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Author |
Baij, L.; Liu, C.; Buijs, J.; Alvarez Martin, A.; Westert, D.; Raven, L.; Geels, N.; Noble, P.; Sprakel, J.; Keune, K. |
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Title |
Understanding and optimizing Evolon® CR for varnish removal from oil paintings |
Type  |
A1 Journal article |
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Year |
2021 |
Publication |
Heritage science |
Abbreviated Journal |
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Volume |
9 |
Issue |
1 |
Pages |
155-17 |
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Keywords |
A1 Journal article; Engineering sciences. Technology; AXES (Antwerp X-ray Analysis, Electrochemistry and Speciation); Antwerp X-ray Imaging and Spectroscopy (AXIS) |
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Wos |
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Publication Date |
2021-11-27 |
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Abbreviated Series Title |
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Series Volume |
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Series Issue |
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Edition |
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ISSN |
2050-7445 |
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Additional Links |
UA library record |
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Impact Factor |
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Times cited |
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Open Access |
Not_Open_Access |
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Notes |
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Approved |
Most recent IF: NA |
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Call Number |
UA @ admin @ c:irua:183747 |
Serial |
8707 |
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Author |
Van Echelpoel, R.; de Jong, M.; Daems, D.; van Espen, P.; De Wael, K. |
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Title |
Unlocking the full potential of voltammetric data analysis : a novel peak recognition approach for (bio)analytical applications |
Type |
A1 Journal article |
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Year |
2021 |
Publication |
Talanta |
Abbreviated Journal |
Talanta |
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Volume |
233 |
Issue |
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Pages |
122605 |
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Keywords |
A1 Journal article; Engineering sciences. Technology; AXES (Antwerp X-ray Analysis, Electrochemistry and Speciation) |
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Abstract |
Bridging the gap between complex signal data output and clear interpretation by non-expert end-users is a major challenge many scientists face when converting their scientific technology into a real-life application. Currently, pattern recognition algorithms are the most frequently encountered signal data interpretation algorithms to close this gap, not in the least because of their straight-forward implementation via convenient software packages. Paradoxically, just because their implementation is so straight-forward, it becomes cumbersome to integrate the expert's domain-specific knowledge. In this work, a novel signal data interpretation approach is presented that uses this domain-specific knowledge as its fundament, thereby fully exploiting the unique expertise of the scientist. The new approach applies data preprocessing in an innovative way that transcends its usual purpose and is easy to translate into a software application. Multiple case studies illustrate the straight-forward application of the novel approach. Ultimately, the approach is highly suited for integration in various (bio)analytical applications that require interpretation of signal data. |
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Wos |
000668000500108 |
Publication Date |
2021-06-11 |
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Series Editor |
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Series Title |
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Abbreviated Series Title |
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Series Volume |
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Series Issue |
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Edition |
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ISSN |
0039-9140; 1873-3573 |
ISBN |
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Additional Links |
UA library record; WoS full record; WoS citing articles |
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Impact Factor |
4.162 |
Times cited |
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Open Access |
OpenAccess |
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Notes |
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Approved |
Most recent IF: 4.162 |
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Call Number |
UA @ admin @ c:irua:179417 |
Serial |
8712 |
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Author |
Dillen, A.; Vandezande, W.; Daems, D.; Lammertyn, J. |
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Title |
Unraveling the effect of the aptamer complementary element on the performance of duplexed aptamers : a thermodynamic study |
Type |
A1 Journal article |
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Year |
2021 |
Publication |
Analytical And Bioanalytical Chemistry |
Abbreviated Journal |
Anal Bioanal Chem |
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Volume |
413 |
Issue |
19 |
Pages |
4739-4750 |
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Keywords |
A1 Journal article; AXES (Antwerp X-ray Analysis, Electrochemistry and Speciation) |
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Abstract |
Duplexed aptamers (DAs) are widespread aptasensor formats that simultaneously recognize and signal the concentration of target molecules. They are composed of an aptamer and aptamer complementary element (ACE) which consists of a short oligonucleotide that partially inhibits the aptamer sequence. Although the design principles to engineer DAs are straightforward, the tailored development of DAs for a particular target is currently based on trial and error due to limited knowledge of how the ACE sequence affects the final performance of DA biosensors. Therefore, we have established a thermodynamic model describing the influence of the ACE on the performance of DAs applied in equilibrium assays and demonstrated that this relationship can be described by the binding strength between the aptamer and ACE. To validate our theoretical findings, the model was applied to the 29-mer anti-thrombin aptamer as a case study, and an experimental relation between the aptamer-ACE binding strength and performance of DAs was established. The obtained results indicated that our proposed model could accurately describe the effect of the ACE sequence on the performance of the established DAs for thrombin detection, applied for equilibrium assays. Furthermore, to characterize the binding strength between the aptamer and ACEs evaluated in this work, a set of fitting equations was derived which enables thermodynamic characterization of DNA-based interactions through thermal denaturation experiments, thereby overcoming the limitations of current predictive software and chemical denaturation experiments. Altogether, this work encourages the development, characterization, and use of DAs in the field of biosensing. |
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Corporate Author |
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Thesis |
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Publisher |
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Place of Publication |
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Editor |
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Wos |
000659366300001 |
Publication Date |
2021-06-10 |
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Series Editor |
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Series Title |
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Abbreviated Series Title |
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Series Volume |
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Series Issue |
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Edition |
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ISSN |
1618-2642; 1618-2650 |
ISBN |
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Additional Links |
UA library record; WoS full record; WoS citing articles |
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Impact Factor |
3.431 |
Times cited |
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Open Access |
Not_Open_Access |
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Notes |
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Approved |
Most recent IF: 3.431 |
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Call Number |
UA @ admin @ c:irua:179163 |
Serial |
8713 |
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Author |
Maso, L.; Trande, M.; Liberi, S.; Moro, G.; Daems, E.; Linciano, S.; Sobott, F.; Covaceuszach, S.; Cassetta, A.; Fasolato, S.; Moretto, L.M.; De Wael, K.; Cendron, L.; Angelini, A. |
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Title |
Unveiling the binding mode of perfluorooctanoic acid to human serum albumin |
Type |
A1 Journal article |
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Year |
2021 |
Publication |
Protein Science |
Abbreviated Journal |
Protein Sci |
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Volume |
30 |
Issue |
4 |
Pages |
830-841 |
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Keywords |
A1 Journal article; AXES (Antwerp X-ray Analysis, Electrochemistry and Speciation) |
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Abstract |
Perfluorooctanoic acid (PFOA) is a toxic compound that is absorbed and distributed throughout the body by noncovalent binding to serum proteins such as human serum albumin (hSA). Though the interaction between PFOA and hSA has been already assessed using various analytical techniques, a high resolution and detailed analysis of the binding mode is still lacking. We report here the crystal structure of hSA in complex with PFOA and a medium-chain saturated fatty acid (FA). A total of eight distinct binding sites, four occupied by PFOAs and four by FAs, have been identified. In solution binding studies confirmed the 4:1 PFOA-hSA stoichiometry and revealed the presence of one high and three low affinity binding sites. Competition experiments with known hSA-binding drugs allowed locating the high affinity binding site in sub-domain IIIA. The elucidation of the molecular basis of the interaction between PFOA and hSA might provide not only a better assessment of the absorption and elimination mechanisms of these compounds in vivo but also have implications for the development of novel molecular receptors for diagnostic and biotechnological applications. |
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Wos |
000625392600001 |
Publication Date |
2021-02-08 |
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Series Editor |
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Series Title |
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Abbreviated Series Title |
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Series Volume |
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Series Issue |
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Edition |
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ISSN |
0961-8368 |
ISBN |
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Additional Links |
UA library record; WoS full record; WoS citing articles |
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Impact Factor |
2.523 |
Times cited |
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Open Access |
Not_Open_Access |
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Notes |
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Approved |
Most recent IF: 2.523 |
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Call Number |
UA @ admin @ c:irua:176725 |
Serial |
8714 |
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Author |
Ortiz-Aguayo, D.; De Wael, K.; del Valle, M. |
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Title |
Voltammetric sensing using an array of modified SPCE coupled with machine learning strategies for the improved identification of opioids in presence of cutting agents |
Type |
A1 Journal article |
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Year |
2021 |
Publication |
Journal Of Electroanalytical Chemistry |
Abbreviated Journal |
J Electroanal Chem |
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Volume |
902 |
Issue |
