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Diagnostyka ogniw paliwowych
- Łukasz Gaweł
2023 Chemia Przemysłowa
Rosnące zapotrzebowanie na zieloną energię elektryczną, ograniczenia związane z normami emisji spalin, większa świadomość ekologiczna społeczeństwa, czy rozwój dolin wodorowych determinują fakt, że ogniwa paliwowe typu PEM będą stanowić ważne źródło energii elektrycznej w niedalekiej przyszłości.
Dielectric Spectroscopy Studies and Modelling of Piezoelectric Properties of Multiferroic Ceramics
- Agata Lisińska-Czekaj
- Dionizy Czekaj
- Barbara Garbarz-Glos
- Wojciech Bąk
- Temesgen Tadeyos Zate
- Jae-Ho Jeon
2023 Pełny tekst Applied Sciences-Basel
Compounds and solid solutions of bismuth ferrite (BiFeO3)—barium titanate (BaTiO3) system are of great scientific and engineering interest as multiferroic and potential high-temperature lead-free piezoelectric materials. In the present paper, the results of research on the synthesis and characterisation of 0.67Bi1.02FeO3–0.33BaTiO3 (67BFBT) ceramics in terms of crystal structure and dielectric and piezoelectric properties are reported. It was found that the produced 67BFBT ceramics were characterised by a tetragonal crystal structure described by the P4mm space group, an average crystallite size <D> 80 nm, and an average strain <#> = 0.01%. Broad-band dielectric spectroscopy (BBDS) was employed to characterise the dielectric response of polycrystalline ceramics. The frequency range from n = 101 Hz to n = 105 Hz was used to characterise the influence of the electric field strength on dielectric response of the ceramic sample at room temperature. The dielectric spectra were checked for consistency with the Kramers–Kronig test, and the high quality of the measurements were confirmed. The electric equivalent circuit method was used to fit the dielectric spectra within the frequency range that corresponded to the occurrence of the resonant spectra of the radial mode for thin disk sample, i.e., from n = 105 Hz to n = 107 Hz and the temperature range from T = 20 C to T = 50 C. The electric equivalent circuit [RsCPE1([L1R1C1]C0)] was used, and good fitting quality was reached. The relevant calculations were performed, and it was found that the piezoelectric charge coefficient exhibited a value of d31 = 35 pC/N and the planar coupling factor was kp = 31% at room temperature. Analysis of impedance spectra performed in terms of circumferential magnetic field made it possible to establish an influence of magnetic field on piezoelectric parameters of 67BFBT multiferroic ceramics. Additionally, the “magnetic” tunability of the modulus of the complex dielectric permittivity makes 67BFBT a sensing material with vast potential.
Differentiating patients with obstructive sleep apnea from healthy controls based on heart rate-blood pressure coupling quantified by entropy-based indices
- Paweł Pilarczyk
- Grzegorz Graff
- Jose Amigo
- Katarzyna Tessmer
- Krzysztof Narkiewicz
- Krzysztof Narkiewicz
- Beata Graff
2023 Pełny tekst CHAOS
We introduce an entropy-based classification method for pairs of sequences (ECPS) for quantifying mutual dependencies in heart rate and beat-to-beat blood pressure recordings. The purpose of the method is to build a classifier for data in which each item consists of two intertwined data series taken for each subject. The method is based on ordinal patterns and uses entropy-like indices. Machine learning is used to select a subset of indices most suitable for our classification problem in order to build an optimal yet simple model for distinguishing between patients suffering from obstructive sleep apnea and a control group.
Digestate Quality Originating from Kitchen Waste
- Joanna Mioduska
- Aleksandra Grabowiec
- Jan Hupka
2023 Pełny tekst Applied Sciences-Basel
This paper examines the influence of biomass directed to anaerobic digestion on the quality of digestate, specifically focusing on the presence of undesirable substances, such as plastics, including biodegradable ones. It analyses the susceptibility of selected bioplastics to degradation and addresses the problem of reliable identification of microplastics in both feedstock—directed to anaerobic digestion—and produced digestate. The review indicates the advantages of using kitchen waste as a feedstock for anaerobic digestion. The constant availability of kitchen waste as a raw material, its homogeneous composition, and the fact that it is not subjected to seasonal fluctuations, facilitates its management in the anaerobic digestion process. However, to ensure the desired quality of a digestate, it is important to carry the selective collection of waste at the source. The review refers to the issues of quality, materials, and regulations, and it may be useful for readers entering the subject of a material loop, as well as those already involved in the subject, including local government units. Anaerobic digestion of kitchen waste is an important part of a renewable economy, providing year-round constantly available substrate for energy production that is not seasonally dependent.
