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The Arnold conjecture in $ \mathbb C\mathbb P^n $ and the Conley index
- Luca Asselle
- Marek Izydorek
- Maciej Starostka
2023 DISCRETE AND CONTINUOUS DYNAMICAL SYSTEMS-SERIES B
n this paper we give an alternative, purely Conley index based proof of the Arnold conjecture in CP^n asserting that a Hamiltonian diffeomorphism of CP^n endowed with the Fubini-Study metric has at least (n+1) fixed points.
The assessment of solar photovoltaic in Poland: the photovoltaics potential, perspectives and development
- Bartłomiej Igliński
- Grzegorz Piechota
- Urszula Kiełkowska
- Wojciech Kujawski
- Michał Bernard Pietrzak
- Mateusz Skrzatek
2023 Pełny tekst Clean Technologies and Environmental Policy
The following article explains the current condition of the photovoltaics sector both in Poland and worldwide. Recently, a rapid development of solar energy has been observed in Poland and is estimated that the country now has about 700,000 photovoltaics prosumers. In October 2021, the total photovoltaics power in Poland amounted to nearly 5.7 GW. The calculated technical potential of photovoltaics in Poland is 153.484 PJ (42.634 TWh). This would cover 26.04% of Poland’s electricity needs. The main aim of the article is to assess the level of development of the photovoltaic market in Poland, the genesis of its creation, description of the current situation and determination of the development opportunities. As part of the aim, programs supporting the development of solar energy in Poland have been described and the SWOT analysis has also been performed. The strengths of photovoltaics include high social acceptance and low costs of photovoltaics system operation, while opportunities include rapidly increasing technological efficiency and decreasing cost of solar systems. On the other hand, weaknesses include the high costs of photovoltaics systems and the disparities in the amount of solar energy reaching the market during the year, whereas climate change and the coronavirus pandemic are threats. In 2020, PV became an investment hit in the energy sector and an economic driver in Poland. In the difficult time of two lockdowns caused by the global pandemic, domestic PV made a significant contribution to the maintenance of investment processes in the amount of PLN 9.5 billion and provided Poland with 35 thousand jobs. In 2020, 1.5% of the country’s electricity came from PV sources. In 2021, it will be 3.5%, and by 2025, solar energy will provide approx. 10% of Poland’s electricity. It is worth examining the development of photovoltaics from a broad and long-term perspective. The spectacular development of photovoltaics in Poland is due to hitting the right time window and reducing technology costs, but most of all, it is based on the cooperation of stakeholders and trust in the regulatory environment.
The Challenge of Quantification: An Interdisciplinary Reading
- Marta Kuc-Czarnecka
- Monica Di Fiore
- Samuele Lo Piano
- Arnald Puy,
- Andrea Saltelli,
2023 Pełny tekst Minerva - A Review of Science, Learning and Policy
The present work looks at what we call “the multiverse of quantification”, where visible and invisible numbers permeate all aspects and venues of life. We review the contributions of different authors who focus on the roles of quantification in society, with the aim of capturing different and sometimes separate voices. Several scholars, including economists, jurists, philosophers, sociologists, communication and data scientists, express concerns or identify critical areas of our relationship with new technologies of ‘numericization’. While mindful of the important specificities of the different families of quantification, we use our broad and holis- tic canvas to explore possible spaces for a more systematic investigation of incumbent and novel quantifications, as to increase communication among disciplinary communities, and among these and society, in the pursuit a democratic agency and self-defence.
