2022 - Repozytorium publikacji - Politechnika Gdańska

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Deterministic versus stochastic modelling of unsaturated flow in a sandy field soil based on dual tracer breakthrough data
- Gunnar Nützmann
- Stanislaw Maciejewski
- Wioletta Gorczewska-Langner
2022 Pełny tekst GEOLOGICAL QUARTERLY
The 216 km2 Neuenhagen Millcreeck catchment can be characterized as a drought sensitive landscape in NE Germany. It is therefore a fundamental human interest to understand how water that fell as precipitation moves through the unsaturated soils and recharges groundwater. Additionally, a better knowledge of nutrient transport from soil to groundwater is important also, especially in landscapes with light sandy soils. For a better understanding of these processes a dual tracer field experiment with bromide (Br-) and deuterium (D2O) was carried out years ago. The aim of the present study is to use results of these data for modelling tracer transport in the unsaturated zone with two different concepts, the classical deterministic advection – dispersion equation and a new stochastic approach. The advantage of the stochastic modelling method proposed here for field scale tracer application is to produce reliable information about expected total solute fluxes from the unsaturated zone to groundwater or mean transit times. Moreover, this allows one to evaluate the mass of solute in the soil profile and to determine the range of water velocity fluctuations. Field experiments should be concentrated on estimation of fluctuation of water flow velocity to make stochastic models more accurate. To summarize, this work contributes to new modelling methods for simulation of water and solute transport in unsaturated sandy soils which are heavily affected by droughts and irregular hydrological processes in the subsurface.
Developing Polycentricity to Shape Resilient Metropolitan Structures: The Case of the Gdansk–Gdynia–Sopot Metropolitan Area
- Piotr Lorens
- Anna Golędzinowska
2022 Pełny tekst Urban Planning
Making the metropolitan area resilient, in many cases, calls for amending its spatial structures. This may take various forms, including both reshaping the metropolitan core and redeveloping the entire regional network of cities and centres, making them part of a coherent structure. The latter strategy is associated with reinforcing secondary urban centres as well as shaping new connections between them. In this case, the term “resilience” is associated not only with environmental aspects but also with socio‐economic and spatial ones. Shaping resilient metropolitan areas is therefore associated with complex planning and development undertakings, in many cases spread over decades. This approach was proven to be correct during the recent Covid‐19 pandemic, which spurred this process of rethinking metropolitan structures and led to generating new approaches to metropolitan development and planning. The article focuses on the Gdansk–Gdynia– Sopot Metropolitan Area, which is potentially the largest polycentric metropolitan area on the southern shore of the Baltic Sea. In this case, polycentricity has a twofold origin—it includes centres with a shaped spatial structure that come closer together as they develop and diffuse suburban structure, the shaping of which remains one of the main challenges of the regional spatial policy. The authors look at both concepts and tools associated with reshaping this metropolitan centre. In particular, they analyse the effects of using both obligatory and optional planning tools which are available according to Polish law. They also try to answer the question of under what conditions a polycentric structure has a chance to become a resistant structure.
Developing the Urban Blue-Green Infrastructure as a Tool for Urban Air Quality Management
- Joanna Badach
- Jakub Szczepański
- Wojciech Bonenberg
- Jacek Gębicki
- Lucyna Nyka
2022 Pełny tekst Sustainability
Urban structure is an important factor that shapes the process of urban ventilation and pollution dispersion. With proper planning of the urban spatial layout, city breathability can be effectively regulated, contributing to urban air quality improvement. This paper investigates the development and current management of urban systems of green and open spaces in four Polish cities: Gda ´nsk, Warsaw, Pozna ´n and Wrocław, with a particular focus on the planning aspects of urban ventilation and air quality management. The initial GIS-based comparison of historical plans and the current spatial layouts of the cities show that these systems, consciously shaped at the beginning of the twentieth century, remain clearly identifiable. However, in some locations, the continuance of these systems was interrupted by later investments. The next step was to develop GIS procedures to effectively map the spatial distribution of selected urban form indicators that are related to urban ventilation, especially the frontal area index. The results made it possible to determine the main features of the current ventilation systems and to identify some of the local problem areas. The last phase of the study was to conduct a local-scale analysis of these problem areas. With this study, the applicability of various analysis and simulation tools for the purpose of improving city breathability by appropriate integrated planning and design decisions was demonstrated. The presented approach, taking into account the city- and micro-scale interactions, should be used in current planning practice to preserve the historically developed ventilation systems.
