|
“Comparison of As- and P-based metamorphic buffers for high performance InP heterojunction bipolar transistor and high electron mobility transistor applications”. Lubyshev D, Fastenau JM, Fang X-M, Wu Y, Doss C, Snyder A, Liu WK, Lamb MSM, Bals S, Song C, Journal of vacuum science &, technology. B. Microelectronics and nanometer structures. Processing, measurement and phenomena 22, 1565 (2004). http://doi.org/10.1116/1.1691412
Abstract: Metamorphic buffers (M-buffers) consisting of graded InAlAs or bulk InP were employed for the production of InP-based epiwafers on GaAs substrates by molecular-beam epitaxy. The graded InAlAs is the standard for production metamorphic high electron mobility transistors (M-HEMTs), while the bulk InP offers superior thermal properties for higher current density circuits. The surface morphology and crystal structure of the two M-buffers showed different relaxation mechanisms. The graded InAlAs gave a cross-hatched pattern with nearly full relaxation and very effective dislocation filtering, while the bulk InP had a uniform isotropic surface with dislocations propagating further up towards the active layers. Both types of M-buffers had atomic force microscopy root-mean-square roughness values around 2030 Å. The Hall transport properties of high electron mobility transistors (HEMTs) grown on the InAlAs M-buffer, and a baseline HEMT grown lattice matched on InP, both had room-temperature mobilities >10 000 cm2/V s, while the M-HEMT on the InP M-buffer showed a decrease to 9000 cm2/V s. Similarly, the dc parameters of a double heterojunction bipolar transistor (DHBT) grown on the InAlAs M-buffer were much closer to the baseline heterojunction bipolar transistor than a DHBT grown on the InP M-buffer. A high breakdown voltage of 11.3 V was achieved on an M-DHBT with the InAlAs M-buffer. We speculate that the degradation in device characteristics on the InP M-buffer was related to the incomplete dislocation filtering.
Keywords: A1 Journal article; Electron microscopy for materials research (EMAT)
Times cited: 25
DOI: 10.1116/1.1691412
|
|
|
“Orthorhombic vs. hexagonal epitaxial SrIrO3 thin films : structural stability and related electrical transport properties”. Bhat SG, Gauquelin N, Sebastian NK, Sil A, Béché, A, Verbeeck J, Samal D, Kumar PSA, Europhysics letters 122, 28003 (2018). http://doi.org/10.1209/0295-5075/122/28003
Abstract: Metastable orthorhombic SrIrO3 (SIO) is an arch-type spin-orbit coupled material. We demonstrate here a controlled growth of relatively thick (200 nm) SIO films that transform from bulk “6H-type” structure with monoclinic distortion to an orthorhombic lattice by controlling growth temperature. Extensive studies based on high-resolution X-ray diffraction and transmission electron microscopy infer a two distinct structural phases of SIO. Electrical transport reveals a weak temperature-dependent semi-metallic character for both phases. However, the temperature-dependent Hall-coefficient for the orthorhombic SIO exhibits a prominent sign change, suggesting a multiband character in the vicinity of E-F. Our findings thus unravel the subtle structure-property relation in SIO epitaxial thin films. Copyright (C) EPLA, 2018
Keywords: A1 Journal article; Electron microscopy for materials research (EMAT)
Impact Factor: 1.957
Times cited: 4
DOI: 10.1209/0295-5075/122/28003
|
|
|
“Investigating the electrochemical profile of methamphetamine to enable fast on-site detection in forensic analysis”. Drăgan A-M, Parrilla M, Sleegers N, Slosse A, Van Durme F, van Nuijs A, Oprean R, Cristea C, De Wael K, Talanta : the international journal of pure and applied analytical chemistry 255, 124208 (2023). http://doi.org/10.1016/J.TALANTA.2022.124208
Abstract: Methamphetamine (MA) is a synthetic psychoactive drug which is consumed both licitly and illicitly. In some countries it is prescribed for attention-deficit and hyperactivity disorder, and short-term treatment of obesity. More often though, it is abused for its psychostimulant properties. Unfortunately, the spread and abuse of this synthetic drug have increased globally, being reported as the most widely consumed synthetic psychoactive drug in the world in 2019. Attempting to overcome the shortcomings of the currently used on-site methods for MA detection in suspected cargos, the present study explores the potential of electrochemical identification of MA by means of square wave voltammetry on disposable graphite screen-printed electrodes. Hence, the analytical characterization of the method was evaluated under optimal conditions exhibiting a linear range between 50 mu M and 2.5 mM MA, a LOD of 16.7 mu M, a LOQ of 50.0 mu M and a sensitivity of 5.3 mu A mM-1. Interestingly, two zones in the potential window were identified for the detection of MA, depending on its concentration in solution. Furthermore, the oxidative pathway of MA was elucidated employing liquid chromatography – mass spectrometry to understand the change in the electrochemical profile. Thereafter, the selectivity of the method towards MA in mixtures with other drugs of abuse as well as common adulterants/cutting agents was evaluated. Finally, the described method was employed for the analysis of MA in confiscated samples and compared with forensic methods, displaying its potential as a fast and easy-to-use method for on-site analysis.