The characterization of collagen‑based scaffolds modified with phenolic acids for tissue engineering application
- Beata Kaczmarek-Szczepańska
- Izabela Polkowska
- Marcin Małek
- Janusz Kluczyński
- Katarzyna Paździor-Czapula
- Marcin Wekwejt
- Michno Anna
- Anna Ronowska
- Anna Pałubicka
- Beata Nowicka
- Iwona Otrocka-Domagała
2023 Pełny tekst Scientific Reports
The aim of the experiment was to study the morphology of collagen-based scaffolds modified by caffeic acid, ferulic acid, and gallic acid, their swelling, and degradation rate, as well as the biological properties of scaffolds, such as antioxidant activity, hemo- and cytocompatibility, histological observation, and antibacterial properties. Scaffolds based on collagen with phenolic acid showed higher swelling rate and enzymatic stability compared to scaffolds based on pure collagen, and the radical scavenging activity was in the range 85–91%. All scaffolds were non-hemolytic and compatible with surrounding tissues. Collagen modified by ferulic acid showed potentially negative effects on hFOB cells as a significantly increased LDH release was found, but all of the studied materials had antimicrobial activity against Staphylococcus aureus and Escherichia coli. It may be assumed that phenolic acids, such as caffeic, ferulic, and gallic acid, are modifiers and provide novel biological properties of collagen-based scaffolds. This paper provides the summarization and comparison of the biological properties of scaffolds based on collagen modified with three different phenolic acids.
The coexistence and competition of canonical and comammox nitrite oxidizing bacteria in a nitrifying activated sludge system – Experimental observations and simulation studies
- Jacek Mąkinia
- Mohamad-Javad Mehrani
- Przemysław Kowal
- Dominika Sobotka
- Martyna Godzieba
- Sławomir Ciesielski
- Jianhua Guo
2023 Pełny tekst SCIENCE OF THE TOTAL ENVIRONMENT
The second step of nitrification can be mediated by nitrite oxidizing bacteria (NOB), i.e. Nitrospira and Nitrobacter, with different characteristics in terms of the r/K theory. In this study, an activated sludge model was developed to account for competition between two groups of canonical NOB and comammox bacteria. Heterotrophic denitrification on soluble microbial products was also incorporated into the model. Four 5-week washout trials were carried out at dissolved oxygen-limited conditions for different temperatures (12℃ vs. 20℃) and main substrates (NH4+-N vs. NO2--N). Due to the aggressive reduction of solids retention time (from 4 to 1 d), the biomass concentrations were continuously decreased and stabilized after two weeks at a level below 400 mg/L. The collected experimental data (N species, biomass concentrations, and microbiological analyses) were used for model calibration and validation. In addition to the standard predictions (N species and biomass), the newly developed model also accurately predicted two microbiological indicators, including the relative abundance of comammox bacteria as well as nitrifiers to heterotrophs ratio. Sankey diagrams revealed that the relative contributions of specific microbial groups to N conversion pathways were significantly shifted during the trial. The contribution of comammox did not exceed 5% in the experiments with both NH4+-N and NO2--N substrates. This study contributes to a better understanding of the novel autotrophic N removal processes (e.g. deammonification) with nitrite as a central intermediate product.
The comparison of antioxidant properties and nutrigenomic redox-related activities of vitamin C, C-vitamers, and other common ascorbic acid derivatives
- Patrycja Jakubek
- Klaudia Suliborska
- Monika Kuczyńska
- Muhammad Asaduzzamana
- Karol Parchem
- Izabela Koss-Mikołajczyk
- Barbara Kusznierewicz
- Wojciech Chrzanowski
- Jacek Namieśnik
- Agnieszka Bartoszek-Pączkowska
2023 FREE RADICAL BIOLOGY AND MEDICINE
The term ‘vitamin C’ describes a group of compounds with antiscorbutic activity of L-ascorbic acid (AA). Despite AA’s omnipresence in plant-derived foods, its derivatives have also been successfully implemented in the food industry as antioxidants, including the D-isomers, which lack vitamin C activity. This study aimed to determine the relationship between redox-related activities for five derivatives of AA using electrochemical, chemical, and biological approaches. Here we report that AA, C-vitamers, and other commonly consumed AA derivatives differ in their redox-related activities. As long as the physiological range of concentrations was maintained, there was no simple relationship between their redox properties and biological activity. Clear distinctions in antioxidant activity were observed mostly at high concentrations, which were strongly correlated with electrochemical and kinetic parameters describing redox-related properties of the studied compounds. Despite obvious similarities in chemical structures and antioxidant activity, we showed that C-vitamers may exhibit different nutrigenomic effects. Together, our findings provide a deeper insight into so far underinvestigated area combining chemical properties with biological activities of commonly applied AA derivatives.
