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Repozytorium publikacji
Politechniki Gdańskiej

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  • Divulging the anti-acetylcholinesterase activity of Colletotrichum lentis strain KU1 extract as sustainable AChE active site inhibitors
    • Anoop Kallingal
    • Aravind Ayyolath
    • Varun Thachan Kundil
    • Akshay M S
    • Tomy Muringayil
    • Józef Haponiuk
    • Sabu Thomas
    • Anu Augustine
    2022 Pełny tekst ARCHIVES OF MICROBIOLOGY

    Alzheimer’s disease (AD), also called senile dementia is a neurodegenerative disease seen commonly in the elderly and is characterised by the formation of β-amyloid plaques and neurofbrillary tangles (NFT). Though a complete understanding of the disease is lacking, recent studies showed the role of the enzyme acetylcholinesterase (AChE) in pathogenesis. Finding new lead compounds from natural sources has always been a quest for researchers. Endophytic fungi are a set of microbes that reside within plants without causing any harm. This study focuses on screening endophytes for the production of active acetylcholinesterase inhibitors. Five endophytic fungi were isolated from Catharanthus roseus and screened for AChE inhibitory activity. Three isolates were found to inhibit AChE inhibitory activity and were distinguished based on molecular and microscopic methods. The mycelial extract was taken for the bioassay-guided column chromatography and TLC was performed on the active fraction. The GC–MS and NMR analysis identifed the active compounds in the extract as 9-hexadecen-1-ol and erucamide. Molecular docking studies revealed that the compounds are thermodynamically feasible and have signifcant glide scores. Computational studies revealed that the hydroxyl group of 9-hexadecen-1-ol forms a hydrogen bond with Ser 293 in the active site of AChE, whereas the active site interactions were predominantly hydrophobic in the case of erucamide and are refected in AChE inhibition assays.

  • DMSO and TMAO—Differences in Interactions in Aqueous Solutions of the K-Peptide
    • Julia Godlewska
    • Bartosz Cieśla
    • Jarosław Wawer
    • Piotr Bruździak
    2022 Pełny tekst INTERNATIONAL JOURNAL OF MOLECULAR SCIENCES

    Interactions between a solvent and their co-solute molecules in solutions of peptides are crucial for their stability and structure. The K-peptide is a synthetic fragment of a larger hen egg white lysozyme protein that is believed to be able to aggregate into amyloid structures. In this study, a complex experimental and theoretical approach is applied to study systems comprising the peptide, water, and two co-solutes: trimethylamide N-oxide (TMAO) or dimethyl sulfoxide (DMSO). Information about their interactions in solutions and on the stability of the K-peptide was obtained by FTIR spectroscopy and differential scanning microcalorimetry. The IR spectra of various osmolyte–water–model-peptide complexes were simulated with the DFT method (B3LYP/6-311++G(d,p)). The FTIR results indicate that both solutes are neutral for the K-peptide in solution. Both co-solutes affect the peptide to different degrees, as seen in the shape of its amide I band, and have different influences on its thermal stability. DFT calculations helped simplify the experimental data for easier interpretation.

  • DNAffinity: a machine-learning approach to predict DNA binding affinities of transcription factors
    • Sandro Barissi
    • Alba Sala
    • Miłosz Wieczór
    • Federica Battistini
    • Modesto Orozco
    2022 Pełny tekst NUCLEIC ACIDS RESEARCH

    We present a physics-based machine learning approach to predict in vitro transcription factor binding affinities from structural and mechanical DNA properties directly derived from atomistic molecular dynamics simulations. The method is able to predict affinities obtained with techniques as different as uPBM, gcPBM and HT-SELEX with an excellent performance, much better than existing algorithms. Due to its nature, the method can be extended to epigenetic variants, mismatches, mutations, or any non-coding nucleobases. When complemented with chromatin structure information, our in vitro trained method provides also good estimates of in vivo binding sites in yeast.

  • Do Leonardo da Vinci’s drawings, room acoustics and radio astronomy have anything in common?
    • Andrzej Kulowski
    2022 Pełny tekst Heritage Science

    After introducing Leonardo da Vinci’s (LdV) predecessors in the field of light propagation research, his drawings on the topic of reflecting light by a spherical mirror are analysed. The discovery of LdV is presented, according to which, at an infinitely distant source of rays, a small fragment of the canopy is enough to generate a focus, while the rest of the mirror forms a caustic for which LdV did not indicate an application. An analytical description of the energy concentration in the focus and on the caustic is given, together with its reference to the geometric representation of the acoustic field in rooms. Based on the general principles of wave motion, symmetry is shown in the description of energy relations in acoustics and electromagnetism. It is explained why in the sound field in existing halls, instead of a whole caustic only its cusp is observed, which is perceived as a point-like sound focus. The size of the mirror aperture, shown graphically by LdV, is determined. How the development of receiving techniques increased the mirror aperture compared to the LdV estimate is also shown. The implementation of these improvements is presented via the example of the Arecibo and FAST radio telescopes.

  • Do We Need a Lighting Detox for Sustainable Cities in the 21st Century?
    • Karolina Zielińska-Dąbkowska
    2022 Pełny tekst ARC Lighting In Architecture

    This article looks at relearning our connection to light and dark in context of sustainability, climate change and urban lighting.

  • Dobre praktyki Spółdzielni Otwartej Edukacji : Jak uczyć kompetencji cyfrowych w bibliotece
    • Andrzej Dominiowski
    • Paulina Gawrych
    • Agnieszka Kaczmarek
    • Agnieszka Kajdaniak
    • Kamila Kokot-Kanikuła
    • Anna Małczuk-Wakulińska
    • Anna Michniuk
    • Iwona Sójkowska
    • Jolanta Tokarek
    • Małgorzata Trąmpczyńska
    2022 Pełny tekst

    Rozwój Spółdzielni Otwartej Edukacji jest możliwy dzięki wspólnej pracy i wiedzy kilkudziesięciu zaangażowanych w nią osób. To samo dotyczy tworzonej przez ostatni rok publikacji podsumowującej dobre praktyki nauczania kompetencji cyfrowych w bibliotece. Do współpracy zostały zaproszone bibliotekarki, które już od pewnego czasu uczestniczyły w projekcie, a teksty merytoryczne powstały między innymi na podstawie materiałów wypracowanych przez trenerki/trenerów i w czasie kursów internetowych.

  • Document centric knowledge processes
    • Magdalena Godlewska
    2022

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  • Does being socially good save firms from bankruptcy? A systematic literature review and bibliometric analysis
    • Muhammad Mushafiq
    • Błażej Prusak
    2022 Pełny tekst Ekonomia i Środowisko

    The purpose of the review was to find out, does being responsible saves firms from bank-ruptcy? What is the relationship between corporate social responsibility and default risk? What meth-ods and measures are used in the literature to evaluate this relationship? And what is the theoretical underpinning of the studies? Moreover, to explore what are the gaps for future work, Web of Science and Scopus databases were utilised to obtain the relevant articles for review. A total of 24 articles were reviewed using PRISMA systematic literature review and bibliometrics. This review finds that the liter-ature has an unidirectional inverse relationship between corporate social responsibility and default risk. Moreover, most literature utilises the stakeholder perspective as the theoretical framework. A research gap exists in explaining the relationship between different theories and extending the model with various aspects of macro- and micro-economics as well as finance. This article contributes to the theoretical aspect by classifying methods, proxies, and theoretical underpinnings used in the research for corporate social responsibility and default risk.