Keywords: A1 Journal article; Toxicological Centre; Antwerp Electrochemical and Analytical Sciences Lab (A-Sense Lab)
Impact Factor: 6.1
DOI: 10.1016/J.TALANTA.2022.124208
|
|
|
“Electrochemical rapid detection of methamphetamine from confiscated samples using a graphene-based printed platform”. Truta F, Drăgan A-M, Tertis M, Parrilla M, Slosse A, Van Durme F, De Wael K, Cristea C, Sensors 23, 6193 (2023). http://doi.org/10.3390/S23136193
Abstract: Methamphetamine (MAP) is a highly addictive and illegal stimulant drug that has a significant impact on the central nervous system. Its detection in biological and street samples is crucial for various organizations involved in forensic medicine, anti-drug efforts, and clinical diagnosis. In recent years, nanotechnology and nanomaterials have played a significant role in the development of analytical sensors for MAP detection. In this study, a fast, simple, and cost-effective electrochemical sensor is presented that is used for the sensitive detection of MAP in confiscated street samples with a complex matrix. The optimized screen-printed sensor based on a carbon working electrode modified with graphene demonstrated an excellent limit of detection, good sensitivity, and a wide dynamic range (1–500 μM) for the target illicit drug both for standard solutions and real samples (seized samples, tap water, and wastewater samples). It can detect MAP at concentrations as low as 300 nM in real samples. This limit of detection is suitable for the rapid preliminary screening of suspicious samples in customs, ports, airports, and on the street. Furthermore, the sensor exhibits a good recovery rate, indicating its reliability and repeatability. This quality is crucial for ensuring consistent and accurate results during screening processes.
Keywords: A1 Journal article; Antwerp Electrochemical and Analytical Sciences Lab (A-Sense Lab)
DOI: 10.3390/S23136193
|
|
|
“Accelerated methane storage in clathrate hydrates using mesoporous (Organo-) silica materials”. Kummamuru NB, Watson G, Ciocarlan R-G, Verbruggen SW, Cool P, Van Der Voort P, Perreault P, Fuel 354, 129403 (2023). http://doi.org/10.1016/J.FUEL.2023.129403
Abstract: Methane (CH4) clathrate hydrates have gained much attention in the ever-growing search for novel energy storage methods; however, they are currently limited due to their poor water-to-hydrate conversions and slow formation kinetics. To surmount these bottlenecks, significant research has been centered on the design of novel methods (porous media). In this vein, the present work explores two hydrophobic mesoporous solids, an alkyl-grafted mesoporous silica (SBA-15 C8) and a periodic mesoporous organosilica (Ring-PMO), in their ability to promote CH4 clathrates. Both materials have shown to facilitate CH4 clathrate formation at mild operating conditions (6 MPa and 269–276 K). The study revealed that the maximal CH4 storage capacities are strongly linked to the critical/optimal quantity of water in the system which was determined to be at 130% and 200% of the pore volume for SBA-15 C8 and Ring-PMO, respectively. Up to 90% and 95% of the maximum water-to-hydrate conversions were achieved in 90 min at the lowest experimental temperature and critical water content for SBA-15 C8 and Ring-PMO, respectively. At these conditions, SBA-15 C8 and Ring-PMO showed a maximum gas uptake of 98.2 and 101.2 mmol CH4/mol H2O, respectively. Both the materials exhibited no chemical or morphological changes post-clathrate formations (characterized using FT-IR, N2 sorption, XRD, and TEM), inferring their viability as clathrate promoters for multiple cycles. An integrated multistep model was considered adequate for representing the hydrate crystallization kinetics and fits well with the experimental kinetic data with a low average absolute deviation in water-to-hydrate conversions among the three distinct kinetic models analyzed. Overall, the results from this study demonstrate hydrophobic porous materials as effective promoters of CH4 clathrates, which could make clathrate-based CH4 storage and transport technology industrially viable.
Keywords: A1 Journal article; Engineering sciences. Technology; Laboratory of adsorption and catalysis (LADCA)
Impact Factor: 7.4
DOI: 10.1016/J.FUEL.2023.129403
|
|
|
“Numerical simulation on particle density and reaction pathways in methane needle-plane discharge plasma at atmospheric pressure”. Yue-Feng Z, Chao W, Wang W-Z, Li L, Hao S, Tao S, Jie P, Wuli xuebao 67, 085202 (2018). http://doi.org/10.7498/APS.67.20172192
Abstract: Methane needle-plane discharge has practical application prospect and scientific research significance since methane conversion heavy oil hydrogenation is formed by coupling methane needle-plane discharge with heavy oil hydrogenation, which can achieve high-efficient heavy oil hydrogenation and increase the yields of high value-added light olefins. In this paper, a two-dimensional fluid model is built up for numerically simulating the methane needle-plane discharge plasma at atmospheric pressure. Spatial and axial distributions of electric intensity, electron temperature and particle densities are obtained. Reaction yields are summarized and crucial pathways to produce various kinds of charged and neutral particles are found out. Simulation results indicate that axial evolutions of CH3+ and CH4+ densities, electric intensity and electron temperature are similar and closely related. The CH5+ and C2H5+ densities first increase and then decrease along the axial direction. The CH3 and H densities have nearly identical spatial and axial distributions. Particle density distributions of CH2, C2H4 and C2H5 are obviously different in the area near the cathode but comparatively resemblant in the positive column region. The CH3+ and CH4+ are produced by electron impact ionizations between electrons and CH4. The CH5+ and C2H5+ are respectively generated by molecular impact dissociations between CH3+ and CH4 and between CH4+ and CH4. Electron impact decomposition between electrons and CH4 is a dominated reaction to produce CH3, CH2, CH and H. The reactions between CH2 and CH4 and between electrons and C2H4 are critical pathways to produce C2H4 and C2H2, respectively. In addition, the yields of electron impact decomposition reactions between electrons and CH4 and reactions between CH2 and CH4 account for 52.15% and 47.85% of total yields of H-2 respectively.