The complexity of bicriteria tree-depth
- Piotr Borowiecki
- Dariusz Dereniowski
- Dorota Osula
2023 THEORETICAL COMPUTER SCIENCE
The tree-depth problem can be seen as finding an elimination tree of minimum height for a given input graph G. We introduce a bicriteria generalization in which additionally the width of the elimination tree needs to be bounded by some input integer b. We are interested in the case when G is the line graph of a tree, proving that the problem is NP-hard and obtaining a polynomial-time additive 2b-approximation algorithm. This particular class of graphs received significant attention in the past, mainly due to a number of potential applications, e.g.in parallel assembly of modular products, or parallel query processing in relational databases, as well as purely combinatorial applications including searching in tree-like partial orders (which in turn generalizes binary search on sorted data).
The congruence of mental models in entrepreneurial teams – implications for performance and satisfaction in teams operating in an emerging economy
- Paweł Ziemiański
- Katarzyna Stankiewicz
- Michał Tomczak
- Beata Krawczyk-Bryłka
2023 Pełny tekst Journal of Entrepreneurship in Emerging Economies
Purpose – The paper aims to explore the relationship between the congruence of mental models held by the members of entrepreneurial teams operating in an emerging economy (Poland) and entrepreneurial outcomes (performance and satisfaction). Design/methodology/approach – The data obtained from 18 nascent and 20 established entrepreneurial teams was analysed to answer hypotheses. The research was quantitative and was conducted using an online questionnaire. Data was collected from each of the teams at two stages. Members of entrepreneurial teams were surveyed independently, which allowedmeasuring the congruence of their mental models pertaining to running a venture. Findings – Findings reveal that team members’ mental model congruence is significantly related to financial performance and members’ satisfaction in the case of established entrepreneurial teams. However, in the case of nascent teams, there is no relationship between analysed variables. Practical implications – Implications for theory and practice are offered with a special emphasis on entrepreneurship education. The concept of team mental model congruence is proposed to be included in training of nascent entrepreneurial teams, experienced companies and students. Originality/value – The concept of team mental models investigated by the authors has been underexplored in entrepreneurship research. Results indicate that at least in some entrepreneurial teams, team mental models’ congruence is related to obtained outcomes. The paper proposes that principles of effectuation and causation can serve as the lens through which the mental model pertaining to running a venture can be analysed. It allows expanding studies on the congruence of team mental models in entrepreneurial teams beyond the strategic consensus.
The correlation between nutritional and health potential and antioxidant properties of raw edible oils from cultivated and wild plants
- Dorota Martysiak-Żurowska
- Małgorzata Orzołek
2023 Pełny tekst INTERNATIONAL JOURNAL OF FOOD SCIENCE AND TECHNOLOGY
The nutritional properties and health potential of oils from 15 various cultivated and wild plants were investigated on the basis of the fatty acids profiles, total carotenoids and tocopherols content, antioxidant properties and health potential indexes such as atherogenicity index (AI). The oil contents of the plants varied between 0.9 g/100 g for lychee seeds and 29.7 g/100 g for borage seeds. The tocopherol content in oils ranged from 0.31 (lingonberry fruits) to 226.23 mg/100 g (hawthorn pulp), carotenoids ranged from 0.36 (borage seeds) to 14.22 mg/100 g (blackcurrant seeds). In four oils (raspberry seed, strawberry seed, lingonberry fruits, blackcurrant seeds) the PUFA contents contributed over 70% of the total fatty acids (FA), which was associated with the best values health potential indexes. It was found that TAC (Total Antioxidant Capacity) can be an indirect measure of the levels of carotenoids and tocopherols in oils. Additionally, a positive correlation between the level of carotenoids and the FA n-3 was demonstrated. Determining such relationships may facilitate research into new sources of valuable edible oils useful for the production of functional foods, dietary supplements and cosmetics.