  • Don't forget the dark side of green transformation
    • Małgorzata Zięba
    • Susanne Durst
    • Martyna Gonsiorowska
    2022 Pełny tekst

    Design/methodology/approach – The study is a continuation of the research by Durst and Zieba (2019) related to knowledge risks and their potential outcomes. This present study makes an update on the literature on knowledge risks and green transformation and describes knowledge risks that can be faced in this process. Originality/value – The paper offers new insights for researchers dealing with the topic of knowledge risks in the context of green transformation and ways of handling them. Practical implications – The study provides useful information for managers and owners of companies who are not always aware of the dark side of knowledge and risks related to it. Additionally, companies are more and more often challenged with the need to make the green transformation and this process can also be a tricky one. Limitations – At this stage of development, the proposed study is of theoretical character. This limitation will be overcome in future research activities that involve a large sample of organizations from various countries and sectors.

  • Dopływ wód podziemnych do Zatoki Puckiej
    • Maciej Matciak
    • Małgorzata Pruszkowska-Caceres
    • Beata Szymczycha
    • Justyna Kobos
    • Żaneta Kłostowska
    • Marta Misiewicz
    • Paweł Owsianny
    2022

    W rozdziale opisano zjawisko SGD czyli dopływu wód podziemnych do akwenu morskiego Zatoki Puckiej. Scharakteryzowano warunki wystepowania i krążenia wód podziemnych, ich skład chemiczny, wielkość i miejsca dopływu oraz obecność i charakter wód wypełniajacych osady denne.

  • Doświadczalno-numeryczna analiza wpływu średnicy pręta na przyczepność w teście pull-out
    • Marcin Burdziński
    • Maciej Niedostatkiewicz
    2022

    W pracy zaprezentowano podstawowe informacje oraz wyniki doświadczalno-numerycznej analizy wpływu średnicy pręta na zachowanie przyczepność w badaniu bezpośredniego wyciąganie pręta z betonowego bloku zwanego testem pull-out (POT).

  • Double ZIF-L structures with exceptional CO2 capacity
    • Iwona Cichowska-Kopczyńska
    • Joanna Mioduska
    • Jakub Karczewski
    2022 CHEMICAL ENGINEERING RESEARCH & DESIGN

    Carbon dioxide emission is an emerging problem nowadays and new methods are designed for its control. In this article, a report on the formation of zeolitic imidazole framework with an apparent double leaf-like morphology DZIF-L is given. The special structure of the materials prevents from aggregation of the particles providing remarkable CO2 capacity. At 0.1 MPa the CO2 uptake was 2.99 ± 0.06 mmol/g. The capacity of synthesized material is higher than that of any other structure that was so far identified between single ZIF-L and ZIF-8. Fourier transform infrared (FT-IR), X-ray diffraction (XRD), scanning electron microscopy (SEM) and Brunauer-Emmett-Teller surface area analysis were used to characterize the material.

  • Double-diffusive natural convection energy transfer in magnetically influenced Casson fluid flow in trapezoidal enclosure with fillets
    • Hasan Shahzad
    • Qurrat Ul Ain
    • Amjad Ali Pasha
    • Kashif Irshad
    • Imtiaz Ali Shah
    • Abuzar Ghaffari
    • Muhammad Bilal Hafeez
    • Marek Krawczuk
    2022 Pełny tekst INTERNATIONAL COMMUNICATIONS IN HEAT AND MASS TRANSFER

    The prime motive of this disquisition is to deal with mathematical analysis of natural convection energy transport driven by combined buoyancy effects of thermal and solutal diffusion in a trapezoidal enclosure. Casson fluid rheological constitutive model depicting attributes of viscoelastic liquids is envisioned. The influence of the inclined magnetic field governed by Lorentz field law is also considered. To raise the essence of the presently used computational and physical domain, an innovative structural design called fillet is capitalized at the edges of the cavity. A numerical solution of the leading formulation is sought through Galerkin finite element discretization. Momentum, temperature, and concentration equations are interpolated by quadratic polynomials, whereas pressure distribution is approximated by a linear interpolating function. Domain discretized version is evaluated in view of triangular and rectangular elements. Newton's scheme is employed to resolve the non-linearly discretized system and a matrix factorization-based non-linear solver renowned as PARADISO is used. Validation of results is ascertained by forming an agreement with existing studies. Streamlines, isothermal and iso concentration contours patterns are portrayed to evaluate variation inflow distributions. Kinetic energy, local heat, and mass fluxes are also divulged in graphical and tabular formats.

  • Drukowanie trwałych elementów z żywic utwardzanych światłem lasera w technologii SLA
    • Dawid Zieliński
    2022 Pełny tekst Materiały & Maszyny Technologiczne

    Żywice stanowią ważny materiał służących do wytarzania określonych elementów technicznych w wielu obszarach współczesnego i nowoczesnego przemysłu. Niniejsze opracowanie poświęcono charakterystyce najstarszej z metod druku 3D na świecie – technologii stereolitografii. Omówiono zasadę działania i budowy modelu fizycznego, a także dokonano charakterystyki jej kluczowych czynników związanych z parametrami drukarki wraz z porównaniem jej różnych konfiguracji, generowaniem struktur podporowych oraz najczęściej występującymi defektami drukowanych części. Ponadto wskazano i scharakteryzowano główne grupy materiałów wykorzystywanych w procesie druku 3D oraz najważniejsze korzyści i ograniczenia w szerszym zastosowaniu technologii stereolitografii. Końcowa część opracowania stanowi podsumowanie, w którym zawarto wykaz praktycznych wskazówek umożliwiających wytwarzanie trwałych elementów żywicznych.

  • Duhem and Natanson: Two Mathematical Approaches to Thermodynamics
    • Janusz Badur
    • Michel Feidt
    • Paweł Ziółkowski
    2022 Pełny tekst ENERGIES

    In this article, the previously unrecognized contributions of Pierre Duhem and Ladislavus Natanson in thermodynamics are shown. The mathematical remodelling of a few of their principal ideas is taken into consideration, despite being neglected in the literature. To emphasize these ideas in an appropriate epistemological order, it would be crucial to first revalue and reconstruct some underrepresented parts of the proceedings process through which Duhem and Natanson created their thermodynamics. Duhem and Natanson’s scientific works are against the background of modern continuum mechanics, presenting relevant approaches. In line with the long-held beliefs of many French and Polish researchers, the article mentions that Duhem and Natanson’s ideas dated back to one century ago. Both scientists were qualified in the same Royal Way, which in this case includes chemistry, mechanic of fluid and solid, electro-chemistry, thermodynamics, electrodynamics, and relativistic and quantum mechanics. Therefore, it is possible to connect and then compare the results of their conceptions and approaches. Duhem and Natanson are both in firm opposition with Newtonian mechanisms. Thus, the Maupertuis least action principle created the ground for their efforts, in which they flourished as an elementary quantum.