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Pages |
115770 |
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Keywords |
A1 Journal article; AXES (Antwerp X-ray Analysis, Electrochemistry and Speciation); Antwerp Electrochemical and Analytical Sciences Lab (A-Sense Lab) |
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Abstract |
This work reports the use of modified screen-printed carbon electrodes (SPCEs) for the identification of three drugs of abuse and two habitual cutting agents, caffeine and paracetamol, combining voltammetric sensing and chemometrics. In order to achieve this goal, codeine, heroin and morphine were subjected to Square Wave Voltammetry (SWV) at pH 7, in order to elucidate their electrochemical fingerprints. The optimized SPCEs electrode array, which have a differentiated response for the three oxidizable compounds, was derived from Carbon, Prussian blue, Cobalt (II) phthalocyanine, Copper (II) oxide, Polypyrrole and Palladium nanoparticles ink-modified carbon electrodes. Finally, Principal Component Analysis (PCA) coupled with Silhouette parameter assessment was used to select the most suitable combination of sensors for identification of drugs of abuse in presence of cutting agents. |
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Corporate Author |
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Place of Publication |
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Wos |
000714415500006 |
Publication Date |
2021-10-13 |
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Series Editor |
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Series Title |
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Abbreviated Series Title |
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Series Volume |
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Series Issue |
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Edition |
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ISSN |
1572-6657; 1873-2569 |
ISBN |
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Additional Links |
UA library record; WoS full record; WoS citing articles |
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Impact Factor |
3.012 |
Times cited |
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Open Access |
OpenAccess |
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Notes |
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Approved |
Most recent IF: 3.012 |
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Call Number |
UA @ admin @ c:irua:184018 |
Serial |
8745 |
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Author |
Parrilla, M.; De Wael, K. |
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Title |
Wearable self‐powered electrochemical devices for continuous health management |
Type |
A1 Journal article |
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Year |
2021 |
Publication |
Advanced Functional Materials |
Abbreviated Journal |
Adv Funct Mater |
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Volume |
31 |
Issue |
50 |
Pages |
2107042 |
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Keywords |
A1 Journal article; Engineering sciences. Technology; AXES (Antwerp X-ray Analysis, Electrochemistry and Speciation); Antwerp Electrochemical and Analytical Sciences Lab (A-Sense Lab) |
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Abstract |
The wearable revolution is already present in society through numerous gadgets. However, the contest remains in fully deployable wearable (bio)chemical sensing. Its use is constrained by the energy consumption which is provided by miniaturized batteries, limiting the autonomy of the device. Hence, the combination of materials and engineering efforts to develop sustainable energy management is paramount in the next generation of wearable self-powered electrochemical devices (WeSPEDs). In this direction, this review highlights for the first time the incorporation of innovative energy harvesting technologies with top-notch wearable self-powered sensors and low-powered electrochemical sensors toward battery-free and self-sustainable devices for health and wellbeing management. First, current elements such as wearable designs, electrochemical sensors, energy harvesters and storage, and user interfaces that conform WeSPEDs are depicted. Importantly, the bottlenecks in the development of WeSPEDs from an analytical perspective, product side, and power needs are carefully addressed. Subsequently, energy harvesting opportunities to power wearable electrochemical sensors are discussed. Finally, key findings that will enable the next generation of wearable devices are proposed. Overall, this review aims to bring new strategies for an energy-balanced deployment of WeSPEDs for successful monitoring of (bio)chemical parameters of the body toward personalized, predictive, and importantly, preventive healthcare. |
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Corporate Author |
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Thesis |
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Publisher |
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Place of Publication |
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Editor |
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Language |
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Wos |
000694642500001 |
Publication Date |
2021-09-09 |
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Series Editor |
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Series Title |
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Abbreviated Series Title |
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Series Volume |
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Series Issue |
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Edition |
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ISSN |
1616-301x |
ISBN |
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Additional Links |
UA library record; WoS full record; WoS citing articles |
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Impact Factor |
12.124 |
Times cited |
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Open Access |
OpenAccess |
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Notes |
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Approved |
Most recent IF: 12.124 |
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Call Number |
UA @ admin @ c:irua:181306 |
Serial |
8750 |
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Author |
Yi, Y.; Li, S.; Cui, Z.; Hao, Y.; Zhang, Y.; Wang, L.; Liu, P.; Tu, X.; Xu, X.; Guo, H.; Bogaerts, A. |
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Title |
Selective oxidation of CH4 to CH3OH through plasma catalysis: Insights from catalyst characterization and chemical kinetics modelling |
Type |
A1 Journal Article;Methane conversion |
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Year |
2021 |
Publication |
Applied Catalysis B-Environmental |
Abbreviated Journal |
Appl Catal B-Environ |
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Volume |
296 |
Issue |
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Pages |
120384 |
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Keywords |
A1 Journal Article;Methane conversion; Plasma catalysis; Selective oxidation; Methanol synthesis; Plasma chemistry; Plasma, laser ablation and surface modeling Antwerp (PLASMANT) ; |
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Abstract |
The selective oxidation of methane to methanol (SOMTM) by molecular oxygen is a holy grail in catalytic chemistry and remains a challenge in chemical industry. We perform SOMTM in a CH4/O2 plasma, at low temperature and atmospheric pressure, promoted by Ni-based catalysts, reaching 81 % liquid oxygenates selectivity and 50 % CH3OH selectivity, with an excellent catalytic stability. Chemical kinetics modelling shows that CH3OH in the plasma is mainly produced through radical reactions, i.e., CH4 + O(1D) → CH3O + H, followed by CH3O + H + M→ CH3OH + M and CH3O + HCO → CH3OH + CO. The catalyst characterization shows that the improved production of CH3OH is attributed to abundant chemisorbed oxygen species, originating from highly dispersed NiO phase with strong oxide support interaction with γ-Al2O3, which are capable of promoting CH3OH formation through E-R reactions and activating H2O molecules to facilitate CH3OH desorption. |
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Address |
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Corporate Author |
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Thesis |
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Publisher |
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Place of Publication |
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Editor |
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Language |
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Wos |
000706860000003 |
Publication Date |
2021-05-21 |
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Series Editor |
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Series Title |
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Abbreviated Series Title |
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Series Volume |
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Series Issue |
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Edition |
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ISSN |
0926-3373 |
ISBN |
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Additional Links |
UA library record; WoS full record; WoS citing articles |
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Impact Factor |
9.446 |
Times cited |
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Open Access |
OpenAccess |
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Notes |
National Natural Science Foundation of China; PetroChina Innovation Foundation; We acknowledge financial support from the PetroChina Innovation Foundation [grant ID: 2018D-5007-0501], the Young Star Project of Dalian Science and Technology Bureau [grant ID: 2019RQ042], the National Natural Science Foundation of China [grant ID: 21503032] and the TOP research project of the Research Fund of the University of Antwerp [grant ID: 32249]. |
Approved |
Most recent IF: 9.446 |
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Call Number |
PLASMANT @ plasmant @c:irua:178816 |
Serial |
6793 |
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Author |
Bahnamiri, O.S.; Verheyen, C.; Snyders, R.; Bogaerts, A.; Britun, N. |
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Title |
Nitrogen fixation in pulsed microwave discharge studied by infrared absorption combined with modelling |
Type |
A1 Journal Article;nitrogen fixation |
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Year |
2021 |
Publication |
Plasma Sources Science & Technology |
Abbreviated Journal |
Plasma Sources Sci T |
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Volume |
30 |
Issue |
6 |
Pages |
065007 |
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Keywords |
A1 Journal Article;nitrogen fixation; pulsed microwave discharge; FTIR spectroscopy; discharge modelling; vibrational excitation; NO yield; energy cost; Plasma, laser ablation and surface modeling Antwerp (PLASMANT) ; |
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Abstract |
A pulsed microwave surfaguide discharge operating at 2.45 GHz was used for the conversion of molecular nitrogen into valuable compounds in several gas mixtures: N2 :O2 , N2 :O2 :CO2 and N2 :CO2 . The ro-vibrational absorption bands of the molecular species were monitored by a Fourier transform infrared apparatus in the post-discharge region in order to evaluate the relative number density of species, specifically NO production. The effects of specific energy input, pulse frequency, gas flow fraction, gas admixture and gas flow rate were studied for better understanding and optimization of the NO production yield and the corresponding energy cost (EC). By both the experiment and modelling, a highest NO yield is obtained at N2 :O2 (1:1) gas ratio in N2 :O2 mixture. The NO yield reveals a small growth followed by saturation when pulse repetition frequency increases. The energy efficiency start decreasing after the energy input reaches about 5 eV/molec, whereas the NO yield rises steadily at the same time. The lowest EC of about 8 MJ mol−1 corresponding to the yield and the energy efficiency of about 7% and 1% are found, respectively, in an optimum discharge condition in our case. |
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Address |
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Corporate Author |
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Thesis |
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Publisher |
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Place of Publication |
