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“Phosphorus scarcity contributes to nitrogen limitation in lowland tropical rainforests”. Vallicrosa H, Lugli LF, Fuchslueger L, Sardans J, Ramirez-Rojas I, Verbruggen E, Grau O, Brechet L, Peguero G, Van Langenhove L, Verryckt LT, Terrer C, Llusia J, Ogaya R, Marquez L, Roc-Fernandez P, Janssens I, Penuelas J, Ecology 104, e4049 (2023). http://doi.org/10.1002/ECY.4049
Abstract: There is increasing evidence to suggest that soil nutrient availability can limit the carbon sink capacity of forests, a particularly relevant issue considering today's changing climate. This question is especially important in the tropics, where most part of the Earth's plant biomass is stored. To assess whether tropical forest growth is limited by soil nutrients and to explore N and P limitations, we analyzed stem growth and foliar elemental composition of the five stem widest trees per plot at two sites in French Guiana after 3 years of nitrogen (N), phosphorus (P), and N + P addition. We also compared the results between potential N-fixer and non-N-fixer species. We found a positive effect of N fertilization on stem growth and foliar N, as well as a positive effect of P fertilization on stem growth, foliar N, and foliar P. Potential N-fixing species had greater stem growth, greater foliar N, and greater foliar P concentrations than non-N-fixers. In terms of growth, there was a negative interaction between N-fixer status, N + P, and P fertilization, but no interaction with N fertilization. Because N-fixing plants do not show to be completely N saturated, we do not anticipate N providing from N-fixing plants would supply non-N-fixers. Although the soil-age hypothesis only anticipates P limitation in highly weathered systems, our results for stem growth and foliar elemental composition indicate the existence of considerable N and P co-limitation, which is alleviated in N-fixing plants. The evidence suggests that certain mechanisms invest in N to obtain the scarce P through soil phosphatases, which potentially contributes to the N limitation detected by this study.
Keywords: A1 Journal article; Plant and Ecosystems (PLECO) – Ecology in a time of change
Impact Factor: 4.8
DOI: 10.1002/ECY.4049
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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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“Surfactant layers on gold nanorods”. Mosquera J, Wang D, Bals S, Liz-Marzan LM, Accounts of chemical research 56, 1204 (2023). http://doi.org/10.1021/ACS.ACCOUNTS.3C00101
Abstract: Gold nanorods (Au NRs) are an exceptionally promising tool in nanotechnology due to three key factors: (i) their strong interaction with electromagnetic radiation, stemming from their plasmonic nature, (ii) the ease with which the resonance frequency of their longitudinal plasmon mode can be tuned from the visible to the near-infrared region of the electromagnetic spect r u m based on their aspect ratio, and (iii) their simple and cost-effective preparation through seed-mediated chemical growth. In this synthetic method, surfactants play a critical role in controlling the size, shape, and colloidal stabi l i t y of Au NRs. For example, surfactants can stabilize specific crystallographic facets during the formation of Au NRs, leading to t h e formation of NRs with specific morphologies. The process of surfactant adsorption onto the NR surface may result in various assemblies of surfactant molecules, such as spherical micelles, elongated micelles, or bilayers. Again, the assembly mode is critical toward determining the further availabi l i t y of the Au NR surface to the surrounding medium. Despite its importance and a great deal of research effort, the interaction between Au NPs and surfactants remains insufficiently understood, because the assembly process is influenced by numerous factors, including the chemical nature of the surfactant, the surface morphology of Au NPs, and solution parameters. Therefore, gaining a more comprehensive understanding of these interactions is essential to unlock the full potential of the seed-mediated growth method and the applications of plasmonic NPs. A plethora of characterization techniques have been applied to reach such an understanding , but many open questions remain. In this Account, we review the current knowledge on the interactions between surfactants and Au NRs. We briefly introduce the state-of-the-art methods for synthesizing Au NRs and highlight the crucial role of cationic surfactants during this process. The self-assembly and organization of surfactants on the Au NR surface is then discussed to better understand their role in seed-mediated growth. Subsequently, we provide examples and elucidate how chemical additives can be used to modulate micellar assemblies, in turn allowing for a finer control over the growth of Au NRs, including chiral NRs. Next, we review the main experimental characterization and computational modeling techniques that have been applied to shed light on the arrangement of surfactants on Au NRs and summarize the advantages and disadvantages for each technique. The Account ends with a “Conclusions and Outlook” section, outlining promising future research directions and developments that we consider are sti l l required, mostly related to the application of electron microscopy in liquid and in 3D. Finally, we remark on the potential of exploiting machine learning techniques to predict synthetic routes for NPs with predefined structures and properties.
Keywords: A1 Journal article; Electron microscopy for materials research (EMAT)
Impact Factor: 18.3
Times cited: 8
DOI: 10.1021/ACS.ACCOUNTS.3C00101
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“Two pathways for the degradation of orpiment pigment (As₂S₃) found in paintings”. Broers FTH, Janssens K, Weker JN, Webb SM, Mehta A, Meirer F, Keune K, Journal of the American Chemical Society 145, 8847 (2023). http://doi.org/10.1021/JACS.2C12271
Abstract: Paintings are complex objects containing many different chemical compounds that can react over time. The degradation of arsenic sulfide pigments causes optical changes in paintings. The main degradation product was thought to be white arsenolite (As2O3), but previous research also showed the abundant presence of As(V) species. In this study, we investigate the influence of the presence of a medium on the degradation mechanism of orpiment (As2S3) using synchrotron radiation (SR)-based tomographic transmission X-ray microscopy, SR-based micro-X-ray fluorescence, and Xray absorption near edge structure spectroscopy. Upon direct illumination of dry orpiment powder using UV-visible light, only the formation of As2O3 was observed. When As2S3 was surrounded by a medium and illuminated, As2O3 was only observed in the area directly exposed to light, while As(V) degradation species were found elsewhere in the medium. Without accelerated artificial light aging, As(V)(aq) species are formed and migrate throughout the medium within weeks after preparation. In both scenarios, the As(V) species form via intermediate As(III)(aq) species and the presence of a medium is necessary. As(V)(aq) species can react with available cations to form insoluble metal arsenates, which induces stress within the paint layers (leading to, e.g., cracks and delamination) or can lead to a visual change of the image of the painting.