  • Dwa dni
    • Krzysztof Wróblewski
    2022

    Dwa Dni, 1995 r., olej/płótno, 116 x 179 cm (dyptyk), sygnowany, datowany i opisany na odwrocie: KRZYSZTOF WRÓBLEWSKI | olej, płótno | "DWA DNI" | 116 x 179 cm | 1995 | monogram KW | wskazówki montażowe

  • Dynamic fracture of brittle shells in a space-time adaptive isogeometric phase field framework
    • Karsten Paul
    • T.j.r. Hughes
    • Chad Landis
    • Roger Sauer
    2022

    Phase field models for fracture prediction gained popularity as the formulation does not require the specification of ad-hoc criteria and no discontinuities are inserted in the body. This work focuses on dynamic crack evolution of brittle shell structures considering large deformations. The energy contributions from in-plane and out-of-plane deformations are separately split into tensile and compressive components and the resulting coupled system is discretized within the isogeometric analysis framework. The resulting system is solved fully monolithically and adaptive local refinement is used in space and time.

  • Dynamic Positioning Capability Assessment for Ship Design Purposes
    • Agnieszka Piekło
    • Anna Witkowska
    • Tomasz Zubowicz
    2022 Pełny tekst

    The article focuses on solving a problem of optimal thrust distribution over the actuators in a ship Dynamic Positioning, according to DNV-ST-0111 standard, Level 1. The classic Quadratic Programming approach is combined with the numerical solusion used to handle the propeller with the rudder constraints in the optimization task and the influence between thrusters and skeg. It is presented as an efficient method of minimizing the power consumption. The resulting tool for performing a Dynamic Positioning capability assessment allows for fast calculations to qualitatively compare different designs. The study has proven that the Quadratic Programming based method gives less optimistic solution in comparison with DNV tool and can be safely applied at an early design stage. Further validation of the tool with the time-domain simulations would contribute to increasing confidence in its application to the daily routine calculations.

  • Dynamical nonlocality in quantum time via modular operators
    • I. L. Paiva
    • Marcin Nowakowski
    • Eliahu Cohen
    2022 Pełny tekst PHYSICAL REVIEW A

    We formalize the concept of the modular energy operator within the Page and Wootters timeless framework. As a result, this operator is elevated to the same status as the more studied modular operators of position and momentum. In analogy with dynamical nonlocality in space associated with the modular momentum, we introduce and analyze the nonlocality in time associated with the modular energy operator. Some applications of our formalization are provided through illustrative examples.

  • Dynamics of Antimicrobial Peptide Encapsulation in Carbon Nanotubes: The Role of Hydroxylation
    • Maryam Zarghami Dehaghani
    • Farrokh Yousefi
    • Farzad Seidi
    • S. Mohammad Sajadi
    • Navid Rabiee
    • Sajjad Habibzadeh
    • Amin Esmaeili
    • Amin Hamed Mashhadzadeh
    • Ebrahim Mostafavi
    • Mohammad Saeb
    2022 Pełny tekst International Journal of Nanomedicine

    Introduction: Carbon nanotubes (CNTs) have been widely employed as biomolecule carriers, but there is a need for further functionalization to broaden their therapeutic application in aqueous environments. A few reports have unraveled biomolecule–CNT interactions as a measure of response of the nanocarrier to drug-encapsulation dynamics. Methods: Herein, the dynamics of encapsulation of the antimicrobial peptide HA-FD-13 (accession code 2L24) into CNTs and hydroxylated CNTs (HCNTs) is discussed. Results: The van der Waals (vdW) interaction energy of CNT–peptide and HCNT–peptide complexes decreased, reaching − 110.6 and − 176.8 kcal.Mol− 1, respectively, once encapsulation of the peptide inside the CNTs had been completed within 15 ns. The free energy of the two systems decreased to − 43.91 and − 69.2 kcal.Mol− 1 in the same order. Discussion: The peptide was encased in the HCNTs comparatively more rapidly, due to the presence of both electrostatic and vdW interactions between the peptide and HCNTs. However, the peptide remained encapsulated throughout the vdW interaction in both systems. The negative values of the free energy of the two systems showed that the encapsulation process had occurred spontaneously. Of note, the lower free energy in the HCNT system suggested more stable peptide encapsulation

  • Dynamiczne relacje pomiędzy matematyką stosowaną, a projektowaniem architektonicznym
    • Anna Czech
    2022 Pełny tekst

    Problematyka badawcza dysertacji dotyczy analizy matematycznego zapisu tworzenia form dwu- oraz trójwymiarowych oraz współczesnych metod matematycznych stosowanych w procesie projektowania architektonicznego. Obszar zainteresowań naukowych skoncentrowano na współczesnych relacjach pomiędzy matematyką stosowaną, a projektowaniem architektonicznym oraz na wykorzystywaniu poszczególnych gałęzi języka matematyki, w celu określenia i klasyfikacji wpływu zagadnienia na jakość projektu architektonicznego. Praca rozważa, czy na obecnym stadium rozwoju możliwości współczesnej matematyki architekci są w stanie określić za pomocą funkcji matematycznych parametry każdego aspektu wpływającego na poprawny projekt oraz czy architekci zmierzają w kierunku, aby proces projektowy całościowo oprzeć na zapisie matematycznym. Praca ma na celu określenie w jakich fazach projektowania, w jakim stopniu i w jakich aspektach sprecyzowanie matematycznego zapisu wymagań projektowych i stosowanie metod matematycznych stanowi efektywny wydźwięk dla końcowego projektu architektonicznego, również w kontekście celów i priorytetów stawianych współczesnej architekturze powiązanych z ideą równoważenia rozwoju i podejściem proekologicznym.

  • Dynamika molekularna oddziaływań przeciwgrzybowych heptaenów aromatycznych i ich izomerów all-trans ze sterolami w błonach lipidowych
    • Julia Borzyszkowska-Bukowska
    2022 Pełny tekst

    Aromatyczne heptaeny (AH) należą do grupy makrolidów polienowych o działaniu przeciwgrzybowym. Antybiotyki z tej grupy były pierwszymi, które zostały wykorzystane w terapii układowych infekcji grzybiczych. Amfoterycyna B (AmB) oraz nystatyna, czyli niearomatyczni przedstawiciele makrolidów heptaenowych, mają istotne znaczenie kliniczne w leczeniu, odpowiednio, grzybic wewnętrznych i zewnętrznych. Molekularne podstawy mechanizmu działania AH nie były do tej pory badane. Można założyć - na podstawie podobieństwa strukturalnego do AmB - że pierwszym i kluczowym etapem dla aktywności i selektywności tych związków jest oddziaływanie z błoną lipidową, a konkretnie sterolami w niej zawartymi. Do tej pory związki należące do grupy AH w swojej natywnej formie nie znalazły szerokiego zastosowania w medycynie. Tym niemniej, wyniki najnowszych badań nad tą podgrupą antybiotyków potwierdzają możliwość uzyskania ich stabilnych pochodnych w postaci izomerów all-trans na drodze fotochemicznej izomeryzacji. Prowadzone badania z wykorzystaniem metod dynamiki molekularnej obejmowały trzech przedstawicieli AH: kandycydynę D, partrycynę A oraz partrycynę B w formie natywnej i all-trans. Eksperymenty obliczeniowe miały na celu, przede wszystkim, określenie zależności pomiędzy geometrią pierścienia makrolidowego a powinowactwem antybiotyku do sterolu. Otrzymane rezultaty mogą stać się pierwszym krokiem na drodze do wyjaśnienie molekularnych podstaw o ponad rząd wielkości wyższej aktywności biologicznej AH w porównaniu do AmB. Ponadto, przeprowadzone badania miały na celu pozwolić na uchwycenie roli aromatycznego łańcucha bocznego w oddziaływaniu tej grupy związków ze składnikami błony lipidowej.

