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“Ion irradiation for improved graphene network formation in carbon nanotube growth”. Neyts EC, Bogaerts A, Carbon 77, 790 (2014). http://doi.org/10.1016/j.carbon.2014.05.083
Abstract: Ion irradiation of carbon nanotubes very often leads to defect formation. However, we have recently shown that Ar ion irradiation in a limited energy window of 1025 eV may enhance the initial cap nucleation process, when the carbon network is in contact with the metal nanocatalyst. Here, we employ reactive molecular dynamics simulations to demonstrate that ion irradiation in a higher energy window of 1035 eV may also heal network defects after the nucleation stage through a non-metal-mediated mechanism, when the carbon network is no longer in contact with the metal nanocatalyst. The results demonstrate the possibility of beneficially utilizing ions in e.g. plasma-enhanced chemical vapour deposition of carbon nanotubes.
Keywords: A1 Journal article; Plasma Lab for Applications in Sustainability and Medicine – Antwerp (PLASMANT)
Impact Factor: 6.337
Times cited: 7
DOI: 10.1016/j.carbon.2014.05.083
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Chirumamilla CS, Palagani A, Kamaraj B, Declerck K, Verbeek MWC, Ryabtsova O, De Bosscher K, Bougarne N, Ruttens B, Gevaert K, Houtman R, De Vos WH, Joossens J, van der Veken P, Augustyns K, van Ostade X, Bogaerts A, De Winter H, Vanden Berghe W (2017) Selective glucocorticoid receptor properties of GSK866 analogs with cysteine reactive warheads. Place of publication unknown, 1324
Abstract: Synthetic glucocorticoids (GC) are the mainstay therapy for treatment of acute and chronic inflammatory disorders. Due to the high adverse effects associated with long-term use, GC pharmacology has focused since the nineties on more selective GC ligand-binding strategies, classified as selective glucocorticoid receptor (GR) agonists (SEGRAs) or selective glucocorticoid receptor modulators (SEGRMs). In the current study, GSK866 analogs with electrophilic covalent-binding warheads were developed with potential SEGRA properties to improve their clinical safety profile for long-lasting topical skin disease applications. Since the off-rate of a covalently binding drug is negligible compared to that of a non-covalent drug, its therapeutic effects can be prolonged and typically, smaller doses of the drug are necessary to reach the same level of therapeutic efficacy, thereby potentially reducing systemic side effects. Different analogs of SEGRA GSK866 coupled to cysteine reactive warheads were characterized for GR potency and selectivity in various biochemical and cellular assays. GR- and NFκB-dependent reporter gene studies show favorable anti-inflammatory properties with reduced GR transactivation of two non-steroidal GSK866 analogs UAMC-1217 and UAMC-1218, whereas UAMC-1158 and UAMC-1159 compounds failed to modulate cellular GR activity. These results were further supported by GR immuno-localization and S211 phospho-GR western analysis, illustrating significant GR phosphoactivation and nuclear translocation upon treatment of GSK866, UAMC-1217, or UAMC-1218, but not in case of UAMC-1158 or UAMC-1159. Furthermore, mass spectrometry analysis of tryptic peptides of recombinant GR ligand-binding domain (LBD) bound to UAMC-1217 or UAMC-1218 confirmed covalent cysteine-dependent GR binding. Finally, molecular dynamics simulations, as well as glucocorticoid receptor ligand-binding domain (GR-LBD) coregulator interaction profiling of the GR-LBD bound to GSK866 or its covalently binding analogs UAMC-1217 or UAMC-1218 revealed subtle conformational differences that might underlie their SEGRA properties. Altogether, GSK866 analogs UAMC-1217 and UAMC-1218 hold promise as a novel class of covalent-binding SEGRA ligands for the treatment of topical inflammatory skin disorders.
Keywords: Administrative Services; A1 Journal article; Pharmacology. Therapy; Plasma Lab for Applications in Sustainability and Medicine – Antwerp (PLASMANT); Medicinal Chemistry (UAMC)
Impact Factor: 6.429
Times cited: 2
DOI: 10.3389/FIMMU.2017.01324
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“OrBITS : label-free and time-lapse monitoring of patient derived organoids for advanced drug screening”. Deben C, Cardenas De La Hoz E, Le Compte M, Van Schil P, Hendriks JMH, Lauwers P, Yogeswaran SK, Lardon F, Pauwels P, van Laere S, Bogaerts A, Smits E, Vanlanduit S, Lin A, Cellular Oncology (2211-3428) , 1 (2022). http://doi.org/10.1007/S13402-022-00750-0
Abstract: Background Patient-derived organoids are invaluable for fundamental and translational cancer research and holds great promise for personalized medicine. However, the shortage of available analysis methods, which are often single-time point, severely impede the potential and routine use of organoids for basic research, clinical practise, and pharmaceutical and industrial applications. Methods Here, we developed a high-throughput compatible and automated live-cell image analysis software that allows for kinetic monitoring of organoids, named Organoid Brightfield Identification-based Therapy Screening (OrBITS), by combining computer vision with a convolutional network machine learning approach. The OrBITS deep learning analysis approach was validated against current standard assays for kinetic imaging and automated analysis of organoids. A drug screen of standard-of-care lung and pancreatic cancer treatments was also performed with the OrBITS platform and compared to the gold standard, CellTiter-Glo 3D assay. Finally, the optimal parameters and drug response metrics were identified to improve patient stratification. Results OrBITS allowed for the detection and tracking of organoids in routine extracellular matrix domes, advanced Gri3D (R)-96 well plates, and high-throughput 384-well microplates, solely based on brightfield imaging. The obtained organoid Count, Mean Area, and Total Area had a strong correlation with the nuclear staining, Hoechst, following pairwise comparison over a broad range of sizes. By incorporating a fluorescent cell death marker, infra-well normalization for organoid death could be achieved, which was tested with a 10-point titration of cisplatin and validated against the current gold standard ATP-assay, CellTiter-Glo 3D. Using this approach with OrBITS, screening of chemotherapeutics and targeted therapies revealed further insight into the mechanistic action of the drugs, a feature not achievable with the CellTiter-Glo 3D assay. Finally, we advise the use of the growth rate-based normalised drug response metric to improve accuracy and consistency of organoid drug response quantification. Conclusion Our findings validate that OrBITS, as a scalable, automated live-cell image analysis software, would facilitate the use of patient-derived organoids for drug development and therapy screening. The developed wet-lab workflow and software also has broad application potential, from providing a launching point for further brightfield-based assay development to be used for fundamental research, to guiding clinical decisions for personalized medicine.