Keywords: A1 Journal article; Plasma Lab for Applications in Sustainability and Medicine – Antwerp (PLASMANT)
Impact Factor: 0.624
DOI: 10.7498/APS.67.20172192
|
|
|
“Interactions of plasma species on nickel catalysts : a reactive molecular dynamics study on the influence of temperature and surface structure”. Somers W, Bogaerts A, van Duin ACT, Neyts EC, Applied catalysis : B : environmental 154, 1 (2014). http://doi.org/10.1016/j.apcatb.2014.01.061
Abstract: Methane reforming by plasma catalysis is a complex process that is far from understood. It requires a multidisciplinary approach which ideally takes into account all effects from the plasma on the catalyst, and vice versa. In this contribution, we focus on the interactions of CHx (x = {1,2,3}) radicals that are created in the plasma with several nickel catalyst surfaces. To this end, we perform reactive molecular dynamics simulations, based on the ReaxFF potential, in a wide temperature range of 4001600 K. First, we focus on the H2 formation as a function of temperature and surface structure. We observe that substantial H2 formation is obtained at 1400 K and above, while the role of the surface structure seems limited. Indeed, in the initial stage, the type of nickel surface influences the CH bond breaking efficiency of adsorbed radicals; however, the continuous carbon diffusion into the surface gradually diminishes the surface crystallinity and therefore reduces the effect of surface structure on the H2 formation probability. Furthermore, we have also investigated to what extent the species adsorbed on the catalyst surface can participate in surface reactions more in general, for the various surface structures and as a function of temperature. These results are part of the ongoing research on the methane reforming by plasma catalysis, a highly interesting yet complex alternative to conventional reforming processes.
Keywords: A1 Journal article; Plasma Lab for Applications in Sustainability and Medicine – Antwerp (PLASMANT)
Impact Factor: 9.446
Times cited: 23
DOI: 10.1016/j.apcatb.2014.01.061
|
|
|
“Aligning graphene in bulk copper : nacre-inspired nanolaminated architecture coupled with in-situ processing for enhanced mechanical properties and high electrical conductivity”. Cao M, Xiong D-B, Tan Z, Ji G, Amin-Ahmadi B, Guo Q, Fan G, Guo C, Li Z, Zhang D, Carbon 117, 65 (2017). http://doi.org/10.1016/J.CARBON.2017.02.089
Abstract: Methods used to strengthen metals generally also cause a pronounced decrease in ductility and electrical conductivity. In this work a bioinspired strategy is applied to surmount the dilemma. By assembling copper submicron flakes cladded with in-situ grown graphene, graphene/copper matrix composites with a nanolaminated architecture inspired by a natural nacre have been prepared. Owing to a combined effect-from the bioinspired nanolaminated architecture and improved interfacial bonding, a synergy has been achieved between mechanical strength and ductility as well as electrical conductivity in the graphene/copper matrix composites. With a low volume fraction of only 2.5% of graphene, the composite shows a yield strength and elastic modulus similar to 177% and similar to 25% higher than that of unreinforced copper matrix, respectively, while retains ductility and electrical conductivity comparable to that of pure copper. The bioinspired nanolaminated architecture enhances the efficiencies of two-dimensional (2D) graphene in mechanical strengthening and electrical conducting by aligning graphene to maximize performance for required loading and carrier transporting conditions, and toughens the composites by crack deflection. Meanwhile, in-situ growth of graphene is beneficial for improving interfacial bonding and structural quality of graphene. The strategy sheds light on the development of composites with good combined structural and functional properties. (C) 2017 Elsevier Ltd. All rights reserved.
Keywords: A1 Journal article; Electron microscopy for materials research (EMAT)
DOI: 10.1016/J.CARBON.2017.02.089
|
|
|
“Direct room-temperature synthesis of methyl-functionalized Ti-MCM-41 nanoparticles and their catalytic performance in epoxidation”. Lin K, Pescarmona PP, Houthoofd K, Liang D, Van Tendeloo G, Jacobs PA, Journal of catalysis 263, 75 (2009). http://doi.org/10.1016/j.jcat.2009.01.013
Abstract: Methyl-functionalized Ti-MCM-41 nanoparticles with a size of 80 to 160 nm (Me-Ti-MCM-41 NP) were directly prepared via a dilute solution route by the co-condensation of tetraethoxysilane and methylalkoxysilanes in sodium hydroxide medium at room temperature. The characterization results showed the existence of ordered hexagonal mesoporous structure and tetrahedral Ti species in the nanoparticles. In the epoxidation of cyclohexene with tert-butyl hydroperoxide and aqueous H2O2, Me-Ti-MCM-41 NP samples displayed higher turnover frequencies (TOFs) for cyclohexene and initial reaction rates compared to Ti-MCM-41 and methyl-functionalized Ti-MCM-41 with normal particle size and to non-functionalized Ti-MCM-41 nanoparticles. Simultaneously, a higher selectivity for cyclohexene epoxide was observed in the case of aqueous H2O2, suggesting that the hydrolysis of cyclohexene epoxide with water is reduced on Me-Ti-MCM-41 NP samples. The improved catalytic behavior of Me-Ti-MCM-41 NP is discussed both in terms of the nanosize and methylation of the surface of the catalyst particles. The regeneration of Me-Ti-MCM-41 NP with tert-butyl hydroperoxide solution was evaluated via washing and calcination approaches.
Keywords: A1 Journal article; Electron microscopy for materials research (EMAT)
Impact Factor: 6.844
Times cited: 89
DOI: 10.1016/j.jcat.2009.01.013
|
|
|
“Molecular shape-selectivity of MFI zeolite nanosheets in n-decane isomerization and hydrocracking”. Verheyen E, Jo C, Kurttepeli M, Vanbutsele G, Gobechiya E, Korányi TI, Bals S, Van Tendeloo G, Ryoo R, Kirschhock CEA, Martens JA;, Journal of catalysis 300, 70 (2013). http://doi.org/10.1016/j.jcat.2012.12.017
Abstract: MFI zeolite nanosheets with thickness of 2 and 8 nm were synthesized, transformed into bifunctional catalysts by loading with platinum and tested in n-decane isomerization and hydrocracking. Detailed analysis of skeletal isomers and hydrocracked products revealed that the MFI nanosheets display transition-state shape-selectivity similar to bulk MFI zeolite crystals. The suppressed formation of bulky skeletal isomers and C5 cracking products are observed both in the nanosheets and the bulk crystals grown in three dimensions. This is typical for restricted transition-state shape-selectivity, characteristic for the MFI type pores. It is a first clear example of transition-state shape-selectivity inside a zeolitic nanosheet. Owing to the short diffusion path across the sheets, expression of diffusion-based discrimination of reaction products in the MFI nanosheets was limited. The 2-methylnonane formation among monobranched C10 isomers and 2,7-dimethyloctane among dibranched C10 isomers, which in MFI zeolite are favored by product diffusion, was much less favored on the nanosheets compared to the reference bulk ZSM-5 material.