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Editor |
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Language |
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Wos |
000659671000001 |
Publication Date |
2021-06-01 |
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Series Editor |
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Series Title |
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Abbreviated Series Title |
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Series Volume |
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Series Issue |
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Edition |
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ISSN |
0963-0252 |
ISBN |
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Additional Links |
UA library record; WoS full record; WoS citing articles |
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Impact Factor |
3.302 |
Times cited |
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Open Access |
OpenAccess |
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Notes |
Fonds De La Recherche Scientifique—FNRS, EOS O005118F ; The research is supported by the FNRS-FWO project ‘NITROPLASM’, EOS O005118F. O Samadi also acknowledges PhD student F Manaigo for cooperation in doing the additional measurements. |
Approved |
Most recent IF: 3.302 |
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Call Number |
PLASMANT @ plasmant @c:irua:179170 |
Serial |
6798 |
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| Permanent link to this record |
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Author |
Van Loenhout, J.; Freire Boullosa, L.; Quatannens, D.; De Waele, J.; Merlin, C.; Lambrechts, H.; Lau, H.W.; Hermans, C.; Lin, A.; Lardon, F.; Peeters, M.; Bogaerts, A.; Smits, E.; Deben, C. |
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Title |
Auranofin and Cold Atmospheric Plasma Synergize to Trigger Distinct Cell Death Mechanisms and Immunogenic Responses in Glioblastoma |
Type |
A1 Journal Article;oxidative stress |
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Year |
2021 |
Publication |
Cells |
Abbreviated Journal |
Cells |
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Volume |
10 |
Issue |
11 |
Pages |
2936 |
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Keywords |
A1 Journal Article;oxidative stress; auranofin; cold atmospheric plasma; glioblastoma; cancer cell death; Plasma, laser ablation and surface modeling Antwerp (PLASMANT) ; |
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Abstract |
Targeting the redox balance of malignant cells via the delivery of high oxidative stress unlocks a potential therapeutic strategy against glioblastoma (GBM). We investigated a novel reactive oxygen species (ROS)-inducing combination treatment strategy, by increasing exogenous ROS via cold atmospheric plasma and inhibiting the endogenous protective antioxidant system via auranofin (AF), a thioredoxin reductase 1 (TrxR) inhibitor. The sequential combination treatment of AF and cold atmospheric plasma-treated PBS (pPBS), or AF and direct plasma application, resulted in a synergistic response in 2D and 3D GBM cell cultures, respectively. Differences in the baseline protein levels related to the antioxidant systems explained the cell-line-dependent sensitivity towards the combination treatment. The highest decrease of TrxR activity and GSH levels was observed after combination treatment of AF and pPBS when compared to AF and pPBS monotherapies. This combination also led to the highest accumulation of intracellular ROS. We confirmed a ROS-mediated response to the combination of AF and pPBS, which was able to induce distinct cell death mechanisms. On the one hand, an increase in caspase-3/7 activity, with an increase in the proportion of annexin V positive cells, indicates the induction of apoptosis in the GBM cells. On the other hand, lipid peroxidation and inhibition of cell death through an iron chelator suggest the involvement of ferroptosis in the GBM cell lines. Both cell death mechanisms induced by the combination of AF and pPBS resulted in a significant increase in danger signals (ecto-calreticulin, ATP and HMGB1) and dendritic cell maturation, indicating a potential increase in immunogenicity, although the phagocytotic capacity of dendritic cells was inhibited by AF. In vivo, sequential combination treatment of AF and cold atmospheric plasma both reduced tumor growth kinetics and prolonged survival in GBM-bearing mice. Thus, our study provides a novel therapeutic strategy for GBM to enhance the efficacy of oxidative stress-inducing therapy through a combination of AF and cold atmospheric plasma. |
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Place of Publication |
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Language |
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Wos |
000807134000001 |
Publication Date |
2021-10-28 |
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Series Editor |
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Series Title |
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Abbreviated Series Title |
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Series Volume |
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Series Issue |
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Edition |
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ISSN |
2073-4409 |
ISBN |
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Additional Links |
UA library record; WoS full record; WoS citing articles |
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Impact Factor |
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Times cited |
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Open Access |
OpenAccess |
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Notes |
Olivia Hendrickx Research Fund, 21OCL06 ; University of Antwerp, FFB160231 ; The authors would express their gratitude to Hans de Reu for technical assistance with flow cytometry. |
Approved |
Most recent IF: NA |
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Call Number |
PLASMANT @ plasmant @c:irua:182915 |
Serial |
6826 |
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| Permanent link to this record |
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Author |
Bal, K.M.; Neyts, E.C. |
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Title |
Quantifying the impact of vibrational nonequilibrium in plasma catalysis: insights from a molecular dynamics model of dissociative chemisorption |
Type |
A1 Journal Article;plasma catalysis |
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Year |
2021 |
Publication |
Journal Of Physics D-Applied Physics |
Abbreviated Journal |
J Phys D Appl Phys |
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Volume |
54 |
Issue |
39 |
Pages |
394004 |
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Keywords |
A1 Journal Article;plasma catalysis; vibrational nonequilibrium; dissociative chemisorption; free energy barriers; Plasma, laser ablation and surface modeling Antwerp (PLASMANT) ; |
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Abstract |
The rate, selectivity and efficiency of plasma-based conversion processes is strongly affected by nonequilibrium phenomena. High concentrations of vibrationally excited molecules are such a plasma-induced effect. It is frequently assumed that vibrationally excited molecules are important in plasma catalysis because their presence lowers the apparent activation energy of dissociative chemisorption reactions and thus increases the conversion rate. A detailed atomic-level understanding of vibrationally stimulated catalytic reactions in the context of plasma catalysis is however lacking. Here, we couple a recently developed statistical model of a plasma-induced vibrational nonequilibrium to molecular dynamics simulations, enhanced sampling methods, and machine learning techniques. We quantify the impact of a vibrational nonequilibrium on the dissociative chemisorption barrier of H2 and CH4 on nickel catalysts over a wide range of vibrational temperatures. We investigate the effect of surface structure and compare the role of different vibrational modes of methane in the dissociation process. For low vibrational temperatures, very high vibrational efficacies are found, and energy in bend vibrations appears to dominate the dissociation of methane. The relative impact of vibrational nonequilibrium is much higher on terrace sites than on surface steps. We then show how our simulations can help to interpret recent experimental results, and suggest new paths to a better understanding of plasma catalysis. |
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Place of Publication |
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Editor |
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Language |
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Wos |
000674464100001 |
Publication Date |
2021-09-30 |
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Series Editor |
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Series Title |
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Abbreviated Series Title |
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Series Volume |
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Series Issue |
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Edition |
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ISSN |
0022-3727 |
ISBN |
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Additional Links |
UA library record; WoS full record; WoS citing articles |
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Impact Factor |
2.588 |
Times cited |
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Open Access |
OpenAccess |
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| |
Notes |
Fonds Wetenschappelijk Onderzoek, 12ZI420N ; K M B was funded as a junior postdoctoral fellow of the FWO (Research Foundation—Flanders), Grant 12ZI420N. The computational resources and services used in this work were provided by the HPC core facility CalcUA of the Universiteit Antwerpen, and VSC (Flemish Supercomputer Center), funded by the FWO and the Flemish Government. HLDA calculations were performed with a script provided by G Piccini. |
Approved |
Most recent IF: 2.588 |
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| |
Call Number |
PLASMANT @ plasmant @c:irua:179830 |
Serial |
6808 |
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| Permanent link to this record |
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Author |
Engelmann, Y.; van ’t Veer, K.; Gorbanev, Y.; Neyts, E.C.; Schneider, W.F.; Bogaerts, A. |
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Title |
Plasma Catalysis for Ammonia Synthesis: A Microkinetic Modeling Study on the Contributions of Eley–Rideal Reactions |
Type |
A1 Journal Article;Plasma catalysis |
| |
Year |
2021 |
Publication |
Acs Sustainable Chemistry & Engineering |
Abbreviated Journal |
Acs Sustain Chem Eng |
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| |
Volume |
9 |
Issue |
39 |
Pages |
13151-13163 |
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| |
Keywords |
A1 Journal Article;Plasma catalysis; Eley−Rideal reactions; Volcano plots; Vibrational excitation; Radical reactions; Dielectric barrier discharge; Plasma, laser ablation and surface modeling Antwerp (PLASMANT) ; |
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Abstract |
Plasma catalysis is an emerging new technology for the electrification and downscaling of NH3 synthesis. Increasing attention is being paid to the optimization of plasma catalysis with respect to the plasma conditions, the catalyst material, and their mutual interaction. In this work we use microkinetic models to study how the total conversion process is impacted by the combination of different plasma conditions and transition metal catalysts. We study how plasma-generated radicals and vibrationally excited N2 (present in a dielectric barrier discharge plasma) interact with the catalyst and impact the NH3 turnover frequencies (TOFs). Both filamentary and uniform plasmas are studied, based on plasma chemistry models that provided plasma phase speciation and vibrational distribution functions. The Langmuir−Hinshelwood reaction rate coefficients (i.e., adsorption reactions and subsequent reactions among adsorbates) are determined using conventional scaling relations. An additional set of Eley−Rideal reactions (i.e., direct reactions of plasma radicals with adsorbates) was added and a sensitivity analysis on the assumed reaction rate coefficients was performed. We first show the impact of different vibrational distribution functions on the catalytic dissociation of N2 and subsequent production of NH3, and we gradually include more radical reactions, to illustrate the contribution of these species and their corresponding reaction pathways. Analysis over a large range of catalysts indicates that different transition metals (metals such as Rh, Ni, Pt, and Pd) optimize the NH3TOFs depending on the population of the vibrational levels of N2. At higher concentrations of plasma-generated radicals, the NH3 TOFs become less dependent on the catalyst material, due to radical adsorptions on the more noble catalysts and Eley−Rideal reactions on the less noble catalysts. |