Keywords: A1 Journal article; Plasma Lab for Applications in Sustainability and Medicine – Antwerp (PLASMANT); Antwerp Surgical Training, Anatomy and Research Centre (ASTARC); Center for Oncological Research (CORE)
Impact Factor: 6.6
DOI: 10.1007/S13402-022-00750-0
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“Does non-thermal plasma modify biopolymers in solution? A chemical and mechanistic study for alginate”. Tampieri F, Espona-Noguera A, Labay C, Ginebra M-P, Yusupov M, Bogaerts A, Canal C, Biomaterials Science (2023). http://doi.org/10.1039/D3BM00212H
Abstract: In the last decades, non-thermal plasma has been extensively investigated as a relevant tool for various biomedical applications, ranging from tissue decontamination to regeneration and from skin treatment to tumor therapies. This high versatility is due to the different kinds and amount of reactive oxygen and nitrogen species that can be generated during a plasma treatment and put in contact with the biological target. Some recent studies report that solutions of biopolymers with the ability to generate hydrogels, when treated with plasma, can enhance the generation of reactive species and influence their stability, resulting thus in the ideal media for indirect treatments of biological targets. The direct effects of the plasma treatment on the structure of biopolymers in water solution, as well as the chemical mechanisms responsible for the enhanced generation of RONS, are not yet fully understood. In this study, we aim at filling this gap by investigating, on the one hand, the nature and extent of the modifications induced by plasma treatment in alginate solutions, and, on the other hand, at using this information to explain the mechanisms responsible for the enhanced generation of reactive species as a consequence of the treatment. The approach we use is twofold: (i) investigating the effects of plasma treatment on alginate solutions, by size exclusion chromatography, rheology and scanning electron microscopy and (ii) study of a molecular model (glucuronate) sharing its chemical structure, by chromatography coupled with mass spectrometry and by molecular dynamics simulations. Our results point out the active role of the biopolymer chemistry during direct plasma treatment. Short-lived reactive species, such as OH radicals and O atoms, can modify the polymer structure, affecting its functional groups and causing partial fragmentation. Some of these chemical modifications, like the generation of organic peroxide, are likely responsible for the secondary generation of long-lived reactive species such as hydrogen peroxide and nitrite ions. This is relevant in view of using biocompatible hydrogels as vehicles for storage and delivery reactive species for targeted therapies.
Keywords: A1 Journal Article; Plasma, laser ablation and surface modeling Antwerp (PLASMANT) ;
Impact Factor: 6.6
DOI: 10.1039/D3BM00212H
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“In Situ Plasma Studies Using a Direct Current Microplasma in a Scanning Electron Microscope”. Grünewald L, Chezganov D, De Meyer R, Orekhov A, Van Aert S, Bogaerts A, Bals S, Verbeeck J, Advanced Materials Technologies (2024). http://doi.org/10.1002/admt.202301632
Abstract: Microplasmas can be used for a wide range of technological applications and to improve the understanding of fundamental physics. Scanning electron microscopy, on the other hand, provides insights into the sample morphology and chemistry of materials from the mm‐ down to the nm‐scale. Combining both would provide direct insight into plasma‐sample interactions in real‐time and at high spatial resolution. Up till now, very few attempts in this direction have been made, and significant challenges remain. This work presents a stable direct current glow discharge microplasma setup built inside a scanning electron microscope. The experimental setup is capable of real‐time in situ imaging of the sample evolution during plasma operation and it demonstrates localized sputtering and sample oxidation. Further, the experimental parameters such as varying gas mixtures, electrode polarity, and field strength are explored and experimental<italic>V</italic>–<italic>I</italic>curves under various conditions are provided. These results demonstrate the capabilities of this setup in potential investigations of plasma physics, plasma‐surface interactions, and materials science and its practical applications. The presented setup shows the potential to have several technological applications, for example, to locally modify the sample surface (e.g., local oxidation and ion implantation for nanotechnology applications) on the µm‐scale.
Keywords: A1 Journal article; Electron microscopy for materials research (EMAT); Plasma Lab for Applications in Sustainability and Medicine – Antwerp (PLASMANT)
Impact Factor: 6.8
DOI: 10.1002/admt.202301632
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“Removal of alachlor in water by non-thermal plasma: Reactive species and pathways in batch and continuous process”. Wardenier N, Gorbanev Y, Van Moer I, Nikiforov A, Van Hulle SWH, Surmont P, Lynen F, Leys C, Bogaerts A, Vanraes P, Water research 161, 549 (2019). http://doi.org/10.1016/j.watres.2019.06.022
Abstract: Pesticides are emerging contaminants frequently detected in the aquatic environment. In this work, a novel approach combining activated carbon adsorption, oxygen plasma treatment and ozonation was studied for the removal of the persistent chlorinated pesticide alachlor. A comparison was made between the removal efficiency and energy consumption for two different reactor operation modes: batchrecirculation and single-pass mode. The kinetics study revealed that the insufficient removal of alachlor by adsorption was significantly improved in terms of degradation efficiency and energy consumption when combined with the plasma treatment. The best efficiency (ca. 80% removal with an energy cost of 19.4 kWh mÀ3) was found for the single-pass operational mode of the reactor. In the batch-recirculating process, a complete elimination of alachlor by plasma treatment was observed after 30 min of treatment. Analysis of the reactive species induced by plasma in aqueous solutions showed that the decomposition of alachlor mainly occurred through a radical oxidation mechanism, with a minor contribution of long-living oxidants (O3, H2O2). Investigation of the alachlor oxidation pathways revealed six different oxidation mechanisms, including the loss of aromaticity which was never before reported for plasma-assisted degradation of aromatic pesticides. It was revealed that the removal rate and energy cost could be further improved with more than 50% by additional O3 gas bubbling in the solution reservoir.