Keywords: A1 Journal article; Electron microscopy for materials research (EMAT)
Impact Factor: 6.844
Times cited: 121
DOI: 10.1016/j.jcat.2012.12.017
|
|
|
“Gas-phase synthesis of Mg-Ti nanoparticles for solid-state hydrogen storage”. Calizzi M, Venturi F, Ponthieu M, Cuevas F, Morandi V, Perkisas T, Bals S, Pasquini L, Physical chemistry, chemical physics 18, 141 (2016). http://doi.org/10.1039/c5cp03092g
Abstract: Mg-Ti nanostructured samples with different Ti contents were prepared via compaction of nanoparticles grown by inert gas condensation with independent Mg and Ti vapour sources. The growth set-up offered the option to perform in situ hydrogen absorption before compaction. Structural and morphological characterisation was carried out by X-ray diffraction, energy dispersive spectroscopy and electron microscopy. The formation of an extended metastable solid solution of Ti in hcp Mg was detected up to 15 at% Ti in the as-grown nanoparticles, while after in situ hydrogen absorption, phase separation between MgH2 and TiH2 was observed. At a Ti content of 22 at%, a metastable Mg-Ti-H fcc phase was observed after in situ hydrogen absorption. The co-evaporation of Mg and Ti inhibited nanoparticle coalescence and crystallite growth in comparison with the evaporation of Mg only. In situ hydrogen absorption was beneficial to subsequent hydrogen behaviour, studied by high pressure differential scanning calorimetry and isothermal kinetics. A transformed fraction of 90% was reached within 100 s at 300 degrees C during both hydrogen absorption and desorption. The enthalpy of hydride formation was not observed to differ from bulk MgH2.
Keywords: A1 Journal article; Engineering Management (ENM); Electron microscopy for materials research (EMAT)
Impact Factor: 4.123
Times cited: 31
DOI: 10.1039/c5cp03092g
|
|
|
“Synchrotron XRF and histological analyses identify damage to digestive tract of uranium NP-exposed Daphnia magna”. Byrnes I, Rossbach LM, Jaroszewicz J, Grolimund D, Sanchez DF, Gomez-Gonzalez MA, Nuyts G, Reinoso-Maset E, Janssens K, Salbu B, Brede DA, Lind OC, Environmental science and technology 57, 1071 (2023). http://doi.org/10.1021/ACS.EST.2C07174
Abstract: Micro-and nanoscopic X-ray techniques were used to investigate the relationship between uranium (U) tissue distributions and adverse effects to the digestive tract of aquatic model organism Daphnia magna following uranium nanoparticle (UNP) exposure. X-ray absorption computed tomography measure-ments of intact daphnids exposed to sublethal concentrations of UNPs or a U reference solution (URef) showed adverse morphological changes to the midgut and the hepatic ceca. Histological analyses of exposed organisms revealed a high proportion of abnormal and irregularly shaped intestinal epithelial cells. Disruption of the hepatic ceca and midgut epithelial tissues implied digestive functions and intestinal barriers were compro-mised. Synchrotron-based micro X-ray fluorescence (XRF) elemental mapping identified U co-localized with morphological changes, with substantial accumulation of U in the lumen as well as in the epithelial tissues. Utilizing high-resolution nano-XRF, 400-1000 nm sized U particulates could be identified throughout the midgut and within hepatic ceca cells, coinciding with tissue damages. The results highlight disruption of intestinal function as an important mode of action of acute U toxicity in D. magna and that midgut epithelial cells as well as the hepatic ceca are key target organs.
Keywords: A1 Journal article; Antwerp X-ray Imaging and Spectroscopy (AXIS)
Impact Factor: 11.4
DOI: 10.1021/ACS.EST.2C07174
|
|
|
“Enhancement of co-production of nutritional protein and carotenoids in Dunaliella salina using a two-phase cultivation assisted by nitrogen level and light intensity”. Sui Y, Muys M, Van de Waal D, D'Adamo S, Vermeir P, Fernandes TV, Vlaeminck SE, Bioresource technology 287, 121398 (2019). http://doi.org/10.1016/J.BIORTECH.2019.121398
Abstract: Microalga Dunaliella salina is known for its carotenogenesis. At the same time, it can also produce high-quality protein. The optimal conditions for D. salina to co-produce intracellular pools of both compounds, however, are yet unknown. This study investigated a two-phase cultivation strategy to optimize combined high-quality protein and carotenoid production of D. salina. In phase-one, a gradient of nitrogen concentrations was tested. In phase-two, effects of nitrogen pulse and high illumination were tested. Results reveal optimized protein quantity, quality (expressed as essential amino acid index EAAI) and carotenoids content in a two-phase cultivation, where short nitrogen starvation in phase-one was followed by high illumination during phase-two. Adopting this strategy, productivities of protein, EAA and carotenoids reached 22, 7 and 3 mg/L/d, respectively, with an EAAI of 1.1. The quality of this biomass surpasses FAO/WHO standard for human nutrition, and the observed level of β-carotene presents high antioxidant pro-vitamin A activity.