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Wos |
000705367800004 |
Publication Date |
2021-10-04 |
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Series Title |
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Abbreviated Series Title |
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Series Volume |
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Series Issue |
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Edition |
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ISSN |
2168-0485 |
ISBN |
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Additional Links |
UA library record; WoS full record; WoS citing articles |
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Impact Factor |
5.951 |
Times cited |
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Open Access |
OpenAccess |
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Notes |
Basic Energy Sciences, DE-SC0021107 ; Vlaamse regering, HBC.2019.0108 ; H2020 European Research Council, 810182 ; Methusalem project – University of Antwerp; Excellence of science FWO-FNRS, GoF9618n ; TOP-BOF – University of Antwerp; DOCPRO3 – University of Antwerp; We acknowledge the financial support from the DOC-PRO3, the TOP-BOF, and the Methusalem project of the University of Antwerp, as well as from the European Research Council (ERC) (grant agreement No, 810182−SCOPE ERC Synergy project), under the European Union’s Horizon 2020 research and innovation programme, the Flemish Government through the Moonshot cSBO project P2C (HBC.2019.0108), and the Excellence of Science FWO-FNRS project (FWO grant ID GoF9618n, EOS ID 30505023). Calculations were carried out using the Turing HPC infrastructure at the CalcUA core facility of the Universiteit Antwerpen, a division of the Flemish Supercomputer Center VSC, funded by the Hercules Foundation, the Flemish Government (Department EWI), 13162 |
Approved |
Most recent IF: 5.951 |
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Call Number |
PLASMANT @ plasmant @c:irua:182482 |
Serial |
6811 |
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Author |
Van Alphen, S.; Slaets, J.; Ceulemans, S.; Aghaei, M.; Snyders, R.; Bogaerts, A. |
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Title |
Effect of N2 on CO2-CH4 conversion in a gliding arc plasmatron: Can this major component in industrial emissions improve the energy efficiency? |
Type |
A1 Journal Article;Plasma-based CO2-CH4 conversion |
| |
Year |
2021 |
Publication |
Journal Of Co2 Utilization |
Abbreviated Journal |
J Co2 Util |
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Volume |
54 |
Issue |
|
Pages |
101767 |
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| |
Keywords |
A1 Journal Article;Plasma-based CO2-CH4 conversion; Effect of N2; Plasma chemistry; Computational modelling; Gliding arc plasmatron; Plasma, laser ablation and surface modeling Antwerp (PLASMANT) ; |
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Abstract |
Plasma-based CO2 and CH4 conversion is gaining increasing interest, and a great portion of research is dedicated to adapting the process to actual industrial conditions. In an industrial context, the process needs to be able to process N2 admixtures, since most industrial gas emissions contain significant amounts of N2, and gas separations are financially costly. In this paper we therefore investigate the effect of N2 on the CO2 and CH4 conversion in a gliding arc plasmatron reactor. The addition of 20 % N2 reduces the energy cost of the conversion process by 21 % compared to a pure CO2/CH4 mixture, from 2.9 down to 2.2 eV/molec (or from 11.5 to 8.7 kJ/L), yielding a CO2 and CH4 (absolute) conversion of 28.6 and 35.9 % and an energy efficiency of 58 %. These results are among the best reported in literature for plasma-based DRM, demonstrating the benefits of N2 present in the mix. Compared to DRM results in different plasma reactor types, a low energy cost was achieved. To understand the underlying mechanisms of N2 addition, we developed a combination of four different computational models, which reveal that the beneficial effect of N2 addition is attributed to (i) a rise in the electron density (increasing the plasma conductivity, and therefore reducing the plasma power needed to sustain the plasma, which reduces the energy cost), as well as (ii) a rise in the gas temperature, which accelerates the CO2 and CH4 conversion reactions. |
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Wos |
000715057300005 |
Publication Date |
2021-10-28 |
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Series Editor |
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Series Title |
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Abbreviated Series Title |
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Series Volume |
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Series Issue |
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Edition |
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ISSN |
2212-9820 |
ISBN |
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Additional Links |
UA library record; WoS full record; WoS citing articles |
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Impact Factor |
4.292 |
Times cited |
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Open Access |
OpenAccess |
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Notes |
This research was supported by the European Research Council (ERC) under the European Union’s Horizon 2020 research and innova tion programme (grant agreement No 810182 – SCOPE ERC Synergy project), the Excellence of Science FWO-FNRS project (FWO grant ID GoF9618n, EOS ID 30505023), and through long-term structural funding (Methusalem). The calculations were performed using the Turing HPC infrastructure at the CalcUA core facility of the Universiteit Antwerpen (UAntwerpen), a division of the Flemish Supercomputer Center VSC, funded by the Hercules Foundation, the Flemish Government (department EWI) and the UAntwerpen. |
Approved |
Most recent IF: 4.292 |
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Call Number |
PLASMANT @ plasmant @c:irua:184044 |
Serial |
6827 |
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Author |
Oliveira, M.C.; Yusupov, M.; Cordeiro, R.M.; Bogaerts, A. |
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Title |
Unraveling the permeation of reactive species across nitrated membranes by computer simulations |
Type |
A1 Journal Article;Reactive oxygen and nitrogen species |
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Year |
2021 |
Publication |
Computers In Biology And Medicine |
Abbreviated Journal |
Comput Biol Med |
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Volume |
136 |
Issue |
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Pages |
104768 |
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Keywords |
A1 Journal Article;Reactive oxygen and nitrogen species; Nitro-oxidative stress; Molecular dynamics simulations; Nitrated membranes; Plasma, laser ablation and surface modeling Antwerp (PLASMANT) ; |
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Abstract |
Reactive oxygen and nitrogen species (RONS) are involved in many biochemical processes, including nitrooxidative stress that causes cancer cell death, observed in cancer therapies such as photodynamic therapy and cold atmospheric plasma. However, their mechanisms of action and selectivity still remain elusive due to the complexity of biological cells. For example, it is not well known how RONS generated by cancer therapies permeate the cell membrane to cause nitro-oxidative damage. There are many studies dedicated to the permeation of RONS across native and oxidized membranes, but not across nitrated membranes, another lipid product also generated during nitro-oxidative stress. Herein, we performed molecular dynamics (MD) simulations to calculate the free energy barrier of RONS permeation across nitrated membranes. Our results show that hydrophilic RONS, such as hydroperoxyl radical (HO2) and peroxynitrous acid (ONOOH), have relatively low barriers compared to hydrogen peroxide (H2O2) and hydroxyl radical (HO), and are more prone to permeate the membrane than for the native or peroxidized membranes, and similar to aldehyde-oxidized membranes. Hydrophobic RONS like molecular oxygen (O2), nitrogen dioxide (NO2) and nitric oxide (NO) even have insignificant barriers for permeation. Compared to native and peroxidized membranes, nitrated membranes are more permeable, suggesting that we must not only consider oxidized membranes during nitro-oxidative stress, but also nitrated membranes, and their role in cancer therapies. |
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Wos |
000696938800003 |
Publication Date |
2021-08-17 |
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Abbreviated Series Title |
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Series Volume |
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Series Issue |
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Edition |
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ISSN |
0010-4825 |
ISBN |
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Additional Links |
UA library record; WoS full record; WoS citing articles |
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Impact Factor |
1.836 |
Times cited |
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Open Access |
OpenAccess |
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Notes |
We thank University of Antwerp and Coordination of Superior Level Staff Improvement (CAPES, Brazil) for the scholarship granted and for providing the computational resources needed for completion of this work. M. Yusupov acknowledges the Flanders Research Foundation (grant 1200219N) for financial support. |
Approved |
Most recent IF: 1.836 |
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Call Number |
PLASMANT @ plasmant @c:irua:181082 |
Serial |
6807 |
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Author |
Van Hoecke, L.; Laffineur, L.; Campe, R.; Perreault, P.; Verbruggen, S.W.; Lenaerts, S. |
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Title |
Challenges in the use of hydrogen for maritime applications |
Type |
A1 Journal Article;Review article, Hydrogen Production, Hydrogen Storage, Maritime Applications |
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Year |
2021 |
Publication |
Energy & Environmental Science |
Abbreviated Journal |
Energ Environ Sci |
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Volume |
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Issue |
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Pages |
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Keywords |
A1 Journal Article;Review article, Hydrogen Production, Hydrogen Storage, Maritime Applications; Sustainable energy, air and water technology (DuEL) |
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Abstract |
Maritime shipping is a key factor that enables the global economy, however the pressure it exerts on the environment is increasing rapidly. In order to reduce the emissions of harmful greenhouse gasses, the search is on for alternative fuels for the maritime shipping industry. In this work the usefulness of hydrogen and hydrogen carriers is being investigated as a fuel for sea going ships. Due to the low volumetric energy density of hydrogen under standard conditions, the need for efficient storage of this fuel is high. Key processes in the use of hydrogen are discussed, starting with the production of hydrogen from fossil and renewable sources. The focus of this review is different storage methods, and in this work we discuss the storage of hydrogen at high pressure, in liquefied form at cryogenic temperatures and bound to liquid or solid-state carriers. In this work a theoretical introduction to different hydrogen storage methods precedes an analysis of the energy-efficiency and practical storage density of the carriers. In the final section the major challenges and hurdles for the development of hydrogen storage for the maritime industry are discussed. The most likely challenges will be the development of a new bunkering infrastructure and suitable monitoring of the safety to ensure safe operation of these hydrogen carriers on board the ship. |
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Wos |
000621101100009 |