Keywords: A1 Journal article; Plasma Lab for Applications in Sustainability and Medicine – Antwerp (PLASMANT)
Impact Factor: 6.942
Times cited: 2
DOI: 10.1016/j.watres.2019.06.022
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“Cytoglobin Silencing Promotes Melanoma Malignancy but Sensitizes for Ferroptosis and Pyroptosis Therapy Response”. De Backer J, Maric D, Zuhra K, Bogaerts A, Szabo C, Vanden Berghe W, Hoogewijs D, Antioxidants 11, 1548 (2022). http://doi.org/10.3390/antiox11081548
Abstract: Despite recent advances in melanoma treatment, there are still patients that either do not respond or develop resistance. This unresponsiveness and/or acquired resistance to therapy could be explained by the fact that some melanoma cells reside in a dedifferentiated state. Interestingly, this dedifferentiated state is associated with greater sensitivity to ferroptosis, a lipid peroxidation-reliant, iron-dependent form of cell death. Cytoglobin (CYGB) is an iron hexacoordinated globin that is highly enriched in melanocytes and frequently downregulated during melanomagenesis. In this study, we investigated the potential effect of CYGB on the cellular sensitivity towards (1S, 3R)-RAS-selective lethal small molecule (RSL3)-mediated ferroptosis in the G361 melanoma cells with abundant endogenous expression. Our findings show that an increased basal ROS level and higher degree of lipid peroxidation upon RSL3 treatment contribute to the increased sensitivity of CYGB knockdown G361 cells to ferroptosis. Furthermore, transcriptome analysis demonstrates the enrichment of multiple cancer malignancy pathways upon CYGB knockdown, supporting a tumor-suppressive role for CYGB. Remarkably, CYGB knockdown also triggers activation of the NOD-, LRR- and pyrin domain-containing protein 3 (NLRP3) inflammasome and subsequent induction of pyroptosis target genes. Altogether, we show that silencing of CYGB expression modulates cancer therapy sensitivity via regulation of ferroptosis and pyroptosis cell death signaling pathways.
Keywords: A1 Journal article; Pharmacology. Therapy; Plasma Lab for Applications in Sustainability and Medicine – Antwerp (PLASMANT); Proteinscience, proteomics and epigenetic signaling (PPES)
Impact Factor: 7
DOI: 10.3390/antiox11081548
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“Plasma-catalytic ammonia decomposition using a packed-bed dielectric barrier discharge reactor”. Andersen JA, Christensen JM, Østberg M, Bogaerts A, Jensen AD, International Journal Of Hydrogen Energy 47, 32081 (2022). http://doi.org/10.1016/J.IJHYDENE.2022.07.102
Abstract: Plasma-catalytic ammonia decomposition as a method for producing hydrogen was studied in a packed-bed dielectric barrier discharge (DBD) reactor at ambient pressure and a fixed plasma power. The influence of packing the plasma zone with various dielectric materials, typically used as catalyst supports, was examined. At conditions (21 W, 75 Nml/min NH3) where an NH3 conversion of 5% was achieved with plasma alone, an improved decomposition was found when introducing dielectric materials with dielectric constants between 4 and 30. Of the tested materials, MgAl2O4 yielded the highest conversion (15.1%). The particle size (0.3-1.4 mm) of the MgAl2O4 packing was found to have a modest influence on the conversion, which dropped from 15.1% to 12.6% with increasing particle size. Impregnation of MgAl2O4 with different metals was found to decrease the NH3 conversion, with the Ni impregnation still showing an improved conversion (7%) compared to plasma-only. The plasma-assisted ammonia decomposition occurs in the gas phase due to micro-discharges, as evident from a linear correlation between the conversion and the frequency of micro-discharges for both plasma alone and with the various solid packing materials. The primary function of the solid is thus to facilitate the gas phase reaction by assisting the creation of micro-discharges. Lastly, insulation of the reactor to raise the temperature to 230 degrees C in the plasma zone was found to have a negative effect on the conversion, as a change from volume discharges to surface discharges occurred. The study shows that NH3 can be decomposed to provide hydrogen by exposure to a non-thermal plasma, but further developments are needed for it to become an energy efficient technology. (C)2022 The Author(s). Published by Elsevier Ltd on behalf of Hydrogen Energy Publications LLC.
Keywords: A1 Journal article; Engineering sciences. Technology; Plasma Lab for Applications in Sustainability and Medicine – Antwerp (PLASMANT)
Impact Factor: 7.2
DOI: 10.1016/J.IJHYDENE.2022.07.102
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“The Quest for Value-Added Products from Carbon Dioxide and Water in a Dielectric Barrier Discharge: A Chemical Kinetics Study”. Snoeckx R, Ozkan A, Reniers F, Bogaerts A, Chemsuschem 10, 409 (2017). http://doi.org/10.1002/cssc.201601234
Abstract: Recycling of carbon dioxide by its conversion into value-added products has gained significant interest owing to the role it can play for use in an anthropogenic carbon cycle. The combined conversion with H2O could even mimic the natural photosynthesis process. An interesting gas conversion technique currently being considered in the field of CO2 conversion is plasma technology. To investigate whether it is also promising for this combined conversion, we performed a series of experiments and developed a chemical kinetics plasma chemistry model for a deeper understanding of the process. The main products formed were the syngas components CO and H2, as well as O2 and H2O2, whereas methanol formation was only observed in the parts-per-billion to parts-per-million range. The syngas ratio, on the other hand, could easily be controlled by varying both the water content and/or energy input. On the basis of the model, which was validated with experimental results, a chemical kinetics analysis was performed, which allowed the construction and investigation of the different pathways leading to the observed experimental results and which helped to clarify these results. This approach allowed us to evaluate this technology on the basis of its underlying chemistry and to propose solutions on how to further improve the formation of value-added products by using plasma technology.
