“Asymmetric dyes align inside carbon nanotubes to yield a large nonlinear optical response”. Cambré, S, Campo J, Beirnaert C, Verlackt C, Cool P, Wenseleers W, Nature nanotechnology 10, 248 (2015). http://doi.org/10.1038/nnano.2015.1
Abstract: Asymmetric dye molecules have unusual optical and electronic properties1, 2, 3. For instance, they show a strong second-order nonlinear optical (NLO) response that has attracted great interest for potential applications in electro-optic modulators for optical telecommunications and in wavelength conversion of lasers2, 3. However, the strong Coulombic interaction between the large dipole moments of these molecules favours a pairwise antiparallel alignment that cancels out the NLO response when incorporated into bulk materials. Here, we show that by including an elongated dipolar dye (p,p′-dimethylaminonitrostilbene, DANS, a prototypical asymmetric dye with a strong NLO response4) inside single-walled carbon nanotubes (SWCNTs)5, 6, an ideal head-to-tail alignment in which all electric dipoles point in the same sense is naturally created. We have applied this concept to synthesize solution-processible DANS-filled SWCNTs that show an extremely large total dipole moment and static hyperpolarizability (β0 = 9,800 × 10−30 e.s.u.), resulting from the coherent alignment of arrays of ∼70 DANS molecules.
Keywords: A1 Journal article; Engineering sciences. Technology; Nanostructured and organic optical and electronic materials (NANOrOPT); Laboratory of adsorption and catalysis (LADCA); Plasma Lab for Applications in Sustainability and Medicine – Antwerp (PLASMANT)
Impact Factor: 38.986
Times cited: 46
DOI: 10.1038/nnano.2015.1
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“Controlled lateral anisotropy in correlated manganite heterostructures by interface-engineered oxygen octahedral coupling”. Liao Z, Huijben M, Zhong Z, Gauquelin N, Macke S, Green RJ, Van Aert S, Verbeeck J, Van Tendeloo G, Held K, Sawatzky GA, Koster G, Rijnders G, Nature materials 15, 425 (2016). http://doi.org/10.1038/nmat4579
Abstract: Controlled in-plane rotation of the magnetic easy axis in manganite heterostructures by tailoring the interface oxygen network could allow the development of correlated oxide-based magnetic tunnelling junctions with non-collinear magnetization, with possible practical applications as miniaturized high-switching-speed magnetic random access memory (MRAM) devices. Here, we demonstrate how to manipulate magnetic and electronic anisotropic properties in manganite heterostructures by engineering the oxygen network on the unit-cell level. The strong oxygen octahedral coupling is found to transfer the octahedral rotation, present in the NdGaO3 (NGO) substrate, to the La2/3Sr1/3MnO3 (LSMO) film in the interface region. This causes an unexpected realignment of the magnetic easy axis along the short axis of the LSMO unit cell as well as the presence of a giant anisotropic transport in these ultrathin LSMO films. As a result we possess control of the lateral magnetic and electronic anisotropies by atomic-scale design of the oxygen octahedral rotation.
Keywords: A1 Journal article; Electron microscopy for materials research (EMAT)
Impact Factor: 39.737
Times cited: 273
DOI: 10.1038/nmat4579
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“In situ study of the formation mechanism of two-dimensional superlattices from PbSe nanocrystals”. Geuchies JJ, van Overbeek C, Evers WH, Goris B, de Backer A, Gantapara AP, Rabouw FT, Hilhorst J, Peters JL, Konovalov O, Petukhov AV, Dijkstra M, Siebbeles LDA, van Aert S, Bals S, Vanmaekelbergh D, Nature materials 15, 1248 (2016). http://doi.org/10.1038/nmat4746
Abstract: Oriented attachment of PbSe nanocubes can result in the formation of two-dimensional (2D) superstructures with long-range nanoscale and atomic order. This questions the applicability of classic models in which the superlattice grows by first forming a nucleus, followed by sequential irreversible attachment of nanocrystals, as one misaligned attachment would disrupt the 2D order beyond repair. Here, we demonstrate the formation mechanism of 2D PbSe superstructures with square geometry by using in situ grazing-incidence X-ray scattering (small angle and wide angle), ex situ electron microscopy, and Monte Carlo simulations. We observed nanocrystal adsorption at the liquid/gas interface, followed by the formation of a hexagonal nanocrystal monolayer. The hexagonal geometry transforms gradually through a pseudo-hexagonal phase into a phase with square order, driven by attractive interactions between the {100} planes perpendicular to the liquid substrate, which maximize facet-to-facet overlap. The nanocrystals then attach atomically via a necking process, resulting in 2D square superlattices.