Publication Date |
2021-01-07 |
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Series Volume |
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Edition |
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ISSN |
1754-5692 |
ISBN |
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Additional Links |
UA library record; WoS full record; WoS citing articles |
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Impact Factor |
29.518 |
Times cited |
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Open Access |
OpenAccess |
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Notes |
For the completion of this work we would like to thank, Compagnie Maritime Belge for initial funding 9 of the research into maritime hydrogen storage and the University of Antwerp for funding of the 10 Doctoral Project that allowed for the completion of this work. |
Approved |
Most recent IF: 29.518 |
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Call Number |
DuEL @ duel @c:irua:174754 |
Serial |
6668 |
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Author |
Gielis, J. |
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Title |
Er bestaan geen absurde, irrationele, onregelmatige of onderling niet-onmeetbare meetkundige getallen |
Type |
A2 Journal article |
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Year |
2021 |
Publication |
Wiskunde en onderwijs |
Abbreviated Journal |
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Volume |
47 |
Issue |
188 |
Pages |
23-33 |
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Keywords |
A2 Journal article; Sustainable Energy, Air and Water Technology (DuEL) |
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ISSN |
2032-0485 |
ISBN |
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Additional Links |
UA library record |
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Impact Factor |
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Times cited |
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Open Access |
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Notes |
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Approved |
Most recent IF: NA |
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Call Number |
UA @ admin @ c:irua:183083 |
Serial |
7934 |
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Author |
Muhammad, S.; Wuyts, K.; De Wael, K.; Samson, R. |
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Title |
Does leaf micro-morphology influence the recognition of particles on SEM images? |
Type |
A3 Journal article |
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Year |
2021 |
Publication |
International Journal of Environmental Pollution and Remediation |
Abbreviated Journal |
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Volume |
9 |
Issue |
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Pages |
22-37 |
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Keywords |
A3 Journal article; AXES (Antwerp X-ray Analysis, Electrochemistry and Speciation); Antwerp Electrochemical and Analytical Sciences Lab (A-Sense Lab) |
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Abstract |
Scanning electron microscopy (SEM) remains a popular approach to determine the shape, size, density and elemental composition of particles collected on leaf surfaces, but the effect of leaf micro-morphology on particle counts is not very well known. In this study, leaves of sixteen urban plant species were examined for particle density in June and September 2016 using SEM. The investigated plant species differed in leaf micro-morphology involving trichomes, raised stomata, epicuticular wax crystals and convex epidermal cells forming deep grooves between cells. The particle density on leaves of the investigated plant species was estimated by particle size fraction and leaf side. Particle density was significantly higher on the adaxial (AD) leaf side compared to the abaxial (AB) leaf side and higher for fine-particles than coarse-particles. The effect of trichome density on particle density of the AB and the AD leaf side was indicated to be significant and positive for both coarse and fine-particles in June but not in September. The successive repeated measurements elucidated that features constructing the topography of a leaf surface such as trichomes, stomata, and epidermal cells frequently contributed towards the edge enhancement effect, resulting in exaggerated particle counts. Besides, the mechanical drift contributed to the disparity in particle density measurements. Lastly, the reduction in particle density between successive measurements were imputed on the charging effect. These results enable us to suggest that in addition to characterization of micro-morphological features on a leaf surface, SEM will continue to be a useful approach for determining the particle: shape, size, elemental composition and density of the deposited particles. Nonetheless, the disparity in particle density measurements can occur due to abnormal particle recognition. Based on the results of September, we recommend that within-session successive repeated measurements (~ n ≥ 5) need to be performed to remove measurement uncertainties and obtain reliable quantitative data of particle counts using SEM. |
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2021-09-15 |
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OpenAccess |
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Approved |
Most recent IF: NA |
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Call Number |
UA @ admin @ c:irua:181797 |
Serial |
7822 |
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Author |
Skorikov, A.; Heyvaert, W.; Albrecht, W.; Pelt, D.M.; Bals, S. |
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Title |
EMAT Simulated 3D Nanoparticle Structures Dataset |
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Dataset |
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Year |
2021 |
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Dataset; Electron microscopy for materials research (EMAT) |
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This dataset contains 1000 simulated nanoparticle-like 3D structures and noisy EDX-like elemental maps based on them. These data are intended to be used for quantitative analysis of data processing methods in (EDX) tomography of nanoparticles and training the data-driven approaches for these tasks. The dataset is structured as follows: voxel_data/clean 3D voxel grid representation of the simulated nanoparticles. Voxel intensities are adjusted so that the total intensity equals 103. All 3D structures have unique identifiers in 0..999 range. The data derived from a 3D structure preserves this unique identifier. sinograms/clean Tilt series of projection images obtained from the corresponding 3D structures over an angular range of -75..75 degrees with a tilt step of 10 degrees to simulate a typical tilt series used in EDX tomography. Total intensity in each projection image equals 103. sinograms/noisy Tilt series of projection images corrupted with Poisson noise and an additional spatially uniform background noise. projections/clean Projection images extracted from the clean tilt series at 0 degrees tilt angle. projections/noisy Projection images extracted from the noisy tilt series at 0 degrees tilt angle. images/clean Visualizations of the clean projections as PNG images with the intensity range adjusted to 0..255 images/noisy Visualizations of the noisy projections as PNG images with the intensity range adjusted to 0..255 |
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Not_Open_Access |
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Approved |
Most recent IF: NA |
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Call Number |
UA @ admin @ c:irua:180615 |
Serial |
6838 |
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Author |
Rivera Julio, J. |
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Title |
Cálculos ab initio de sistemas 2D y de baja dimensionalidad |
Type |
Doctoral thesis |
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Year |
2021 |
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137 p. |
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Doctoral thesis; Condensed Matter Theory (CMT) |
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Most recent IF: NA |
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Call Number |
UA @ admin @ c:irua:176996 |
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6718 |
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Author |
Skorikov, A. |
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Title |
Fast approaches for investigating 3D elemental distribution in nanomaterials |
Type |
Doctoral thesis |
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2021 |
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143 p. |
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Doctoral thesis; Electron microscopy for materials research (EMAT) |
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Most recent IF: NA |
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Call Number |
UA @ admin @ c:irua:178855 |
Serial |
6795 |
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Author |
Pedrazo Tardajos, A. |
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Advanced graphene supports for 3D in situ transmission electron microscopy |
Type |
Doctoral thesis |
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2021 |
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Pages |
247 p. |
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Doctoral thesis; Electron microscopy for materials research (EMAT) |
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Transmission electron microscopy (TEM) is an ideal tool to investigate nanomaterials. The information from TEM experiments allows us to link the structure and composition of nanomaterials to their intrinsic physical properties. However, despite the significant evolution of the TEM field during the last two decades, major progress is still possible through the development of optimal TEM techniques and supports. The results presented in this thesis focus on the optimization of sample supports and their application. Among the different options, graphene has previously been reported as useful sample support for electron microscopy due to its unparalleled properties, for example, it is the thinnest known support and provides a protective effect to the sample under investigation. Unfortunately, commercial graphene grids show poor quality, in terms of intactness and cleanness, inhibiting their wide application within the field. Therefore, this thesis focuses on the application of optimized graphene TEM grids, obtained by transferring high quality graphene using an advanced procedure. This improvement on the transfer has enabled the visualization of materials with low contrast and high sensitivity towards the electron beam, such as surface ligands capping gold nanoparticles or metal halide perovskites. Furthermore, the implemented protocol is not only of interest for conventional TEM grids but also a major benefit for in situ TEM studies, where the sample is investigated in real time under certain stimuli. Hence, the same graphene transfer technology can be also applied to advanced in situ MEMS holders dedicated for both heating and gas experiments, where the thickness and insulating nature of the silicon nitride (Si3N4) support may hamper some applications. By engineering periodic arrays of holes in their Si3N4 membrane by focused ion beam, onto which the graphene is transferred, it has been possible to get proof-of-concept 3D in situ investigations of heat-induced morphological and compositional transformations of complex nanosystems. As an example, it has enabled the investigation of the possible phase-transition of metal halide perovskites upon heating using 2D and 3D structural characterization. Moreover, it has allowed the study of in situ three-dimensional nanoparticle dynamics during gas phase catalysis as well as the first steps that would lead towards the design and creation of the first Graphene Gas Cell. Consequently, implementation of the advanced graphene transfer technology described in this thesis is envisaged to impact a broad range of future experiments. |
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UA @ admin @ c:irua:181143 |
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6836 |
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Du, K. |
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In situ TEM study on the manipulation of ferroelectrics |
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Doctoral thesis |
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2021 |
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91 p. |