Keywords: A1 Journal article; Engineering sciences. Technology; Plasma Lab for Applications in Sustainability and Medicine – Antwerp (PLASMANT)
Impact Factor: 7.226
Times cited: 25
DOI: 10.1002/cssc.201601234
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“The Chemical Route to a Carbon Dioxide Neutral World”. Martens JA, Bogaerts A, De Kimpe N, Jacobs PA, Marin GB, Rabaey K, Saeys M, Verhelst S, Chemsuschem 10, 1039 (2017). http://doi.org/10.1002/cssc.201601051
Abstract: Excessive CO2 emissions in the atmosphere from anthropogenic activity can be divided into point sources and diffuse sources. The capture of CO2 from flue gases of large industrial installations and its conversion into fuels and chemicals with fast catalytic processes seems technically possible. Some emerging technologies are already being demonstrated on an industrial scale. Others are still being tested on a laboratory or pilot scale. These emerging chemical technologies can be implemented in a time window ranging from 5 to 20 years. The massive amounts of energy needed for capturing processes and the conversion of CO2 should come from low-carbon energy sources, such as tidal, geothermal, and nuclear energy, but also, mainly, from the sun. Synthetic methane gas that can be formed from CO2 and hydrogen gas is an attractive renewable energy carrier with an existing distribution system. Methanol offers advantages as a liquid fuel and is also a building block for the chemical industry. CO2 emissions from diffuse sources is a difficult problem to solve, particularly for CO2 emissions from road, water, and air transport, but steady progress in the development of technology for capturing CO2 from air is being made. It is impossible to ban carbon from the entire energy
supply of mankind with the current technological knowledge, but a transition to a mixed carbon–hydrogen economy can reduce net CO2 emissions and ultimately lead to a CO2-neutral world.
Keywords: A1 Journal article; Engineering sciences. Technology; Plasma Lab for Applications in Sustainability and Medicine – Antwerp (PLASMANT)
Impact Factor: 7.226
Times cited: 75
DOI: 10.1002/cssc.201601051
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“Nitrogen Fixation by Gliding Arc Plasma: Better Insight by Chemical Kinetics Modelling”. Wang W, Patil B, Heijkers S, Hessel V, Bogaerts A, Chemsuschem 10, 2110 (2017). http://doi.org/10.1002/cssc.201700611
Abstract: The conversion of atmospheric nitrogen into valuable compounds, that is, so-called nitrogen fixation, is gaining increased interest, owing to the essential role in the nitrogen cycle of the biosphere. Plasma technology, and more specifically gliding arc plasma, has great potential in this area, but little is known about the underlying mechanisms. Therefore, we developed a detailed chemical kinetics model for a pulsed-power gliding-arc reactor operating at atmospheric pressure for nitrogen oxide synthesis. Experiments are performed to validate the model and reasonable agreement is reached between the calculated and measured NO and NO2 yields and the corresponding energy efficiency for NOx formation for different N2/O2 ratios, indicating that the model can provide a realistic picture of the plasma chemistry. Therefore, we can use the model to investigate the reaction pathways for the formation and loss of NOx. The results indicate that vibrational excitation of N2 in the gliding arc contributes significantly to activating the N2 molecules, and leads to an energy efficient way of NOx production, compared to the thermal process. Based on the underlying chemistry, the model allows us to propose solutions on how to further improve the NOx formation by gliding arc technology. Although the energy efficiency of the gliding-arc-based nitrogen fixation process at the present stage is not comparable to the world-scale Haber–Bosch process, we believe our study helps us to come up with more realistic scenarios of entering a cutting-edge innovation in new business cases for the decentralised production of fertilisers for agriculture, in which lowtemperature plasma technology might play an important role.
Keywords: A1 Journal Article; Plasma, laser ablation and surface modeling Antwerp (PLASMANT) ;
Impact Factor: 7.226
DOI: 10.1002/cssc.201700611
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“Gliding Arc Plasmatron: Providing an Alternative Method for Carbon Dioxide Conversion”. Ramakers M, Trenchev G, Heijkers S, Wang W, Bogaerts A, Chemsuschem 10, 2642 (2017). http://doi.org/10.1002/cssc.201700589
Abstract: Low-temperature plasmas are gaining a lot of interest for environmental and energy applications. A large research field in these applications is the conversion of CO2 into chemicals and fuels. Since CO2 is a very stable molecule, a key performance indicator for the research on plasma-based CO2 conversion is the energy efficiency. Until now, the energy efficiency in atmospheric plasma reactors is quite low, and therefore we employ here a novel type of plasma reactor, the gliding arc plasmatron (GAP). This paper provides a detailed experimental and computational study of the CO2 conversion, as well as the energy cost and efficiency in a GAP. A comparison with thermal conversion, other plasma types and other novel CO2 conversion technologies is made to find out whether this novel plasma reactor can provide a significant contribution to the much-needed efficient conversion of CO2. From these comparisons it becomes evident that our results are less than a factor of two away from being cost competitive and already outperform several other new technologies. Furthermore, we indicate how the performance of the GAP can still be improved by further exploiting its non-equilibrium character. Hence, it is clear that the GAP is very promising for CO2 conversion.
Keywords: A1 Journal article; Engineering sciences. Technology; Plasma Lab for Applications in Sustainability and Medicine – Antwerp (PLASMANT)
Impact Factor: 7.226
Times cited: 42
DOI: 10.1002/cssc.201700589
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“Nitrogen fixation by gliding arc plasma : better insight by chemical kinetics modelling”. Wang W, Patil B, Heijkers S, Hessel V, Bogaerts A, Chemsuschem 10, 2145 (2017). http://doi.org/10.1002/CSSC.201700095
Abstract: The conversion of atmospheric nitrogen into valuable compounds, that is, so-called nitrogen fixation, is gaining increased interest, owing to the essential role in the nitrogen cycle of the biosphere. Plasma technology, and more specifically gliding arc plasma, has great potential in this area, but little is known about the underlying mechanisms. Therefore, we developed a detailed chemical kinetics model for a pulsed-power gliding-arc reactor operating at atmospheric pressure for nitrogen oxide synthesis. Experiments are performed to validate the model and reasonable agreement is reached between the calculated and measured NO and NO2 yields and the corresponding energy efficiency for NOx formation for different N2/O2 ratios, indicating that the model can provide a realistic picture of the plasma chemistry. Therefore, we can use the model to investigate the reaction pathways for the formation and loss of NOx. The results indicate that vibrational excitation of N2 in the gliding arc contributes significantly to activating the N2 molecules, and leads to an energy efficient way of NOx production, compared to the thermal process. Based on the underlying chemistry, the model allows us to propose solutions on how to further improve the NOx formation by gliding arc technology. Although the energy efficiency of the gliding-arc-based nitrogen fixation process at the present stage is not comparable to the world-scale HaberBosch process, we believe our study helps us to come up with more realistic scenarios of entering a cutting-edge innovation in new business cases for the decentralised production of fertilisers for agriculture, in which low-temperature plasma technology might play an important role.