The correlation of fractal dimension to fracture surface slope for fatigue crack initiation analysis under bending-torsion loading in high-strength steels
- Wojciech Macek
- Ricardo Branco
- Przemysław Podulka
- Reza Masoudi Nejad
- José Domingos Costa
- J. A. M. Ferreira
- C. Capela
2023 MEASUREMENT
In this study, the fractal dimension of fatigue fracture surfaces is investigated in order to find an alternative failure loading indicator. Some of many metrological factors are generalized by reducing the fracture surface structure to one factor and develop an entire fracture surface procedure by analyzing the impact of surface slope and calculation resolution. Three notched geometries are studied under cyclic bending-torsion: 34CrNiMo6 high-strength steel bars with transverse blind holes; (ii) 34CrNiMo6 high-strength steel bars with lateral U-shaped notches; and (iii) 18Ni300 maraging steel hollow bars with transverse holes produced by selective laser melting. The surface topographies of fatigue fractures were measured with an optical profilometer. The bending-torsion ratio, maximum local von Mises equivalent stress and the number of cycles to crack initiation are examined using the fractal dimension. Moreover, a comparison was also made for conventional surface topography parameters such as root mean square height and void volume. A fatigue crack initiation model based on surface topography and loading conditions is proposed. The model relies on the product of the maximum local von Mises equivalent stress and the fractal dimension divided by the root mean square height to void volume ratio. The results show that the fracture plane geometry, expressed by the fractal dimension Df, can facilitate the estimation of post-failure loading history. In particular, the analysis based on the enclosing boxes method (EBM) is more accurate when it is used as an extra-fine resolution without any plane leveling.
The Cultures of Knowledge Organizations: Knowledge, Learning, Collaboration (KLC)
- Wioleta Kucharska
- Denise A. D. Bedford
2023
This book focuses on seeing, understanding, and learning to shape an organization’s essential cultures. The book is grounded on a fundamental assumption that every organization has a de facto culture. These “de facto cultures” appear at first glance to be serendipitous, vague, invisible, and unmanaged. An invisible and unrecognized de facto culture can undermine business goals and strategies and lead to business failures. The authors believe that humans can learn to “see” culture around them and understand their influence on individuals, teams, organizations, and societies. At its core, the book lays out the levels of culture to help the reader “see” and learn how to shape a knowledge organization’s cultures. Learning to see and understand the culture, mainly organizational culture, is critical in today’s hyperdynamic knowledge economy. Culture will always dominate strategy in any economy. However, it can play an even more significant role in the knowledge economy, where knowledge is the primary form of capital and the most critical production factor. To thrive and survive in the knowledge economy, managers must “see” their company culture’s power to shape the company’s course and learn to gain and sustain knowledge, learning, and collaboration (KLC) cultures synergy. Hyperdynamic business reality requires smart actions. When managers “see” their cultures as an asset, they have an opportunity to shape those cultures and use them for the company’s best.
The dependence of linear viscoelasticity limits of cold-recycled mixtures on time of curing and compaction method
- Mariusz Jaczewski
- Cezary Szydłowski
- Bohdan Dołżycki
2023 Materials Today: Proceedings
Cold-recycled mixtures are currently among the most widely used and investigated methods that enable recycling of old pavement structures in an environmentally friendly manner. Upon milling, the old pavement structure – whose gradation can be improved with addition of virgin aggregate – is mixed and compacted at ambient temperature. The main binding agents are bituminous emulsion and cement. Due to their dual binding behaviour, cold-recycled mixtures present various problems and challenges in terms of correct testing. One of such challenges is the testing of stiffness modulus of cold-recycled mixtures. Apart from dependence of modulus on test temperature and time of curing, recent research proved its highly nonlinear behaviour, much wider than that of classical asphalt mixtures. The paper presents the results of research of linear viscoelasticity limits based on testing conducted in Simple Performance Tester (SPT) device for one cold-recycled mixture recipe, using samples prepared and compacted in different manner. One mixture was prepared in laboratory conditions from materials obtained from the field section. Second mixture was prepared on the basis of field-mixed materials (material prepared and mixed in field, compacted in laboratory). Additionally, cores obtained from the field at 28 and 180 days after compaction were tested. All mixtures were tested at the temperature of 20 C. Tests were performed 7, 14, 28, 42, 90 and 180 days after compaction. The controlled strain mode was chosen, with strain ranging from 20 to 200 lstrain. Stiffness modulus and phase angle were measured. The test showed that the linear viscoelasticity limits for stiffness modulus testing changed with the time that had elapsed since the compaction for all specimens – the initially low values (of 45–55 lstrain) increased with time and reached constant values (of 75–95 lstrain), with different levels depending on the specimen preparation method.