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Doctoral thesis; Engineering sciences. Technology; Electron microscopy for materials research (EMAT) |
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The strong correlated oxide systems attract a lot of attentions of scientists recently, the coexistence and interplay between various degrees of freedom, such as charge, spin and orbital, has been demonstrated to induce some fancy physical properties and phenomenon, including metal-insulator transition, high temperature superconductivity, colossal magnetoresistance. As a part of the strong correlated oxide systems, the ferroelectrics is abundant in both physical properties and application. First, if the electric dipole continuously rotating around a stable core then a topological structure is produced. If people could manipulate the topological structure and simultaneously observe the structure evolution, with external field applied on the topological structure, then it is very likely for such kind of ferroelectrics to be the next generation of storage, for it is reported to need low power input and produce high density of storage. In the other hand, in solids, charge polarity can one-to-one correspond to spin polarity phenomenologically, such as ferroelectricity and ferromagnetism, antiferroelectricity and antiferromagnetism, but ferrielectricity and ferrimagnetism kept telling a disparate story in microscopic level. The claimed “ferrielectrics” in existing research is equivalent to ferroelectric ones, thus the findings of such a real irreducible solids would complete the last piece of the ferroelectrics family. While solving the above two questions remain challengeable: the size of topological structure is small (typically below 10 nm), general characterization methods are insufficient for such high demand on space resolution, not to mention manipulating and observing its dynamic behavior at an atomic level. Here, employing the spherical aberration corrected electron microscope, we applied external field (heating and bias) on ferroelectrics. Combined with high-end characterization methods including the high-angle annular dark field (HAADF-STEM) image, Electron Energy Loss Spectroscopy (EELS) and integrated differential phase contrast (iDPC), the dynamic evolution of ferroelectrics are observed and analyzed. The main findings of this paper could be concluded as listed here: (1) PbTiO3(001)// SrTiO3(001) is grown on DyScO3 and SrRuO3 by pusled laser deposition, the atomical EDS mapping results reveal that the interface between PTO and STO is atomically sharp. Increasing the thickness of PTO from 1 uc to 21 uc, the topological structure wihtin PTO layer would transform from a/c domain to wave, vortex and finally flux closure domain. The geometric phase analysis results (GPA) reveal that above topological structures are corresponding to various strain. (2) Combined with in-situ biasing holder, the electric bias was applied on polar vortex, and it evolved from vortex (0 V) to polar wave (2 V) and finally polar down (5 V). EELS analysis was performed and we find that negative charge is gathered at vortex core, which turns the Ti4+ to Ti3+ there. The oxygen vacancy at negative polarization surface and the negative charge at the positive polarization surface realized the polarization screening of polar down domain. (3) Through the atomic inspection and analysis on lattice structure of BaFe2Se3, the near ladders within single unit are found to be different in degree of tetramerization, thus leading to a residual polarization along the a-axis. The further in-situ heating and biasing experiment was conducted on BaFe2Se3, and the strong and weak ladders are proved to be independent for their behavior under external field. This findings distinguishes ferrielectrics from ferroelectrics in solids. |
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UA @ admin @ c:irua:179310 |
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6842 |
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Prabhakara, V. |
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Strain measurement for semiconductor applications with Raman spectroscopy and Transmission electron microscopy |
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Doctoral thesis |
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2021 |
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149 p. |
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Doctoral thesis; Engineering sciences. Technology; Electron microscopy for materials research (EMAT) |
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Scaling down the size of transistors has been a trend for several decades which has led to improved transistor performance, increased transistor density and hence the overall computation power of IC chips. The trend slowed in recent years due to reliability and power consumption issues at the nanoscale. Hence strain is introduced into transistor channels that has beneficial effects on improving the mobility of charge carriers, providing an alternative pathway for enhancing transistor performance. Therefore, monitoring strain is vital for the semiconductor industry. With the recent trend of decreasing device dimensions (FinFETS ~ 10-20nm) and strain modulation being used throughout, industry needs a reliable and fast method as quality control or defect characterisation. Such a universal strain measurement method does not exist, and one relies on a combination of quantitative in-line methods and complex off-line approaches. In this thesis, I investigated TEM and Raman spectroscopy-based methodologies for strain measurement. In terms of TEM methodologies, advancements are made for the STEM moiré imaging, targeting strain spatial resolution enhancement. I introduce advanced quadrature demodulation and phase stepping interferometry applied to STEM moiré that greatly enhances the spatial resolution while providing enhanced field of view and sensitivity for strain measurement. We introduce ways to reduce scan distortions in strain maps using an alternative scan strategy called “Block scanning” and the non-linear regression applied for strain extraction. Prospects for 3D strain analysis using high-resolution tomography is also investigated which gives direct access for the full second order strain tensors calculation. Finally, we compare strain measurements from TEM techniques with inline techniques like Raman spectroscopy. Raman stress measurement involves sensitive identification of the TO and LO phonon peaks. Raman spectrum of strained Ge transistor channel consists of strongly overlapping peaks within the spectral resolution of the spectrometer. Hence, the process of deconvolution of the two peaks is rather challenging. Hence, we explore new polarisation geometries like radially polarised incoming light which was shown to ease the deconvolution problem resulting in improved precision for Raman stress–strain measurements. |
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UA @ admin @ c:irua:182261 |
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6847 |
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Velazco Torrejón, A. |
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Alternative scan strategies for high resolution STEM imaging |
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Doctoral thesis |
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2021 |
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131 p. |
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Doctoral thesis; Electron microscopy for materials research (EMAT) |
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Currently, a large variety of materials are studied by transmission electron microscopy (TEM) as it offers the possibility to perform structural and elemental analysis at a local scale. Relatively recent advances in aberration correctors and electron sources allow the instrument to achieve atomic resolution. Along with these advances, a state-of-the-art technology has been reached in TEM. However, the instrument is far from being perfect and imperfections or external sources can make the interpretation of information troublesome. Environmental factors such as acoustic and mechanical vibrations, temperature fluctuations, etc., can induce sample drift and create image distortions. These distortions are enhanced in scanning operation because of the serial acquisition of the information, which are more apparent at atomic resolution as small field of views are imaged. In addition, scanning distortions are induced due to the finite time response of the scan coils. These types of distortions would reduce precision in atomic-scale strain analysis, for instance, in semiconductors. Most of the efforts to correct these distortions are focused on data processing techniques post-acquisition. Another limitation in TEM is beam damage effects. Beam damage arises because of the energy transferred to the sample in electron-sample interactions. In scanning TEM, at atomic resolution, the increased electron charge density (electron dose) carried on a sub-Å size electron probe may aggravate beam damage effects. Soft materials such as zeolites, organic, biological materials, etc., can be destroyed under irradiation limiting the amount of information that can be acquired. Current efforts to circumvent beam damage are mostly based on low electron dose acquisitions and data processing methods to maximize the signal at low dose conditions. In this thesis, a different approach is given to address drift and scanning distortions, as well as beam damage effects. Novel scan strategies are proposed for that purpose, which are shown to substantially overcome these issues compared to the standard scan method in TEM. |
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UA @ admin @ c:irua:180973 |
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6852 |
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Roegiers, J. |
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Development of combined photocatalytic and active carbon fiber technology for indoor air purification based on Multiphysics models |
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Doctoral thesis |
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2021 |
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XXX, 197 p. |
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Doctoral thesis; Engineering sciences. Technology; Electron microscopy for materials research (EMAT); Sustainable Energy, Air and Water Technology (DuEL) |
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Exposure to volatile organic compounds (VOCs) remains a major public health concern. Indoor VOC concentrations typically far exceed outdoor levels due to a variety of emission sources and the stringent insulation measures that are imposed today. Many attempts have been made to use photocatalysis for indoor air purification. In an ideal situation, photocatalysis is capable of complete mineralization of VOCs to H2O and CO2, without any byproduct formation. Moreover, the process can take place at standard atmospheric conditions, i.e. ambient temperature and atmospheric pressure. However, successful exploitation is still impeded due to low conversion efficiency, significant pressure loss (and hence a high energy consumption) and byproduct formation. In the first part of this thesis an attempt was made to tackles these problems by designing a novel type of photocatalytic (PCO) reactor. The PCO device consists of a cylindrical vessel filled with TiO2-coated glass tubes and equipped with UV fluorescence lamps. It was investigated in terms of fluid dynamics, coating properties, UV-light distribution and photocatalytic activity. Experimental data was later used to develop and calibrate a Multiphysics model. The model proved to be a useful tool for designing and upscaling the PCO reactor. Consequently, an optimized prototype reactor was constructed and tested according the CEN-EN-16846-1 standard for VOC removal. Although the prototype showed promising results for lab-scale conditions, it struggled with byproduct formation when purifying ppb-level VOCs. In the second part of this thesis, activated carbon adsorption was investigated in order to combine it with photocatalysis. Activated carbon fiber was opted for its fast kinetics, high adsorption capacity and thermo-electrical regeneration. The filter was studied in detail regarding the adsorption of polar and apolar VOCs at indoor air concentration levels and regeneration capabilities. Experimental data was used to develop a Multiphysics model for activated carbon adsorption as well. Consequently, a novel type of ACF filter was developed using the Multiphysics model, which was equipped with electrodes in the tips of the pleats for effective thermal regeneration. In the last part, the combination of both ACF and PCO was studied using a realistic case study. Based on the Multiphysics model, the feasibility of a so-called hybrid air purification device could be investigated. The Multiphysics model shows promising results for this hybrid PCO-ACF system and hence, a demo setup was constructed for future research. |