Keywords: A1 Journal article; Engineering sciences. Technology; Plasma Lab for Applications in Sustainability and Medicine – Antwerp (PLASMANT)
Impact Factor: 7.226
Times cited: 42
DOI: 10.1002/CSSC.201700095
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“Dry Reforming of Methane in a Gliding Arc Plasmatron: Towards a Better Understanding of the Plasma Chemistry”. Cleiren E, Heijkers S, Ramakers M, Bogaerts A, Chemsuschem 10, 4025 (2017). http://doi.org/10.1002/cssc.201701274
Abstract: Dry reforming of methane (DRM) in a gliding arc plasmatron is studied for different CH4 fractions in the mixture. The CO2 and CH4 conversions reach their highest values of approximately 18 and 10%, respectively, at 25% CH4 in the gas mixture, corresponding to an overall energy cost of 10 kJ L@1 (or 2.5 eV per molecule) and an energy efficiency of 66%. CO and H2 are the major products, with the formation of smaller fractions of C2Hx (x=2, 4, or 6) compounds and H2O. A chemical kinetics model is used to investigate the underlying chemical processes. The calculated CO2 and CH4 conversion and the energy efficiency are in good agreement with the experimental data. The model calculations reveal that the reaction of CO2 (mainly at vibrationally excited levels) with H radicals is mainly responsible for
the CO2 conversion, especially at higher CH4 fractions in the mixture, which explains why the CO2 conversion increases with increasing CH4 fraction. The main process responsible for CH4 conversion is the reaction with OH radicals. The excellent energy efficiency can be explained by the non-equilibrium character of the plasma, in which the electrons mainly activate the gas molecules, and by the important role of the vibrational kinetics of CO2. The results demonstrate that a gliding arc plasmatron is very promising for DRM.
Keywords: A1 Journal article; Engineering sciences. Technology; Plasma Lab for Applications in Sustainability and Medicine – Antwerp (PLASMANT)
Impact Factor: 7.226
Times cited: 23
DOI: 10.1002/cssc.201701274
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“Carbon dioxide splitting in a dielectric barrier discharge plasma : a combined experimental and computational study”. Aerts R, Somers W, Bogaerts A, Chemsuschem 8, 702 (2015). http://doi.org/10.1002/cssc.201402818
Abstract: Plasma technology is gaining increasing interest for the splitting of CO2 into CO and O2. We have performed experiments to study this process in a dielectric barrier discharge (DBD) plasma with a wide range of parameters. The frequency and dielectric material did not affect the CO2 conversion and energy efficiency, but the discharge gap can have a considerable effect. The specific energy input has the most important effect on the CO2 conversion and energy efficiency. We have also presented a plasma chemistry model for CO2 splitting, which shows reasonable agreement with the experimental conversion and energy efficiency. This model is used to elucidate the critical reactions that are mostly responsible for the CO2 conversion. Finally, we have compared our results with other CO2 splitting techniques and we identified the limitations as well as the benefits and future possibilities in terms of modifications of DBD plasmas for greenhouse gas conversion in general.
Keywords: A1 Journal article; Plasma Lab for Applications in Sustainability and Medicine – Antwerp (PLASMANT)
Impact Factor: 7.226
Times cited: 131
DOI: 10.1002/cssc.201402818
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“How the alignment of adsorbed ortho H pairs determines the onset of selective carbon nanotube etching”. Khalilov U, Bogaerts A, Xu B, Kato T, Kaneko T, Neyts EC, Nanoscale 9, 1653 (2017). http://doi.org/10.1039/C6NR08005G
Abstract: Unlocking the enormous technological potential of carbon nanotubes strongly depends on our ability to specifically produce metallic or semiconducting tubes. While selective etching of both has already been demonstrated, the underlying reasons, however, remain elusive as yet. We here present computational and experimental evidence on the operative mechanisms at the atomic scale. We demonstrate that during the adsorption of H atoms and their coalescence, the adsorbed ortho hydrogen pairs on single-walled carbon nanotubes induce higher shear stresses than axial stresses, leading to the elongation of HC–CH bonds as a function of their alignment with the tube chirality vector, which we denote as the γ-angle. As a result, the C–C cleavage occurs more rapidly in nanotubes containing ortho H-pairs with a small γ-angle. This phenomenon can explain the selective etching of small-diameter semiconductor nanotubes with a similar curvature. Both theoretical and experimental results strongly indicate the important role of the γ-angle in the selective etching mechanisms of carbon nanotubes, in addition to the nanotube curvature and metallicity effects and lead us to clearly understand the onset of selective synthesis/removal of CNT-based materials.
Keywords: A1 Journal article; Engineering sciences. Technology; Plasma Lab for Applications in Sustainability and Medicine – Antwerp (PLASMANT)
Impact Factor: 7.367
Times cited: 6
DOI: 10.1039/C6NR08005G
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“Formation of single layer graphene on nickel under far-from-equilibrium high flux conditions”. Neyts EC, van Duin ACT, Bogaerts A, Nanoscale 5, 7250 (2013). http://doi.org/10.1039/c3nr00153a
Abstract: We investigate the theoretical possibility of single layer graphene formation on a nickel surface at different substrate temperatures under far-from-equilibrium high precursor flux conditions, employing state-of-the-art hybrid reactive molecular dynamics/uniform acceptance force bias Monte Carlo simulations. It is predicted that under these conditions, the formation of a single layer graphene-like film may proceed through a combined depositionsegregation mechanism on a nickel substrate, rather than by pure surface segregation as is typically observed for metals with high carbon solubility. At 900 K and above, nearly continuous graphene layers are obtained. These simulations suggest that single layer graphene deposition is theoretically possible on Ni under high flux conditions.