The Design of Cavity Resonators and Microwave Filters Applying Shape Deformation Techniques
- Michał Baranowski
- Łukasz Balewski
- Adam Lamęcki
- Michał Mrozowski
- Jaione Galdeano
2023 Pełny tekst IEEE TRANSACTIONS ON MICROWAVE THEORY AND TECHNIQUES
This article introduces shape deformation as a new approach to the computer-aided design (CAD) of high-frequency components. We show that geometry deformation opens up new design possibilities and offers additional degrees of freedom in the 3-D modeling of microwave structures. Such design flexibility is highly desirable if the full potential of additive manufacturing (AM) is to be exploited in the fabrication of RF and microwave devices. The use of deformation techniques in the design of high-frequency components allows the attainment of improved electrical parameters, such as high-quality factors for cavity resonators and wide higher-order mode separation. In this work, shape deformation with radial basis functions (RBFs) is integrated with an electromagnetic field simulator based on the 3-D finite-element method (FEM), allowing the semiautomated optimization of microwave components, such as cavity resonators and filters. The proposed strategy is used for the design of high Q-factor cavity resonators, cavity bandpass filters with improved spurious mode separation, and a compact twisted waveguide filter. Three designs of waveguide cavity filters with complex geometry are experimentally verified using 3-D-printed prototypes fabricated with selective laser melting (SLM) technology
The Double Cognitive Bias of Mistakes: A Measurement Method
- Wioleta Kucharska
- Denise A. D. Bedford
- Aleksandra Kopytko
2023 Pełny tekst
There is no learning without mistakes. However, making mistakes among knowledge workers is s�ll seeing shameful. There is a clash between posi�ve a�tudes and beliefs regarding the power of gaining new (tacit) knowledge by ac�ng in new contexts and nega�ve a�tudes and beliefs toward accompanying mistakes that are sources of learning. These contradictory a�tudes create a bias that is doubled by the other shared solid belief that “BOSSES NEVER MAKE MISTAKES.” The double cogni�ve bias of mistakes introduced by Kucharska and Bedford (2023) is assumed in this paper to harm organiza�onal learning and collec�ve intelligence development. To jus�fy this point empirically in this paper, the authors propose a procedure enabling the measurement of the double cogni�ve bias of mistakes. Moreover, to validate the proposed method, authors empirically examine the influence of the KLC cultures’ synergy on knowledge sharing and organiza�onal intelligence and compare obtained results with the effect observed for the sample free of the double bias of mistakes. Novelty: this studyis the first to propose iden�fying the double bias of mistakes and empirically exposing its impacts.
The Effect of C45 Carbon Black-Phosphomolybdic Acid Nanocomposite on Hydrogenation and Corrosion Resistance of La2Ni9Co Hydrogen Storage Alloy
- Krystyna Giza
- Edyta Owczarek
- Andrzej Miszczyk
2023 Pełny tekst ENERGIES
In this paper, we analysed the influence of corrosion processes and the addition of a carbon black-heteropoly phosphomolybdic acid (C45-MPA) nanocomposite on the operating parameters of a hydride electrode obtained on the basis of the intermetallic compound La2Ni9Co. The electrochemical properties of negative electrodes for NiMH batteries were studied using galvanostatic charge/discharge curves, the potentiostatic method, and electrochemical impedance spectroscopy (EIS). The morphology and chemical composition analysis of the studied electrodes were investigated by means of scanning electron microscopy (SEM) with supporting energy-dispersive X-ray analysis (EDS). For more structural information, FTIR analysis was performed. The results indicate that the presence of the C45-MPA nanocomposite in the electrode material increased both the discharge capacity of the hydride electrode and the exchange current density of the H2O/H2 system. The heteropoly acid-modified electrode is also more resistant to high discharge current densities due to its catalytic activity.