  • Early Stages of RNA-Mediated Conversion of Human Prions
    • Emilia Lubecka
    • Ulrich H. E. Hansmann
    2022 Pełny tekst JOURNAL OF PHYSICAL CHEMISTRY B

    Prion diseases are characterized by the conversion of prion proteins from a PrPC fold into a disease-causing PrPSC form that is self-replicating. A possible agent to trigger this conversion is polyadenosine RNA, but both mechanism and pathways of the conversion are poorly understood. Using coarse-grained molecular dynamic simulations we study the time evolution of PrPC over 600 μs. We find that both the D178N mutation and interacting with polyadenosine RNA reduce the helicity of the protein and encourage formation of segments with strand-like motifs. We conjecture that these transient β-strands nucleate the conversion of the protein to the scrapie conformation PrPSC.

  • Edge-Computing based Secure E-learning Platforms
    • Sameer Ahmad Bhat
    • Dalia Alyahya
    • Muneer Ahmad Dar
    • Saadiya Shah
    2022 Pełny tekst

    Implementation of Information and Communication Technologies (ICT) in E-Learning environments have brought up dramatic changes in the current educational sector. Distance learning, online learning, and networked learning are few examples that promote educational interaction between students, lecturers and learning communities. Although being an efficient form of real learning resource, online electronic resources are subject to threats and vulnerabilities on the internet. Authentication, access and storage of data is a major concern among many organizations implementing E-learning platforms. This study provides a literature review of past five-year research studies, and proposes Edge-computing based solution to the currently existing authentication and data access problems that prevail in the current E-learning management systems using cloud services for data storage. The study guides researchers towards enabling Edge-computing based E-learning platforms to support low power computing devices running Elliptic Curve Cryptography for secure access and authentication.

  • Education Towards The Use Of BIM On The Example Of Polish Universities
    • Waldemar Kosiedowski
    • Marek Wirkus
    2022 Pełny tekst Organization Technology and Management in Construction

    BIM (Building Information Modeling) has been one of the rapidly developing fields of digital techniques supporting the realization of construction projects in recent years. Further development, and especially the use of these techniques, depends to a large extent on the qualifications of young construction engineers who start their professional careers in this field. The article attempts to synthetically list and compare subjects, specializations or fields related to teaching about the BIM methodology in Polish universities curricula. The aim of the study is to present the key factors and differences in the approach to education in this field and on this basis an attempt to formulate conclusions regarding the optimal way of conducting the didactic process in the field of BIM education. The subject of the research were BIM education offers at Polish universities at various levels of education. The places where education occur at Polish universities were identified and the time of implementing BIM technology teaching was compared. The levels, paths, graduate profile, educational programs, the presence of practical elements, the achieved results as well as the types, forms and modes of conducting classes at individual universities were analyzed. The analysis was conducted on the basis of information available on the Internet about the faculties and programs of education of individual universities, supplemented with additional information obtained in e-mail correspondence and conducted by telephone interviews. As a result of the analyzes, the key guidelines for conducting education at the university level were proposed.

  • Educational Dataset of Handheld Doppler Blood Flow Recordings
    • Tomasz Kocejko
    2022 Pełny tekst

    Vital signals registration plays a significant role in biomedical engineering and education process. Well acquired data allow future engineers to observe certain physical phenomena as well learn how to correctly process and interpret the data. This dataset was designed for students to learn about Doppler phenomena and to demonstrate correctly and incorrectly acquired signals as well as the basic methods of signal processing. This paper presents three corresponding datasets consisting of 21 recording of signals acquired from the neck area with USG gel applied and 21 distorted recordings acquired without gel.

  • EE-ISAC—Practical Cybersecurity Solution for the Energy Sector
    • Tania Wallis
    • Rafał Leszczyna
    2022 Pełny tekst ENERGIES

    A recent survey of cybersecurity assessment methods proposed by the scientific community revealed that their practical adoption constitutes a great challenge. Further research that aimed at identifying the reasons for that situation demonstrated that several factors influence the applicability, including the documentation level of detail, the availability of supporting tools, and the continuity of support. This paper presents the European Energy Information Sharing and Analysis Centre (EE-ISAC)—a cybersecurity platform for the energy sector that has been adopted by multiple organisations. The platform facilitates sharing information about cybersecurity incidents, countermeasures, and assessment results. Prospectively, it is envisaged to be integrated with the threat intelligence platform that enables real-time situational awareness. By considering both fault and attack scenarios together, threat awareness can be mapped onto operational contexts to prioritise decisions and responses. This paper analyses EE-ISAC’s approach based on the conceptual applicability framework developed during the research, to improve the applicability and usefulness of this platform for energy sector participants and to identify areas that require further development.

  • Effect of asymmetric fluid flow distribution on flow boiling in a microchannel heat sink – An experimental investigation
    • Kumar Ritunesh
    • Gurjeet Singh
    • Dariusz Mikielewicz
    2022 Pełny tekst APPLIED THERMAL ENGINEERING

    Flow boiling in microchannels is emerging as an exclusive cooling solution for miniaturized high-power electronic devices alongside having other high heat flux applications. Size miniaturization at microscale strangely increases heat transfer performance as well as flow boiling instabilities. Many flow boiling instabilities are interrelated and result from imperfect hydrodynamic conditions. One of such problems is flow maldistribution among parallel channels of a microchannel heat sink. Very limited studies have dedicatedly investigated the negative effects of flow aldistribution on the boiling process in microchannels. A microchannel heat sink with twenty-five rectangular microchannels (width × height × length = 0.45 × 0.725 × 25 mm) made on a copper block base of 25 × 25 × 85 mm using wire electrical discharge machining under an I-type flow configuration is investigated for that purpose. Flow boiling patterns of central and side microchannels as well as the temperature profile of central and side microchannels are recorded. The boiling process always incepts in side microchannels and rapidly converts into a periodic flow reversal up to the inlet manifold, whereas weak, stable, bubbly flow and single-phase liquid flow are observed in the neighboring and central microchannels, respectively. Furthermore, with the increase of heat flux, flow boiling intensity increases and more parallel microchannels start experiencing rapid bubble growth; consequently, the intensity of flow reversal in side channels also increases. At high heat fluxes, the vapor backflow of side microchannels reaches the central microchannel and blocks the flow through it, named mirage flow confinement. Boiling in the central channel aggravates under the influence of the mirage flow reversal processes. Temperature non-uniformity across the microchannel heat sink increases with the increase of heat flux and mass flux caused by the early appearance of a partial dryout of side channels and the escalation of the flow distribution asymmetry. Whereas, better temperature distribution is observed at higher inlet fluid temperatures.

