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  • Synagogi dawnej Polski - ich teraźniejszość i przyszłość
    • Joanna Kabrońska
    2021

    Tekst stanowi próbę ujęcia w szerszej perspektywie złożonego zjawiska zmiany formy użytkowania ocalałych obiektów kultu religijnego. Postępująca sekularyzacja współczesnych społeczeństw stanowi wyzwanie dla religijnych społeczności różnych wyznań, przynosząc również pytania dotyczące zmiany przeznaczenia pustoszejących świątyń. Biorąc pod uwagę społeczny kontekst zarysowany powyżej, ocalałe budynki synagog można uznać za odrębny, trudny problem. Dawne społeczności żydowskie, będące gospodarzami obiektów, stały się ofiarami wojny, a nieliczni, którzy przetrwali wojnę, wyjechali z Polski w kolejnych falach emigracji. Pozostały bóżnice i cmentarze, którymi nie ma się kto opiekować, ponieważ nie istnieje już wspólnota religijna. Wskazanie formy użytkowania budynków, które pierwotnie były domami modlitwy i miejscami zebrań gminy żydowskiej, nie byłoby właściwe bez dopuszczenia do głosu współczesnej społeczności żydowskiej. Jednak różnorodność poglądów i interpretacji, związana z tym problemem, czyni zadanie jeszcze trudniejszym. Rozpatrując zjawisko zmiany formy użytkowania ocalałych synagog, warto również zwrócić uwagę na rolę artystów, którzy uczynili architekturę ocalałych obiektów kultu religijnego tworzywem swoich działań artystycznych. Często jako pierwsi ujawniają oni wrośnięte w krajobraz budynki i przywołują ich pierwotne przeznaczenie, czyniąc sztukę w pewnym sensie narzędziem resakralizacji tych obiektów i jednocześnie ukazując nowe kierunki myślenia o ich przyszłości.

  • Synergistic Effects of Propolis Combined with 2-Phenoxyethanol and Antipyretics on the Growth of Staphylococcus aureus
    • Katarzyna Grecka
    • Piotr Szweda
    2021 Pełny tekst Pharmaceutics

    The present investigation aimed to assess the combinational effect of commonly usedantipyretics and antiseptics with ethanolic extracts of propolis (EEPs) on the growth inhibition ofStaphylococcus aureus. The broth microdilution checkerboard assay revealed synergistic interactionsbetween all investigated antipyretics, namely acetylsalicylic acid, ibuprofen, and acetaminophen,with EEPs samples. The values of the fractional inhibitory concentration (ΣFIC) index for all thesecombinations were <0.5. While, in the case of considered antiseptics, namely chlorhexidine, octenidinedihydrochloride, and 2-phenoxyethanol, the positive interaction was confirmed only for the last one(values ofΣFIC in the range 0.0625–0.25). Combinations of two other agents with all four samples ofEEPs resulted in an important antagonistic effect (values ofΣFIC≥4.5). Propolis is mostly dedicatedto the treatment of skin/wound infections; thus, these findings are of particular practical importance.The outcomes of the study also support the hypothesis that the propolis’s antimicrobial effect is dueto the combined (synergistic) action of several ingredients rather than the presence of one componentof high antibacterial activity. The composition of 13 ingredients of EEPs (at a concentration belowthe MIC (minimum inhibitory concentration) of the most active agent) exhibited considerably highanti-staphylococcal efficiency with MIC = 128μg/mL.

  • Synteza, struktura chemiczna i właściwości bezizocyjanianowych poliuretanów otrzymywanych z wykorzystaniem CO2 oraz surowców pochodzenia naturalnego.
    • Kamila Rohde
    2021