Digital data and tools in transformative education to preserve architecture and cultural heritage: case studies from Italy and Poland
- Justyna Borucka
- Sandro Parrinello
- Francesca Picchio
2023 Pełny tekst Global Journal of Engineering Education
In this article, the authors present the findings and results of a recent study focused on various collaborative activities mostly between Italy and Poland, and digital teaching platforms aimed at educating future architects. These architects are envisioned as curators of digital data and experts in using digital tools in the field of architecture and architectural heritage. The investigation had two main objectives. Firstly, it aimed to develop an educational programme that serves the aforementioned purpose, and secondly, to facilitate educational experiments by integrating education and research in the realm of digital architecture, specifically in support of architectural and urban heritage. All teaching experiments conducted in this study were closely related to the ongoing European Union (EU) research and didactic projects: H2020 PROMETHEUS and EMDMVREA. The authors propose that a European approach to digital transformation for cultural heritage sustainability should emphasise the consolidation of knowledge for young students, enabling them to interact and collaborate with the creative industries and virtual products. This can be achieved by familiarising students with the languages and practices of digitisation and content enrichment.
Digital Transformation and Its Influence on Sustainable Manufacturing and Business Practices
- Issam A. R. Moghrabi
- Sameer Ahmad Bhat
- Piotr Szczuko
- Rawan A. AlKhaled
- Muneer Ahmad Dar
2023 Pełny tekst Sustainability
The paper focuses on the relationship between businesses and digital transformation, and how digital transformation has changed manufacturing in several ways. Aspects like Cloud Computing, vertical and horizontal integration, data communication, and the internet have contributed to sustainable manufacturing by decentralizing supply chains. In addition, digital transformation inventions such as predictive analysis and big data analytics have helped optimize sustainable manufacturing by reducing overproduction or underproduction through predicting customer demands. It integrates digital technology to enhance business operations, consumer engagement, supply chains, and coordination, the manufacturing process, energy conservation, efficiency, and environmental conservation and culture to satisfy business needs. Businesses’ failure to embrace digital transformation in this era contributes to their demise. This research paper will analyze and contrast several businesses and the extent of digital transformation’s influence on them during COVID-19. A twostage study is conducted, the first stage assesses a chosen exemplary business success over three years. The second stage investigates the reasons for success, or otherwise, and the connection to digitalization in the business. Our outcomes suggest that digital transformation strongly influences firms’ effectiveness and survival from a technology-centric and business model standpoint. Some essential generic recommendations are suggested based on the results obtained.
Digitalization and digital skills development patterns. Evidence for European countries
- Ewa Lechman
- Helena Anacka
2023
This chapter contextualizes the digitalization process and the digital skills concept. It discusses the very process of technology diffusion, emphasizing several unique features of digital technologies that make them globally available. Next, it turns to the digital skills concept, clarifying how and why they reshape the societal and economic landscape. It also briefly addresses the digital divide and skill-biased technological change. The provided conceptual considerations are supported by numerical evidence regarding digital technologies and digital skills in Europe in the time span between 1980 and 2021. Using the logistic growth model, it draws digital diffusion trajectories for selected ICT indicators; it also examines the cross-country digital inequalities considering not only access to and use of ICT but also in terms of digital skills.