Keywords: A1 Journal article; Engineering sciences. Technology; Sustainable Energy, Air and Water Technology (DuEL)
DOI: 10.1016/J.BIORTECH.2019.121398
|
|
|
“Continuous cultivation of microalgae yields high nutrient recovery from nitrified urine with limited supplementation”. De Paepe J, Garcia Gragera D, Arnau Jimenez C, Rabaey K, Vlaeminck SE, Gòdia F, Journal of environmental management 345, 118500 (2023). http://doi.org/10.1016/J.JENVMAN.2023.118500
Abstract: Microalgae can play a key role in the bioeconomy, particularly in combination with the valorisation of waste streams as cultivation media. Urine is an example of a widely available nutrient-rich waste stream, and alkaline stabilization and subsequent full nitrification in a bioreactor yields a stable nitrate-rich solution. In this study, such nitrified urine served as a culture medium for the edible microalga Limnospira indica. In batch cultivation, nitrified urine without additional supplements yielded a lower biomass concentration, nutrient uptake and protein content compared to modified Zarrouk medium, as standard medium. To enhance the nitrogen uptake efficiency and biomass production, nitrified urine was supplemented with potentially limiting elements. Limited amounts of phosphorus (36 mg L−1), magnesium (7.9 mg L−1), calcium (12.2 mg L−1), iron (2.0 mg L−1) and EDTA (88.5 mg Na2-EDTA.2H2O L−1) rendered the nitrified urine matrix as effective as modified Zarrouk medium in terms of biomass production (OD750 of 1.2), nutrient uptake (130 mg N L−1) and protein yield (47%) in batch culture. Urine precipitates formed by alkalinisation could in principle supply enough phosphorus, calcium and magnesium, requiring only external addition of iron, EDTA and inorganic carbon. Subsequently, the suitability of supplemented nitrified urine as a culture medium was confirmed in continuous Limnospira cultivation in a CSTR photobioreactor. This qualifies nitrified urine as a valuable and sustainable microalgae growth medium, thereby creating novel nutrient loops on Earth and in Space, i.e., in regenerative life support systems for human deep-space missions.
Keywords: A1 Journal article; Sustainable Energy, Air and Water Technology (DuEL)
Impact Factor: 8.7
DOI: 10.1016/J.JENVMAN.2023.118500
|
|
|
“High variability in nutritional value and safety of commercially available Chlorella and Spirulina biomass indicates the need for smart production strategies”. Muys M, Sui Y, Schwaiger B, Lesueur C, Vandenheuvel D, Vermeir P, Vlaeminck SE, Bioresource technology 275, 247 (2019). http://doi.org/10.1016/J.BIORTECH.2018.12.059
Abstract: Microalgal biomass production is a resource-efficient answer to the exponentially increasing demand for protein, yet variability in biomass quality is largely unexplored. Nutritional value and safety were determined for Chlorella and Spirulina biomass from different producers, production batches and the same production batch. Chlorella presented a similar protein content (47 ± 8%) compared to Spirulina (48 ± 4%). However, protein quality, expressed as essential amino acid index, and digestibility were lower for Chlorella (1.1 ± 0.1 and 51 ± 9%, respectively) compared to Spirulina (1.3 ± 0.1 and 61 ± 4%, respectively). Generally, variability was lower between batches and within a batch. Heavy metals, pesticides, mycotoxins, antibiotics and nitrate did not violate regulatory limits, while polycyclic aromatic hydrocarbon levels exceeded the norm for some samples, indicating the need for continuous monitoring. This first systematic screening of commercial microalgal biomass revealed a high nutritional variability, necessitating further optimization of cultivation and post-processing conditions. Based on price and quality, Spirulina was preferred above Chlorella.
Keywords: A1 Journal article; Engineering sciences. Technology; Sustainable Energy, Air and Water Technology (DuEL)
DOI: 10.1016/J.BIORTECH.2018.12.059
|
|
|
“Numerical analysis of direct-current microdischarge for space propulsion applications using the particle-in-cell/Monte Carlo collision (PIC/MCC) method”. Kong L, Wang W, Murphy AB, Xia G, Journal of physics: D: applied physics 50, 165203 (2017). http://doi.org/10.1088/1361-6463/AA623F
Abstract: Microdischarges are an important type of plasma discharge that possess several unique characteristics, such as the presence of a stable glow discharge, high plasma density and intense excimer radiation, leading to several potential applications. The intense and controllable gas heating within the extremely small dimensions of microdischarges has been exploited in microthruster technologies by incorporating a micro-nozzle to generate the thrust. This kind of microthruster has a significantly improved specific impulse performance compared to conventional cold gas thrusters, and can meet the requirements arising from the emerging development and application of micro-spacecraft. In this paper, we performed a self-consistent 2D particle-in-cell simulation, with a Monte Carlo collision model, of a microdischarge operating in a prototype micro-plasma thruster with a hollow cylinder geometry and a divergent micro-nozzle. The model takes into account the thermionic electron emission including the Schottky effect, the secondary electron emission due to cathode bombardment by the plasma ions, several different collision processes, and a non-uniform argon background gas density in the cathode-anode gap. Results in the high-pressure (several hundreds of Torr), high-current (mA) operating regime showing the behavior of the plasma density, potential distribution, and energy flux towards the hollow cathode and anode are presented and discussed. In addition, the results of simulations showing the effect of different argon gas pressures, cathode material work function and discharge voltage on the operation of the microdischarge thruster are presented. Our calculated properties are compared with experimental data under similar conditions and qualitative and quantitative agreements are reached.
