole Nawrot
    • Janusz Pempkowiak
    • Hanna Obarska-Pempkowiak
    • Krzysztof Czerwionka
    2021 Full text International Journal of Conservation Science

    The pressure on the world’s water resources is rapidly increasing due to population growth and climatic changes. Valorisation of stormwater as a water resource for non-potable reuse can reduce high-quality water demands and save it for potable uses. In this context, not only roof runoff but also drained stormwater outflow, representing considerably higher pollution levels, should be considered as a potential resource. We analysed the quality of stormwater runoff from the municipal separate sewer system in a residential catchment located in a medium-sized town in Poland. The changes in concentrations of TSS, COD, BOD5, and E. coli with rainfall duration were assessed during 7 torrential rainfalls with an intensity exceeding 15 L/s·ha. The concentrations of contaminants in the “first flush” of stormwater varied from 93 to 1598 mg/L TSS, from 112 to 815 mg O2/L for COD, and from 7 to 48 mg O2/L for BOD5 and significantly dropped with rainfall duration. The number of E.coli in stormwater outflow fluctuated from 2.5·103 to 8.1·105 MPN/100 mL. Rapid filtration on sand filters was applied in laboratory-scale for the treatment of raw stormwater outflow, providing removal efficiencies of 87-88% for COD, 50-90% for TN, and 88-96% for TP. The quality of raw and treated stormwater was discussed with regard to the existing and developing European standards for water reuse. The results from our study show that treated stormwater outflows can be applied for landscape irrigation. Moreover, rapid filtration is appropriate for stormwater treatment and can be applied either with the support of pre-sedimentation or even as the only separation process.

  • Strain sequence effect on fatigue life and fracture surface topography of 7075-T651 aluminium alloy
    • Wojciech Macek
    • Ricardo Branco
    • José Domingos Costa
    • Cândida Pereira
    2021 Full text MECHANICS OF MATERIALS

    The paper studies the effect of strain-loading sequence on fatigue lifetime and fracture surface topographies in 7075-T651 aluminum alloy specimens. Fatigue tests were performed in two ways: (i) constant-amplitude loading and (ii) two series of variable amplitude loading with non-zero mean strain values. The topography of the fatigue fractures was measured over their entire surfaces with the help of an optical confocal measurement system. The results of fatigue tests in the form of equivalent strains, εaeq, such as the weighted mean of strain components, εa1, εa2, and fatigue life, Nf, were used as the sum of the partial number of cycles N1, and N2. This study indicates, inter alia, that the values of the fracture surface parameter core height Sk, found in the two-step loading pro gram, are linearly dependent on the equivalent strain, and logarithmically dependent on the fatigue life.

  • STRAJK!
    • Krzysztof Wróblewski
    2021

    Strajk – według „Słownika wyrazów obcych" (PWN, Warszawa 1999) – to: zbiorowe, dobrowolne zaprzestanie na pewien okres pracy przez pracowników jednego lub wielu zakładów, będące formą walki o zrealizowanie ich żądań ekonomicznych lub politycznych. Lata 70. ubiegłego wieku – dziesięciolecie rządów Gierka i jego ekipy – kończył głęboki kryzys struktur władzy i gospodarki, społeczne rozgoryczenie i brak perspektyw na godne życie. Brakowało żywności, mieszkań, przysłowiowego „papieru toaletowego i sznurka do snopowiązałek". Wszystkiego. (...) 14 sierpnia 1980 roku rozpoczął się strajk w Stoczni Gdańskiej im. Lenina, który błyskawicznie podjęto w stoczniach i fabrykach Gdyni, Szczecina, Elbląga, Słupska, a następnie i innych miejscach w kraju. Oprócz żądań ekonomicznych, związanych z poprawą warunków życia, domagano się wolnych związków zawodowych. Toczyła się znacząca, rozważna gra o przyszłość kraju. Gra, którą wygrali robotnicy. Powstał niezależny, samorządny związek zawodowy SOLIDARNOŚĆ, narodził się spontaniczny ruch społeczny, który doprowadził do zmian ustrojowych i demokratyzacji życia publicznego. Strajki latem 1980 roku zmieniły bieg dziejów Polski. Istotą działań artystycznych tamtego czasu było komentowanie robotniczych i rolniczych strajków i protestów, interpretowanie istniejących w przestrzeni społecznej ograniczeń, zła, niesprawiedliwości, prześladowań. Sztuka odzwierciedlała znaczenie sprzeciwu wobec panującego reżimu, występujących wynaturzeń, rozbudowanych ograniczeń wolności i niezależności. Pomagała w zrozumieniu zachodzących zmian, inspirowała do kolejnych przemian, uświadamiała, że o wolność i dobro trzeba walczyć każdego dnia. Artyści zwracali uwagę na społeczne problemy, niepokoje i rozterki, polityczną rzeczywistość; dokumentowali polską drogę do wolności, podkreślali znaczenie i konieczność dialogu. Wystawa STRAJK! przypomina, że narodziny „Solidarności" poprzedzały Czerwiec '56, Marzec '68, Grudzień '70, Czerwiec '76, które wywołały nie tylko procesy przeobrażeń ustrojowych i społecznych, ale również przeobraziły warunki życia Polek i Polaków; spowodowały, że ludzkie działania ponownie stały się odzwierciedleniem myśli, emocji, marzeń i przekonań.