Digitalization of Building Site Management in the Construction Industry
- Çağatay Takva
- Jan Cudzik
- Zeynep İlerisoy
2023 Pełny tekst International Journal of Sustainable Construction Engineering and Technology
With Industry 4.0, a digital transformation has started in the construction industry. However, 4.0 technologies have difficulties in the integration of digital systems due to the diversity and complexity of the processes in the construction industry. Multidisciplinary work in architectural projects and the need for high productivity require digital renovation planning in the construction industry. The application of the technologies that emerged because of digital transformation on the building site has revealed the concept of the smart building site. Within the framework of many current issues such as the smart building site, the digital transformation on the building sites needs to be explored and defined. In this study, a bibliometric analysis was carried out on the publications in this field by evaluating the transformation potentials of the digitalized building sites of the future. Academic publications that will raise awareness in the improvement of building site management and the development of digital systems have been determined. Conceptual integrity was created by seeing the research gap for digitalization in building site management and it was aimed to guide researchers in future studies. As a result, based on the research area analysis and the diversity of academic publications, it was seen that the studies in the field of architecture were insufficient compared to the engineering fields.
Diiodo-BODIPY Sensitizing of the [Mo3S13]2– Cluster for Noble-Metal-Free Visible-Light-Driven Hydrogen Evolution within a Polyampholytic Matrix
- Daniel Costabel
- Afshin Nabiyan
- Avinash Chettri
- Franz Jacobi
- Magdalena Heiland
- Julien Guthmuller
- Stephan Kupfer
- Maria WäCHTLER
- Benjamin Dietzek-Ivanšić
- Carsten Streb
- Felix H. Schacher
- Kalina Peneva
2023 Pełny tekst ACS Applied Materials & Interfaces
We report on a photocatalytic setup that utilizes the organic photosensitizer (PS) diiodo-BODIPY and the non-precious-metal-based hydrogen evolution reaction (HER) catalyst (NH4)2[Mo3S13] together with a polyampholytic unimolecular matrix poly(dehydroalanine)-graft-poly(ethyleneglycol) (PDha-g-PEG) in aqueous media. The system shows exceptionally high performance with turnover numbers (TON > 7300) and turnover frequencies (TOF > 450 h−1) that are typical for noble-metal- containing systems. Excited state absorption spectra reveal the formation of a long-lived triplet state of the PS in both aqueous and organic media. The system is a blueprint for developing noble-metal-free HER in water. Component optimization, e.g., by modification of the meso substituent of the PS and the composition of the HER catalyst, is further possible.
Dimensionality-Reduced Antenna Modeling with Stochastically Established Constrained Domain
- Anna Pietrenko-Dąbrowska
- Sławomir Kozieł
2023 KNOWLEDGE-BASED SYSTEMS
Over the recent years, surrogate modeling methods have become increasingly widespread in the design of contemporary antenna systems. On the one hand, it is associated with a growing awareness of numerical optimization, instrumental in achieving high-performance structures. On the other hand, considerable computational expenses incurred by massive full-wave electromagnetic (EM) analyses, routinely employed as a major design tool, foster the development of novel design techniques that exhibit practically acceptable costs while ensuring reliability. In this context, substituting EM simulations by fast surrogates is a profitable solution. Data-driven modeling is arguably the most popular approach owing to its versatility and the abundance of specific methods. Yet, a construction of approximation surrogates is severely encumbered by the curse of dimensionality, and even more so by the broad ranges of material and geometry parameters the model should cover to be applicable for solving practical design tasks. The recently reported performance-driven modeling paradigm offers workaround these obstacles by restricting the surrogate rendition to a small section of the parameter space, containing designs of sufficiently high quality according to performance requirements imposed on the system under study. Nevertheless, identification of this region is based on database designs that have to be pre-optimized, which is associated with significant CPU expenses. The usage of the reference designs can be replaced by stochastic domain identification, leading to considerable computational savings. This paper introduces a further advancement, where the metamodel domain is outlined based on the spectral analysis of the random observables pre-selected using an automated decision-making process. Our procedure retains the benefits of the prior techniques but also reduces the domain dimensionality, which translates into additional cost reduction of training data acquisition. These have been conclusively demonstrated through numerical validation involving three microstrip antennas and comprehensive comparisons with six state-of-the-art benchmark techniques.