Keywords: A1 Journal article; Electron microscopy for materials research (EMAT)
Impact Factor: 39.737
Times cited: 182
DOI: 10.1038/nmat4746
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“Evidence for anionic redox activity in a tridimensional-ordered Li-rich positive electrode β-Li2IrO3”. Pearce PE, Perez AJ, Rousse G, Saubanère M, Batuk D, Foix D, McCalla E, Abakumov AM, Van Tendeloo G, Doublet M-L, Tarascon J-M, Nature materials 16, 580 (2017). http://doi.org/10.1038/nmat4864
Abstract: Lithium-ion battery cathode materials have relied on cationic redox reactions until the recent discovery of anionic redox activity in Li-rich layered compounds which enables capacities as high as 300 mAh g(-1). In the quest for new high-capacity electrodes with anionic redox, a still unanswered question was remaining regarding the importance of the structural dimensionality. The present manuscript provides an answer. We herein report on a beta-Li2IrO3 phase which, in spite of having the Ir arranged in a tridimensional (3D) framework instead of the typical two-dimensional (2D) layers seen in other Li-rich oxides, can reversibly exchange 2.5 e(-) per Ir, the highest value ever reported for any insertion reaction involving d-metals. We show that such a large activity results from joint reversible cationic (Mn+) and anionic (O-2)(n-) redox processes, the latter being visualized via complementary transmission electron microscopy and neutron diffraction experiments, and confirmed by density functional theory calculations. Moreover, beta-Li2IrO3 presents a good cycling behaviour while showing neither cationic migration nor shearing of atomic layers as seen in 2D-layered Li-rich materials. Remarkably, the anionic redox process occurs jointly with the oxidation of Ir4+ at potentials as low as 3.4 V versus Li+/Li-0, as equivalently observed in the layered alpha-Li2IrO3 polymorph. Theoretical calculations elucidate the electrochemical similarities and differences of the 3D versus 2D polymorphs in terms of structural, electronic and mechanical descriptors. Our findings free the structural dimensionality constraint and broaden the possibilities in designing high-energy-density electrodes for the next generation of Li-ion batteries.
Keywords: A1 Journal article; Electron microscopy for materials research (EMAT)
Impact Factor: 39.737
DOI: 10.1038/nmat4864
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“Ion exchange in atomically thin clays and micas”. Zou Y-C, Mogg L, Clark N, Bacaksiz C, Milanovic S, Sreepal V, Hao G-P, Wang Y-C, Hopkinson DG, Gorbachev R, Shaw S, Novoselov KS, Raveendran-Nair R, Peeters FM, Lozada-Hidalgo M, Haigh SJ, Nature Materials 20, 1677 (2021). http://doi.org/10.1038/S41563-021-01134-9
Abstract: The physical properties of clays and micas can be controlled by exchanging ions in the crystal lattice. Atomically thin materials can have superior properties in a range of membrane applications, yet the ion-exchange process itself remains largely unexplored in few-layer crystals. Here we use atomic-resolution scanning transmission electron microscopy to study the dynamics of ion exchange and reveal individual ion binding sites in atomically thin and artificially restacked clays and micas. We find that the ion diffusion coefficient for the interlayer space of atomically thin samples is up to 10(4) times larger than in bulk crystals and approaches its value in free water. Samples where no bulk exchange is expected display fast exchange at restacked interfaces, where the exchanged ions arrange in islands with dimensions controlled by the moire superlattice dimensions. We attribute the fast ion diffusion to enhanced interlayer expandability resulting from weaker interlayer binding forces in both atomically thin and restacked materials. This work provides atomic scale insights into ion diffusion in highly confined spaces and suggests strategies to design exfoliated clay membranes with enhanced performance. Layered clays are of interest for membranes and many other applications but their ion-exchange dynamics remain unexplored in atomically thin materials. Here, using electron microscopy, it is found that the ion diffusion for few-layer two-dimensional clays approaches that of free water and that superlattice cation islands can form in twisted and restacked materials.
Keywords: A1 Journal article; Condensed Matter Theory (CMT)
Impact Factor: 39.737
Times cited: 2
DOI: 10.1038/S41563-021-01134-9
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“Structural phase transition at the percolation threshold in epitaxial (La0.7Ca0.3MnO3)1-x:(MgO)x nanocomposite films”. Moshnyaga V, Damaschke B, Shapoval O, Belenchuk A, Faupel J, Lebedev OI, Verbeeck J, Van Tendeloo G, Mücksch M, Tsurkan V, Tidecks R, Samwer K, Nature materials 2, 247 (2003). http://doi.org/10.1038/nmat859
Abstract: 'Colossal magnetoresistance' in perovskite manganites such as La0.7Ca0.3MnO3 (LCMO), is caused by the interplay of ferro-paramagnetic, metal-insulator and structural phase transitions. Moreover, different electronic phases can coexist on a very fine scale resulting in percolative electron transport. Here we report on (LCMO)(1-x):(MgO)(x) (0 < x less than or equal to 0.8) epitaxial nano-composite films in which the structure and magnetotransport properties of the manganite nanoclusters can be tuned by the tensile stress originating from the MgO second phase. With increasing x, the lattice of LCMO was found to expand, yielding a bulk tensile strain. The largest colossal magnetoresistance of 10(5)% was observed at the percolation threshold in the conductivity at x(c) approximate to 0.3, which is coupled to a structural phase transition from orthorhombic (0 < x less than or equal to 0.1) to rhombohedral R (3) over barc structure (0.33 less than or equal to x less than or equal to 0.8). An increase of the Curie temperature for the R (3) over barc phase was observed. These results may provide a general method for controlling the magnetotransport properties of manganite-based composite films by appropriate choice of the second phase.