Development and Assessment of Regeneration Methods for Peptide-Based QCM Biosensors in VOCs Analysis Applications
- Tomasz Wasilewski
- Bartosz Szulczyński
- Dominik Dobrzyniewski
- Weronika Jakubaszek
- Jacek Gębicki
- Wojciech Kamysz
2022 Pełny tekst Biosensors-Basel
Cleaning a quartz crystal microbalance (QCM) plays a crucial role in the regeneration of its biosensors for reuse. Imprecise removal of a receptor layer from a transducer’s surface can lead to unsteady operation during measurements. This article compares three approaches to regeneration of the piezoelectric transducers using the electrochemical, oxygen plasma and Piranha solution methods. Optimization of the cleaning method allowed for evaluation of the influence of cleaning on the surface of regenerated biosensors. The effectiveness of cleaning the QCM transducers with a receptor layer in the form of a peptide with the KLLFDSLTDLKKKMSEC-NH2 sequence was described. Preliminary cleaning was tested for new electrodes to check the potential impact of the cleaning on deposition and the transducer’s operation parameters. The effectiveness of the cleaning was assessed via the measurement of a resonant frequency of the QCM transducers. Based on changes in the resonant frequency and the Sauerbrey equation, it was possible to evaluate the changes in mass adsorption on the transducer’s surface. Moreover, the morphology of the QCM transducer’s surface subjected to the selected cleaning techniques was presented with AFM imaging. The presented results confirm that each method is suitable for peptide-based biosensors cleaning. However, the most invasive seems to be the Piranha method, with the greatest decrease in performance after regeneration cycles (25% after three cycles). The presented techniques were evaluated for their efficiency with respect to a selected volatile compound, which in the future should allow reuse of the biosensors in particular applications, contributing to cost reduction and extension of the sensors’ lifetime.
Development and performance analysis of a novel multiphase doubly-fed induction generator
- Roland Ryndzionek
- Krzysztof Blecharz
- Filip Kutt
- Michał Michna
- Grzegorz Kostro
2022 Pełny tekst Archives of Electrical Engineering
This paper presents the research into the design and performance analysis of a novel five-phase doubly-fed induction generator (DFIG). The designed DFIG is developed based on standard induction motor components and equipped with a five-phase rotor winding supplied from the five-phase inverter. This approach allows the machine to be both efficient and reliable due to the ability of the five-phase rotor winding to operate during single or dual-phase failure. The paper presents the newly designed DFIG validation and verification based on the finite element analysis (FEA) and laboratory tests.
Development of a Response Assessment Tool for a Floating Dock System
- Jianan Zhang
- Lin Li
- Muk Chen Ong
- Omar El Beshbichi
- Aleksander Kniat
2022
Docking operations of ships require a response assessment to ensure structural and personnel safety. Environmental loads and improper ballast adjustments are the main threats to the docking operations. They can cause severe structural damages and stability loss to a floating dock system which includes a floating dock and a docked vessel, even if the velocities of the dock and the vessel are very low during the docking process. Response assessment of the floating dock system, including structural strength analysis and stability check, needs to be performed for a safe docking operation. This paper aims to propose a framework of a floating dock system’s response assessment. The stages of ship docking operations are firstly described. The environmental and operational risks involved in those stages are discussed in detail. Then, relevant studies on the structural strength assessment and stability analysis of floating docks are reviewed. Based on the review, a framework to perform a response assessment of a floating dock system is proposed and discussed with a focus on the dynamic response analysis. A numerical model of the dynamic response assessment is established using the language Modelica. A preliminary case study of a single dock under pure wave conditions is presented.