Keywords: A1 Journal article; Antwerp X-ray Imaging and Spectroscopy (AXIS)
Impact Factor: 15
DOI: 10.1021/JACS.2C12271
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“Enhanced NH3Synthesis from Air in a Plasma Tandem-Electrocatalysis System Using Plasma-Engraved N-Doped Defective MoS2”. Zheng J, Zhang H, Lv J, Zhang M, Wan J, Gerrits N, Wu A, Lan B, Wang W, Wang S, Tu X, Bogaerts A, Li X, JACS Au 3, 1328 (2023). http://doi.org/10.1021/jacsau.3c00087
Abstract: We have developed a sustainable method to produce NH3 directly from air using a plasma tandem-electrocatalysis system that operates via the N2−NOx−NH3 pathway. To efficiently reduce NO2− to NH3, we propose a novel electrocatalyst consisting of defective N-doped molybdenum sulfide nanosheets on vertical graphene arrays (N-MoS2/VGs). We used a plasma engraving process to form the metallic 1T phase, N doping, and S vacancies in the electrocatalyst simultaneously. Our system exhibited a remarkable NH3 production rate of 7.3 mg h−1 cm−2 at −0.53 V vs RHE, which is almost 100 times higher than the state-of-the-art electrochemical nitrogen reduction reaction and more than double that of other hybrid systems. Moreover, a low energy consumption of only 2.4 MJ molNH3−1 was achieved in this study. Density functional theory calculations revealed that S vacancies and doped N atoms play a dominant role in the selective reduction of NO2− to NH3. This study opens up new avenues for efficient NH3 production using cascade systems.
Keywords: A1 Journal Article; Plasma, laser ablation and surface modeling Antwerp (PLASMANT) ;
DOI: 10.1021/jacsau.3c00087
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Van Oijstaeijen W, Finizola e Silva M, Back P, Collins A, Verheyen K, De Beelde R, Cools J, Van Passel S (2023) The Nature Smart Cities business model : a rapid decision-support and scenario analysis tool to reveal the multi-benefits of green infrastructure investments. 127923–14
Abstract: Incorporating natural spaces within urban areas has been shown to have multiple benefits. However, despite greening and adaptation strategies at different levels of government, progress remains slow with a lack of easy to use and comprehensive tools identified as key to overcoming this. This paper presents a co-designed tool with academic and local authority partners to demonstrate the ecosystem service benefits of small-scale urban green infrastructure projects. Through the tool, users can readily assess the impact of green infrastructure investments on the delivery of a selection of ecosystem services in the early stages of a project. Furthermore, the tool provides a standardised assessment of cultural ecosystem services' contributions, as well as offering a method to score spatial designs on the impact on habitat for biodiversity. Use of the tool is demonstrated using a pilot study in Kapelle, the Netherlands. The results set out an overview of the impacts of the spatial design on estimated ecosystem service delivery. They also show the tool's potential to add value in early project stages and as a planning and design tool, helping to maximise the benefits that can be achieved through green infrastructure design. Complementing these arguments with ball-park estimations on green infrastructure costs, the Nature Smart Cities Business Model aims to offer public sector officers the means to create a business case for green infrastructure measures, facilitating the translation from strategies to actual plans, thus benefitting green infrastructure implementation in the public realm.
Keywords: Administrative Services; A1 Journal article; Art; Engineering Management (ENM)
Impact Factor: 6.4
DOI: 10.1016/J.UFUG.2023.127923
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“Chester supersolid of spatially indirect excitons in double-layer semiconductor heterostructures”. Conti S, Perali A, Hamilton AR, Milošević, MV, Peeters FM, Neilson D, Physical review letters 130, 057001 (2023). http://doi.org/10.1103/PHYSREVLETT.130.057001
Abstract: A supersolid, a counterintuitive quantum state in which a rigid lattice of particles flows without resistance, has to date not been unambiguously realized. Here we reveal a supersolid ground state of excitons in a double-layer semiconductor heterostructure over a wide range of layer separations outside the focus of recent experiments. This supersolid conforms to the original Chester supersolid with one exciton per supersolid site, as distinct from the alternative version reported in cold-atom systems of a periodic density modulation or clustering of the superfluid. We provide the phase diagram augmented by the supersolid. This new phase appears at layer separations much smaller than the predicted exciton normal solid, and it persists up to a solid-solid transition where the quantum phase coherence collapses. The ranges of layer separations and exciton densities in our phase diagram are well within reach of the current experimental capabilities.
Keywords: A1 Journal article; Condensed Matter Theory (CMT)
Impact Factor: 8.6
Times cited: 7
DOI: 10.1103/PHYSREVLETT.130.057001
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“Absence of a pressure gap and atomistic mechanism of the oxidation of pure Co nanoparticles”. Vijayakumar J, Savchenko TM, Bracher DM, Lumbeeck G, Béché, A, Verbeeck J, Vajda Š, Nolting F, Vaz Caf, Kleibert A, Nature communications 14, 174 (2023). http://doi.org/10.1038/s41467-023-35846-0
Abstract: Understanding chemical reactivity and magnetism of 3<italic>d</italic>transition metal nanoparticles is of fundamental interest for applications in fields ranging from spintronics to catalysis. Here, we present an atomistic picture of the early stage of the oxidation mechanism and its impact on the magnetism of Co nanoparticles. Our experiments reveal a two-step process characterized by (i) the initial formation of small CoO crystallites across the nanoparticle surface, until their coalescence leads to structural completion of the oxide shell passivating the metallic core; (ii) progressive conversion of the CoO shell to Co<sub>3</sub>O<sub>4</sub>and void formation due to the nanoscale Kirkendall effect. The Co nanoparticles remain highly reactive toward oxygen during phase (i), demonstrating the absence of a pressure gap whereby a low reactivity at low pressures is postulated. Our results provide an important benchmark for the development of theoretical models for the chemical reactivity in catalysis and magnetism during metal oxidation at the nanoscale.