Direct design of Controlled Modulus Columns (CMC) based on in-situ testing
- Kamila Mikina
2023 Pełny tekst
In this paper, the serviceability limit state and bearing capacity of tension screw displacement piles were analyzed using the results of static pile load tests, carried out on the test plot near the Elbląg city, and field, and laboratory tests. The paper presents the methodology of determining the pile load-settlement curve using different types of t-z transfer functions. The new method of constructing the pile load-settlement curves using the trilinear transfer curves, analogous to the functions developed by Frank and Zhao (1982) based on pressuremeter test, is proposed taking into consideration the results of flat dilatometer test. The analogy between pile shaft friction mobilization and direct shearing of the concrete-soil interface was used. The proposed method was derived from 44 shear-displacement curves of cohesionless, cohesive and organic soils in tests performed in a direct shear apparatus on rough or smooth concrete interfaces. The maximum shear stresses on interface were determined, and the slope of skin friction mobilization was expressed as a function of constrained modulus from DMT. Separate friction mobilization functions were proposed for coarse-grained soils (sands), fine-grained (cohesive), and organic soils. The proposed transfer curves takes into account the installation effects, i.e. the applied pile technology. The soil parameters and stress state before and after pile installation were evaluated using the results of CPTU and DMT soundings. The proposed method was validated using the results of eight static load pull-out tests on screw displacement piles performed on the trial test plot. The study is also focused on the determination of soil parameters before and after pile installation using the results of CPT and DMT soundings. The results of uplift static pile load tests were analyzed and the influence of pile length and the after their construction (set-up) on bearing capacity was studied. Currently used CPT-based methods (direct methods) for pile bearing capacity were discussed in this thesis. They were applied then to estimate the bearing capacities of three piles of different lengths. The results were compared with the bearing capacities obtained from the method elaborated by the author. In conclusion, the possibilities for future research to expand the proposed method were presented and its limitations were discussed.
Direct determination of paraquat herbicide by square-wave voltammetry by two-step transfer mechanism at heterogeneous boron-doped carbon nanowall electrodes
- Sourav Sain
- Mateusz Ficek
- Adrian Olejnik
- Mirosław Sawczak
- Robert Bogdanowicz
- Susanta Sinha Roy
2023 Pełny tekst DIAMOND AND RELATED MATERIALS
Boron-doped carbon nanowalls (B:CNW) versus boron-doped diamond (BDD) materials were investigated for the effective electrochemical detection of highly toxic herbicide paraquat (PQ). Depending on the surface morphology and functional groups of BDD and B:CNWs, the electrochemical absorption and detection of the target analyte PQ revealed different detection mechanisms. The surface absorption mechanism was mainly observed for BDD, while for B:CNWs, both surficial and edge absorption were observed due to the sharp edges of carbon nanowalls. This effectually drives the high heterogenous electron transfer kinetics at absorption sites. Detection of PQ was carried out in phosphate buffer solution with an optimized pH of 10 and parameters of the square-wave voltammetry. Comparative studies show higher voltammetric current peak heights for B:CNWs (∼90.5 μA) than BDD (∼7.5 μA) at a much lower PQ concentration of 4 μM. B:CNWs show a higher sensitivity of 11 μA/μM/cm2 than BDD of 2.23 μA/μM/cm2, hence BDD shows a LOD of 1.8 μM, whereas B:CNWs have a much lower LOD of 0.47 μM. Density functional theory calculations (DFT) show a higher propensity of the B:CNW models toward electrocatalytic reduction of the PQ. Moreover, the proposed two-step detection mechanism is strongly supported by the distribution of the PQ electrostatic potential in different oxidation states in conjunction with the slab surfaces. The higher the sensitivity, the lower the LOD, and the excellent performance of B:CNWs in the detection of PQ in real water samples also suggests its potential for use in the environmental monitoring and assessment of emerging pollutants.