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UA @ admin @ c:irua:181137 |
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6860 |
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De wael, A. |
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Model-based quantitative scanning transmission electron microscopy for measuring dynamic structural changes at the atomic scale |
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2021 |
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xiv, 146 p. |
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Doctoral thesis; Electron microscopy for materials research (EMAT) |
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Nanomaterialen kunnen uiterst interessante eigenschappen vertonen voor een verscheidenheid aan veelbelovende toepassingen, gaande van zonnecrème tot batterijen voor elektrische auto’s. Een nanometer is een miljard keer kleiner dan een meter. Op deze schaal kunnen de materiaaleigenschappen volledig verschillen van bulkmaterialen op grotere schaal. Bovendien hangen de eigenschappen van nanomaterialen sterk af van hun exacte grootte en vorm. Kleine verschillen in de posities van de atomen, in de grootte-orde van een picometer (nog eens duizend maal kleiner dan een nanometer), kunnen de fysische eigenschappen al drastisch beïnvloeden. Daarom is een betrouwbare kwantificering van de atomaire structuur van kritisch belang om de evolutie naar materiaalontwerp mogelijk te maken en inzicht te verwerven in de relatie tussen de fysische eigenschappen en de structuur van nanomaterialen. Daarnaast kan de atomaire structuur van nanomaterialen ook veranderen in de loop van de tijd ten gevolge van verschillende fysische processen. Het onderzoek dat in deze thesis gepresenteerd wordt, maakt het mogelijk om de dynamische structuurveranderingen van nanomaterialen betrouwbaar te kwantificeren op atomaire schaal door gebruik te maken van raster transmissie elektronenmicroscopie (STEM). Ik heb dit gerealiseerd door methodes te ontwikkelen waarmee ik het aantal atomen “achter elkaar” kan tellen in elke atoomkolom van een nanomateriaal, en dit op basis van beelden opgenomen met een elektronenmicroscoop. Een belangrijk verschil met telmethodes voor de analyse van een enkel beeld is het schatten van de kans dat een atoomkolom atomen zal verliezen of bijkrijgen van het ene naar het andere beeld in de tijdreeks. Deze kwantitatieve methode kan het ontrafelen van de tijdsafhankelijke structuur-eigenschappen relatie van een nanomateriaal mogelijk maken, wat uiteindelijk kan leiden tot efficiënter design en productie van nanomaterialen voor innovatieve toepassingen. |
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UA @ admin @ c:irua:179514 |
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6870 |
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Jannis, D. |
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Novel detection schemes for transmission electron microscopy |
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2021 |
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iv, 208 p. |
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Doctoral thesis; Electron microscopy for materials research (EMAT) |
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Electron microscopy is an excellent tool which provides resolution down to the atomic scale with up to pm precision in locating atoms. The characterization of materials in these length scales is of utmost importance to answer questions in biology, chemistry and material science. The successful implementation of aberration-corrected microscopes made atomic resolution imaging relatively easy, this could give the impression that the development of novel electron microscopy techniques would stagnate and only the application of these instruments as giant magnifying tools would continue. This is of course not true and a multitude of problems still exist in electron microscopy. Two of such issues are discussed below. One of the biggest problems in electron microscopy is the presence of beam damage which occurs due the fact that the highly energetic incoming electrons have sufficient kinetic energy to change the structure of the material. The amount of damage induced depends on the dose, hence minimizing this dose during an experiment is beneficial. This minimizing of the total dose comes at the expense of more noise due to the counting nature of the electrons. For this reason, the implementation of four dimensional scanning transmission electron microscopy (4D STEM) experiments has reduced the total dose needed per acquisition. However, the current cameras used to measure the diffraction patterns are still two orders of magnitude slower than to the conventional STEM methods. Improving the acquisition speed would make the 4D STEM technique more feasible and is of utmost importance for the beam sensitive materials since less dose is used during the acquisition. In TEM there is not only the possibility to perform imaging experiments but also spectroscopic measurements. There are two frequently used methods: electron energy-loss spectroscopy (EELS) and energy dispersive x-ray spectroscopy (EDX). EELS measures the energy-loss spectrum of the incoming electron which gives information on the available excitations in the material providing elemental sensitivity. In EDX, the characteristic x-rays, arising from the decay of an atom which is initially excited due to the incoming electrons, are detected providing similar elemental analysis. Both methods are able to provide comparable elemental information where in certain circumstances one outperforms the other. However, both methods have a detection limit of approximately 100-1000 ppm which is not sufficient for some materials. In this thesis, two novel techniques which can make significant progress for the two problems discussed above. |
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UA @ admin @ c:irua:182404 |
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6872 |
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Peeters, M. |
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The added value of Smart Product-Service Systems to real estate developments |
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2021 |
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117 p. |
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Doctoral thesis; Economics; Engineering Management (ENM); Internet Data Lab (IDLab) |
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Socially responsible investments can be defined as an investment process that integrates ethical values and environmental protection, improving social conditions, and good governance into a traditional investment decision. This integration is mainly a consequence of the growing importance that investors give to environmental, social, and governance (ESG) criteria, resulting in more sustainable development. Also, in the real estate sector, increased attention is being paid to the contributions made to integrate economic, environmental, and social factors into decisions. The ESG framework looks closely at how companies are managed, and the impact related to their market value. The factors for investors’ focus are summarized as environmental, social, and governance. The term ESG was coined in a 2004 United Nations (UN) report titled “Who Cares Wins,” aimed at raising awareness regarding the importance of environmental, social, and corporate governance issues in financial markets. The ESG criteria’s specific purpose is to guide investors in recognizing sustainable investments without evaluating how sustainable the asset is or the investment value represented by sustainability. It is essential to underline that ESG does not take specific economic interests into account. The rationale behind this apparent gap is that investors investigate the economic aspects before investing. However, by not explicitly linking ESG and economic criteria, attractive investments are often misjudged and not implemented. For example, investments that only show their value in the longer term or indirectly influence value by achieving a higher retention rate among incumbent tenants, reducing or eliminating friction costs. A product–service system (PSS) refers to a market proposition (business model) that builds on a product’s traditional functionality by incorporating additional services. Although services are already offered, the PSS function is to link the service to a product. The service thereby supports the operation of the product and generates additional benefits. It encompasses the integrated solutions of products and services to satisfy customers' needs and generate maximum value. According to Sutanto et al., a PSS is designed to focus on sustainability characterized in three dimensions. 1. The economic dimension 2. The environmental dimension 3. The social dimension When discussing sustainability in this thesis, we use the criteria listed above related to socially responsible investments. The link between PSS and ESG is that a PSS focuses on creating a sustainable system, and ESG makes sustainability more visible to investors. Therefore, when PSS are recognized and implemented in buildings, they must be evaluated using ESG analysis methods. Product-Service Systems (PSS) try to find a way to offer services on top of a product. The product is essentially secondary to the result that is delivered from the services. For example, the modem (product) that a cable company provides will be of secondary importance to the connectivity (service). Alternatively, it will be less critical how heat is made (product) than the intended set point is achieved in the building. PSSs transform the supply of products into services. In doing so, the responsibility shifts from delivering a product (once only) to continuous service delivery. Therefore, it is in the best interest of the service provider to deliver the outcome of the service as efficiently (read: lowest cost) as possible. A direct consequence of this is that the service provider will want to use the product as efficiently as possible and as long as possible to reduce his costs. Therefore, the supplier will also want to recover and maximize the reuse of his product based on the same rationale. A positive impact on the environment and the used raw materials is thus to be expected. The whole process of servitization (transforming products into services) in real estate will positively impact the Economic, Environmental and Social factors. Therefore, demonstrating this proposition is the main objective of this thesis. Smart PSS is the same idea as Product-Service systems but in which the digitization of the services plays a key role. It will be shown that by digitizing services, a broader range can be offered. It will be demonstrated that products that provide services at the building level can, through their interconnectedness, also provide services to external systems (e.g. electricity grid, urban planning, mobility, ...). At the same time, digitizing the products and services will also underpin trust in the systems and allow for proper remuneration. In this PhD, different standard systems in a building, such as the reservation system, the water heater, or the fire detection system, are equipped with additional services. A PSS is often specifically designed to focus on economic, social, and environmental dimensions. These dimensions correspond to the investor’s examination as part of the ESG analysis before investing. As the PSS is often specifically designed to integrate sustainability, there is a close link between the sustainability performance of the PSS and the ESG criteria evaluated by the investor. Throughout the work, the owner is considered to be the user of the building. It is not the case that only an owner-user can generate cash flow. In essence, if they have sufficient rights to the underlying product, any building user can activate services that generate cash flow. In today's market, it is logical that this is viewed in the owner-user context as they will usually choose the products to be installed in larger technical installations. They may have previously used a PSS or choose to move to one. However, a building’s tenant could choose to lease out their meeting rooms if they are not contractually prohibited from doing so since, in practice, contracts have begun to prohibit certain services. For example, rental contracts that actively prohibit renting out a property through platforms such as Airbnb. Thus, the user’s function could potentially impact how the PSS is designed. This