Keywords: A1 Journal article; Engineering sciences. Technology; Electron microscopy for materials research (EMAT)
Impact Factor: 16.6
Times cited: 1
DOI: 10.1038/s41467-023-35846-0
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“A simple way to calculate the volume and surface area of avian eggs”. Shi P, Chen L, Quinn BK, Yu K, Miao Q, Guo X, Lian M, Gielis J, Niklas KJ, Annals of the New York Academy of Sciences 1524, 118 (2023). http://doi.org/10.1111/NYAS.15000
Abstract: Egg geometry can be described using Preston's equation, which has seldom been used to calculate egg volume (V) and surface area (S) to explore S versus V scaling relationships. Herein, we provide an explicit re-expression of Preston's equation (designated as EPE) to calculate V and S, assuming that an egg is a solid of revolution. The side (longitudinal) profiles of 2221 eggs of six avian species were digitized, and the EPE was used to describe each egg profile. The volumes of 486 eggs from two avian species predicted by the EPE were compared with those obtained using water displacement in graduated cylinders. There was no significant difference in V using the two methods, which verified the utility of the EPE and the hypothesis that eggs are solids of revolution. The data also indicated that V is proportional to the product of egg length (L) and maximum width (W) squared. A 2/3-power scaling relationship between S and V for each species was observed, that is, S is proportional to (LW2)(2/3). These results can be extended to describe the shapes of the eggs of other species to study the evolution of avian (and perhaps reptilian) eggs.
Keywords: A1 Journal article; Engineering sciences. Technology; Sustainable Energy, Air and Water Technology (DuEL)
Impact Factor: 5.2
DOI: 10.1111/NYAS.15000
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“Gaussian approximation potentials for accurate thermal properties of two-dimensional materials”. Kocabas T, Keceli M, Vazquez-Mayagoitia A, Sevik C, Nanoscale 15, 8772 (2023). http://doi.org/10.1039/D3NR00399J
Abstract: Two-dimensional materials (2DMs) continue to attract a lot of attention, particularly for their extreme flexibility and superior thermal properties. Molecular dynamics simulations are among the most powerful methods for computing these properties, but their reliability depends on the accuracy of interatomic interactions. While first principles approaches provide the most accurate description of interatomic forces, they are computationally expensive. In contrast, classical force fields are computationally efficient, but have limited accuracy in interatomic force description. Machine learning interatomic potentials, such as Gaussian Approximation Potentials, trained on density functional theory (DFT) calculations offer a compromise by providing both accurate estimation and computational efficiency. In this work, we present a systematic procedure to develop Gaussian approximation potentials for selected 2DMs, graphene, buckled silicene, and h-XN (X = B, Al, and Ga, as binary compounds) structures. We validate our approach through calculations that require various levels of accuracy in interatomic interactions. The calculated phonon dispersion curves and lattice thermal conductivity, obtained through harmonic and anharmonic force constants (including fourth order) are in excellent agreement with DFT results. HIPHIVE calculations, in which the generated GAP potentials were used to compute higher-order force constants instead of DFT, demonstrated the first-principles level accuracy of the potentials for interatomic force description. Molecular dynamics simulations based on phonon density of states calculations, which agree closely with DFT-based calculations, also show the success of the generated potentials in high-temperature simulations.
Keywords: A1 Journal article; Engineering sciences. Technology; Condensed Matter Theory (CMT)
Impact Factor: 6.7
DOI: 10.1039/D3NR00399J
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“Valley-polarized and enhanced transmission in graphene with a smooth strain profile”. Wang S, Tian H, Sun M, Journal of physics : condensed matter 35, 304002 (2023). http://doi.org/10.1088/1361-648X/ACCBF9
Abstract: We explore the influence of strain on the valley-polarized transmission of graphene by employing the wave-function matching and the non-equilibrium Green's function technique. When the transmission is along the armchair direction, we show that the valley polarization and transmission can be improved by increasing the width of the strained region and increasing (decreasing) the extensional strain in the armchair (zigzag) direction. It is noted that the shear strain does not affect transmission and valley polarization. Furthermore, when we consider the smooth strain barrier, the valley-polarized transmission can be enhanced by increasing the smoothness of the strain barrier. We hope that our finding can shed new light on constructing graphene-based valleytronic and quantum computing devices by solely employing strain.
Keywords: A1 Journal article; Condensed Matter Theory (CMT)
Impact Factor: 2.7
DOI: 10.1088/1361-648X/ACCBF9
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“Superconductivity in functionalized niobium-carbide MXenes”. Sevik C, Bekaert J, Milošević, MV, Nanoscale 15, 8792 (2023). http://doi.org/10.1039/D3NR00347G
Abstract: We detail the effects of Cl and S functionalization on the superconducting properties of layered (bulk) and monolayer niobium carbide (Nb2C) MXene crystals, based on first-principles calculations combined with Eliashberg theory. For bulk layered Nb2CCl2, the calculated superconducting transition temperature (T-c) is in very good agreement with the recently measured value of 6 K. We show that T-c is enhanced to 10 K for monolayer Nb2CCl2, due to an increase in the density of states at the Fermi level, and the corresponding electron-phonon coupling. We further demonstrate feasible gate- and strain-induced enhancements of T-c for both bulk-layered and monolayer Nb2CCl2 crystals, resulting in T-c values of around 38 K. In the S-functionalized Nb2CCl2 crystals, our calculations reveal the importance of phonon softening in understanding their superconducting properties. Finally, we predict that Nb3C2S2 in bulk-layered and monolayer forms is also superconducting, with a T-c of around 28 K. Considering that Nb2C is not superconducting in pristine form, our findings promote functionalization as a pathway towards robust superconductivity in MXenes.
Keywords: A1 Journal article; Engineering sciences. Technology; Condensed Matter Theory (CMT)
Impact Factor: 6.7
DOI: 10.1039/D3NR00347G
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“Wave-packet scattering at a normal-superconductor interface in two-dimensional materials : a generalized theoretical approach”. Linard FJA, Moura VN, Covaci L, Milošević, MV, Chaves A, Physical review B 107, 165306 (2023). http://doi.org/10.1103/PHYSREVB.107.165306
Abstract: A wave-packet time evolution method, based on the split-operator technique, is developed to investigate the scattering of quasiparticles at a normal-superconductor interface of arbitrary profile and shape. As a practical application, we consider a system where low-energy electrons can be described as Dirac particles, which is the case for most two-dimensional materials, such as graphene and transition-metal dichalcogenides. However, the method is easily adapted for other cases such as electrons in few-layer black phosphorus or any Schrodinger quasiparticles within the effective mass approximation in semiconductors. We employ the method to revisit Andreev reflection in mono-, bi-, and trilayer graphene, where specular-and retro-reflection cases are observed for electrons scattered by a steplike superconducting region. The effect of opening a zero-gap channel across the superconducting region on the electron and hole scattering is also addressed, as an example of the versatility of the technique proposed here.