    Z uwagi na wciąż rosnącą świadomość proekologiczną, politykę zrównoważonego rozwoju, a także nurt zielonej chemii wiodącym trendem w przemyśle tworzyw sztucznych jest poszukiwanie alternatywnych metod otrzymywania materiałów polimerowych. Komercyjnie poliuretany otrzymywane są w wyniku reakcji poliaddycji di- lub poliizocyjanianów z poliolami i małocząsteczkowymi przedłużaczami łańcucha. Z uwagi na niekorzystne właściwości diizocyjanianów, a także prognozowane zmniejszenie zasobów ropy naftowej i związany z tym wzrost cen rynkowych surowców, ośrodki naukowo-badawcze poszukują nowych metod syntezy tych materiałów. Głównym celem prezentowanej rozprawy doktorskiej było otrzymanie bezizocyjanianowych poliuretanów w wyniku reakcji poliaddycji cyklicznych węglanów oraz di- lub poliamin z zastosowaniem monomerów pochodzenia roślinnego i dwutlenku węgla, jako reagenta wbudowywanego w strukturę eterów diglicydylowych. Cel realizowano poprzez wykorzystanie komercyjnie dostępnego poli(glikolu trimetylenowego) pochodzenia roślinnego oraz aminowych pochodnych zdimeryzowanych kawasów tłuszczowych. Ponadto, dwutlenek węgla w reakcji cykloaddycji wbudowywano w strukturę półproduktów zakończonych grupami oksiranowymi. Opracowana metoda nie wymaga zastosowania podwyższonego ciśnienia, możliwe jest kontrolowanie prędkości przepływu gazu, a także nie ma konieczności stosowania toksycznych rozpuszczalników organicznych. Niniejsza rozprawa doktorska oparta jest na czterech artykułach opublikowanych w recenzowanych czasopismach naukowych. W ramach prowadzonych prac badawczych szczegółowo scharakteryzowano strukturę chemiczną, a także wybrane właściwości otrzymywanych na każdym etapie prac produktów.

  • Synthesis and Characterization of Poly(zwitterionic) Structures for Energy Conversion and Storage
    • Adrian Olejnik
    • Siuzdak Katarzyna
    • Katarzyna Grochowska
    2021

    Zwitterions are unique class of molecules that possess two functional groups bearing electric charges, one positive and second negative. This setup results in peculiar properties such as high water retention and anti-fouling capability. Therefore, zwitterionic coatings and gels are commonly applied in e.g. biosensing and bioelectronic devices. Despite those applications, there are other perspectives for zwitterionic materials. Recently, they have gained attention in the fields of energy storage and conversion. In particular, gel electrolytes for batteries and solid state supercapacitors based on zwitterionic polymers have significantly higher ionic conductivity compared to standard electrolytes based on e.g. poly(vinyl alcohol). Moreover,the capacitance of devices with zwitterionic electrolytes is generally few times higher and retained after a larger number of cycles. Zwitterions are also prominent interlayers between photoactive materials and electrical contacts in organic and perovskite solar cells facilitating charge injection. Considering the unique properties of zwitterions and a large variety of available structures, they have become animportant point of scientific attention in the field of energy storage and conversion. Despite some concepts have already been developed, there is plenty to be discovered about these materials. In our opinion zwitterions can be regarded as the most prospective ones in energy fields.

  • Synthesis and Physicochemical Characteristics of Chitosan-Based Polyurethane Flexible Foams
    • Agnieszka Piotrowska-Kirschling
    • Adam Olszewski
    • Jakub Karczewski
    • Łukasz Piszczyk
    • Joanna Brzeska
    2021 Pełny tekst Processes

    The use of shrimp waste to obtain chitosan (Ch) is an essential issue, considering a circular economy, waste management, and its application to environmentally friendly materials. In this study, northern prawn shells were utilized to obtain Ch, which could then be used for synthesizing chitosan-based polyurethane (PUR+Ch) foams with different Ch concentration. The chemical structure, morphology, hardness, thermal properties, viscoelastic properties, and sorption properties in relation to oil and water of these materials were determined. The results present that the addition of Ch into PUR influences the physicochemical characteristics and properties of the tested materials. PUR+Ch foams with 1–3 wt% Ch had more open cells and were softer than neat PUR. PUR+Ch1 had the best thermal properties. PUR+Ch2 foam with 2 wt% Ch as a whole was characterized as having the highest water sorption. The PUR+Ch1 foam with 1 wt% Ch had the best oil sorption. This paper shows that the modification of PUR by Ch is a very promising solution, and PUR+Ch foams can be applied in the water treatment of oil spills, which can be dangerous to the water environment.