Development of an AI-based audiogram classification method for patient referral
- Michał Kassjański
- Marcin Kulawiak
- Tomasz Przewoźny
2022
Hearing loss is one of the most significant sensory disabilities. It can have various negative effects on a person's quality of life, ranging from impeded school and academic performance to total social isolation in severe cases. It is therefore vital that early symptoms of hearing loss are diagnosed quickly and accurately. Audiology tests are commonly performed with the use of tonal audiometry, which measures a patient's hearing threshold both in air and bone conduction at different frequencies. The graphic result of this test is represented on an audiogram, which is a diagram depicting the values of the patient's measured hearing thresholds.In the course of the presented work several different artificial neural network models, including MLP, CNN and RNN, have been developed and tested for classification of audiograms into two classes - normal and pathological represented hearing loss. The networks have been trained on a set of 2400 audiograms analysed and classified by professional audiologists. The best classification performance was achieved by the RNN architecture (represented by simple RNN, GRU and LSTM), with the highest out-of-training accuracy being 98\% for LSTM. In clinical application, the developed classifier can significantly reduce the workload of audiology specialists by enabling the transfer of tasks related to analysis of hearing test results towards general practitioners. The proposed solution should also noticeably reduce the patient's average wait time between taking the hearing test and receiving a diagnosis. Further work will concentrate on automating the process of audiogram interpretation for the purpose of diagnosing different types of hearing loss.
Development of cluster analysis methodology for identification of model rainfall hyetographs and its application at an urban precipitation field scale
- Karol Mikołajewski
- Marek Ruman
- Klaudia Kosek
- Marcin Glixelli
- Paulina Dzimińska
- Piotr Ziętara
- Paweł Licznar
2022 Pełny tekst SCIENCE OF THE TOTAL ENVIRONMENT
Despite growing access to precipitation time series records at a high temporal scale, in hydrology, and particularly urban hydrology, engineers still design and model drainage systems using scenarios of rainfall temporal distributions predefined by means of model hyetographs. This creates the need for the availability of credible statistical methods for the development and verification of already locally applied model hyetographs. The methodology development for identification of similar rainfall models is also important from the point of view of systems controlling stormwater runoff structure in real time, particularly those based on artificial intelligence. This paper presents a complete methodology of division of storm rainfalls sets into rainfalls clusters with similar temporal distributions, allowing for the final identification of local model hyetographs clusters. The methodology is based on cluster analysis, including the hierarchical agglomeration method and k-means clustering. The innovativeness of the postulated methodology involves: the objectivization of clusters determination number based on the analysis of total within sum of squares (wss) and the Caliński and Harabasz Index (CHIndex), verification of the internal coherence and external isolation of clusters based on the bootmean parameter, and the designated clusters profiling. The methodology is demonstrated at a scale of a large urban precipitation field of Kraków city on a total set of 1806 storm rainfalls from 25 rain gauges. The obtained results confirm the usefulness and repeatability of the developed methodology regarding storm rainfall clusters division, and identification of model hyetographs in particular clusters, at a scale of an entire city. The applied methodology can be successfully transferred on a global scale and applied in large urban agglomerations around the world.