Keywords: A1 Journal article; Engineering sciences. Technology; Plasma Lab for Applications in Sustainability and Medicine – Antwerp (PLASMANT)
Impact Factor: 7.367
Times cited: 25
DOI: 10.1039/c3nr00153a
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“Reactive molecular dynamics simulations on SiO2-coated ultra-small Si-nanowires”. Khalilov U, Pourtois G, Bogaerts A, van Duin ACT, Neyts EC, Nanoscale 5, 719 (2013). http://doi.org/10.1039/c2nr32387g
Abstract: The application of coreshell SiSiO2 nanowires as nanoelectronic devices strongly depends on their structure, which is difficult to tune precisely. In this work, we investigate the formation of the coreshell nanowires at the atomic scale, by reactive molecular dynamics simulations. The occurrence of two temperature-dependent oxidation mechanisms of ultra-small diameter Si-NWs is demonstrated. We found that control over the Si-core radius and the SiOx (x ≤ 2) oxide shell is possible by tuning the growth temperature and the initial Si-NW diameter. Two different structures were obtained, i.e., ultrathin SiO2 silica nanowires at high temperature and Si core|ultrathin SiO2 silica nanowires at low temperature. The transition temperature is found to linearly decrease with the nanowire curvature. Finally, the interfacial stress is found to be responsible for self-limiting oxidation, depending on both the initial Si-NW radius and the oxide growth temperature. These novel insights allow us to gain control over the exact morphology and structure of the wires, as is needed for their application in nanoelectronics.
Keywords: A1 Journal article; Engineering sciences. Technology; Plasma Lab for Applications in Sustainability and Medicine – Antwerp (PLASMANT)
Impact Factor: 7.367
Times cited: 17
DOI: 10.1039/c2nr32387g
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“Microscopic mechanisms of vertical graphene and carbon nanotube cap nucleation from hydrocarbon growth precursors”. Khalilov U, Bogaerts A, Neyts EC, Nanoscale 6, 9206 (2014). http://doi.org/10.1039/c4nr00669k
Abstract: Controlling and steering the growth of single walled carbon nanotubes is often believed to require controlling of the nucleation stage. Yet, little is known about the microscopic mechanisms governing the nucleation from hydrocarbon molecules. Specifically, we address here the dehydrogenation of hydrocarbon molecules and the formation of all-carbon graphitic islands on metallic nanoclusters from hydrocarbon molecules under conditions typical for carbon nanotube growth. Employing reactive molecular dynamics simulations, we demonstrate for the first time that the formation of a graphitic network occurs through the intermediate formation of vertically oriented, not fully dehydrogenated graphitic islands. Upon dehydrogenation of these vertical graphenes, the islands curve over the surface, thereby forming a carbon network covering the nanoparticle. The results indicate that controlling the extent of dehydrogenation offers an additional parameter to control the nucleation of carbon nanotubes.
Keywords: A1 Journal article; Engineering sciences. Technology; Plasma Lab for Applications in Sustainability and Medicine – Antwerp (PLASMANT)
Impact Factor: 7.367
Times cited: 21
DOI: 10.1039/c4nr00669k
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“Thermodynamics at the nanoscale : phase diagrams of nickel-carbon nanoclusters and equilibrium constants for face transitions”. Engelmann Y, Bogaerts A, Neyts EC, Nanoscale 6, 11981 (2014). http://doi.org/10.1039/C4NR02354D
Abstract: Using reactive molecular dynamics simulations, the melting behavior of nickelcarbon nanoclusters is examined. The phase diagrams of icosahedral and Wulff polyhedron clusters are determined using both the Lindemann index and the potential energy. Formulae are derived for calculating the equilibrium constants and the solid and liquid fractions during a phase transition, allowing more rational determination of the melting temperature with respect to the arbitrary Lindemann value. These results give more insight into the properties of nickelcarbon nanoclusters in general and can specifically be very useful for a better understanding of the synthesis of carbon nanotubes using the catalytic chemical vapor deposition method.
Keywords: A1 Journal article; PLASMANT
Impact Factor: 7.367
Times cited: 20
DOI: 10.1039/C4NR02354D
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“Thermodynamics at the nanoscale: phase diagrams of nickel-carbon nanoclusters and equilibrium constants for phase transitions”. Engelmann, Bogaerts A, Neyts EC, Nanoscale 6, 11981 (2014). http://doi.org/10.1039/c4nr02354d
Abstract: Using reactive molecular dynamics simulations, the melting behavior of nickel-carbon nanoclusters is examined. The phase diagrams of icosahedral and Wulff polyhedron clusters are determined using both the Lindemann index and the potential energy. Formulae are derived for calculating the equilibrium constants and the solid and liquid fractions during a phase transition, allowing more rational determination of the melting temperature with respect to the arbitrary Lindemann value. These results give more insight into the properties of nickel-carbon nanoclusters in general and can specifically be very useful for a better understanding of the synthesis of carbon nanotubes using the catalytic chemical vapor deposition method.
Keywords: A1 Journal article; Engineering sciences. Technology; Plasma Lab for Applications in Sustainability and Medicine – Antwerp (PLASMANT)
Impact Factor: 7.367
Times cited: 20
DOI: 10.1039/c4nr02354d
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“Post-plasma quenching to improve conversion and energy efficiency in a CO2 microwave plasma”. Mercer Er, Van Alphen S, van Deursen Cfam, Righart Twh, Bongers Wa, Snyders R, Bogaerts A, van de Sanden Mcm, Peeters Fjj, Fuel 334, 126734 (2023). http://doi.org/10.1016/j.fuel.2022.126734
Abstract: Transforming CO2 into value-added chemicals is crucial to realizing a carbon–neutral economy, and plasma-based conversion, a Power-2-X technology, offers a promising route to realizing an efficient and scalable process. This paper investigates the effects of post-plasma placement of a converging–diverging nozzle in a vortex-stabilized 2.45 GHz CO2 microwave plasma reactor to increase energy efficiency and conversion. The CDN leads to a 21 % relative increase in energy efficiency (31 %) and CO2 conversion (13 %) at high flow rates and near-atmospheric conditions. The most significant performance improvement was seen at low flow rates and sub-atmospheric pressure (300 mbar), where energy efficiency was 23 % and conversion was 28 %, a 71 % relative increase over conditions without the CDN. Using CFD simulations, we found that the CDN produces a change in the flow geometry, leading to a confined temperature profile at the height of the plasma, and forced extraction of CO to the post-CDN region.