Direct electrical brain stimulation of human memory: lessons learnt and future perspectives
- Michał Kucewicz
2023 Brain: A Journal of Neurology
Modulation of cognitive functions supporting human declarative memory is one of the grand challenges of neuroscience, and of vast importance for a variety of neuropsychiatric, neurodegenerative and neurodevelopmental diseases. Despite a recent surge of successful attempts at improving performance in a range of memory tasks, the optimal approaches and parameters for memory enhancement have yet to be determined. On a more fundamental level, it remains elusive how delivering electrical current in a given brain area leads to enhanced memory processing. Starting from the local and distal physiological effects on neural populations, the mechanisms of enhanced memory encoding, maintenance, consolidation, or recall in response to direct electrical stimulation are only now being unraveled. With the advent of innovative neurotechnologies for concurrent recording and stimulation intracranially in the human brain, it becomes possible to study both acute and chronic effects of stimulation on memory performance and the underlying neural activities. In this review, we summarize the effects of various invasive stimulation approaches for modulating memory functions. We first outline the challenges that were faced in the initial studies of memory enhancement and the lessons learned. Electrophysiological biomarkers are then reviewed as more objective measures of the stimulation effects than behavioral outcomes. Finally, we classify the various stimulation approaches into continuous and phasic modulation with open or closed loop for responsive stimulation based on analysis of the recorded neural activities. Although the potential advantage of closed-loop responsive stimulation over the classic open-loop approaches is inconclusive, we foresee the emerging results from ongoing longitudinal studies and clinical trials to shed light on both the mechanisms and optimal strategies for improving declarative memory. Adaptive stimulation based on the biomarker analysis over extended periods of time is proposed as a future direction for obtaining lasting effects on memory functions. Chronic tracking and modulation of neural activities intracranially through adaptive stimulation opens tantalizing new avenues to continually monitor and treat memory and cognitive deficits in a range of brain disorders.
Direct injection liquid chromatography-mass spectrometry (DI-LC-MS) analysis for rapid lipidomic profiling of extracellular vesicles
- Weronika Hewelt-Belka
- Michał Młynarczyk
- Jorge Matinha-Cardoso
- Felicja Gajdowska
- Paulo Oliveira
- Danuta Gutowska-Owsiak
2023
Extracellular vesicles (EVs) are small, spherical particles produced by eukaryotic and prokaryotic cells, surrounded by a bilayer membrane and carrying various bioactive molecules, such as proteins, surface receptors, membrane and soluble proteins, lipids, and nucleic acids. EVs are of substantial interest because of their important roles in cell communication, epigenetic regulation and possible application in disease diagnosis and therapeutic strategies. Lipids are essential components of EVs since they are the building blocks of their bilayer membrane. Although the EV's lipid composition and its biological role are still unknown, this topic is gaining considerable attention in recent years. Lipidomics is a useful tool for characterisation of EVs' lipid profiles. However, such analysis can be challenging due to the limited size of sample (especially for EV obtained from primary cells), low lipid concentration and detection limits. Usually, extraction is performed before MS analysis to isolate lipids and remove interfering compounds such as proteins. In this work, we have tested the approach of direct injection LC-MS (DI-LC-MS) analysis of EV to characterize the lipidome without lipid extraction. RP-LC-Q-TOF-MS was used for the lipidomic profiling. EVs from various origins isolated by ultracentrifugation have been tested: from bovine and human sera, and EV derived from cultured eukaryotic and bacteria cells (incl. exosome-enriched small EVs, microvesicles and apoptotic bodies). We have evaluated the lipidome coverage and repeatability of the DI approach and compared it with the conventional extraction techniques used for the EVs' lipidomics. The results showed that injection of intact EVs allows the lipid analysis without a priori extraction, where high content of organic solvents in the mobile phase enables EV disintegration and lipid separation on the chromatographic column. The lipidome coverage obtained from conventional extraction and direct injection was comparable. However, the chemical background was reduced in DI approach in comparison to lipid extraction. The DI approach requires small injection volume (e.g. 0.1 µL depending on the EV particle number) and does not require an evaporation step. DI approach simplifies the procedure and makes EV lipidomic analysis fast and convenient without loss of lipidome coverage or repeatability.
Discovering relationships between data in an enterprise information system using log analysis
- Łukasz Korzeniowski
- Krzysztof Goczyła
2023 Pełny tekst
Enterprise systems are inherently complex and maintaining their full, up-to-date overview poses a serious challenge to the enterprise architects’ teams. This problem encourages the search for automated means of discovering knowledge about such systems. An important aspect of this knowledge is understanding the data that are processed by applications and their relationships. In our previous work, we used application logs of an enterprise system to derive knowledge about the interactions taking place between applications. In this paper, we further explore logs to discover correspondence between data processed by different applications. Our contribution is the following: we propose a method for discovering relationships between data using log analysis, we validate our method against a benchmark system AcmeAir and we validate our method against a real-life system running at Nordea Bank.