work does not explicitly explore the impact of this aspect. The owner-user is assumed throughout this manuscript. The second chapter describes the state of affairs concerning PSSs in a broad framework evolving towards focusing on the real estate sector. After which, in the second chapter, ESG and the link to real estate and how smart real estate (smart buildings) is missing from this evaluation are discussed in more detail. Chapter 3 shows from a fire alarm system, which was extended with an evacuation support system, the usefulness, and the risk of data. Further work was done to demonstrate the added value in terms of Economic, Environmental and Social factors of standard installations in buildings. In Chapter 4, a simple sanitary hot water boiler is extended with a service that allows controlling this boiler according to the status of the electricity grid (surplus or shortage of energy). The supply and demand of energy on the power grid must be equal at all times. By equipping a classic water heater (product) with additional intelligence (service), it becomes possible to adjust the energy use to the grid's needs. The grid operators are prepared to pay for this. This payment can be linked to different energy markets (long term market, spot market, ...). This study looked at the fee that would have to be paid when the adjustment of the energy use can be made instantaneously so that the fee must be settled according to the prices on the imbalance market. In chapter 5, we look at the impact of the service to rent out free spaces as co-working places on a broad market (external to the building), compared to a regular reservation system. By renting out unused workplaces on a broad market, the utilization of the existing patrimony will be higher. The demand for new square meters with the same function will decrease as the supply-demand curve changes, and so will the price. This makes it less interesting to build new buildings. Less construction of new buildings will result in fewer resources being used, which will positively affect the environment. In addition, fewer new buildings with an office function will leave more space for buildings with another function. Also, the city's infrastructure will be less burdened (roads, sewerage, electricity grid,...). In The Hague, the decreasing need for new square meters of office buildings can lead to more space for affordable housing, for which the city has a great need. Chapter 6 will frame the valuation of service as a real options method that gives an impetus to a general valuation methodology to value the flexibility that Smart PSS inherently has. Finally, this thesis demonstrates that (smart) PSSs impact real estate profitability, while positively influencing environmental and social factors. Further research and the limitations of the studies conducted are documented. This PhD concludes that Product-Service systems should break the silos between different stakeholders, resulting in a lower total cost of ownership of buildings in the longer term. This can only be achieved if the valuation of Product-Service systems is done correctly and is recognized by every stakeholder in the real estate process. |
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UA @ admin @ c:irua:183415 |
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6912 |
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Saviuc, I. |
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Assessment of electric residential microgrids in the EU context : role of energy storage, interactions with the main grid, and policy scenarios |
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2021 |
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158 p. |
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Doctoral thesis; Engineering Management (ENM) |
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As decentralized electricity generation plays an important role in the reform of the energy system in the EU, electric residential microgrids merit an assessment of their position and potential. The work on this dissertation focuses on the synergy between the development of microgrids that are powered by PV panels, and the adoption of energy storage, with the aim to identify shortcomings and propose solutions. Techno-economic assessment indicates that, for a microgrid that aims to maximize its self-consumption, the electricity pricing mechanisms that are current practice across the EU are detrimental to the economic viability of using energy storage. Case studies and simulations in Belgium, Greece, Denmark, Italy, Finland, Spain and Germany show conclusively how existing tariff structures (Net-Metering, Time-of-Use, Feed-in Tariff, with or without the option of a Capacity tariff) are suitable for stimulating renewable generation, but not storage. Another underlying reason that affects the economic viability of a residential microgrid in the current context relates to the technology losses, which cannot be compensated by electricity pricing mechanisms. Having established the need for a different approach in order to improve the economic viability of microgrids with storage, this work investigated whether a form of direct support to the microgrid operator can be envisioned. A cost-benefit analysis revealed that the benefits coming from decentralized energy generation toward the main electricity grid can be compared with the cost of including and operating energy storage, and therefore a direct support from the network operator and the public can be justified in order to attain the economic viability of a microgrid with storage. This way, the electricity network can benefit from an increased number of flexible, enriched microgrids within the system, the microgrid operators are incentivized to include energy storage, and the society contributes towards a sturdier energy supply with more engaged prosumers and less polluting emissions. Entrepreneurial diversity: a career motives’ perspective – Ilse D |
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UA @ admin @ c:irua:177112 |
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6915 |
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Esguerra, J.L. |
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Developing strategies for improved economic performance and reduced climate impact of landfill mining in Europe |
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2021 |
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xiv, 99 p. |
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Landfill mining refers to the re-circulation of resources from the previously deposited wastes–integrating resource recovery with traditional site remediation. Several resources that can be recovered include scrap metals, combustibles, and inert materials. In addition, land can be recovered or landfill void space can be liberated for future wastes. At present, landfill mining is still an emerging concept with few project implementations. Consequently, the assessments of its economic and climate implications are case study-specific, limiting the understanding of its potential in a wider geographical scope. This thesis aims to assess the economic performance and climate impact of landfill mining in Europe towards the development of sound strategies for implementation. Different project setups are assessed in relation to varying factors at the site level such as waste composition and landfill settings, and at the system level such as policy and market conditions and background material and energy. In doing so, a factor-based method is developed and applied to generate multiple scenarios (531, 441 scenarios per project setup) and determine the underlying important factors and their interrelations that drive the results. Such understanding is used to develop and discuss strategies for improvement by addressing relevant questions for specific stakeholders, including project investors (i.e., which landfill sites to prioritize?), landfill mining practitioners (i.e., how to set up such projects?), and policymakers (i.e., which policy instruments can effectively support such projects?). Results show that landfill mining is preferable in terms of climate than economy. Possible improvements are shown by internalizing thermal treatment of combustibles and extending fines residue utilization as construction aggregates. In relation to the choice of project setups, preferable site and system-level conditions are identified in general but it is also discussed that the plausibility of finding such conditions may be difficult at present. This steers the development of more tailored strategies on what can be done now by the landfill practitioners in terms of setting up projects under current policy and market conditions in specific regions, or what can be done by the policymakers in terms of implementing various policy instruments that can drive such changes at the system level. Through this thesis, the future of landfill mining research is guided towards addressing key challenges and potential solutions for improvement. Furthermore, this thesis highlights the role of assessment as a tool for learning and guiding the development of emerging concepts such as landfill mining. |
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978-91-7929-056-6 |
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UA @ admin @ c:irua:183155 |
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6920 |
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Chekol Zewdie, M. |
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How irrigation water impacts Ethiopian agriculture : an applied economics study |
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2021 |
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xiv, 152 p. |
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In recent decades, as crop production has increased in many areas where irrigation projects have been implemented, the global agricultural development community has promoted irrigation investments. However, due to the disappointing performance of irrigation farming in developing countries, irrigation intervention in Africa South of the Sahara including Ethiopia is an issue of debate. Moreover, several gaps exist in the Ethiopian irrigation farming literature. For instance, evidence about the direct and indirect effects of irrigation water on agriculture is not well documented. The irrigation farming literature has not disentangled the indirect effects of having access to irrigation water from the direct effect and the indirect effects have been underrepresented. Furthermore, most previous studies have applied either a quantitative or qualitative approach and have relied only on revealed data as main type of methodology, making studies that combine qualitative and quantitative research and that use both stated and revealed data underrepresented. In this study, different approaches have been applied to investigate how irrigation water impacts Ethiopia agriculture with special attention being given to disentangling the direct and indirect effects of irrigation water on Ethiopian agriculture. Using a structural equation model, a stochastic production frontier approach, and a discrete choice experiment, I drew evidence regarding the direct and indirect effects of irrigation water on crop revenue of smallholder farmers, the technical efficiency of irrigation user farmers, and the farmers’ willingness to pay to improve poor irrigation schemes from field observations, semi-structured interviews and focus group discussions with farmers, and key informant interviews with the local agricultural agents from the Koga and Fogera Districts of Amhara Region Ethiopia. The results indicate that irrigation water in general has both direct and indirect positive effects on agriculture, and the indirect effect is mediated by both improved farm inputs and the type of crops produced. The results also show that – due to poor extension services and backward agronomic practices, the mean technical efficiency of farmers in Ethiopia is very low, and that large-scale irrigation users are less technically efficient than small-scale irrigation users. Moreover, the results show that improving irrigation schemes shifts the frontier up, and smallholder farmers are strongly willing to contribute financially to the maintenance costs of irrigation schemes. The results offer relevant lessons for policymakers that providing irrigation water supply must be embedded in a comprehensive support package including access to extension services, improved input supply, and access to stable markets. |
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978-90-5728-700-8 |
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UA @ admin @ c:irua:180816 |
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6928 |
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