The effect of hybridization of fire retarded epoxy/flax-cotton fiber laminates by expanded vermiculite: Structure-property relationship study
- Mateusz Barczewski
- Kamila Sałasińska
- Wojciech Raś
- Aleksander Hejna
- Sławomir Michałowski
- Paulina Kosmela
- Joanna Aniśko
- Anna Boczkowska
- Marek Szostak
2023 Pełny tekst Advanced Industrial and Engineering Polymer Research
The study describes the hybridization of epoxy/flax-cotton (EP/FF) composites containing ammonium polyphosphate (APP) with micrometric expanded vermiculite (VMT) (1–10 wt%). The efficiency of hybridization of flame retarded epoxy/flax-cotton composites was assessed by performing static tensile and flexural strength evaluation, supplemented by impact strength measurements of the composites. Moreover, thermal and thermomechanical analyses (DMA, DSC, and TGA) were performed. Epoxy composites were subjected to flammability using a PCFC microcalorimeter and cone calorimeter measurement to assess the burning behavior of composites. The introduction of the low-cost plate-shaped filler resulted in several favorable thermal effects while deteriorating the structure of the composite. The addition of small amounts of vermiculite (1–2 wt%) into the matrix modified with APP enabled the reduction of heat release rate (HRR) and total heat release (THR) by 60% and 20%, respectively. The comprehensive structure-properties analysis determined the critical filler contents, yielding synergistic flame-retardant effects with a limited negative impact on the composites' performance.
The effect of impacted third molars on second molar external root resorption, a cross-sectional cone beam computed tomography study
- G. Gürses
- A. Akçakaya
- A. Aktı
- Olgun Aydin
2023 Medicina Oral Patologia Oral y Cirugia Bucal
Background: Third molars have the highest prevalence of impaction in teeth and can cause pathological damage on the adjacent second molars. This study aims to evaluate the effects of factors related to impacted third molars on external root resorption (ERR) in adjacent second molars using cone-beam computed tomography (CBCT). Material and Methods: In CBCTs, the effect of impacted third molars on the root surface of adjacent second molars was investigated. Inclusion criteria for subjects were being older than 16 and younger than 55, presence of at least one impacted third molar and adjacent second molar. Exclusion criteria were pathology, a follicle gap greater than 5 mm, crowned second molar, severe decay, an artifact on a radiologic image, and previous surgery on the second or third molars. The investigations were made based on age range, gender, tooth inclination, Pell-Gregory classification, retention type, contact area, root formation, pericoronal width, and tooth absence on the same quadrant for potential risk factors. The collected data were statistically analyzed with R software. The Chi-Square test was used to find out any significant difference. Logistic regression analyses were done for potential risk factors for ERR. Results: A total of 437 impacted third molars and adjacent second molars were investigated using CBCT. Of these, 381 met the inclusion criteria. Mesioangular and horizontal inclination, Pell-Gregory Class B-C, contact area, and retention type were found the statistically potential risk factors for ERR. Conclusions: The impacted third molar with horizontal or mesioangular position, and osseous retention, with Pell and Gregory Class B and C, are more likely to cause external root resorption in adjacent second molars
The effect of multiaxial geocomposite reinforcement on fatigue performance and crack propagation delay in double-layered asphalt beams
- Piotr Jaskuła
- Dawid Ryś
- Cezary Szydłowski
- Michał Golos
- K. Kornacka
- Joanna Żółtko
- Jacek Kawalec
- Marcin Stienss
2023 Pełny tekst Road Materials and Pavement Design
The presented study investigates the effect of a recently developed multiaxial geocomposite made of polypropylene geogrid and non-woven fabric on the delay of crack propagation, based on four-point bending tests of large asphalt concrete beams – both for reinforced and non-reinforced specimens. Several approaches are described in this study, including analysis of stiffness modulus decrease and analysis of crack propagation using dissipated energy. The study also includes investigation of the impact of reinforcement on shear resistance of the inter-layer bond. The reinforced system displays reduced decrease in stiffness during cyclic loading; it is able to bear loads over a longer period, in contrast to the unreinforced system. An increase in fatigue life by a factor of 10–22 is possible, as compared to the unreinforced system. The factor of relative increase in the number of cycles to the first initiation of crack in lower asphalt layer when reinforcement is introduced ranges from 5 to 10.