  • Synthesis and structural characterization of bio-based bis(cyclic carbonate)s for the preparation of non-isocyanate polyurethanes
    • Kamila Błażek
    • Hynek Beneš
    • Zuzana Walterová
    • Sabina Abbrent
    • Arantxa Eceiza
    • Tamara Calvo-Correas
    • Janusz Datta
    2021 Polymer Chemistry

    Bio-based cyclic carbonates are of significant research interest as monomers for non-isocyanate polyurethane (NIPU) synthesis. This research describes the synthesis of a series of five-membered bis(cyclic carbonate)s using bio-based polyether polyols (PO3G) with different molecular weights (250, 650 and 1000 g mol−1) and carbon dioxide as green feedstocks. The utilization of CO2 as a source of carbon in the chemical reaction is in agreement with the sustainable chemical industry. Furthermore, in order to support the green and sustainable polymer chemistry approach, the syntheses were attempted under solvent-free conditions. The implemented synthetic methods are focused on the design of processes and final products that minimize negative environmental impact. Detailed chemical structure analysis of synthesized products was performed using a combination of spectroscopy techniques (ATR-FTIR as well as 1D and 2D NMR techniques), mass spectrometry (MALDI-TOF MS) and chromatography analysis (SEC). The formation of the main product with two terminal cyclic carbonates was confirmed and the formed side products were also identified, characterized and quantified. Finally, as a proof of concept, the synthesized bis(cyclic carbonate)s were successfully used for the preparation of NIPU thermosets. Chemical and mechanical properties of the produced materials suggest their high potential for future applications, e.g. as sound absorbing materials.

  • Synthesis and Structure of Novel Copper(II) Complexes with N,O- or N,N-Donors as Radical Scavengers and a Functional Model of the Active Sites in Metalloenzymes
    • Joanna Masternak
    • Małgorzata Zienkiewicz-Machnik
    • Iwona Łakomska
    • Maciej Hodorowicz
    • Katarzyna Kazimierczuk
    • Milena Nosek
    • Amelia Majkowska-Młynarczyk
    • Joanna Wietrzyk
    • Barbara Barszcz
    2021 Pełny tekst INTERNATIONAL JOURNAL OF MOLECULAR SCIENCES

    Toevaluatetheantioxidantactivityofpotentialsyntheticenzymemimetics,wepreparednewfivecopper(II)complexesviaaself‐assemblymethodandnamedthem[Cu(2‐(HOCH2)py)3](ClO4)2(1),[Cu(2‐(HOCH2)py)2(H2O)2]SiF6(2),[Cu2(2‐(HOCH2CH2)py)2(2‐(OCH2CH2)py)2](ClO4)2(3),[Cu(pyBIm)3](BF4)2∙1.5H2O(4)and[Cu(py2C(OH)2)2](ClO4)2(5).ThesyntheticprotocolinvolvedN,O‐ orN,N‐donors:2‐(hydroxymethyl)pyridine(2‐(HOCH2)py),2‐(hydroxyethyl)pyridine(2‐(HOCH2CH2)py),2‐(2‐pyridyl)benzimidazole(pyBIm),di(2‐pyridyl)ke‐tone(py2CO).TheobtainedCu(II)complexeswerefullycharacterisedbyelementalanalysis,FTIR,EPR,UV‐Vis,single‐crystalX‐raydiffractionandHirshfeldsurfaceanalysis.Crystallographicandspectroscopicanalysesconfirmedchromophoresofbothmonomeric({CuN3O3}(1),{CuN2O4}(2),{CuN6}(4),{CuN4O2}(5))anddimericcomplex({CuN2O3}(3)).Mostoftheobtainedspeciespos‐sessedadistortedoctahedralenvironment,exceptdimer3,whichconsistedoftwocoppercentreswithsquarepyramidalgeometries.Thewater‐solublecompounds(1,3and5)wereselectedforbiologicaltesting.Theresultsofthestudyrevealedthatcomplex1insolutionsdisplayedbetterradicalscavengingactivitythancomplexes3,5andfreeligands.Therefore,complex1hasbeenselectedforfurtherstudiestotestitsactivityasanenzymemimetic.Thechosencompoundwastestedontheerythrocytelysateoftwogroupsofpatientsafterundergoingchemotherapyandchemoradiotherapy.Theeffectofthetestedcompound(1)onenzymeactivitylevels(TAS,SODandCAT)suggeststhattheselectedcomplexcanbetreatedasafunctionalmimeticoftheenzymes.