Development of fragility curves in adjacent steel moment-resisting frames considering pounding effects through improved wavelet-based refined damage-sensitive feature
- Omid Yazdanpanah
- Benyamin Mohebi
- Farzin Kazemi
- Iman Mansouri
- Robert Jankowski
2022 MECHANICAL SYSTEMS AND SIGNAL PROCESSING
Fragility curves present useful information related to earthquake-induced probability assessment ‎of steel moment-resisting frames (MRFs) and determine the probability of the damage ‎exceedance at different floor levels of MRFs. The review of the literature shows that most of the ‎previous studies dealing with the fragility curves were based on conventional measures, such as ‎spectral acceleration at the first mode period, peak ground acceleration, and/or engineering ‎demand parameters (e.g. maximum story drift ratio (max SDR)) to estimate the structure's ‎damage state. In this article, a new approach is developed to map the fragility curves in adjacent ‎MRFs including effects of pounding through improved wavelet-based refined damage-sensitive ‎feature (WB-rDSF) which considers contributions of the upper modes. Morlet and complex ‎Morlet (cmorfb-fc) wavelets, which is known as extremely precise rDSF, were extended to map ‎the fragility curves. The correlation coefficient between rDSF and max SDR is evaluated as a ‎criterion to determine the efficiency of wavelets-based damage index (WB-DI). The steel MRFs ‎with six and nine stories are selected to implement the proposed approach concerning adjacent ‎MRFs prone to structural pounding during earthquakes. Acceleration responses recorded at the ‎roof of both colliding and non-colliding MRFs were determined using incremental dynamic ‎analysis (IDA) including different seismic ground motion records to formulate the damage index. ‎Moreover, the first mode structural period, used in assembling the WB-rDSF, is estimated via ‎auto-regressive moving-average with exogenous input method along with a stabilization diagram. ‎The results show that the fragility curves, derived from cmorfb-fc WB-rDSF for both colliding ‎and non-colliding MRFs due to higher correlation coefficient, have lower damage probabilities ‎and are more efficient than the estimated fragility curves based on Morlet WB-rDSF which ‎consider only the structural period of the first mode. Furthermore, due to the pounding ‎phenomenon, the lower MRF experiences more damages with a larger probability.‎
Development of novel (BiO)2OHCl/BiOBr enriched with boron doped-carbon nanowalls for photocatalytic cytostatic drug degradation: Assessing photocatalytic process utilization in environmental condition
- Patrycja Wilczewska
- Aleksandra Bielicka-giełdoń
- Jacek Ryl
- Michał Sobaszek
- Mirosław Sawczak
- Robert Bogdanowicz
- Karol Szczodrowski
- Anna Malankowska
- Fei Qi
- Ewa Siedlecka
2022 APPLIED SURFACE SCIENCE
In this work, a series of novel (BiO)2OHCl/BiOBr-x%B:DGNW (x = 0%, 1%, 1.5%, 2%) composites with different content of boron-doped diamond/graphene nanowalls (B:DGNW) were fabricated by simple solvothermal synthesis. A boron-doped diamond/graphene nanowalls (B:DGNW) were prepared by CVD method. A series of analyses: XRD, XPS, SEM, and TEM showed that the photocatalyst (BiO)2OHCl/BiOBr-x%B:DGNW with a “flower-like” morphology was successfully synthesized. The photocatalytic activity of the obtained composites in the degradation of 5-fluorouracil (5-FU) in various water matrices (deionized water, sea, and surface water) under the influence of artificial solar radiation was assessed. The results showed that all the prepared (BiO)2OHCl/BiOBr-x%B:DGNW composites were characterized by excellent photocatalytic activity. The calculated pseudo-first rate constant for 5-FU degradation increased with the elevation of amount of B:DGNW up to 1.5% in (BiO)2OHCl/BiOBr, and it dropped down to value obtained for non-riched material by B:DGNW, when of 2% B:DGNW was introduced to composite. The results showed that B:DGNW play a key role in the separation of charge carriers h+/e- enhancing degradation rate of 5-FU. The photoactivity of (BiO)2OHCl/BiOBr-1.5%B:DGNW composite to 5-FU removal was also satisfied in natural water, although its structure has changed in seawater.