Discrete identification of continuous non-linear and non-stationary dynamical systems that is insensitive to noise correlation and measurement outliers
- Janusz Kozłowski
- Zdzisław Kowalczuk
2023 Pełny tekst Archives of Control Sciences
The paper uses specific parameter estimation methods to identify the coefficients of continuous-time models represented by linear and non-linear ordinary differential equations. The necessary approximation of such systems in discrete time in the form of utility models is achieved by the use of properly tuned `integrating filters' of the FIR type. The resulting discrete-time descriptions retain the original continuous parameterization and can be identified, for example, by the classical least squares procedure. Since in the presence of correlated noise, the estimated parameter values are burdened with an unavoidable systematic error (manifested by asymptotic bias of the estimates), in order to significantly improve the identification consistency, the method of instrumental variables is used here. In our research we use an estimation algorithm based on the LA criterion of the least sum of absolute values, which is optimal in identifying linear and non-linear systems in the case of sporadic measurement errors. In the paper, we propose a procedure for determining the instrumental variable for a continuous model with non-linearity (related to the Wienerian system) in order to remove the evaluation bias, and a recursive sub-optimal version of the LA estmator. This algorithm is given in a simple (LA) version and in an instrumental variable version (IV-LA), which is robust to outliers, removes evaluation bias, and is suited to the task of identifying processes with non-linear dynamics (semi-Wienerian/NLID). In conclusion, the effectiveness of the proposed algorithmic solutions has been demonstrated by numerical simulations of the mechanical system, which is an essential part of the suspension system of a wheeled vehicle.
Discriminating macromolecular interactions based on an impedimetric fingerprint supported by multivariate data analysis for rapid and label-free Escherichia coli recognition in human urine
- Adrian Koterwa
- Mattia Pierpaoli
- Bożena Nejman-Faleńczyk
- Sylwia Bloch
- Artur Zieliński
- Wioletta Adamus-Białek
- Zofia Jeleniewska
- Bartosz Trzaskowski
- Robert Bogdanowicz
- Grzegorz Węgrzyn
- Paweł Niedziałkowski
- Jacek Ryl
2023 Pełny tekst BIOSENSORS & BIOELECTRONICS
This manuscript presents a novel approach to address the challenges of electrode fouling and highly complex electrode nanoarchitecture, which are primary concerns for biosensors operating in real environments. The proposed approach utilizes multiparametric impedance discriminant analysis (MIDA) to obtain a fingerprint of the macromolecular interactions on flat glassy carbon surfaces, achieved through self-organized, drop-cast, receptor-functionalized Au nanocube (AuNC) patterns. Real-time monitoring is combined with singular value decomposition and partial least squares discriminant analysis, which enables selective identification of the analyte from raw impedance data, without the use of electric equivalent circuits. As a proof-of-concept, the authors demonstrate the ability to detect Escherichia coli in real human urine using an aptamer-based biosensor that targets RNA polymerase. This is significant, as uropathogenic E. coli is a difficult-to-treat pathogen that is responsible for the majority of hospital-acquired urinary tract infection cases. The proposed approach offers a limit of detection of 11.3 CFU/mL for the uropathogenic E. coli strain No. 57, an analytical range in all studied concentrations (up to 105 CFU/mL), without the use of antifouling strategies, yet not being specific vs other E.coli strain studied (BL21(DE3)). The MIDA approach allowed to identify negative overpotentials (−0.35 to −0.10 V vs Ag/AgCl) as most suitable for the analysis, offering over 80% sensitivity and accuracy, and the measurement was carried out in just 2 min. Moreover, this approach is scalable and can be applied to other biosensor platforms.