Keywords: A1 Journal article; Electron microscopy for materials research (EMAT)
Impact Factor: 39.737
Times cited: 177
DOI: 10.1038/nmat859
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“Corrigendum: Structural phase transition at the percolation threshold in epitaxial (La0.7Ca0.3MnO3)1-x:(MgO)x nanocomposite films”. Moshnyaga V, Damaschke B, Shapoval O, Belenchuk A, Faupel J, Lebedev OI, Verbeeck J, Van Tendeloo G, Mücksch M, Tsurkan V, Tidecks R, Samwer K, Nature materials 4, 104 (2005)
Keywords: A1 Journal article; Electron microscopy for materials research (EMAT)
Impact Factor: 39.737
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“Electronically coupled complementary interfaces between perovskite band insulators”. Huijben M, Rijnders G, Blank DHA, Bals S, Van Aert S, Verbeeck J, Van Tendeloo G, Brinkman A, Hilgenkamp H, Nature materials 5, 556 (2006). http://doi.org/10.1038/nmat1675
Keywords: A1 Journal article; Electron microscopy for materials research (EMAT)
Impact Factor: 39.737
Times cited: 315
DOI: 10.1038/nmat1675
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“Linking a completely three-dimensional nanostrain to a structural transformation eigenstrain”. Tirry W, Schryvers D, Nature materials 8, 752 (2009). http://doi.org/10.1038/NMAT2488
Abstract: NiTi is one of the most popular shape-memory alloys, a phenomenon resulting from a martensitic transformation. Commercial NiTi-based alloys are often thermally treated to contain Ni4Ti3 precipitates. The presence of these precipitates can introduce an extra transformation step related to the so-called R-phase. It is believed that the strain field surrounding the precipitates, caused by the matrixprecipitate lattice mismatch, lies at the origin of this intermediate transformation step. Atomic-resolution transmission electron microscopy in combination with geometrical phase analysis is used to measure the elastic strain field surrounding these precipitates. By combining measurements from two different crystallographic directions, the three-dimensional strain matrix is determined from two-dimensional measurements. Comparison of the measured strain matrix to the eigenstrain of the R-phase shows that both are very similar and that the introduction of the R-phase might indeed compensate the elastic strain introduced by the precipitate.
Keywords: A1 Journal article; Electron microscopy for materials research (EMAT)
Impact Factor: 39.737
Times cited: 53
DOI: 10.1038/NMAT2488
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“Atomic-scale determination of surface facets in gold nanorods”. Goris B, Bals S, van den Broek W, Carbó-Argibay E, Gómez-Graña S, Liz-Marzán LM, Van Tendeloo G, Nature materials 11, 930 (2012). http://doi.org/10.1038/NMAT3462
Abstract: It is widely accepted that the physical properties of nanostructures depend on the type of surface facets1, 2. For Au nanorods, the surface facets have a major influence on crucial effects such as reactivity and ligand adsorption and there has been controversy regarding facet indexing3, 4. Aberration-corrected electron microscopy is the ideal technique to study the atomic structure of nanomaterials5, 6. However, these images correspond to two-dimensional (2D) projections of 3D nano-objects, leading to an incomplete characterization. Recently, much progress was achieved in the field of atomic-resolution electron tomography, but it is still far from being a routinely used technique. Here we propose a methodology to measure the 3D atomic structure of free-standing nanoparticles, which we apply to characterize the surface facets of Au nanorods. This methodology is applicable to a broad range of nanocrystals, leading to unique insights concerning the connection between the structure and properties of nanostructures.