  • Effect of Chitosan Solution on Low-Cohesive Soil’s Shear Modulus G Determined through Resonant Column and Torsional Shearing Tests
    • Marta Bocheńska
    • Marcin Bujko
    • Ireneusz Dyka
    • Piotr E. Srokosz
    • Rafał Ossowski
    2022 Pełny tekst Applied Sciences-Basel

    In this study the effect of using a biopolymer soil stabilizer on soil stiffness characteristics was investigated. Chitosan is a bio-waste material that is obtained by chemical treatment of chitin (a chemical component of fungi or crustaceans’ shells). Using chitosan solution as a soil stabilizer is based on the assumption that the biopolymer forms temporary bonds with soil particles. What is important is that these bonds are biodegradable, so the product does not leave any harmful waste and has high eco-compatibility. The biopolymer itself is a by-product of many industrial chemical processes, so its application is compliant with the goals of sustainable geotechnical engineering. The effect of chitosan on soil shear strength, permeability or surface erosion has already been investigated in several different studies. In this study specimens of low-cohesive soil stabilized with two different chitosan solutions were subject to cyclic loading (torsional shearing test) and dynamic loading (resonant column) to obtain soil shear modulus G as a function of strain values. It has been shown that chitosan solution added to medium-grained materials improves their shear modulus G substantially (up to 3 times) even for relatively low chitosan concentration solutions (1.5 g of chitosan per 1 kg of dry silica sand). The results obtained in this study and the known chitosan properties suggest that chitosan solutions can be a very effective and eco-friendly short-term stabilizer for temporary geotechnical structures, e.g., working platforms.

  • Effect of convection and microwave heating on the retention of bioactive components in human milk
    • Dorota Martysiak-Żurowska
    • Edyta Malinowska-Pańczyk
    • Małgorzata Orzołek
    • Bogumiła Kiełbratowska
    • Elena Sinkiewicz-Darol
    2022 Pełny tekst FOOD CHEMISTRY

    Bioactive substances are very important components of human milk (HM), especially for premature newborns. The effects of convection (CH) and microwave heating (MWH) at 62.5 and 66 °C, on the level of selected bioactive components of HM: lysozyme (LZ), lactoferrin (LF), secretory immunoglobulin A (sIgA), basal lipase (BL), cytokine TGF-2, vitamin C and total antioxidant capacity (TAC) was compared. Regardless of the used heating methods the TAC of HM, determined by TEAC and ORAC-FL assay, proved to be insensitive to temperature pasteurization, in contrary to BL. MWH in the conditions of 62.5 for 5 min and 66 °C for 3 min are ensuring microbiological safety with a higher retention of most of the tested active HM proteins compared to CH. Only in the case of LZ the MWH had a more degradative effect on its concentration. Controlled conditions of MWH preserve the bioactive components of the HM better than CH.

  • Effect of elliptical defect orientation on the durability of specimens subjected to cyclic bending
    • Zbigniew Marciniak
    • Ricardo Branco
    • Rui F. Martins
    • Dariusz Rozumek
    • Wojciech Macek
    2022 Pełny tekst Procedia Structural Integrity

    This work presents the effect of elliptical defects orientation on the durability of specimens made of C45 steel. Three kinds of specimens with elliptical defects in the form of a one-sided notch oriented at different angles 45, 60, and 90 degrees were subjected to cyclic bending (R=-1). The stress state analysis was performed using local and non-local methods to determine an equivalent amplitude of stress, and then the results were compared with those obtained for smooth specimens.

  • Effect of Ion and Binding Site on the Conformation of Chosen Glycosaminoglycans at the Albumin Surface
    • Piotr Sionkowski
    • Piotr Bełdowski
    • Natalia Kruszewska
    • Piotr Weber
    • Beata Marciniak
    • Krzysztof Domino
    2022 Pełny tekst ENTROPY

    Albumin is one of the major components of synovial fluid. Due to its negative surface charge, it plays an essential role in many physiological processes, including the ability to form molecular complexes. In addition, glycosaminoglycans such as hyaluronic acid and chondroitin sulfate are crucial components of synovial fluid involved in the boundary lubrication regime. This study presents the influence of Na+, Mg2+ and Ca2+ ions on human serum albumin–hyaluronan/chondroitin-6- sulfate interactions examined using molecular docking followed by molecular dynamics simulations. We analyze chosen glycosaminoglycans binding by employing a conformational entropy approach. In addition, several protein–polymer complexes have been studied to check how the binding site and presence of ions influence affinity. The presence of divalent cations contributes to the decrease of conformational entropy near carboxyl and sulfate groups. This observation can indicate the higher affinity between glycosaminoglycans and albumin. Moreover, domains IIIA and IIIB of albumin have the highest affinity as those are two domains that show a positive net charge that allows for binding with negatively charged glycosaminoglycans. Finally, in discussion, we suggest some research path to find particular features that would carry information about the dynamics of the particular type of polymers or ions

  • Effect of ionic liquids on surface and photocatalytic properties of selected semiconducttors
    • Anna Pancielejko
    2022

    The main aim of this doctoral dissertation was to explain the role of ionic liquids in shaping the morphology of selected semiconductors, thereby enhancing the photocatalytic activity. In order to achieve this goal, the following research steps were taken: (i) developing synthesis methods of selected semiconductors, with particular emphasis on the electrochemical oxidation method; (ii) understanding the influence of the selected ionic liquids introduced into the reaction environment on the surface and photocatalytic properties of selected photocatalysts; (iii) explaining the role of ionic liquids in the mechanism of the photocatalytic reaction; (iv) correlating the morphological parameters and structural/surface properties with the photocatalytic activity of the obtained nanomaterials. The doctoral dissertation discusses the results of two research areas: (i) TiO2 nanotubes obtained in the presence of [EAN][NO3] or [BPy][Cl] with added traditional organic electrolyte; (ii) thin film BiOBr/Bi2WO6 heterojunction prepared via a two-step approach involving electrochemical oxidation and hydrothermal transformation in the presence of [BPy][Br]. The experimental results show that by using ionic liquids during the synthesis of semiconductors, it is possible to control their surfaces, and thus, photocatalytic properties.

  • Effect of microwave and convection heating on selected nutrients of human milk
    • Dorota Martysiak-Żurowska
    • Edyta Malinowska-Pańczyk
    • Małgorzata Orzołek
    • Barbara Kusznierewicz
    • Bogumiła Kiełbratowska
    2022 Pełny tekst FOOD CHEMISTRY

    The aim of this study was to determine the influence of the microwave heating method (MWH) on selected determinants of the nutritional value of human milk (HM) and compare to the effect exerted by the standard convection heating (CH) method, including holder pasteurization (HoP). It was showed that using MWH under conditions assumed to ensure microbiological safety, changes in the level of the nutrients were not observed. In these conditions concentration of fatty acids (FAs), lipid peroxides (LP) and α-lactalbumin (α-La) were on a similar level as in raw milk, and furosine was not formed. MWH treatment of HM led to slight increase in the malonaldehyde (MDA) and protein carbonyls (PC) content. However, MDA content in HM as a result of MWH was lower than after application CH.