  • Strategie kontroli biokorozji
    • Edyta Malinowska-Pańczyk
    2021

    W rozdziale omówiono sposoby ograniczania destrukcyjnej działalności mikroorganizmów powodujących biokorozję.

  • Strength analysis of container ship subjected to torsional loading
    • Krzysztof Wołoszyk
    • Mateusz Jabłoński
    • Marian Bogdaniuk
    2021

    The objective of this work is to investigate the torsional response of a container ship, with particular consideration of the warping effect. Two different models are investigated. In the first case, the full length model of a ship is analyzed and a distributed load is applied with the use of a novel approach. The model is supported in the torsional centre of the cross-section, which is derived analytically. In the second case, the three cargo hold model is analyzed, where the influence of fore and aft parts of the ship is simulated by ‘end-constraint beams’. A constant, concentrated torsional moment is applied in the shear centre of the fore and aft end cross-section. The structural responses of these two models are obtained and distributions of normal stress across the critical cross-sections are derived. The studies revealed that three cargo hold model subjected to torsional moment underestimates the level of normal stresses caused by the warping effect when compared to the full-length ship model subjected to a distributed load.

  • Strong ellipticity conditions and infinitesimal stability within nonlinear strain gradient elasticity
    • Victor Eremeev
    2021 Full text MECHANICS RESEARCH COMMUNICATIONS

    We discuss connections between the strong ellipticity condition and the infinitesimal instability within the nonlinear strain gradient elasticity. The strong ellipticity (SE) condition describes the property of equations of statics whereas the infinitesimal stability is introduced as the positive definiteness of the second variation of an energy functional. Here we establish few implications which simplify the further analysis of stability using formulated SE conditions. The results could be useful for the analysis of solutions of homogenized models of beam-lattice materials at different scales.

  • Strong-coupling superconductivity of SrIr2 and SrRh2 : Phonon engineering of metallic Ir and Rh
    • Sylwia Gutowska
    • Karolina Górnicka
    • Paweł Wójcik
    • Tomasz Klimczuk
    • Bartlomiej Wiendlocha
    2021 Full text PHYSICAL REVIEW B

    Experimental and theoretical studies on superconductivity in SrIr2 and SrRh2 Laves phases are presented. The measured resistivity, heat capacity, and magnetic susceptibility confirm the superconductivity of these compounds with Tc = 6.07 and 5.41 K, respectively. Electronic structure calculations show that the Fermi surface is mostly contributed by 5d (4d) electrons of Ir (Rh), with Sr atoms playing the role of electron donors. The effect of the spin-orbit coupling is analyzed and found to be important in both materials. Lattice dynamics and electron-phonon coupling (EPC) are studied and the strong electron-phonon interaction is found, contributed mostly by the low-frequency Ir and Rh vibrations. The enhancement of EPC, when compared to weakly coupled metallic Ir and Rh, is explained by the strong modifications in the propagation of phonons in the network of Ir (Rh) tetrahedrons, which are the building blocks of the Laves phase, and originate from the metallic fcc structures of elemental iridium and rhodium.

  • Structural Adaptive, Self-Separating Material for Removing Ibuprofen from Waters and Sewage
    • Anna Skwierawska
    • Dominika Nowacka
    • Paulina Nowicka
    • Sandra Rosa
    • Katarzyna Kozłowska-Tylingo
    2021 Full text Materials

    -cyclodextrin nanosponge (CDM) was used for the adsorption of ibuprofen (IBU) from water and sewage. The obtained material was characterized by scanning electron microscopy (SEM), Fourier transform infrared spectroscopy (FTIR), Brunauer–Emmett–Teller (BET), Barrett– Joyner–Halenda (BJH), Harkins and Jura t-Plot, zeta potential, thermogravimetric analysis (TGA), differential scanning calorimetry (DSC) and elementary analysis (EA). Batch adsorption experiments were employed to investigate the effects of the adsorbent dose, initial IBU concentration, contact time, electrolyte ions and humic acids, and sewage over adsorption efficiency. The experimental isotherms were show off using Langmuir, Freundlich, Hill, Halsey and Sips isotherm models and thermodynamic analysis. The fits of the results were estimated according to the Sips isotherm, with a maximum adsorption capacity of 86.21 mg g1. The experimental kinetics were studied by pseudofirst- order, pseudo-second-order, Elovich, modified Freundlich, Weber Morris, Bangham’s pore diffusion, and liquid film diffusion models. The performed experiments revealed that the adsorption process fits perfectly to the pseudo-second-order model. The Elovich and Freundlich models indicate chemisorption, and the kinetic adsorption model itself is complex. The data obtained throughout the study prove that this nanosponge (NS) is extremely stable, self-separating, and adjusting to the guest structure. It also represents a potential biodegradable adsorbent for the removal IBU from wastewaters.