Development of Safirinium dyes for new applications: fluorescent staining of bacteria, human kidney cells, and the horny layer of the epidermis
- Joanna Fedorowicz
- Dagmara Bazar
- Wioletta Brankiewicz
- Hanna Kapica
- Krzesimir Ciura
- Beata Zalewska-Piątek
- Rafał Piątek
- Krzysztof Cal
- Krystyna Mojsiewicz-pieńkowska
- Jarosław Sączewski
2022 Pełny tekst Scientific Reports
Low-molecular synthetic fluorophores are convenient tools in bioimaging applications. Several derivatives of Safirinium dyes as well as their reactive N-hydroxysuccinimide (NHS) esters bearing diverse substituents were synthesized and evaluated experimentally in terms of their lipophilicity by means of reverse-phase and immobilized artificial membrane high-performance liquid chromatography. Subsequently, the selected compounds were employed as novel cellular imaging agents for staining Gram-positive and Gram-negative bacteria, human kidney cell line, as well as human skin tissue. The analyzed dyes allowed for visualization of cellular structures such as mitochondria, endoplasmic reticulum, and cellular nuclei. They proved to be useful in fluorescent staining of stratum corneum, especially in the aspect of xenobiotic exposure and its penetration into the skin. The best results were obtained with the use of moderately lipophilic NHS esters of Safirinium Q. The development of Safirinium dyes is a promising alternative for commercially available dyes since the reported molecules have low molecular masses and exhibit efficient staining and remarkable water solubility. Moreover, they are relatively simple and low-cost in synthesis.
Development of SPME fiber coatings with tunable porosity for physical confinement of ionic liquids as an extraction media
- Karolina Delińska
- Grzegorz Machowski
- Adam Kloskowski
2022 MICROCHEMICAL JOURNAL
Extending the use of ionic liquids in sample preparation techniques remains a challenge. This paper presents procedures enabling the easy application of ionic liquids to the SPME technique. For this purpose, two approaches for producing a porous silica coating on a metal rod were investigated. Two silica precursor and porogen systems were used in the research: K2SiO3 + Formamide and Tetramethyl-orthosilicate + Polyethylene oxide. The procedure was optimized concerning its operational parameters: the possibility of immobilization of a possibly large volume of ionic liquid and mechanical strength and thermal resistance. In the course of the research, it was shown that the optimal parameters are ensured by using K2SiO3 with Formamide. The obtained material had an average pore diameter equal to 0.326 μm with a surface area of the pores similar to 6.33 m2/g. The size of the pores allows for the quantitative introduction of the ionic liquid and its immobilization to the extent of enabling the extraction of VOC and their subsequent thermal desorption. Finally, the conducted experiments showed that the dominant mechanism of retaining analytes in the IL-silica hybrid material is their dissolution in the ionic liquid, while adsorption on the silica surface plays a lesser role.
Development of Sulfamoylated 4‑(1-Phenyl‑1H‑1,2,3-triazol-4-yl)phenol Derivatives as Potent Steroid Sulfatase Inhibitors for Efficient Treatment of Breast Cancer
- Karol Biernacki
- Olga Ciupak
- Mateusz Daśko
- Janusz Rachon
- Witold Kozak
- Janusz Rak
- Konrad Kubiński
- Maciej Masłyk
- Aleksandra Martyna
- Magdalena Śliwka-Kaszyńska
- Joanna Wietrzyk
- Marta Świtalska
- Alessio Nocentini
- Claudiu T. Supuran
- Sebastian Demkowicz
2022 Pełny tekst JOURNAL OF MEDICINAL CHEMISTRY
We present here the advances achieved in the development of new sulfamoylated 4-(1-phenyl-1H-1,2,3-triazol-4-yl)phenol derivatives as potent steroid sulfatase (STS) inhibitors for the treatment of breast cancer. Prompted by promising biological results and in silico analysis, the initial series of similar compounds were extended, appending a variety of m-substituents at the outer phenyl ring. The inhibition profiles of the newly synthesized compounds were evaluated using a radioisotope enzymatic assay and, together with the preceding reported derivatives, using a radioisotope assay in MCF-7 cells. The most active compound, 5l, demonstrated an extraordinary STS inhibitory potency in MCF-7 cells with an IC50 value improved 5-fold compared to that of the reference Irosustat (0.21 vs 1.06 nM). The five most potent compounds were assessed in vivo in a 67NR mouse mammary gland cancer model, with 4b measured to induce up to 51% tumor growth inhibition at 50 mg/kg with no evidence of side effects and toxicity.