  • Effect of Nb and Al on in vitro dissolution behavior and structure of Na2O-MgO CaO-P2O5 glasses
    • Natalia Wójcik
    • Stefania Wolff
    • Jakub Karczewski
    • Małgorzata Rutkowska
    • Sharafat Ali
    2022 Pełny tekst JOURNAL OF NON-CRYSTALLINE SOLIDS

    In vitro dissolution, structure, and thermal properties of the glass series Na2O-MgOsingle bondCaOsingle bondNb2O5 -Al2O3-P2O5 were studied. The dissolution behavior in phosphate-buffered saline (PBS) confirmed the potential bioactive properties of tested glasses. The dissolution process was found to depend on the Al, Nb, and Mg contents. Al, respectively, suppresses the Nb and accelerates the Mg release process from the glasses. Moreover, Al stays highly bonded in the phosphate network during 14 days of immersion. In all glasses, the phosphate network was found to be highly disrupted and built mostly of Q1 units. Al and Mg addition decreases the polymerization of the glass network. The Nb addition effect was found to be the opposite. Thermal properties were correlated mostly with the Nb and Al contents. However, the fragility index of glasses increases with the content of P and Al.

  • Effect of Particle Size of Fly Ash Microspheres (FAMs) on the Selected Properties of Concrete
    • Elżbieta Haustein
    • Aleksandra Kuryłowicz-Cudowska
    2022 Pełny tekst Minerals

    This paper presents the investigations of selected properties of concrete containing two fractions of fly ash microspheres (FAMs) with grain size up to 200 μm and up to 500 μm. Concrete mixtures with ordinary Portland cement and three substitution rates of cement by FAMs, 1.3%, 2.0%, and 2.6%, were investigated. For all concrete mixes, the constant water–binder ratio (w/b) equal to 0.50 was used. The research program included the determination of chemical composition, particle size distribution, and pozzolanic activity of FAMs. The analysis showed that the microspheres consist of three main elements: silicon, aluminum, and iron, whose oxides constitute about 89% of the material. The total content of air pores, measured in concrete at 28 days, ranges from 1.3 to 3.1% for the grain sizes below 200 μm and from 1.4% to 3.9% for the grain sizes up to 500 μm. The FAMs with a particle diameter < 200 μm have a relatively high level of activity pozzolanic at 28 days. The SEM analysis proved that the use of microspheres reduces gaps and increases the CSH phase. The compression test showed that the addition of fly ash microspheres with grain size below 200 μm increases long‐term concrete strength.

  • Effect of Porosity on the Thermo-Mechanical Behavior of Friction-Stir-Welded Spark-Plasma-Sintered Aluminum Matrix Composites with Bimodal Micro- and Nano-Sized Reinforcing Al2O3 Particles
    • Behzad Sadeghi
    • Behzad Sadeghian
    • Aboozar Taherizadeh
    • Aleksandra Laska
    • Pasquale Cavaliere
    • Arun Gopinathan
    2022 Pełny tekst Metals

    The thermo-mechanical behavior of nanosized Al2O3 particles reinforcing aluminum was analyzed in the present paper. The material was prepared by spark plasma sintering and friction stir welding. The thermal stresses affecting the composite behavior during welding were modeled through COMSOL MultiPhysics, and the results were validated by the analyses of the composites’ mechanical properties. The spark-plasma-sintered materials presented limited porosity, which was taken into account during the modeling phase. Both model and experiments revealed that higher heat input is related to better material mixing during welding and sound mechanical properties. Thermal stresses lead to residual stresses close to 300 MPa in the thermo-mechanically affected zone for processing conditions of 1900 RPM and 37 mm/min. This leads to an increase in hardness up to 72 HV.

  • EFFECT OF PRESS DRYING ON DIMENSION STABILITY AND DENSITY OF BEECH WOOD,
    • Ivan Klement
    • Peter Vilkovský
    • Tatiana Vilkovská
    • Jacek Barański
    • Aleksandra Suchta
    2022 Pełny tekst Trieskove a Beztrieskove Obrabanie Dreva

    Timber is traditionally dried in kilns by processes that often take several days or weeks to complete. At present, it is possible to apply several methods of rapid drying of timber, including, for example, press drying. This research is based on the use of this process. Drying was performed using the heating plates with a temperature of 160 °C. Three pressures were compared in the research 1.0 MPa, 1.4 MPa, and 1.8 MPa. The density of the samples remarkably increased during press drying. The pressure of the heating plates had a substantial effect. The difference in the average density between the pressure of 1.0 MPa and 1.8 MPa was more than 92 kg.m-3 . A larger increase in density was discovered for radial samples (ranging between +95.31 to+110.85). The difference in the change of sample thickness was larger in the case of the tangential samples. For both groups of samples (radial, tangential) and all ressures, the samples dried by the contact method were more stable during swelling than the samples dried by the convection method.

  • Effect of Processing Parameters on Strength and Corrosion Resistance of Friction Stir-Welded AA6082
    • Aleksandra Laska
    • Marek Szkodo
    • Damian Koszelow
    • Pasquale Cavaliere
    2022 Pełny tekst Metals

    The friction stir welding method is increasingly attracting interest in the railway sector due to its environmental friendliness, low cost, and ease of producing high-quality joints. Using aluminum alloys reduces the weight of structures, increasing their payload and reducing fuel consumption and running costs. The following paper presents studies on the microstructure, strength, and corrosion resistance of AA6082 aluminum alloy sheets joined via friction stir welding. The sheets were joined by employing two different traverse speeds (200 and 250 mm/min), two different rotational speeds (1000 and 1250 rpm), and two different tool tilt angles (0◦ and 2◦ ). It was observed that the use of the inclined tool provides finer microstructure in the nugget zone, higher value of microhardness, and better corrosion resistance, compared to the tilt angle equal to 0◦ . By increasing the value of revolutionary pitch, finer grains are observed in the nugget zone and the measured hardness is higher. It was also observed that the change in process parameters strongly influences the radius of the nugget zone and the potentiodynamic properties of the friction stir-welded material. The joints produced with the tool tilt angle equal to 2◦ , the tool traverse speed of 200 mm/min, and its rotational speed of 1250 rpm revealed the highest hardness in the nugget zone (about 92% of the base material). Moreover, the finest grain size in the nugget with the average value of 9.8 ± 1.5 µm was found. The lowest corrosion current density equal to 16.029 µA cm−2 was noted for the sample with the highest strength, which also provides its good corrosion resistance.