Keywords: A1 Journal article; Electron microscopy for materials research (EMAT); Condensed Matter Theory (CMT)
Impact Factor: 3.7
DOI: 10.1103/PHYSREVB.107.165306
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“Ginzburg-Landau surface energy of multiband superconductors : derivation and application to selected systems”. Bekaert J, Bringmans L, Milošević, MV, Journal of physics : condensed matter 35, 325602 (2023). http://doi.org/10.1088/1361-648X/ACD217
Abstract: We determine the energy of an interface between a multiband superconducting and a normal half-space, in presence of an applied magnetic field, based on a multiband Ginzburg-Landau (GL) approach. We obtain that the multiband surface energy is fully determined by the critical temperature, electronic densities of states, and superconducting gap functions associated with the different band condensates. This furthermore yields an expression for the thermodynamic critical magnetic field, in presence of an arbitrary number of contributing bands. Subsequently, we investigate the sign of the surface energy as a function of material parameters, through numerical solution of the GL equations. Here, we consider two distinct cases: (i) standard multiband superconductors with attractive interactions, and (ii) a three-band superconductor with a chiral ground state with phase frustration, arising from repulsive interband interactions. Furthermore, we apply this approach to several prime examples of multiband superconductors, such as metallic hydrogen and MgB2, based on microscopic parameters obtained from first-principles calculations.
Keywords: A1 Journal article; Condensed Matter Theory (CMT)
Impact Factor: 2.7
DOI: 10.1088/1361-648X/ACD217
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“Suppressing hydrogen blistering in a magnesium-rich healable laser powder bed fusion aluminum alloy analyzed by in-situ high resolution techniques”. Gheysen J, Kashiwar A, Idrissi H, Villanova J, Simar A, Materials &, design 231, 112024 (2023). http://doi.org/10.1016/J.MATDES.2023.112024
Abstract: Hydrogen blistering, i.e. precipitation of supersaturated hydrogen at elevated temperatures, increases porosity during heat treatments in 4xxx series Al alloys manufactured by laser powder bed fusion (LPBF), as demonstrated by 3D X-ray nano-imaging in AlSi12. This paper proposes the design of a healable Al alloy to suppress hydrogen blistering and improve the damage management. The strategy consists of solute atoms diffusing towards nano-voids and precipitating on their surface, thereby filling the damage sites. A new healable Al alloy was thus developed and successfully manufactured by LPBF. 3D X-ray nano-imaging evidenced that the addition of Mg in 4xxx series Al alloys suppresses the hydrogen blistering. This is expectedly due to Mg in solid solution which increases the hydrogen solubility in the Al matrix and due to the healing of these hydrogen pores. Moreover, a significant healing of voids smaller than 500 nm diameter is observed. In-situ heating inside transmission electron microscopy pointed out that Al matrix diffuses inside the fractured Mg2Si particles, thereby demonstrating the healing ability of the new alloy. This has opened the doors to development of new healable Al alloys manufactured by LPBF as well as to new post-treatments to tailor mechanical properties and microstructure without hydrogen blistering.
Keywords: A1 Journal article; Engineering sciences. Technology; Electron microscopy for materials research (EMAT)
Impact Factor: 8.4
DOI: 10.1016/J.MATDES.2023.112024
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“Critical challenges towards the commercial rollouts of a LOHC-based H2 economy”. Perreault P, Van Hoecke L, Pourfallah H, Kummamuru NB, Boruntea C-R, Preuster P, Current opinion in green and sustainable chemistry 41, 100836 (2023). http://doi.org/10.1016/J.COGSC.2023.100836
Abstract: This short review discusses recent developments related to the storage and release of hydrogen from liquid organic hydrogen carriers (LOHCs). It focusses on three areas of recent literature: the application and development of novel, alternative LOHC systems, process development and process integration in the storage and release of hydrogen from LOHCs, and the electrochemical conversion of LOHCs. For the novel LOHC systems, we briefly focus on reaction enthalpy and storage capacity as main KPIs for the comparison of those systems and discuss the technical availability on a relevant scale. In the field of process- and reactor development our emphasis lies on the power density of the chemical conversion units. The LOHC technology still requires further development to reach the necessary energy efficiency, flexibility and overall research maturity for market competitivity and commercial impact.
Keywords: A1 Journal article; Engineering sciences. Technology; Sustainable Energy, Air and Water Technology (DuEL)
Impact Factor: 9.3
DOI: 10.1016/J.COGSC.2023.100836
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“Assessing the future of second-generation bioethanol by 2030 : a techno-economic assessment integrating technology learning curves”. Vasilakou K, Nimmegeers P, Thomassen G, Billen P, Van Passel S, Applied energy 344, 121263 (2023). http://doi.org/10.1016/J.APENERGY.2023.121263
Abstract: Lignocellulosic biomass is the most abundant source of renewable biomass and is seen as a high-potential replacement for petroleum-based resources. The conversion technologies to advanced biofuels are still at a low maturity level, thus allowing for future cost reductions through technological learning. This fact is barely considered in state-of-the-art techno-economic assessments and a structured approach to account for technological learning in techno-economic assessments is needed. In this study, a framework for techno-economic assessments of advanced biofuels, integrating learning curves, is proposed. As a validation of this framework, the economic feasibility of the valorization of corn stover for the production of second-generation bioethanol in Belgium is studied. Process flowsheet simulations in Aspen Plus are developed, with an emphasis on the comparison of four different pretreatment technologies and two plant capacities at 156 dry kt biomass/y and 667 dry kt/y. The dilute acid pretreatment model of the large-scale biorefinery required the lowest minimum learning rate to reach an economically feasible biorefinery by 2030, being 3.9%, almost half as the one calculated for the smaller scale plant. This learning rate seems to be achievable based on learning rates commonly estimated in literature. We conclude that there is a potential for advanced ethanol production in Belgium under the current state of technology for large-scale biorefineries, which require additional biomass imports, when accounting for future cost reductions through learning
Keywords: A1 Journal article; Economics; Engineering sciences. Technology; Engineering Management (ENM); Intelligence in PRocesses, Advanced Catalysts and Solvents (iPRACS)
Impact Factor: 11.2
DOI: 10.1016/J.APENERGY.2023.121263
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“Modeling the hygrothermal behavior of green walls in Comsol Multiphysics®, : validation against measurements in a climate chamber”. Alvarado-Alvarado AA, De Bock A, Ysebaert T, Belmans B, Denys S, Building and environment 238, 110377 (2023). http://doi.org/10.1016/J.BUILDENV.2023.110377
Abstract: Green walls (GW) can diminish building's surface temperature through shading, insulation, and evapotranspiration mechanisms. These can be analyzed by computer models that account for heat and mass transfer phenomena. However, most previous models were one-dimensional thermal simulations in which boundary conditions (BC), like convective moisture transport, were not or only partly considered. The present work proposes a more comprehensive way to predict GW's hygrothermal behavior by integrating a 3D multiphysics model that couples heat and moisture transport in Comsol Multiphysics®. The air cavity that usually separates the GW from the building was also considered. Heat sink terms were added to represent plants' transpiration and substrates' evaporation, considering the leaf area density (LAD) and substrate's water saturation (Sr). The model was validated against experiments where four green wall-test panels (GW-TPs) were evaluated in a climate chamber under steady-state conditions. This provides a much sounder approach for validation than what currently exists (r = 0.97; RMSE = 0.33 °C). The four GW-TPs decreased the masonry's surface temperature in the range of 0.89–1.14 °C (0.97 ± 0.11 SD °C). The average contribution of the evapotranspiration effect was 30%, whereas the contribution of the air cavity was 60.7 ± 0.09%. The temperature at the substrate's rear was reduced on average by 0.57 ± 0.15 SD °C. When solar radiation was considered as a BC, the GW-TPs decreased the building's surface temperature by 10 °C. Lastly, high values of LAD and Sr translated into increased temperature reduction values.