Keywords: A1 Journal article; Plasma Lab for Applications in Sustainability and Medicine – Antwerp (PLASMANT)
Impact Factor: 2.588
Times cited: 8
DOI: 10.1088/1361-6463/AA623F
|
|
|
“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 Science (EMAT) ;
Impact Factor: 6.8
DOI: 10.1002/admt.202301632
|
|
|
“In vitro and ex vivo assessment of microporous Faujasite zeolite (NaX-FAU) as a carrier for the oral delivery of danazol”. Kontogiannidou E, Karavasili C, Kouskoura MG, Filippousi M, Van Tendeloo G, Andreadis II, Eleftheriadis GK, Kontopoulou I, Markopoulou CK, Bouropoulos N, Fatouros DG, Journal of drug delivery science and technology 51, 177 (2019). http://doi.org/10.1016/J.JDDST.2019.02.036
Abstract: Microporous zeolite NaX-FAU has been systemically evaluated for the oral delivery of the poorly water-soluble compound danazol. For this purpose, danazol-loaded zeolitic particles were prepared by the incipient wetness method and were characterized by means of N-2 physisorption, X-ray diffraction (XRD), differential scanning calorimetry (DSC), thermogravimetric analysis (TGA) and high-resolution transmission electron microscopy (HRTEM). The zeolitic formulation shows a high drug payload and drug stability over a period of six months under accelerated storage conditions. The dissolution profile of danazol-loaded zeolitic particles was assessed in simulated gastric fluid (SGF) pH 1.2; fasted state simulated intestinal fluids (FaSSIF) and fed state simulated intestinal fluid (FeSSIF) showing a gradual and increasing drug dissolution in the different media. Ex vivo studies using the everted gut sac model show an increased drug transport across rat intestinal epithelium when loaded in the zeolitic particles. Our results suggest that microporous Faujasite zeolite (NaX-FAU) could be used as a drug delivery system to facilitate the oral delivery of poorly water soluble compounds.
Keywords: A1 Journal article; Pharmacology. Therapy; Electron microscopy for materials research (EMAT)
Impact Factor: 1.194
Times cited: 3
DOI: 10.1016/J.JDDST.2019.02.036
|
|
|
“Development of an electrochemiluminescent oligonucleotide-based assay for the quantification of prostate cancer associated miR-141-3p in human serum”. Campos R, Thiruvottriyur Shanmugam S, Daems E, Ribeiro R, De Wael K, Bioelectrochemistry: an international journal devoted to electrochemical aspects of biology and biological aspects of electrochemistry 153, 108495 (2023). http://doi.org/10.1016/J.BIOELECHEM.2023.108495
Abstract: MicroRNAs (miRNAs) are small oligonucleotides (18–25 bases), biologically relevant for epigenetic regulation of key processes, particularly in association with cancer. Research effort has therefore been directed towards the monitoring and detection of miRNAs to progress (early) cancer diagnoses. Traditional detection strategies for miRNAs are expensive, with a lengthy time-to-result. In this study we develop an oligonucleotide-based assay using electrochemistry for the specific, selective and sensitive detection of a circulating miRNA (miR-141) associated with prostate cancer. In the assay, the excitation and readout of the signal are independent: an electrochemical stimulation followed by an optical readout. A ‘sandwich’ approach is incorporated, consisting of a biotinylated capture probe immobilised on streptavidin-functionalised surfaces and a detection probe labelled with digoxigenin. We show that the assay allows the detection of miR-141 in human serum, even in the presence of other miRNAs, with a LOD of 0.25 pM. The developed electrochemiluminescent assay has, therefore, the potential for efficient universal oligonucleotide target detection via the redesign of capture and detection probes.
Keywords: A1 Journal article; Engineering sciences. Technology; Antwerp Electrochemical and Analytical Sciences Lab (A-Sense Lab)
Impact Factor: 5
DOI: 10.1016/J.BIOELECHEM.2023.108495
|
|
|
“Using self-driven microswimmers for particle separation”. Yang W, Misko VR, Nelissen K, Kong M, Peeters FM, Soft matter 8, 5175 (2012). http://doi.org/10.1039/c2sm07382j
Abstract: Microscopic self-propelled swimmers capable of autonomous navigation through complex environments provide appealing opportunities for localization, pick-up and delivery of micro and nanoscopic objects. Inspired by motile cells and bacteria, man-made microswimmers have been fabricated, and their motion in patterned surroundings has been experimentally studied. We propose to use self-driven artificial microswimmers for the separation of binary mixtures of colloids. We revealed different regimes of separation, including one with a velocity inversion. Our findings could be of use for various biological and medical applications.
Keywords: A1 Journal article; Condensed Matter Theory (CMT)
Impact Factor: 3.889
Times cited: 45
DOI: 10.1039/c2sm07382j
|
|
|
“In situ investigation of the fast microstructure evolution during electropulse treatment of cold drawn NiTi wires”. Malard B, Pilch J, Sittner P, Delville R, Curfs C, Acta materialia 59, 1542 (2011). http://doi.org/10.1016/j.actamat.2010.11.018
Abstract: Microstructural changes taking place during the heat treatment of cold-worked NiTi alloy are of key interest in shape memory alloy technology, since they are responsible for setting the austenite shape and functional properties of the heat-treated alloy. In this work, microstructural evolution during non-conventional electropulse heat treatment of thin NiTi filaments was investigated in a unique high-speed in situ synchrotron X-ray diffraction experiment with simultaneous evaluation of the tensile force and electrical resistivity of the treated wire. The in situ results provide direct experimental evidence on the evolution of the internal stress and density of defects during fast heating from 20 °C to ∼700 °C. This evidence is used to characterize a sequence of dynamic recovery and recrystallization processes responsible for the microstructure and superelastic functional property changes during the electropulse treatments.
Keywords: A1 Journal article; Electron microscopy for materials research (EMAT)
Impact Factor: 5.301
Times cited: 48
DOI: 10.1016/j.actamat.2010.11.018
|
|
|
“Microscopic investigation of as built and hot isostatic pressed Hastelloy X processed by Selective Laser Melting”. Pourbabak S, Montero-Sistiaga ML, Schryvers D, Van Humbeeck J, Vanmeensel K, Materials characterization 153, 366 (2019). http://doi.org/10.1016/j.matchar.2019.05.024
Abstract: Microstructural characteristics of Hastelloy X produced by Selective Laser Melting have been investigated by various microscopic techniques in the as built (AB) condition and after hot isostatic pressing (HIP). At sub-grain level the AB material consists of columnar high density dislocation cells while the HIP sample consists of columnar sub-grains with lower dislocation density that originate from the original dislocation cells, contradicting existing models. The sub-grains contain nanoscale precipitates enriched in Al, Ti, Cr and O, located at sub-grain boundaries in the AB condition and within the grains after HIP. At some grain boundaries, micrometer sized chromium carbides are detected after HIP. Micro hardness within the grains was found to decrease after HIP, which was attributed to the decrease in dislocation density due to recovery annealing.