  • Synthesis, characteristics, and photocatalytic activity of zinc oxide nanoparticles stabilized on the stone surface for degradation of metronidazole from aqueous solution
    • Amir Naser Alibeigi
    • Neda Javid
    • Majid Amiri Gharaghani
    • Zhila Honarmandrad
    • Fatemeh Parsaie
    2021 Pełny tekst Environmental Health Engineering and Management Journal

    Abstract Background: The presence of antibiotics such as metronidazole in wastewater even at low concentrations requires searching for a suitable process such as advanced oxidation process (AOP) to reduce the level of pollutants to a standard level in water. Methods: In this study, zinc oxide (ZnO) nanoparticles were synthesized by thermal method using zinc sulfate (ZnSO4) as a precursor, then, stabilized on stone and was used as a catalyst, in order to degrade metronidazole by photocalytic process. Effective factors on the removal efficiency of metronidazole including the initial metronidazole concentration, contact time, pH, and 0.9 gL-1 ZnO stabilized on the stone surface were investigated. Results: The X-ray diffraction (XRD) studies showed that the synthesized nanomaterials have hexagonal Wurtzite structure. Also, scanning electron microscopy (SEM) analysis revealed that the average crystalline size of the synthesized ZnO particles was in the range of 1.9-3.2 nm. The spectra represented a sharp absorption edge at 390 nm for ZnO nanoparticles corresponding to band gap of 3.168 eV. The BET-BJH specific surface area of the synthesized ZnO nanoparticles was 25.504 m2/g. The EDS spectrum of ZnO nanoparticles showed four peaks, which were identified as Zn and O. The maximum removal efficiency was 98.36% for the synthetic solution under a specific condition (pH = 11, reaction time = 90 minutes, ZnO concentration = 0.9 gL-1, and the initial concentration of metronidazole = 10 mgL-1). The photocatalytic degradation was found to follow pseudo-first-order degradation kinetics. Conclusion: Therefore, the ZnO nanoparticles synthesized by thermal decomposition are suitable and effective photocatalytic materials for degradation of pharmaceutical contaminants.

  • Synthesis of Phosphonated Carbon Nanotubes: New Insight into Carbon Nanotubes Functionalization
    • Małgorzata Nadolska
    • Marta Prześniak-Welenc
    • Marcin Łapiński
    • Kamila Sadowska
    2021 Pełny tekst Materials

    Carbon nanotubes were successfully functionalized for the first time in a free radical phosphonylation reaction. Three synthetic protocols were proposed. Carbon nanotubes and diethylphosphite reacted in the presence of known radical initiator, such as azobisisobutyronitrile, single electron oxidant—Mn(OAc)3, or under UV radiation. The functionalized material was fully characterized by means of spectroscopic methods, together with microscopic, surface area and thermogravimetric analyses. UV-illumination was found to be the most effective approach for introducing phosphonates onto carbon nanotubes. X-ray photoelectron spectroscopy analysis showed 6% phosphorus in this sample. Moreover, the method was performed at room temperature for only one hour, using diethylphosphite as a reactant and as a solvent. The functionalized carbon nanotubes showed an improved thermal stability, with a decomposition onset temperature increase of more than 130 °C. This makes it very promising material for flame retarding applications.

  • SYNTHETIZED MEMBRANES FOR ULTRASOUND-ASSISTED SOLVENT EXTRACTION OF POROUS MEMBRANE PACKED SOLID SAMPLES.
    • Martyna Jurczyk
    • Justyna Płotka-Wasylka
    • Emilia Gontarek-Castro
    2021 Pełny tekst

    Membranes are becoming more and more popular in analytical chemistry, which is why they are used, among others, in extraction processes. Therefore, this work focuses on the process of synthesis PVDF membranes and its optimization. The obtained membranes were used as bags for the phthalate extraction in disposable diapers for babies. Extraction was accomplished by method ultrasound-assisted solvent extraction of porous PVDF membrane packed solid samples. As a result of the research, it was found that the most optimal temperature for the synthesis of membranes was 40°C. The phthalates were extracted in this process. However, the reproducibility was insufficient.