Development of Technical Creativity Featuring Modified TRIZ-AM Inventive Principle to Support Design for Additive Manufacturing
- Siti Nur Humaira Mazlan
- Aini Zuhra Abdul Kadir
- Mariusz Deja
- Dawid Zieliński
- Mohd Rizal Alkahari
2022 Pełny tekst JOURNAL OF MECHANICAL DESIGN
he design for additive manufacturing (DFAM) processing was introduced to fully utilise the design freedom provided by additive manufacturing (AM). Consequently, appropriate design methodologies have become essential for this technology. Recently, many studies have identified the importance of DFAM method utilisation to produce AM parts, and TRIZ is a strategy used to formalise design methodologies. TRIZ is a problem-solving tool developed to assist designers to find innovative and creative solutions. However, the pathway for synergising TRIZ and DFAM is not clearly explained with respect to AM capabilities and complexities. This is mainly because most methods continue to involve use of the classical TRIZ principle, which was developed early in 1946, 40 years before AM technologies were introduced in the mid-1980s. Therefore, to tackle this issue, this study aims to enhance the 40 principles of classical TRIZ to accommodate AM design principles. A modified TRIZ-AM principle has been developed to define the pathway to AM solutions. TRIZ-AM cards are tools that assist designers to select inventive principles (IPs) in the early phases of product design and development. The case study illustrates that even inexperienced AM users can creatively design innovative AM parts.
Diagnostyka cienkościennych żelbetowych sklepień kolebkowych w budynku zabytkowym
- Tomasz Majewski
- Maciej Niedostatkiewicz
2022 Pełny tekst Przegląd Budowlany
Artykuł stanowi studium przypadku oceny stanu technicznego cienkościennych żelbetowych sklepień kolebkowych stanowiących przekrycie Hali Głównej Dworca Głównego PKP w Gdańsku. W artykule szczegółowo opisano metodologie prac diagnostycznych oraz przedstawiono zaproponowany sposób naprawy sklepień
Diagnostyka i naprawy dylatacji konstrukcyjnych w płytach posadzkowych
- Sylwia Świątek-Żołyńska
- Maciej Niedostatkiewicz
- Sebastian Kasprzak
2022 Pełny tekst Przegląd Budowlany
Artykuł obejmuje problematykę napraw dylatacji konstrukcyjnych w płytach posadzkowych wykonanych na gruncie wraz z omówieniem sposobów naprawy
Diagnostyka i wyjaśnienie aktualnego stanu 40-letniego wiaduktu kolejowego
- Jakub Zembrzuski
- Bartosz Sobczyk
- Mikołaj Miśkiewicz
2022 Pełny tekst
Praca zawiera krótką ocenę stanu technicznego, opis przeprowadzonych badań nieniszczących in-situ oraz wykonanych modeli MES, służących do przeprowadzenia analiz na poziomie globalnym jak i lokalnym. Przedstawiono i omówiono wyniki analiz numerycznych, wykorzystanych do oceny stanu konstrukcji i mających na celu rozwiązanie sformułowanych problemów badawczych. Wykonane obliczenia na poziomie globalnym z uszczegółowieniem w obrębie fragmentu skrajnego przęsła dostarczyły wyjaśnienia przyczyny nie wystąpienia awarii, która miałaby być spowodowana brakami w spoinie czołowej blach płyty ortotropowej. Wykazano, że styk pozostaje w równowadze i nie ulega rozwarciu, ponieważ występują w nim jedynie naprężenia ściskające i blachy „zakleszczają” się wzajemnie. Znaleziono również przyczynę powstania gwałtownego przyrostu wartości na wykresie naprężeń w przekroju poprzecznicy. W wyniku analizy przeprowadzonej na modelu lokalnym, wykonanym w programie ABAQUS wykazano, że przyczyną wystąpienia „skoku” wartości był fakt lokalizacji punktów pomiarowych odkształceń (naprężeń) w strefie silnej koncentracji naprężeń. Co istotne, podczas analizy zagadnienia i wprowadzanych do modeli numerycznych modyfikacji, zaaplikowano z sukcesem uproszczony sposób modelowania połączenia nitowanego, wykorzystujący częściowo techniki modelowania numerycznego stosowane zwykle w analizach na poziomie globalnym, a pozwalający uzyskiwać zadowalające wyniki w analizach lokalnych. Uzyskane wyniki mają duże znaczenie na polu możliwości oceny pracy konstrukcji mostowych z płytą ortotropową. Etapowe dochodzenie do rozwiązania problemu od modelu numerycznego globalnego do szczegółowego, co więcej z wykorzystaniem wyników badań in-situ, mogą stanowić wytyczne do oceny stanu analogicznych do badanego obiektów mostowych.