Keywords: A1 Journal article; Engineering sciences. Technology; Plasma Lab for Applications in Sustainability and Medicine – Antwerp (PLASMANT)
Impact Factor: 7.4
DOI: 10.1016/j.fuel.2022.126734
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“Plasma-based dry reforming of CH4: Plasma effects vs. thermal conversion”. Slaets J, Loenders B, Bogaerts A, Fuel 360, 130650 (2024). http://doi.org/10.1016/j.fuel.2023.130650
Abstract: In this work we evaluate the chemical kinetics of dry reforming of methane in warm plasmas (1000–4000 K) using modelling with a newly developed chemistry set, for a broad range of parameters (temperature, power density and CO2/CH4 ratio). We compare the model against thermodynamic equilibrium concentrations, serving as validation of the thermal chemical kinetics. Our model reveals that plasma-specific reactions (i.e., electron impact collisions) accelerate the kinetics compared to thermal conversion, rather than altering the overall kinetics pathways and intermediate products, for gas temperatures below 2000 K. For higher temperatures, the kinetics are dominated by heavy species collisions and are strictly thermal, with negligible influence of the electrons and ions on the overall kinetics. When studying the effects of different gas mixtures on the kinetics, we identify important intermediate species, side reactions and side products. The use of excess CO2 leads to H2O formation, at the expense of H2 formation, and the CO2 conversion itself is limited, only approaching full conversion near 4000 K. In contrast, full conversion of both reactants is only kinetically limited for mixtures with excess CH4, which also gives rise to the formation of C2H2, alongside syngas. Within the given parameter space, our model predicts the 30/70 ratio of CO2/CH4 to be the most optimal for syngas formation with a H2/CO ratio of 2.
Keywords: A1 Journal article; Engineering sciences. Technology; Plasma Lab for Applications in Sustainability and Medicine – Antwerp (PLASMANT)
Impact Factor: 7.4
DOI: 10.1016/j.fuel.2023.130650
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“Plasma-based conversion of CO2 and CH4 into syngas: A dive into the effect of adding water”. Wanten B, Gorbanev Y, Bogaerts A, Fuel 374, 132355 (2024). http://doi.org/10.1016/j.fuel.2024.132355
Abstract: Plasma technology can play a vital role in the electrification and decarbonization of chemical processes. In this work, we carried out the bi-reforming of methane (BRM), producing syngas out of H2O vapor and the greenhouse gases CO2 and CH4, in an atmospheric pressure glow discharge reactor. Compared to dry reforming of methane (DRM), the addition of H2O helps in counteracting soot formation, and thus avoids severe destabilization of the generated plasma. A mixture of 14–41-45 vol% (CO2-CH4-H2O) leads to the overall best results in terms of stable plasma and performance metrics. We obtained a CO2 and CH4 conversion of 49 % and 74 %, respectively, at a SEI of 210 kJ/mol. The energy cost is 390 kJ/mol converted reactants, which is below the target defined for plasmabased syngas production to be competitive with other technologies. Moreover, we reached CO and H2 yields of
59 % and 49 %, and a syngas ratio (SR) of 2, which is ideal for further methanol synthesis.
Keywords: A1 Journal Article; Plasma Bi-reforming of methane Atmospheric pressure glow discharge Hydrogen-rich syngas; Plasma, laser ablation and surface modeling Antwerp (PLASMANT) ;
Impact Factor: 7.4
DOI: 10.1016/j.fuel.2024.132355
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“Dry reforming of methane in an atmospheric pressure glow discharge: Confining the plasma to expand the performance”. Wanten B, Maerivoet S, Vantomme C, Slaets J, Trenchev G, Bogaerts A, Journal Of Co2 Utilization 56, 101869 (2022). http://doi.org/10.1016/j.jcou.2021.101869
Abstract: We present a confined atmospheric pressure glow discharge plasma reactor, with very good performance towards dry reforming of methane, i.e., CO2 and CH4 conversion of 64 % and 94 %, respectively, at an energy cost of 3.5–4 eV/molecule (or 14–16 kJ/L). This excellent performance is among the best reported up to now for all types of plasma reactors in literature, and is due to the confinement of the plasma, which maximizes the fraction of gas passing through the active plasma region. The main product formed is syngas, with H2O and C2H2 as byproducts. We developed a quasi-1D chemical kinetics model, showing good agreement with the experimental results, which provides a thorough insight in the reaction pathways underlying the conversion of CO2 and CH4 and the formation of the different products.
Keywords: A1 Journal article; Plasma Lab for Applications in Sustainability and Medicine – Antwerp (PLASMANT)
Impact Factor: 7.7
DOI: 10.1016/j.jcou.2021.101869
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“Editorial: Special issue on CO2 utilization with plasma technology”. Li S, Liu C, Bogaerts A, Gallucci F, Journal Of Co2 Utilization 61, 102017 (2022). http://doi.org/10.1016/j.jcou.2022.102017
Abstract: Plasma technology has advanced significantly in recent years, with application ranging from chemical conversion, to surface treatment, material development and several other fields. Special attention has been paid to the development of possible novel approaches for the conversion of chemicals in a more sustainable way. Plasma technology offers advantages over thermochemical routes such as high process versatility, mild reaction condition, one-step synthesis, fast reaction and instant control. More importantly, it can be easily combined with electricity generated from various renewable sources and is suitable for energy storage via the conversion of intermittent renewable energy into carbon-neutral fuels or other chemicals. In recent years, there has been a growing interest in the development of plasma technology for CO2 utilization. Investigation on different reactions such as CO2 splitting, dry reforming of methane (DRM) and CO2 hydrogenation with different types of plasma reactors and catalysts have been reported by researchers worldwide. Although technological maturity still needs to be increased, the potential of plasma has been well-recognized by the scientific community and industry. More research output in the future is expected as a result of intensive research activities and various kinds of investment. In this context, we present this special issue on CO2 utilization with plasma technology, which collects 22 articles, covering topics in related areas such as plasma reactor design, plasma catalysis, plasmamaterial interaction, modeling and new ideas for possible applications.