  • System do diagnostyki dermatofitowych zakażeń powierzchniowych oparty na technice Real-Time PCR
    • Natalia Kobylak
    2021 Pełny tekst

    Dermatofity należą do blisko spokrewnionej grupy grzybów, które wykazują wysokie powinowactwo do skeratynizowanych tkanek. Cecha ta czyni je odpowiedzialnymi za powierzchniowe grzybice skóry, paznokci oraz włosów. Szacuje się, iż nawet do 20% ludzi na całym świecie dotkniętych jest infekcjami powodowanymi przez dermatofity. Ich leczenie wymaga długotrwałego zastosowania leków przeciwgrzybiczych. W celu dobrania odpowiedniego leczenia należy zapewnić prawidłową diagnozę, która przy zastosowaniu konwencjonalnych metod jest nie tylko długotrwała, ale również kosztowna, jak i wymaga wieloletniego doświadczenia diagnosty. Biorąc powyższe pod uwagę, niezmiernie istotne jest stworzenie szybkiego i prostego testu diagnostycznego, opartego na metodach molekularnych, który zapewni identyfikację gatunkową. Celem badań prowadzonych w ramach niniejszej pracy doktorskiej było opracowanie testu diagnostycznego, który w pierwszym etapie wykrywałby dermatofity, a w drugim etapie zapewniłby identyfikację gatunkową oraz co wydawało się największym wyzwaniem opracowanie jednoetapowej metody przygotowania DNA, które mogłoby być stosowane w technice Real-Time PCR. W pierwszym etapie pracy wykazano możliwość zastosowanie DNA wyizolowanego szybką, dwuetapową w reakcjach Real-Time PCR przy użyciu starterów wykrywających DNA wszystkich dermatofitów oraz starterów wykrywających DNA gatunku Trichophyton rubrum. Następnie, zostały zaprojektowane startery umożliwiające wykrycie DNA gatunków Epidermophyton floccosum, Microsporum canis, Microsporum audouinii/Microsporum ferrugineum oraz kompleksu Trichophyton mentagrophytes. Zaprojektowane układy przetestowano na 246 izolatach oraz wstępnie potwierdzono możliwość ich zastosowania z użyciem próbek klinicznych. Na sam koniec opracowano nową metodę szybszej izolacji DNA dermatofitów, charakteryzującą się mniejszym ryzykiem kontaminacji w porównaniu z istniejącymi metodami.

  • Systematic Assessment of Product Quality
    • Radosław Drozd
    • Radosław Wolniak
    2021 Pełny tekst Journal of Open Innovation: Technology, Market, and Complexity

    The article describes an innovative metrizable idea for systemic assessments of product quality within the baking industry. Complex product quality analysis requires the employment of metrizability criteria for factors that impact the quality of the product, and these are called determinants. Therefore, such analysis is only possible with the use of systems engineering. A system represents the potential of a manufacturing process, of major impact on quality. Composites of the manufacturing process make up the determinants of bread quality, grouped into three sets: raw materials, manufacturing technology, and manufacturing organization and technique. This paper also contains methodological implications for the construction of algorithms for manufacturing process potential determinants. Metrizable product quality assessment is a very important issue in the context of its implementation in manufacturing companies. Its use allows for obtaining comprehensive data on the quality status of a product. It is an important tool for analyzing and forecasting modern quality trends. The method presented in the article is new, innovative, and practical; and its vector representation may prove useful in Quality 4.0. The method could be an important point of reference for managers, directors, and decision makers who must determine the best metrizability criteria for systemic product quality assessments, and could prove useful in Industry 4.0 in the bakery industry. The main value of the paper is the presentation of a new, extensive method for systemic assessments of product quality based on vector analysis in industrial organization. We trialed the method in the baking industry. We concluded that the method is a contribution to management science, especially in the field of quality management, because this approach is not used in business and is not described in relevant international literature.