The effect of PEDOT morphology on hexavalent chromium reduction over 2D TiO2/PEDOT photocatalyst under UV–vis light
- Agnieszka Sulowska
- Agnieszka Fiszka Borzyszkowska
- Karolina Cysewska
- Katarzyna Siwińska-Ciesielczyk
- Konstantin Nikiforow
- Grzegorz Trykowski
- Anna Zielińska-Jurek
2023 MATERIALS CHEMISTRY AND PHYSICS
The present study represents an approach to apply organic-inorganic hybrid materials for photocatalytic removal of heavy metals from the aqueous environment. The photocatalytic activity of the semiconductor modified with the conjugated polymer may depends on the conjugated polymer type, its amount and morphology. Therefore, in the present study the effect of poly (3, 4-ethylenedioxythiophene) (PEDOT) morphology on adsorption and photoreduction of Cr(VI) to Cr(III) under simulated solar light (UV–vis) and vis light (λ > 400 nm) was investigated. The composite of titanium (IV) oxide and PEDOT of different morphology was obtained using the waterin- oil microemulsion method. The obtained hybrid photocatalysts were characterized by diffuse reflectance spectroscopy (DR/UV–vis), Fourier transform infrared spectroscopy (FTIR), X-ray diffraction (XRD), scanning and transmission electron microscopy (SEM, TEM), specific surface area (BET) and X-ray photoelectron spectroscopy (XPS) analyzes. PEDOT and its composites with TiO2 nanosheets of anatase were used for the degradation of highly toxic Cr(VI) under the simulated solar light. The 2D TiO2/PEDOT composite with PEDOT microvesicular morphology reveals the highest efficiency of Cr(VI) photoreduction to Cr(III). The synergistic
The Effect of Sodium Tetrafluoroborate on the Properties of Conversion Coatings Formed on the AZ91D Magnesium Alloy by Plasma Electrolytic Oxidation
- Lukasz Florczak
- Ginter Nawrat
- Kazimierz Darowicki
- Jacek Ryl
- Jan Sieniawski
- Małgorzata Wierzbińska
- Krzysztof Raga
- Andrzej Sobkowiak
2023 Pełny tekst Processes
Magnesium and its alloys are widely used in many areas because of their light weight, excellent dimensional stability, and high strength-to-weight ratio. However, the material exhibits poor wear and corrosion resistance, which limits its use. Plasma electrolytic oxidation (PEO) is an effective surface modification method for producing ceramic oxide layers on Mg and their alloys. The influence of the additions of sodium tetrafluoroborate (NaBF4) and sodium fluoride (NaF) into alkaline-silicate electrolyte on the properties of the conversion layers formed in the magnesium AZ91D alloy has been investigated. Surface morphology and chemical composition were determined by scanning electron microscopy (SEM) and X-ray photoelectron spectroscopy (XPS). The anticorrosive properties of the layers were evaluated by electrochemical impedance spectroscopy (EIS) and potentiodynamic polarization (PDP) methods in simulated body fluid (SBF). The presence of NaBF4 or NaF in the electrolyte increases the corrosion resistance of the protective layer. However, the best anticorrosive properties show the layers obtained in the presence of NaBF4. This is probably caused by the incorporation of boron and fluorine in the form of Mg (BF4)2 mainly in the barrier layer.