  • Effect of slag coal ash and foamed glass on the mechanical properties of two-stage concrete
    • Hakim S. Abdelgader
    • Marzena Kurpińska
    • Mugahed Amran
    2022 Materials Today: Proceedings

    Two-stage concrete (TSC) is known by various names such as colcrete, Polcrete, preplaced aggregate concrete and prepacked concrete. It is different from traditional concrete in two fundamental ways, namely method of construction and mix proportion. Two-stage concrete (TSC) is defined as firstly, coarse aggregates are placed into the formwork and grout is applied to fill in the between coarse aggregate particles voids. Secondly, the percentage of coarse aggregates in the mix proportion of TSC is higher than that in normal concrete. The typical value is about 60% as compared with 40% in traditional concrete. As coarse aggregates are preplaced first, they can occupy up to 60–70% of the total volume. As coarse aggregates are not involved in the mixing process, TSC is environmentally friendly with lesser consumption of energy. With a higher content of aggregates, TSC reduces the use of cement by 20–30% and may minimize the temperature rise. Engineering properties of TSC, including its stress–strain relationship, is mainly governed by the properties of coarse aggregates as stress is transferred from the skeleton of aggregates to hardened grout. Main advantages of TSC include a higher volume of coarse aggregates and the ability to use larger size coarse aggregates. The latter also reduces the cost of crushing. TSC has beneficial properties such as low drying shrinkage, high bonding strength, high modulus of elasticity, and excellent durability. The method of TSC has proved particularly useful in a number of applications like underwater construction, and masonry repair, where placement by conventional methods is extremely difficult. The method is also applicable in case of massive concrete where low heat of hydration is required. It is studied the feasibility of casting two stage concrete with 100% steel slag as coarse aggregate. In term of formulation, to adopt two stage concreting method we could minimize the risk of concrete bleeding and segregation due to high water absorption and quite high density of slag aggregate. The effect of slag coal ash and foamed glass on the mechanical properties of two-stage concrete has rarely been reported. Thus, the development of an eco-efficient alkali-activated grout for two-stage concrete is a new research topic that has no robust results to draw solid conclusions and it should blaze the track towards a cleaner production of building materials with outstanding sustainability.

  • Effect of temperature change on refractive index of an egg white and yolk: a preliminary study
    • Patryk Sokołowski
    2022 Pełny tekst Photonics Letters of Poland

    In this article, the refractive index of an egg white and yolk depending on temperature in range 30 - 47 °C over 1550 nm was determined. The measurement head was constructed as fiber optic Fabry-Perot interferometer with interference between polished fiber end-face and aluminum weighing dish. The measurement setup has been made of an optical spectrum analyzer, a superluminescent diode with a central wevelength of 1550 nm, 2:1 fiber coupler and heat plate.

  • Effect of the ionic liquids on extraction of aromatic and sulfur compounds from the model petrochemical stream
    • Wiśniewski Piotr
    • Konrad Bołoz
    • Anna Wiśniewska
    • Zbigniew Dąbrowski
    • Dominika Kubica
    • Justyna Łuczak
    • Urszula Domańska
    2022 FLUID PHASE EQUILIBRIA

    Suitability of a imidazolium ionic liquids (ILs) as solvents in dearomatization and desulfurization in the ternary systems and in a model multicomponent systems has been analyzed. With this aim, ternary liquid-liquid phase equilibrium data (LLE) have been obtained for ternary mixtures of {IL + benzene, or toluene, or thiophene, or 2-butanethiol + hexane}, or {IL + benzene + 2-methylpentane} at T = 298.15 K and ambient pressure, as well as for multicomponent systems –model petrochemical stream {IL + model stream (benzene, toluene, thiophene, 2-butanethiol) + hexane} at T = 303.15 K and ambient pres- sure. Two ILs have been studied: 1-ethyl-3-methylimidazolium thiocyanate, [EMIM][SCN] and 1-ethyl- 3-methylimidazolium dicyanamide, [EMIM][DCA]. The values of solute distribution ratio and selectivity have been evaluated. It has been shown that ILs investigated in this work are able to extract sulfur com- pounds in preference to benzene and toluene. The solute distribution ratios for both ILs are similar. The selectivity of the aromatic and sulfur compounds are higher for [EMIM][SCN]. The best distribution ratio ( > 1.98) and selectivity ( > 242) was observed for thiophene extracted from the model stream 1:1.

  • Effect of Tool Positioning Factors on the Strength of Dissimilar Friction Stir Welded Joints of AA7075-T6 and AA6061-T6
    • Amir Ghiasvand
    • Saja Mohammed Noori
    • Wanich Suksatan
    • Jacek Tomków
    • Shabbir Memon
    • Hesamoddin Aghajani Derazkola
    2022 Pełny tekst Materials

    Friction Stir Welding (FSW) is a solid-state bonding technique. There are many direct and indirect factors affecting the mechanical and microstructural properties of the FSW joints. Tool offset, tilt angle, and plunge depth are determinative tool positioning in the FSW process. Investigating the effect of these factors simultaneously with other parameters such as process speeds (rotational speed and translational speed) and tool geometry leads to a poor understanding of the impact of these factors on the FSW process. Because the three mentioned parameters have the same origin, they should be studied separately from other process parameters. This paper investigates the effects of tilt angle, plunge depth, and tool offset on Ultimate Tensile Stress (UTS) of joints between AA6061-T6 and AA7075-T6. To design the experiments, optimization, and statistical analysis, Response Surface Methodology (RSM) has been used. Experimental tests were carried out to find the maximum achievable UTS of the joint. The optimum values were determined based on the optimization procedure as 0.7 mm of tool offset, 2.7 degrees of tilt angle, and 0.1 mm of plunge depth. These values resulted in a UTS of 281 MPa. Compared to the UTS of base metals, the joint efficiency of the optimized welded sample was nearly 90 percent.

  • Effect of tube bundle arrangement on performance of shell-and-tube latent heat storage system
    • Maciej Fabrykiewicz
    • Janusz Cieśliński
    2022

    This work presents the results of experimental investigation on charging and discharging of latent heat storage systems (LHSS) in the form of shell-and-tube heat exchangers with a variable arrays of the tube bundles. The tests included two tube arrangements – in-line and triangular (staggered), a variable number of tubes in a bundle, two pitch ratios, and different tube positions in a bundle. Three commercial products (LTP56, RT54HC, P1808) from the group of aliphatic hydrocarbons were used as PCM. Systematic experimental studies have shown that regardless of the type of the tested PCM, the shortest charging / discharging rates for the tested LHSS were achieved for a bundle of 7 tubes in a staggered arrangement and a pitch ratio of 4.5.

  • Effect of Tube Bundle Arrangement on the Performance of PCM Heat Storage Units
    • Maciej Fabrykiewicz
    • Janusz Cieśliński
    2022 Pełny tekst ENERGIES

    The results of comprehensive study on charging and discharging of latent heat storage systems (LHSS) are presented. The multi tube shell-and-tube unit with a variable layouts of the tube bundles are examined. Two tube arrangements – in-line and staggered are tested. A variable number of tubes and different tube positions in a bundle are investigated. Moreover, two pitch ratios are studied. Three commercially available substances are used as phase change material (PCM). The results show that increasing the number of tubes reduces both charging and dis-charging times. It is found that for a bundle of 7 tubes with the pitch ratio s/d=4.5, the in-line tube arrangement results in shorter charging time, but the discharging time is shorter for staggered tube arrangement.