Diagnostyka uszkodzeń żelbetowej, monolitycznej ściany w realizowanym budynku wielorodzinnym
- Maciej Niedostatkiewicz
- Tomasz Majewski
2022 Pełny tekst Materiały Budowlane
W artykule przedstawiono przypadek uszkodzeń żelbetowej, monolitycznej ściany, do którego doszło podczas demontażu systemowych szalunków prefabrykowanych. W miejscu uderzenia beton uległ wykruszenia, poniżej przy górnej części ściana rozwarstwiła się. Wykonane badania diagnostycze za pomocą metody ultradźwiękowej umożliwiły określenie zakresu uszkodzenia i opracowani optymalnej metody naprawy
Diamond investments – Is the market free from multiple price bubbles?
- Marcin Potrykus
2022 Pełny tekst International Review of Financial Analysis
The following study aims to investigate whether multiple price bubbles, in which the quoted market price of diamonds significantly deviates from their fundamental value, exist in the diamond market. It was conducted using ADF, SADF and GSADF tests, with the latter found to be an optimal form of evaluating the analysed issue. The presented results support the conclusion that the diamond market is not free from periods defined as price bubbles. The study revealed price bubbles related to the leading, albeit declining in recent years, position of De Beers within the market and its activities, the financial crisis of 2008, the subsequent European debt crisis, and the crisis caused by the aggression of the Russian Federation against Ukraine in 2022. However, the identified periods of speculative bubbles in the diamond market are short and tend to affect the rough diamond segment earlier than the broader diamond market.
Diamond protection for reusable ZnO coated fiber-optic measurement head in optoelectrochemical investigation of bisphenol A
- Małgorzata Szczerska
- Monika Kosowska
- Paulina Listewnik
- Michał Rycewicz
- Mikhael Bechelany
- Yafit Fleger
- Dror Fixler
- Paweł Jakóbczyk
2022 Pełny tekst MEASUREMENT
Due to the global problem with plastic contaminating the environment, with bisphenol A (BPA) being one of the highest demand, effective monitoring and purification of the pollutants are required. The electrochemical methods constitute a good solution but, due to polymerization of electrochemical oxidation bisphenol A products and their adsorption to the surfaces, measurement head elements are clogged by the formed film. In this research, we propose a nanocrystalline diamond sheet protection for securing elements in direct contact with bisphenol A during electrochemical processes. The solution was presented on the example of a zinc oxide (ZnO) coating deposited on a fiber-optic end-face by Atomic Layer Deposition. Series of optical and electrochemical measurements were performed in a dedicated hybrid setup. The results show that ZnO can be modified during the electrochemistry leading to the drastic change of its properties. Such degradation did not show in case of nanocrystalline diamond sheet-protected sample proving the solution’s effectiveness, giving a possibility of re-using the measurement element and prolonging its lifespan.