Keywords: Editorial; Plasma Lab for Applications in Sustainability and Medicine – Antwerp (PLASMANT)
Impact Factor: 7.7
DOI: 10.1016/j.jcou.2022.102017
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“Enhancing CO2 conversion with plasma reactors in series and O2 removal”. Vertongen R, Trenchev G, Van Loenhout R, Bogaerts A, Journal Of Co2 Utilization 66, 102252 (2022). http://doi.org/10.1016/j.jcou.2022.102252
Abstract: In this work, we take a crucial step towards the industrial readiness of plasma-based CO2 conversion. We present a stepwise method to study plasma reactors in series as a first approach to a recycle flow. By means of this procedure, the CO2 conversion is enhanced by a factor of 3, demonstrating that a single-pass plasma treatment performs far below the optimal capacity of the reactor. Furthermore, we explore the effect of O2 in the mixture with our flexible procedure. Addition of O2 in the mixture has a clear detrimental effect on the conversion, in agreement with other experiments in atmospheric pressure plasmas. O2 removal is however highly beneficial, demonstrating a conversion per pass that is 1.6 times higher than the standard procedure. Indeed, extracting one of the products prevents recombination reactions. Based on these insights, we discuss opportunities for further improvements, especially in the field of specialised separation techniques.
Keywords: A1 Journal article; Plasma Lab for Applications in Sustainability and Medicine – Antwerp (PLASMANT)
Impact Factor: 7.7
DOI: 10.1016/j.jcou.2022.102252
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“Effect of plasma-induced oxidative stress on the glycolysis pathway of Escherichia coli”. Ranjbar S, Shahmansouri M, Attri P, Bogaerts A, Computers In Biology And Medicine 127, 104064 (2020). http://doi.org/10.1016/j.compbiomed.2020.104064
Abstract: Antibiotic resistance is one of the world’s most urgent public health problems. Due to its antibacterial properties, cold atmospheric plasma (CAP) may serve as an alternative method to antibiotics. It is claimed that oxidative stress caused by CAP is the main reason of bacteria inactivation. In this work, we computationally investigated the effect of plasma-induced oxidation on various glycolysis metabolites, by monitoring the production of the biomass. We observed that in addition to the significant reduction in biomass production, the rate of some reactions has increased. These reactions produce anti-oxidant products, showing the bacterial defense mechanism to escape the oxidative damage. Nevertheless, the simulations show that the plasma-induced oxidation effect is much stronger than the defense mechanism, causing killing of the bacteria.
Keywords: A1 Journal article; Plasma Lab for Applications in Sustainability and Medicine – Antwerp (PLASMANT)
Impact Factor: 7.7
DOI: 10.1016/j.compbiomed.2020.104064
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“Dual-vortex plasmatron: A novel plasma source for CO2 conversion”. Trenchev G, Bogaerts A, Journal Of Co2 Utilization 39, 101152 (2020). http://doi.org/10.1016/j.jcou.2020.03.002
Abstract: Atmospheric pressure gliding arc (GA) discharges are gaining increasing interest for CO2 conversion and other gas conversion applications, due to their simplicity and high energy efficiency. However, they are characterized by some drawbacks, such as non-uniform gas treatment, limiting the conversion, as well as the development of a hot cathode spot, resulting in severe electrode degradation. In this work, we built a dual-vortex plasmatron, which is a GA plasma reactor with innovative electrode configuration, to solve the above problems. The design aims to improve the CO2 conversion capability of the GA reactor by elongating the arc in two directions, to increase the residence time of the gas inside the arc, and to actively cool the cathode spot by rotation of the arc and gas convection. The measured CO2 conversion and corresponding energy efficiency indeed look very promising. In addition, we developed a fluid dynamics non-thermal plasma model with argon chemistry, to study the arc behavior in the reactor and to explain the experimental results.
Keywords: A1 Journal article; Plasma Lab for Applications in Sustainability and Medicine – Antwerp (PLASMANT)
Impact Factor: 7.7
DOI: 10.1016/j.jcou.2020.03.002
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“Arc plasma reactor modification for enhancing performance of dry reforming of methane”. Dinh DK, Trenchev G, Lee DH, Bogaerts A, Journal Of Co2 Utilization 42, 101352 (2020). http://doi.org/10.1016/j.jcou.2020.101352
Abstract: Arc plasma technology is gaining increasing interest for a variety of chemical reaction applications. In this study, we demonstrate how modifying the reactor geometry can significantly enhance the chemical reaction performance. Using dry reforming of methane as a model reaction, we studied different rotating arc reactors (conventional rotating arc reactor and nozzle-type rotating arc reactor) to evaluate the effect of attaching a downstream nozzle. The nozzle structure focuses the heat to a confined reaction volume, resulting in enhanced heat transfer from the arc into gas activation and reduced heat losses to the reactor walls. Compared to the conventional rotating arc reactor, this yields much higher CH4 and CO2 conversion (i.e., 74% and 49%, respectively, versus 40% and 28% in the conventional reactor, at 5 kJ/L) as well as energy efficiency (i.e., 53% versus 36%). The different performance in both reactors was explained by both experiments (measurements of temperature and oscillogram of current and voltage) and numerical modelling of the gas flow dynamics, heat transfer and fluid plasma of the reactor chambers. The results provide important insights for design optimization of arc plasma reactors for various chemical reactions.
Keywords: A1 Journal article; Plasma Lab for Applications in Sustainability and Medicine – Antwerp (PLASMANT)
Impact Factor: 7.7
DOI: 10.1016/j.jcou.2020.101352
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