  • Szczególne widoki mostów i odczucia obserwatorów. Cz. II
    • Zbigniew Cywiński
    • Ewa Maria Kido
    2021 Mosty

    Szczególne widoki mostów i odczucia obserwatorów. Część II

  • Sztuczna inteligencja w onkologii - nowe narzędzia do diagnostyki i medycyny spersonalizowanej
    • Krzysztof Pastuszak
    • Michał Żuk
    • Anna Supernat
    2021

    statnie dekady doprowadziły do rozwoju zaawansowanych technologii badawczych, cechujących się wysoką przepustowością. Zmienia to oblicze medycyny, doprowadzając do generowania ogromnej ilości danych. Z każdym kolejnym rokiem przybywa pacjentów onkologicznych, a zebrane informacje o pacjentach przekraczają możliwości lekarzy i naukowców w zakresie samodzielnej analizy tzw. big data. Właśnie dlatego świat nauki coraz częściej zwraca się ku algorytmom sztucznej inteligencji (AI, ang. – artificial intelligence).

  • Święto Otwartej Nauki w Bibliotece Politechniki Gdańskiej w ramach Open Access Week 2021
    • Kamila Kokot-Kanikuła
    • Agnieszka Szymik
    2021 Pełny tekst Pismo PG

    W dniach 25–31 października 2021 roku odbyła się kolejna edycja Open Access Week, imprezy w Polsce znanej jako Tydzień Otwartej Nauki. Biblioteka PG aktywnie włączyła się w promocję tego naukowego święta poprzez organizację webinariów, prezentacji i spotkań.

  • Tacit knowledge awareness and sharing as a focal part of knowledge production, Polish-US view on IT, healthcare, and construction industry
    • Wioleta Kucharska
    2021

    In the knowledge economy era, knowledge production and dissemination are of key interest to individuals, organizations, and economies. Tacit knowledge results from experience, leading to innovation. The learning culture can facilitate the transformation of errors into experiences. This study explores whether mistake acceptance facilitates tacit knowledge awareness and sharing in the information technology, healthcare, and construction industries in Poland and the United States. The findings show the influence of mistake acceptance on knowledge production and the differences between countries and industries. The US showed a higher level of mistake acceptance, which was similar across the three industries, than did Poland, which showed differences between sectors. In general, the higher the acceptance of mistakes, the greater the effect of tacit knowledge awareness on sharing. This study shows that there is no knowledge production without learning and no learning without mistake acceptance.

  • Tailoring properties of indium tin oxide thin films for their work in both electrochemical and optical label-free sensing systems
    • Petr Sezemsky
    • Dariusz Burnat
    • Jiri Kratochvil
    • Harm Wulff
    • Angela Kruth
    • Katarzyna Lechowicz
    • Monika Janik
    • Robert Bogdanowicz
    • Martin Cada
    • Zdenek Hubicka
    • Paweł Niedziałkowski
    • Wioleta Białobrzeska
    • Vitezslav Stranak
    • Mateusz Śmietana
    2021 Pełny tekst SENSORS AND ACTUATORS B-CHEMICAL

    This work is devoted to the identification properties of indium tin oxide (ITO) thin films responsible for their possible application in combined optical and electrochemical label-free sensing systems offering enhanced functionalities. Since any post-processing would make it difficult to identify direct relation between deposition parameters and properties of the ITO films, especially when deposition on temperature-sensitive substrates is considered, the films were deposited using reactive high power impulse magnetron sputtering (HiPIMS) at low temperature and with no post-deposition annealing. We focused mainly on the impact of reactive gases, such as oxygen or nitrogen introduced to the process chamber, on control over plasma parameters and subsequently properties of the films. The properties of the films were investigated using X-ray diffractometry, spectroscopic ellipsometry, four-point probe, and cyclic voltammetry. For presenting optical sensing capabilities, the tailored ITO films in addition to silicon and glass wafers were also deposited on the core of optical fibers to induce the lossy-mode resonance (LMR) phenomenon. The existence of specific deposition conditions resulting in ITO film properties offering both high-quality electrochemical and LMR responses has been experimentally proven. It has been found that the crystalline structure of ITO plays a key role in the determination of both the sensing capabilities. Finally, label-free sensing of antibody-antibody interactions in both optical and electrochemical domains for the sensor with tailored ITO film has been shown.