Keywords: A1 Journal article; Engineering sciences. Technology; Sustainable Energy, Air and Water Technology (DuEL); Energy and Materials in Infrastructure and Buildings
Impact Factor: 7.4
DOI: 10.1016/J.BUILDENV.2023.110377
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“Challenges in unconventional catalysis”. Bogaerts A, Centi G, Hessel V, Rebrov E, Catalysis today 420, 114180 (2023). http://doi.org/10.1016/j.cattod.2023.114180
Abstract: Catalysis science and technology increased efforts recently to progress beyond conventional “thermal” catalysis and face the challenges of net-zero emissions and electrification of production. Nevertheless, a better gaps and opportunities analysis is necessary. This review analyses four emerging areas of unconventional or less- conventional catalysis which share the common aspect of using directly renewable energy sources: (i) plasma catalysis, (ii) catalysis for flow chemistry and process intensification, (iii) application of electromagnetic (EM) fields to modulate catalytic activity and (iv) nanoscale generation at the catalyst interface of a strong local EM by plasmonic effect. Plasma catalysis has demonstrated synergistic effects, where the outcome is higher than the sum of both processes alone. Still, the underlying mechanisms are complex, and synergy is not always obtained. There is a crucial need for a better understanding to (i) design catalysts tailored to the plasma environment, (ii) design plasma reactors with optimal transport of plasma species to the catalyst surface, and (iii) tune the plasma conditions so they work in optimal synergy with the catalyst. Microfluidic reactors (flow chemistry) is another emerging sector leading to the intensification of catalytic syntheses, particularly in organic chemistry. New unconventional catalysts must be designed to exploit in full the novel possibilities. With a focus on (a) continuous-flow photocatalysis, (b) electrochemical flow catalysis, (c) microwave flow catalysis and (d) ultra sound flow activation, a series of examples are discussed, with also indications on scale-up and process indus trialisation. The third area discussed regards the effect on catalytic performances of applying oriented EM fields spanning several orders of magnitude. Under well-defined conditions, gas breakdown and, in some cases, plasma formation generates activated gas phase species. The EM field-driven chemical conversion processes depend further on structured electric/magnetic catalysts, which shape the EM field in strength and direction. Different effects influencing chemical conversion have been reported, including reduced activation energy, surface charging, hot spot generation, and selective local heating. The last topic discussed is complementary to the third, focusing on the possibility of tuning the photo- and electro-catalytic properties by creating a strong localised electrical field with a plasmonic effect. The novel possibilities of hot carriers generated by the plasmonic effect are also discussed. This review thus aims to stimulate the reader to make new, creative catalysis to address the challenges of reaching a carbon-neutral world.
Keywords: A1 Journal article; Engineering sciences. Technology; Plasma Lab for Applications in Sustainability and Medicine – Antwerp (PLASMANT)
Impact Factor: 5.3
DOI: 10.1016/j.cattod.2023.114180
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“Towards a novel strategy for soot removal from water-soluble materials : the synergetic effect of hydrogels and cyclomethicone on gelatine emulsion-based photographs”. Ortega Saez N, Arno R, Marchetti A, Cauberghs S, Janssens K, Van der Snickt G, Al-Emam E, Heritage science 11, 78 (2023). http://doi.org/10.1186/S40494-023-00916-5
Abstract: Gels are a popular cleaning method for paper conservators and a lot of research has been done concerning gel cleaning of paper objects over the last 15 years. Despite the close interconnection between the conservation fields of paper and photographic material, research on using gels for cleaning photographs is very scarce. However, gels can provide an excellent cleaning method for photographic material. Cleaning silver gelatine prints with aqueous solvents is very complex due to the hydrophilic properties and fragility of the gelatine layer which makes mechanical cleaning difficult. The properties of gels ensure better control over the flow and evaporation of the solvent, facilitating the cleaning process. This study is the first insight into the viability of using gellan gum gel and polyvinyl acetate-borax (PVAc-borax) gel to clean contaminants from the surface of silver gelatine photographs. It is based on self-made samples that were artificially aged and contaminated with soot. Water, ethanol (EtOH), and Kodak Photo-flo were studied as solvents to remove the soot from the silver gelatine-based prints. These solvents were loaded into the aforementioned gels and applied to the samples in two different methods. These gel cleaning methods were subsequently compared with traditional cleaning methods. In addition, the usage of cyclomethicone D4 as a protective mask for the gelatine layer was studied. Measuring methods used to evaluate the cleaning were visual comparison, microscopic observation, and densitometry. ATR-FTIR measurements were also conducted to investigate potential side-effects of the cleaning methods on the prints, such as unwanted chemical transformations or the presence of gel residues after the treatments. Most of the gel cleaning methods within this study proved to be inadequate, with the exception of the gellan gum gel loaded with 30% EtOH. It was used as a granulated gel applied mechanically on a print saturated with cyclomethicone (octamethylcyclotetrasiloxane D4). Cyclomethicone proved to be a very effective protective barrier for the water-sensitive gelatine layer with minimal reduction in cleaning effectiveness.