Keywords: A1 Journal article; Engineering sciences. Technology; Electron microscopy for materials research (EMAT)
Impact Factor: 2.714
Times cited: 2
DOI: 10.1016/j.matchar.2019.05.024
|
|
|
“Microstructure of adiabatic shear bands in Ti6Al4V”. Peirs J, Tirry W, Amin-Ahmadi B, Coghe F, Verleysen P, Rabet L, Schryvers D, Degrieck J, Materials characterization 75, 79 (2013). http://doi.org/10.1016/j.matchar.2012.10.009
Abstract: Microstructural deformation mechanisms in adiabatic shear bands in Ti6Al4V are studied using traditional TEM and selected area diffraction, and more advanced microstructural characterisation techniques such as energy dispersive X-ray spectroscopy, high angle annular dark field STEM and conical dark field TEM. The shear bands under investigation are induced in Ti6Al4V samples by high strain rate compression of cylindrical and hat-shaped specimens in a split Hopkinson pressure bar setup. Samples from experiments interrupted at different levels of deformation are used to study the evolution of the microstructure in and nearby the shear bands. From the early stages of adiabatic shear band formation, TEM revealed strongly elongated equiaxed grains in the shear band. These band-like grains become narrower towards the centre of the band and start to fraction even further along their elongated direction to finally result in a nano-crystalline region in the core. In fully developed shear bands, twins and a needle-like martensite morphology are observed near the shear band.
Keywords: A1 Journal article; Electron microscopy for materials research (EMAT)
Impact Factor: 2.714
Times cited: 56
DOI: 10.1016/j.matchar.2012.10.009
|
|
|
“Microstructure of quenched Ni-rich Ni-Ti shape memory alloys”. Somsen C, Kästner J, Wassermann EF, Boullay P, Schryvers D, Journal de physique: 4
T2 –, 8th European Symposium on Martensitic Transformations (ESOMAT2000), SEP 04-08, 2000, COMO, ITALY 11, 445 (2001). http://doi.org/10.1051/jp4:2001874
Abstract: Microstructural investigations with transmission electron microscopy were carried out on quenched Ni-Ti alloys with 52 and 54.5 at% Ni. For the Ni52Ti48 specimen long time exposed diffraction patterns of a single grain show besides the expected reflections of the B2-phase, two sets of extra reflections in different zones. The first type of spots is explained by lattice displacement waves, which are regarded as precursors of the martensitic Ni-Ti phases, B 19' and R-phase, respectively. The second set of reflection with more diffuse intensity than the other reflections is related to Ni4Ti3 precipitates in an early state of formation. For the Ni-richer Ni54.5Ti45.5 alloy only Ni4Ti3 precipitates in an early state of formation are found but no precursors of the B 19'- and R-phase.
Keywords: A1 Journal article; Electron microscopy for materials research (EMAT)
Times cited: 2
DOI: 10.1051/jp4:2001874
|
|
|
“Nanodiamonds do not provide unique evidence for a Younger Dryas impact”. Tian H, Schryvers D, Claeys P, Proceedings of the National Academy of Sciences of the United States of America 108, 40 (2011). http://doi.org/10.1073/pnas.1007695108
Abstract: Microstructural, δ13C isotope and C/N ratio investigations were conducted on excavated material from the black Younger Dryas boundary in Lommel, Belgium, aiming for a characterisation of the carbon content and structures. Cubic diamond nanoparticles are found in large numbers. The larger ones with diameters around or above 10 nm often exhibit single or multiple twins. The smaller ones around 5 nm in diameter are mostly defect-free. Also larger flake-like particles, around 100 nm in lateral dimension, with a cubic diamond structure are observed as well as large carbon onion structures. The combination of these characteristics does not yield unique evidence for an exogenic impact related to the investigated layer.
Keywords: A1 Journal article; Electron microscopy for materials research (EMAT)
Impact Factor: 9.661
Times cited: 32
DOI: 10.1073/pnas.1007695108
|
|
|
“Microstructure and defect characterization at interfaces in TiN/CrN multilayer coatings”. Major L, Tirry W, Van Tendeloo G, Surface and coatings technology 202, 6075 (2008). http://doi.org/10.1016/j.surfcoat.2008.07.005
Abstract: Microstructures of TiN/CrN multilayer coatings deposited on austenite steel (Cr Ni 18 8) by pulsed laser deposition (PLD) are characterized using transmission electron microscopy while their mechanical properties were assessed in a ball-on-disk test. All coatings have the same total thickness of about 1 ìm. The individual layers show a highly defective columnar structure, which is characterized by conventional electron microscopy (TEM) as well as by high resolution TEM. These techniques, combined with measurements of the local chemical composition through EDS prove that PLD allows to produce fully separated CrN and TiN layers. The friction, and consequently the wear, are lowered by increasing the total number of layers in the coating.