Dissimilar autogenous TIG joint of Alloy 617 and AISI 304H steel for AUSC application
- Sachin Sirohi
- Amit Kumar
- Shailesh M. Pandey
- Priyambada Purohit
- Dariusz Fydrych
- Sanjeev Kumar
- Chandan Pandey
2023 Pełny tekst Heliyon
To reduce costs and improve high-temperature performance in Advanced Ultra Super Critical (AUSC) boilers, it is necessary to weld austenitic steel to Inconel alloy. In this study, the autogenous tungsten inert gas (TIG) welding process was used to join Alloy 617 and an austenitic AISI 304H steel plate of thickness 5 mm. Microstructural analysis showed that the microstructure formation was uneven along the weldments, with columnar and cellular dendrites near the interface while the central area of the weld exhibited a combination of columnar, cellular, and equiaxed dendrites. The use of energy dispersive spectroscopy and electron probe micro-analysis unveiled the presence of an unmixed layer at the interface between the weld and AISI 304H steel. Furthermore, a notable variation in the concentration of alloying elements such as Fe, Cr, Ni, Co, and Mo was observed. Within the weld metal, inter-dendritic areas showed the presence of precipitates rich in Cr, Ti, and Mo. Meanwhile, the heat-affected zone (HAZ) of Alloy 617 exhibited the presence of phases like Cr and Mo-rich M23C6 as well as Mo-rich M6C. Hardness tests showed non-uniform hardness along the weldments, with a hardness of 199 ± 6 HV in the weld metal and 225 ± 4 HV in Alloy 617 HAZ, and 207 ± 7 HV in AISI 304H HAZ. The Mo and Cr segregation in the inter-dendritic spaces led to a decline in the tensile properties of the welded parts and resulted in failure from the region of the weld metal.
Dissociative Electron Attachment to 5-Iodo-4-thio-2′-deoxyuridine: A Potential Radiosensitizer of Hypoxic Cells
- Muhammad Saqib
- Eugene Arthur-Baidoo
- Farhad Izadi
- Adrian Szczyrba
- Magdalena Datta
- Sebastian Demkowicz
- Janusz Rak
- Stephan Denifl
2023 Pełny tekst Journal of Physical Chemistry Letters
In the search for effective radiosensitizers for tumor cells, halogenated uracils have attracted more attention due to their large cross section for dissociation upon the attachment of low-energy electrons. In this study, we investigated dissociative electron attachment (DEA) to 5-iodo-4-thio-2'-deoxyuridine, a potential radiosensitizer using a crossed electron-molecule beam experiment coupled with quadrupole mass spectrometry. The experimental results were supported by calculations on the threshold energies of formed anions and transition state calculations. We show that low-energy electrons with kinetic energies near 0 eV may effectively decompose the molecule upon DEA. The by far most abundant anion observed corresponds to the iodine anion (I-). Due to the associated bond cleavage, a radical site is formed at the C5 position, which may initiate strand break formation if the molecule is incorporated into a DNA strand. Our results reflect the conclusion from previous radiolysis studies with the title compound, suggesting its potential as a radiosensitizer.
Dissolution of Nb-doped hydroxyapatite prepared via low-temperature mechanochemical method: Spectroscopy studies
- Wojciech Korzeniewski
- Agnieszka Witkowska
2023 NUCLEAR INSTRUMENTS & METHODS IN PHYSICS RESEARCH SECTION B-BEAM INTERACTIONS WITH MATERIALS AND ATOMS
Calcium phosphate glass ceramics with nominal hydroxyapatite stoichiometry doped with niobium were synthesized using simple as well as low-temperature mechanochemical method and then in the form of compressed pellet were submitted to the static dissolution process in distilled water for one month. The results of structural analysis, performed mainly on the base of spectroscopic methods such as: infrared absorption spectroscopy, energy-dispersive X-ray spectroscopy, photoelectron spectroscopy as well as soft and tender X-ray absorption spectroscopies, indicate that during the dissolution process the presence of niobium reduced the dynamics of the calcium phosphate new layer formation, without a significant impact on the morphology and stoichiometry of this layer. Moreover, the Nb addition favored the formation of hydroxyapatite and Ca-deficient hydroxyapatite, both during the synthesis and dissolution processes, and facilitated the incorporation of the CO3-2 groups into the ceramic matrix, leading to the formation of B-type carbonated apatite.