Keywords: A1 Journal article; Engineering sciences. Technology; Art; Antwerp Cultural Heritage Sciences (ARCHES); Antwerp X-ray Imaging and Spectroscopy (AXIS)
Impact Factor: 2.5
DOI: 10.1186/S40494-023-00916-5
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“Phototoxicity and cell passage affect intracellular reactive oxygen species levels and sensitivity towards non-thermal plasma treatment in fluorescently-labeled cancer cells”. Verswyvel H, Deben C, Wouters A, Lardon F, Bogaerts A, Smits E, Lin A, Journal of physics: D: applied physics 56, 294001 (2023). http://doi.org/10.1088/1361-6463/accc3d
Abstract: Live-cell imaging with fluorescence microscopy is a powerful tool, especially in cancer research, widely-used for capturing dynamic cellular processes over time. However, light-induced toxicity (phototoxicity) can be incurred from this method, via disruption of intracellular redox balance and an overload of reactive oxygen species (ROS). This can introduce confounding effects in an experiment, especially in the context of evaluating and screening novel therapies. Here, we aimed to unravel whether phototoxicity can impact cellular homeostasis and response to non-thermal plasma (NTP), a therapeutic strategy which specifically targets the intracellular redox balance. We demonstrate that cells incorporated with a fluorescent reporter for live-cell imaging have increased sensitivity to NTP, when exposed to ambient light or fluorescence excitation, likely through altered proliferation rates and baseline intracellular ROS levels. These changes became even more pronounced the longer the cells stayed in culture. Therefore, our results have important implications for research implementing this analysis technique and are particularly important for designing experiments and evaluating redox-based therapies like NTP.
Keywords: A1 Journal article; Plasma Lab for Applications in Sustainability and Medicine – Antwerp (PLASMANT); Center for Oncological Research (CORE)
Impact Factor: 3.4
DOI: 10.1088/1361-6463/accc3d
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Yang T (2023) Characterization of Laves phase structural evolution and regulation of its precipitation behavior in Al-Zn-Mg based alloys. ii, 106 p
Abstract: Al-Zn-Mg-based high strength alloys are widely used in aerospace applications due to their low density and excellent mechanical properties. A systematic study of the structural evolution of the nano-precipitation phase and its growth mechanism is an important guide for the design of new high-strength alloys. In this work, the Laves structure precipitates in Al-Zn-Mg(-Cu/Y) alloy was systematically characterized. Based on the structure evolution, the structure of submicron Laves particles and quasicrystalline particles in the alloy at microscale, as well as the regulation of the precipitation behavior after adding Y at nanoscale were further investigated. The main innovative results are summarized as follows: (1) Investigation on coexistence of defect structures in Laves structural nanoprecipitates. Three types of Laves structures can coexist within the η-MgZn2 precipitates: C14, C15 and C36, and the Laves structure transition sequence of C14→C36→C15 in this system was determined. Meanwhile, it was found that there are diverse defect structures in the MgZn2 phase, including stacking faults, planar defects and five-fold domain structures, which have significant effects on relieving the internal stress/strain of the precipitates. (2) Investigation on multiple phase transition of Laves structural nanoprecipitates from C14 to C36 and from C14 to quasicrystal clusters. It is found that C14 precipitates can be completely transformed into the C36 precipitates. And it is also found that the C14 Laves phase structure can also transform into quasicrystalline clusters. These investigations on various phase transition mechanisms among Laves phases provide theoretical support for the microstructural characterization of materials containing multi-scale Laves phases. (3) Characterization of Laves and quasicrystal structural particles in submicron scale. Submicron-scale quasicrystal particles were obtained in conventional casting Al-Zn-Mg-Cu alloys for the first time. Industrial impurity elements Fe and Ni can induce the formation of quasicrystalline particles. When there is no Fe/Ni enriched in particles, the structure is characterized as C15-Laves phase. When Fe/Ni is as quasicrystalline core, a stable core-shell quasicrystalline structure with Al-Fe-Ni nucleus and Mg-Cu-Zn shell can be formed. (4) Investigation on the regulation of nanoscale Laves precipitates’ growth. To regulate the defect structure of the precipitates, rare earth element Y was added in Al-Zn-Mg alloys and its influence on the precipitation behavior was investigated. The addition of Y element can dynamically combine with different alloying elements during aging process, which can refine the size of precipitate and further improve the nucleation rate and precipitation rate of the precipitates.
Keywords: Doctoral thesis; Electron microscopy for materials research (EMAT)
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Voordeckers D (2023) Design to breathe : understanding and altering wind patterns in street canyons to reduce human exposure to air pollution. xxii, 303 p
Abstract: Air pollution is proclaimed by the World Health Organiaation (WHO) as the biggest environmental threat to human health. Street canyons, or urban roads flanked by a continuous row of high buildings on both sides, are perceived as typical bottleneck areas for air quality due to their lack of natural ventilation. This doctoral thesis aims to integrate expert knowledge on in-canyon flow fields and pollution dispersion in street canyons from the specialized field of (bio)engineering into the field of urban planning and vice versa. In Chapter 1, a Geospatial Information System (GIS) method was developed to detect exposure zones and hotspot street canyons. A critical combination between aspect ratio (AR > 0.65) and traffic volume (TVmax > 300) was detected and subsequently used to detect hotspot street canyons in three major European cities (Antwerp, London and Paris). Chapter 2 focusses on acquiring in-depth knowledge on flow and concentration fields in street canyons by conducting an extensive literature review on over 200 studies and translates this knowledge into nineteen guidelines and eleven spatial tools, comprised in a toolbox for urban planning. Subsequently, computational fluid dynamics (CFD) was used into a research trough design process (Chapter 4) to illustrate how the design tools can be applied to a specific case study (Belgiëlei, Antwerp). Alternations to traffic lanes (traffic lane reduction and lateral displacement) combined with low boundary walls (LBWs), were found to reduce NO2 levels in the entire pedestrian area up to – 3.6 % and peak pollutions were reduced by -8 %. A maximum NO2 reduction was reached by combining a traffic lane displacement with hedges, adjustments to the tree planting pattern and an increased ground-level permeability, leading to reductions up to – 4.5 % in the pedestrian areas. In conclusion, urban design was found to be a valuable tool to enhance the effect of emission reduction strategies and draw in-canyon concentrations closer to the value of the background concentration. However, the background concentration seemed to dominate the efficiency of the urban design interventions and therefore, additional measures should be taken to reduce background pollution levels. This dissertation aims to contribute to the awareness of air pollution in street canyons, as well as support local governments in taking action by delivering spatial tools and guidelines applicable for urban planning and represents a framework for the dissemination of expert information on air quality in street canyons to the field of urban planning.