Keywords: A1 Journal article; Electron microscopy for materials research (EMAT)
Impact Factor: 2.589
Times cited: 23
DOI: 10.1016/j.surfcoat.2008.07.005
|
|
|
“Carbon dioxide dissociation in a microwave plasma reactor operating in a wide pressure range and different gas inlet configurations”. Belov I, Vermeiren V, Paulussen S, Bogaerts A, Journal of CO2 utilization 24, 386 (2018). http://doi.org/10.1016/j.jcou.2017.12.009
Abstract: Microwave (MW) plasmas represent a promising solution for efficient CO2 dissociation. MW discharges are also very versatile and can be sustained at various pressure and gas flow regimes. To identify the most favorable conditions for the further scale-up of the CO2 decomposition reaction, a MW plasma reactor operating in pure CO2 in a wide pressure range (200 mbar–1 bar) is studied. Three different gas flow configurations are explored: a direct, reverse and a vortex regime. The CO2 conversion and energy efficiency drop almost linearly with increasing pressure, regardless of the gas flow regime. The results obtained in the direct flow configuration underline the importance of post-discharge cooling, as the exhaust of the MW plasma reactor in this regime expanded into the vacuum chamber without additional quenching. As a result, this system yields exhaust temperatures of up to 1000 K, which explains the lowest conversion (∼3.5% at 200 mbar and 2% at 1 bar). A post-discharge cooling step is introduced for the reverse gas inlet regime and allows the highest conversion to be achieved (∼38% at 200 mbar and 6.2% at 1 bar, with energy efficiencies of 23% and 3.7%). Finally, a tangential gas inlet is utilized in the vortex configuration to generate a swirl flow pattern. This results in the generation of a stable discharge in a broader range of CO2 flows (15–30 SLM) and the highest energy efficiencies obtained in this study (∼25% at 300 mbar and ∼13% at 1 bar, at conversions of 21% and 12%). The experimental results are complemented with computational fluid dynamics simulations and with the analysis of the latest literature to identify the further research directions.
Keywords: A1 Journal article; Plasma Lab for Applications in Sustainability and Medicine – Antwerp (PLASMANT)
Impact Factor: 4.292
Times cited: 8
DOI: 10.1016/j.jcou.2017.12.009
|
|
|
“Modeling of CO2Splitting in a Microwave Plasma: How to Improve the Conversion and Energy Efficiency”. Berthelot A, Bogaerts A, The journal of physical chemistry: C : nanomaterials and interfaces 121, 8236 (2017). http://doi.org/10.1021/acs.jpcc.6b12840
Abstract: Microwave plasmas are one of the most promising techniques for CO2 conversion into value-added chemicals and fuels since they are very energy efficient. Nevertheless, experiments show that this high energy efficiency is only reached at low pressures and significantly drops toward atmospheric pressure, which is a clear limitation for industrial applications. In this paper, we use a zerodimensional reaction kinetics model to simulate a CO2 microwave plasma in a pressure range from 50 mbar to 1 bar, in order to evaluate the reasons for this decrease in energy efficiency at atmospheric pressure. The code includes a detailed description of the vibrational kinetics of CO2, CO, and O2 as well as the energy exchanges between them because the vibrational kinetics is known to be crucial for energy efficient CO2 splitting. First, we use a self-consistent gas temperature calculation in order to assess the key performance indicators for CO2 splitting, i.e., the CO2 conversion and corresponding energy efficiency. Our results indicate that lower pressures and higher power densities lead to more vibrational excitation, which is beneficial for the conversion. We also demonstrate the key role of the gas temperature. The model predicts the highest conversion and energy efficiencies at pressures around 300 mbar, which is in agreement with experiments from the literature. We also show the beneficial aspect of fast gas cooling in the afterglow at high pressure. In a second step, we study in more detail the effects of pressure, gas temperature, and power density on the vibrational distribution function and on the dissociation and recombination mechanisms of CO2, which define the CO2 splitting efficiency. This study allows us to identify the limiting factors of CO2 conversion and to propose potential solutions to improve the process.
Keywords: A1 Journal article; Plasma Lab for Applications in Sustainability and Medicine – Antwerp (PLASMANT)
Impact Factor: 4.536
Times cited: 47
DOI: 10.1021/acs.jpcc.6b12840
|
|
|
“Direct Imaging of ALD Deposited Pt Nanoclusters inside the Giant Pores of MIL-101”. Meledina M, Turner S, Filippousi M, Leus K, Lobato I, Ramachandran RK, Dendooven J, Detavernier C, Van Der Voort P, Van Tendeloo G, Particle and particle systems characterization 33, 382 (2016). http://doi.org/10.1002/ppsc.201500252
Abstract: MIL-101 giant-pore metal-organic framework (MOF) materials have been loaded with Pt nanoparticles using atomic layer deposition. The final structure has been investigated by aberration-corrected annular dark-field scanning transmission electron microscopy under strictly controlled low dose conditions. By combining the acquired experimental data with image simulations, the position of the small clusters within the individual pores of a metal-organic framework has been determined. The embedding of the Pt nanoparticles is confirmed by electron tomography, which shows a distinct ordering of the highly uniform Pt nanoparticles. The results show that atomic layer deposition is particularly well-suited for the deposition of individual nanoparticles inside MOF framework pores and that, upon proper regulation of the incident electron dose, annular dark-field scanning transmission electron microscopy is a powerful tool for the characterization of this type of materials at a local scale.
Keywords: A1 Journal article; Engineering sciences. Technology; Electron microscopy for materials research (EMAT)
Impact Factor: 4.474
Times cited: 11
DOI: 10.1002/ppsc.201500252
|
|
|
“Analysis of X-ray spectra excited by X rays, electrons, and protons in monazite”. Annegarn HJ, Madiba CCP, Sellschop JPF, Genz H, Hoffmann DHH, Low W, Richter A, Van Grieken RE, Physical review : C : nuclear physics 16, 379 (1977). http://doi.org/10.1103/PHYSREVC.16.379
Abstract: Mineral monazite from Malaysia has been investigated by energy dispersive x-ray analysis employing three different methods: x-ray, relativistic electron and proton induced excitation. An upper limit of 15 ppm has been placed on the possible concentration of the superheavy element with Z=126.
Keywords: A1 Journal article; AXES (Antwerp X-ray Analysis, Electrochemistry and Speciation)
DOI: 10.1103/PHYSREVC.16.379
|
|