  • Tax Policy Tools of Selected European Countries as a Mechanism for Counteracting the Effects of the Crisis Caused by the COVID-19 Disease Pandemic
    • Piotr Kasprzak
    • Jerzy Frankowski
    2021

    Crises play an important role in a economics life. They are common and it is impossible to omit them. This following study investigates the concept of ‘crisis’ in the context of economic situation. This text describes the most important financial crises that took place in the past. After that authors passes on a detailed analysis of the actual corona-crisis and the way that it affects the economy globally. The main goal of this study is to show the European state governments reactions and action to this unusual crisis that were made in the context of tax regulations. In conclusion the target was reached what resulted in this study.

  • T-colorings, divisibility and circular chromatic number
    • Robert Janczewski
    • Anna Maria Trzaskowska
    • Krzysztof Turowski
    2021 Pełny tekst Discussiones Mathematicae Graph Theory

    Let T be a T-set, i.e., a finite set of nonnegative integers satisfying 0 ∈ T, and G be a graph. In the paper we study relations between the T-edge spans espT (G) and espd⊙T (G), where d is a positive integer and d ⊙ T = {0 ≤ t ≤ d (max T + 1): d |t ⇒ t/d ∈ T} . We show that espd⊙T (G) = d espT (G) − r, where r, 0 ≤ r ≤ d − 1, is an integer that depends on T and G. Next we focus on the case T = {0} and show that espd⊙{0} (G) = ⌈d(χc(G) − 1)⌉, where χc(G) is the circular chromatic number of G. This result allows us to formulate several interesting conclusions that include a new formula for the circular chromatic number χc(G) = 1 + inf espd⊙{0} (G)/d: d ≥ 1 and a proof that the formula for the T-edge span of powers of cycles, stated as conjecture in [Y. Zhao, W. He and R. Cao, The edge span of T-coloring on graph C d n , Appl. Math. Lett. 19 (2006) 647–651], is true.

  • Technical and Economic Analysis of the Supercritical Combined Gas-Steam Cycle
    • Marcin Jamróz
    • Marian Piwowarski
    • Paweł Ziemiański
    • Gabriel Pawlak
    2021 Pełny tekst ENERGIES

    Combined cycle power plants are characterized by high efficiency, now exceeding 60%. The record-breaking power plant listed in the Guinness Book of World Records is the Nishi-Nagoya power plant commissioned in March 2018, located in Japan, and reaching the gross efficiency of 63.08%. Research and development centers, energy companies, and scientific institutions are taking various actions to increase this efficiency. Both the gas turbine and the steam turbine of the combined cycle are modified. The main objective of this paper is to improve the gas-steam cycle efficiency and to reach the efficiency that is higher than in the record-breaking Nishi-Nagoya power plant. To do so, a number of numerical calculations were performed for the cycle design similar to the one used in the Nishi-Nagoya power plant. The paper assumes the use of the same gas turbines as in the reference power plant. The process of recovering heat from exhaust gases had to be organized so that the highest capacity and efficiency were achieved. The analyses focused on the selection of parameters and the modification of the cycle design in the steam part area in order to increase overall efficiency. As part of the calculations, the appropriate selection of the most favorable thermodynamic parameters of the steam at the inlet to the high-pressure (HP) part of the turbine (supercritical pressure) allowed the authors to obtain the efficiency and the capacity of 64.45% and about 1.214 GW respectively compared to the reference values of 63.08% and 1.19 GW. The authors believe that efficiency can be improved further. One of the methods to do so is to continue increasing the high-pressure steam temperature because it is the first part of the generator into which exhaust gases enter. The economic analysis revealed that the difference between the annual revenue from the sale of electricity and the annual fuel cost is considerably higher for power plants set to supercritical parameters, reaching approx. USD 14 million per annum. It is proposed that investments in adapting components of the steam part to supercritical parameters may be balanced out by a higher profit.