Keywords: Doctoral thesis; Engineering sciences. Technology; Sustainable Energy, Air and Water Technology (DuEL); Research Group for Urban Development; Intelligence in PRocesses, Advanced Catalysts and Solvents (iPRACS)
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“Detailed nitrogen and phosphorus flow analysis, nutrient use efficiency and circularity in the agri-food system of a livestock-intensive region”. Vingerhoets R, Spiller M, De Backer J, Adriaens A, Vlaeminck SE, Meers E, Journal of cleaner production 410, 137278 (2023). http://doi.org/10.1016/J.JCLEPRO.2023.137278
Abstract: The agri-food value chain is a major cause of nitrogen (N) and phosphorus (P) emissions and associated environmental and health impacts. The EU's farm-to-fork strategy (F2F) demands an agri-food value chain approach to reduce nutrient emissions by 50% and fertilizer use by 20%. Substance flow analysis (SFA) is a method that can be applied to study complex systems such as the agri-food chain. A review of 60 SFA studies shows that they often lack detail by not sufficiently distinguishing between nodes, products and types of emissions. The present study aims to assess the added value of detail in SFAs and to illustrate that valuable indicators can be derived from detailed assessments. This aim will be attained by presenting a highly-detailed SFA for the livestock-intensive region of Flanders, Belgium. The SFA distinguishes 40 nodes and 1827 flows that are classified into eight different categories (e.g. by-products, point source emissions) following life cycle methods. Eight novel indicators were calculated, including indicators that assess the N and P recovery potential. Flanders has a low overall nutrient use efficiency (11% N, 18% P). About 55% of the N and 56% of the P embedded in recoverable streams are reused providing 35% and 37% of the total N and P input. Optimized nutrient recycling could replace 45% of N and 48% of P of the external nutrient input, exceeding the target set by the F2F strategy. Detailed accounting for N and P flows and nodes leads to the identification of more recoverable streams and larger N and P flows. More detailed flow accounting is a prerequisite for the quantification of technological intervention options. Future research should focus on including concentration and quality as a parameter in SFAs.
Keywords: A1 Journal article; Engineering sciences. Technology; Sustainable Energy, Air and Water Technology (DuEL)
Impact Factor: 11.1
DOI: 10.1016/J.JCLEPRO.2023.137278
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“Functionalization of graphitic carbon nitride systems by cobalt and cobalt-iron oxides boosts solar water oxidation performances”. Benedet M, Andrea Rizzi G, Gasparotto A, Gauquelin N, Orekhov A, Verbeeck J, Maccato C, Barreca D, Applied surface science 618, 156652 (2023). http://doi.org/10.1016/j.apsusc.2023.156652
Abstract: The ever-increasing energy demand from the world population has made the intensive use of fossil fuels an overarching threat to global environment and human health. An appealing alternative is offered by sunlight-assisted photoelectrochemical water splitting to yield carbon-free hydrogen fuel, but kinetic limitations associated to the oxygen evolution reaction (OER) render the development of cost-effective, eco-friendly and stable electrocatalysts an imperative issue. In the present work, OER catalysts based on graphitic carbon nitride (g-C3N4) were deposited on conducting glass substrates by a simple decantation procedure, followed by functionalization with low amounts of nanostructured CoO and CoFe2O4 by radio frequency (RF)-sputtering, and final annealing under inert atmosphere. A combination of advanced characterization tools was used to investigate the interplay between material features and electrochemical performances. The obtained results highlighted the formation of a p-n junction for the g-C3N4-CoO system, whereas a Z-scheme junction accounted for the remarkable performance enhancement yielded by g-C3N4-CoFe2O4. The intimate contact between the system components also afforded an improved electrocatalyst stability in comparison to various bare and functionalized g-C3N4-based systems. These findings emphasize the importance of tailoring g-C3N4 chemico-physical properties through the dispersion of complementary catalysts to fully exploit its applicative potential.
Keywords: A1 Journal article; Electron microscopy for materials research (EMAT)
Impact Factor: 6.7
Times cited: 11
DOI: 10.1016/j.apsusc.2023.156652
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“Integration of smart nanomaterials for highly selective disposable sensors and their forensic applications in amphetamine determination”. Almabadi MH, Truta FM, Adamu G, Cowen T, Tertis M, Alanazi KDM, Stefan M-G, Piletska E, Kiss B, Cristea C, De Wael K, Piletsky SA, Cruz AG, Electrochimica acta 446, 142009 (2023). http://doi.org/10.1016/J.ELECTACTA.2023.142009
Abstract: Screening drugs on the street and biological samples pose a challenge to law enforcement agencies due to existing detection methods and instrument limitations. Herein we present a graphene-assisted molecularly imprinted polymer nanoparticle-based sensor for amphetamine. These nanoparticles are electroactive by incorporating ferrocene in their structure. These particles act as specific actuators in electrochemical sensors, and the presence of a ferrocene redox probe embedded in the structure allows the detection of non-electroactive amphetamine. In a control approach, nanoparticles were covalently immobilised onto electrochemical sensors by drop-casting using silanes. Alternatively, nanoparticles were immobilised employing 3D printing and a graphene ink composite. The electrochemical performance of both approaches was evaluated. As a result, 3D printed nanoMIPs/graphene sensors displayed the highest selectivity in spiked human plasma, with sensitivity at 73 nA nM-1, LOD of 68 nM (RSD 2.4%) when compared to the silane drop cast electrodes. The main advantage of the optimised 3D printing technology is that it allows quantitative determination of amphetamine, a nonelectroactive drug, challenging to detect with conventional electrochemical sensors. In addition, the costefficient 3D printing method makes these sensors easy to manufacture, leading to robust, highly selective and sensitive sensors. As proof of concept, sensors were evaluated on the street specimens and clinically relevant samples and successfully validated using UPLC-MS.