  • Effectiveness of a dual surface modification of metallic interconnects for application in energy conversion devices
    • Łukasz Mazur
    • Justyna Ignaczak
    • Maciej Bik
    • Sebastian Molin
    • Maciej Sitarz
    • Aleksander Gil
    • Tomasz Brylewski
    2022 Pełny tekst INTERNATIONAL JOURNAL OF HYDROGEN ENERGY

    A dual surface modification of an SOFC metallic interconnect with a Gd2O3 layer and an MnCo2O4 coating was evaluated. The tested samples were oxidized for 7000 h in air at 1073 K. Oxidation products were characterized using XRD, SEM-EDS, and confocal Raman imaging, and ASR was measured. The effect of gadolinium segregation at grain boundaries in Cr2O3 was evaluated using S/TEM-EDS. Area specific-resistance was measured and fuel cell tests investigating electrochemical performance and Cr contamination of electrodes were also performed. The results show that the proposed dual modification was more advantageous than either modification applied separately. The fuel cell tests performed after aging in humidified hydrogen at 1073 K and involving an actual interconnect made of this dual-modified material showed that after 250 h of aging its electrochemical parameters were nearly identical to those of the non-aged reference electrode. Moreover, the modification protected the electrodes from Cr poisoning.

  • Effectiveness of Random Field Approach in Serviceability Limit State Analysis of Strip Foundation
    • Karol Winkelmann
    • Kamil Żyliński
    • Aleksandra Korzec
    • Jarosław Górski
    2022 Pełny tekst Geotechnical and Geological Engineering

    This work conducts a probabilistic inquiry on how the variability of the parameter defining soil deformability affects the settlement of the foundation located on the soil. The analysis addresses the random foundation model to relevantly estimate the probability of allowable deflection exceedance. The constitutive model parameter is based either on a single random variable or a random field. The computations incorporate direct Monte Carlo sampling and the variance reduction techniques, i.e. Stratified Sampling and Latin Hypercube Sampling. The work focuses on soil parameter modelling by random fields defined by various correlation functions. One of the analytical means is the application of a non-homogeneous function capable of reflecting the soil strata. The probabilistic methods proposed in the paper are tested on a standard example of a foundation strip featuring load eccentricity. It is proved that the modelling mode of the soil—a single variable or a random field—substantially affects the results, i.e. foundation settlements. It was detected that incorporating random fields in soil analysis allows for a valid reliability assessment of a foundation in respect to Serviceability Limit State. The relevantly adjusted correlation functions of random fields allow for a realistic subsoil analysis even in the case of a limited in situ measurement database.

  • Effects of Column Base Flexibility on Seismic Response of Steel Moment-Frame Buildings
    • Tomasz Falborski
    • Ahmad Hassan
    • Amit Kanvinde
    2022

    Steel Moment Resisting Frames (SMRFs) are very popular lateral load resisting systems in many seismically active regions. However, their seismic response is strongly dependent on the rotational fixity of column base connections. Despite many studies (both experimental and numerical) in this particular area, available approaches for estimating column base flexibility have been validated only against laboratory test data. In the present paper these approaches are examined based on strong motion recordings from two instrumented SMRF buildings in California (CA) to introduce best practices for seismic response simulation. Three-dimensional simulation models are constructed for these buildings, including the gravity framing and non-structural stiffness. For each building, the base fixities are parametrically varied. These include pinned and fixed bases, as well as intermediate fixities determined from previously developed models that are appropriate for simulating the specific types of base connections used in the buildings. The simulated response of these buildings is compared to strong motion recordings to propose optimal approaches for simulating rotational fixity of column base connections.

  • Effects of full displacement pile installation on the stress and deformation state of surrounding soil: review
    • Worku Firomsa Kabeta
    2022 Pełny tekst Archives of Civil Engineering

    Several field and model tests have been conducted to investigate the impact of pile installation on bearing capacity. However, little is known about how piles behave during installation, how they interact with the surrounding soil, and how this affects sandy soil properties. This review paper investigates the effect of pile driving on surrounding sandy soil as it compacts sandy soil near to the pile. For this purpose, various related literature was studied based on the observation of the pile installation effect on earth pressure or lateral stress, relative density, and pore water pressure in the sandy soil. A change in the deformation and stress state of surrounding sandy soil due to pile driving was presented. The installation of fully displacement piles can lead to significant stresses and deformations in the surrounding sandy soil. This is one of the main causes of uncertainty in the design and analysis of pile foundations. According to this study, the sandy soil around the pile is compacted during pile driving, resulting in lateral and upward displacement. This leads to the densification effect of pile driving on loose sandy soil. Sandy soil improvement with driven piles depends on pile shape, installation method, and pile driving sequences. This study concludes that in addition to its advantages of transferring superstructure load to deep strata, the increased relative density of loose sand, the change in the horizontal stress, and the influence of compaction on the sandy soil parameters during pile driving should be considered during pile design and analysis.

  • Effects of La0.8Sr0.2MnO3 and Ag electrodes on bismuth-oxide-based low-temperature solid electrolyte oxygen generators
    • Jeng-Ting Tsai
    • Sea-Fue Wang
    • Yung-Fu Hsu
    • Piotr Jasiński
    2022 CERAMICS INTERNATIONAL

    In this study, La0.8Sr0.2MnO3 (LSM) was used as the ceramic electrode in a (Bi1.50Y0.50)0.98Zr0.04O3+δ (BYO)-based solid electrolyte oxygen generator (SEOG) and its performance was compared with that of a previously studied high-fire Ag electrode. Among La0.6Sr0.4Co0.2Fe0.8O3, LaNi0.6Fe0.4O3, Cu1.4Mn1.6O4, and LSM materials, only LSM materials did not trigger any chemical reaction or interdiffusion with BYO at temperatures up to 900 °C. Two cell designs, Cell A, with a Bi1.71Nb0.25Ba0.04O3+δ (BBNO) interlayer and high-fire Ag electrode, and Cell B, with an LSM-BYO composite electrode, were obtained in this study. The cells were sandwiched between two modular SUS 316 planar interconnects using a ZnO–SiO2–Al2O3 glass sealant to form the SEOG device. Although Cells A and B possessed similar ohmic resistance (Ro) values, the polarization resistance (Rp) values of Cell A were 3.6 times larger than those of Cell B. Furthermore, the stability study of the cells operated at 600 °C for 12 h revealed that Ro increased from 0.79 to 3.17 Ω cm2 and Rp from 3.12 to 12.58 Ω cm2 for the Cell A, while Ro increased from 0.76 to 0.77 Ω cm2 and Rp from 0.87 to 1.12 Ω cm2 for the Cell B. Therefore, minor variations in the Ro and Rp of Cell B indicate the excellent stability of the electrode. The degradation of Cell A was caused by the migration of Ag and formation of voids and cracks adjacent to the anode/electrolyte interface under the DC field. Furthermore, the Cell A experienced a decrease in faradaic efficiency for current densities greater than 0.20 A cm−2 owing to the partial decomposition of BYO at the cathode. In contrast, the Cell B generated an oxygen flux of 1.29 cm⋅min−1 at 600 °C. In addition, the faradaic efficiency of Cell B remained consistent for current densities up to 0.35 A cm−2. Therefore, the SEOG using LSM-BYO as the cell electrode exhibited excellent stability and electrochemical performance.