Keywords: A1 Journal article; Antwerp Electrochemical and Analytical Sciences Lab (A-Sense Lab)
Impact Factor: 6.6
DOI: 10.1016/J.ELECTACTA.2023.142009
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“Epitaxial growth of the candidate ferroelectric Rashba material SrBiO3by pulsed laser deposition”. Verdierre G, Gauquelin N, Jannis D, Birkhölzer YA, Mallik S, Verbeeck J, Bibes M, Koster G, APL materials 11, 031109 (2023). http://doi.org/10.1063/5.0138222
Abstract: Among oxides, bismuthates have been gaining much interest due to their unique features. In addition to their superconducting properties, they show potential for applications as topological insulators and as possible spin-to-charge converters. After being first investigated in their bulk form in the 1980s, bismuthates have been successfully grown as thin films. However, most efforts have focused on BaBiO<sub>3</sub>, with SrBiO<sub>3</sub>receiving only little attention. Here, we report the growth of epitaxial films of SrBiO<sub>3</sub>on both TiO<sub>2</sub>-terminated SrTiO<sub>3</sub>and NdO-terminated NdScO<sub>3</sub>substrates by pulsed laser deposition. SrBiO<sub>3</sub>has a pseudocubic lattice constant of ∼4.25 Å and grows relaxed on NdScO<sub>3</sub>. Counter-intuitively, it grows with a slight tensile strain on SrTiO<sub>3</sub>despite a large lattice mismatch, which should induce compressive strain. High-resolution transmission electron microscopy reveals that this occurs as a consequence of structural domain matching, with blocks of 10 SrBiO<sub>3</sub>unit planes matching blocks of 11 SrTiO<sub>3</sub>unit planes. This work provides a framework for the synthesis of high quality perovskite bismuthates films and for the understanding of their interface interactions with homostructural substrates.
Keywords: A1 Journal article; Engineering sciences. Technology; Electron microscopy for materials research (EMAT)
Impact Factor: 6.1
DOI: 10.1063/5.0138222
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“Insights into the Photoelectrocatalytic Behavior of gCN-Based Anode Materials Supported on Ni Foams”. Benedoue S, Benedet M, Gasparotto A, Gauquelin N, Orekhov A, Verbeeck J, Seraglia R, Pagot G, Rizzi GA, Balzano V, Gavioli L, Noto VD, Barreca D, Maccato C, Nanomaterials 13, 1035 (2023). http://doi.org/10.3390/nano13061035
Abstract: Graphitic carbon nitride (gCN) is a promising n-type semiconductor widely investigated for photo-assisted water splitting, but less studied for the (photo)electrochemical degradation of aqueous organic pollutants. In these fields, attractive perspectives for advancements are offered by a proper engineering of the material properties, e.g., by depositing gCN onto conductive and porous scaffolds, tailoring its nanoscale morphology, and functionalizing it with suitable cocatalysts. The present study reports on a simple and easily controllable synthesis of gCN flakes on Ni foam substrates by electrophoretic deposition (EPD), and on their eventual decoration with Co-based cocatalysts [CoO, CoFe2O4, cobalt phosphate (CoPi)] via radio frequency (RF)-sputtering or electrodeposition. After examining the influence of processing conditions on the material characteristics, the developed systems are comparatively investigated as (photo)anodes for water splitting and photoelectrocatalysts for the degradation of a recalcitrant water pollutant [potassium hydrogen phthalate (KHP)]. The obtained results highlight that while gCN decoration with Co-based cocatalysts boosts water splitting performances, bare gCN as such is more efficient in KHP abatement, due to the occurrence of a different reaction mechanism. The related insights, provided by a multi-technique characterization, may provide valuable guidelines for the implementation of active nanomaterials in environmental remediation and sustainable solar-to-chemical energy conversion.
Keywords: A1 Journal article; Engineering sciences. Technology; Electron microscopy for materials research (EMAT)
Impact Factor: 5.3
Times cited: 3
DOI: 10.3390/nano13061035
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“Quasicrystalline clusters transformed from C14-MgZn₂, nanoprecipitates in Al alloys”. Yang T, Kong Y, Li K, Lu Q, Wang Y, Du Y, Schryvers D, Materials characterization 199, 112772 (2023). http://doi.org/10.1016/J.MATCHAR.2023.112772
Abstract: Ultrafine faulty C14-MgZn2 Laves phase precipitates containing quasicrystalline clusters and demonstrating the formation of binary quasicrystalline precipitates with Penrose-like random-tiling were observed in the over-aged FCC matrix of a commercial 7N01 Al-Zn-Mg alloy, using high angle annular dark field scanning transmission electron microscopy. The evolution from C14-Laves phase to quasicrystalline clusters is illustrated, and five-fold symmetry can be found in both real and reciprocal spaces. Our findings reveal the possibility of quasicrystalline formation from Laves phase in a highly plastic metal matrix like Al and demonstrate the structural relationship between Laves phase and quasicrystals.
Keywords: A1 Journal article; Engineering sciences. Technology; Electron microscopy for materials research (EMAT)
Impact Factor: 4.7
DOI: 10.1016/J.MATCHAR.2023.112772
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“Black phosphorus as tunable Van der Waals quantum wells with high optical quality”. Zhang G, Huang S, Chaves A, Yan H, ACS nano 17, 6073 (2023). http://doi.org/10.1021/ACSNANO.3C00904
Abstract: Van der Waals quantum wells, naturally formed in two-dimensional layered materials with nanoscale thickness, possess many inherent advantages over conventional molecular beam epitaxy grown counterparts, and could bring up intriguing physics and applications. However, optical transitions originated from the series of quantized states in these emerging quantum wells are still elusive. Here, we show that multilayer black phosphorus appears to be an excellent candidate for van der Waals quantum wells with well-defined subbands and high optical quality. Using infrared absorption spectroscopy, we probe subband structures of multilayer black phosphorus with tens of atomic layers, revealing clear signatures for optical transitions with subband index as high as 10, far from what was attainable previously. Surprisingly, in addition to allowed transitions, an unexpected series of “forbidden” transitions is also evidently observed, which enables us to determine energy spacings separately for conduction and valence subbands. Furthermore, the linear tunability of subband spacings by temperature and strain is demonstrated. Our results are expected to facilitate potential applications for infrared optoelectronics based on tunable van der Waals quantum wells.
Keywords: A1 Journal article; Engineering sciences. Technology; Condensed Matter Theory (CMT)
Impact Factor: 17.1
DOI: 10.1021/ACSNANO.3C00904
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