Keywords: A1 Journal article; Electron microscopy for materials research (EMAT)
Impact Factor: 39.737
Times cited: 261
DOI: 10.1038/NMAT3462
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“Design of zeolite by inverse sigma transformation”. Verheyen E, Joos L, Van Havenbergh K, Breynaert E, Kasian N, Gobechiya E, Houthoofd K, Martineau C, Hinterstein M, Taulelle F, Van Speybroeck V, Waroquier M, Bals S, Van Tendeloo G, Kirschhock CEA, Martens JA;, Nature materials 11, 1059 (2012). http://doi.org/10.1038/NMAT3455
Abstract: Although the search for new zeolites has traditionally been based on trial and error, more rational methods are now available. The theoretical concept of inverse transformation of a zeolite framework to generate a new structure by removal of a layer of framework atoms and contraction has for the first time been achieved experimentally. The reactivity of framework germanium atoms in strong mineral acid was exploited to selectively remove germanium-containing four-ring units from an UTL type germanosilicate zeolite. Annealing of the leached framework through calcination led to the new all-silica COK-14 zeolite with intersecting 12- and 10-membered ring channel systems. An intermediate stage of this inverse transformation with dislodged germanate four-rings still residing in the pores could be demonstrated. Inverse transformation involving elimination of germanium-containing structural units opens perspectives for the synthesis of many more zeolites.
Keywords: A1 Journal article; Electron microscopy for materials research (EMAT)
Impact Factor: 39.737
Times cited: 140
DOI: 10.1038/NMAT3455
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Erni R, Abakumov AM, Rossell MD, Batuk D, Tsirlin AA, Né,nert G, Van Tendeloo G (2014) Nanoscale phase separation in perovskites revisited. London, 216–217
Keywords: L1 Letter to the editor; Electron microscopy for materials research (EMAT)
Impact Factor: 39.737
Times cited: 5
DOI: 10.1038/nmat3865
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“Extreme mobility enhancement of two-dimensional electron gases at oxide interfaces by charge-transfer-induced modulation doping”. Chen YZ, Trier F, Wijnands T, Green RJ, Gauquelin N, Egoavil R, Christensen DV, Koster G, Huijben M, Bovet N, Macke S, He F, Sutarto R, Andersen NH, Sulpizio JA, Honig M, Prawiroatmodjo GEDK, Jespersen TS, Linderoth S, Ilani S, Verbeeck J, Van Tendeloo G, Rijnders G, Sawatzky GA, Pryds N, Nature materials 14, 801 (2015). http://doi.org/10.1038/nmat4303
Abstract: Two-dimensional electron gases (2DEGs) formed at the interface of insulating complex oxides promise the development of all-oxide electronic devices. These 2DEGs involve many-body interactions that give rise to a variety of physical phenomena such as superconductivity, magnetism, tunable metalinsulator transitions and phase separation. Increasing the mobility of the 2DEG, however, remains a major challenge. Here, we show that the electron mobility is enhanced by more than two orders of magnitude by inserting a single-unit-cell insulating layer of polar La1−xSrxMnO3 (x = 0, 1/8, and 1/3) at the interface between disordered LaAlO3 and crystalline SrTiO3 produced at room temperature. Resonant X-ray spectroscopy and transmission electron microscopy show that the manganite layer undergoes unambiguous electronic reconstruction, leading to modulation doping of such atomically engineered complex oxide heterointerfaces. At low temperatures, the modulation-doped 2DEG exhibits Shubnikovde Haas oscillations and fingerprints of the quantum Hall effect, demonstrating unprecedented high mobility and low electron density.
Keywords: A1 Journal article; Electron microscopy for materials research (EMAT)
Impact Factor: 39.737
Times cited: 170
DOI: 10.1038/nmat4303
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“Origin of voltage decay in high-capacity layered oxide electrodes”. Sathiya M, Abakumov AM, Foix D, Rousse G, Ramesha K, Saubanère M, Doublet M , Vezin H, Laisa CP, Prakash AS, Gonbeau D, Van Tendeloo G, Tarascon JM, Nature materials 14, 230 (2015). http://doi.org/10.1038/nmat4137
Abstract: Although Li-rich layered oxides (Li1+xNiyCozMn1−x−y−zO2 > 250 mAh g−1) are attractive electrode materials providing energy densities more than 15% higher than todays commercial Li-ion cells, they suffer from voltage decay on cycling. To elucidate the origin of this phenomenon, we employ chemical substitution in structurally related Li2RuO3 compounds. Li-rich layered Li2Ru1−yTiyO3 phases with capacities of ~240 mAh g−1 exhibit the characteristic voltage decay on cycling. A combination of transmission electron microscopy and X-ray photoelectron spectroscopy studies reveals that the migration of cations between metal layers and Li layers is an intrinsic feature of the chargedischarge process that increases the trapping of metal ions in interstitial tetrahedral sites. A correlation between these trapped ions and the voltage decay is established by expanding the study to both Li2Ru1−ySnyO3 and Li2RuO3; the slowest decay occurs for the cations with the largest ionic radii. This effect is robust, and the finding provides insights into new chemistry to be explored for developing high-capacity layered electrodes that evade voltage decay.
Keywords: A1 Journal article; Electron microscopy for materials research (EMAT)
Impact Factor: 39.737
Times cited: 395
DOI: 10.1038/nmat4137
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“Comparison of seed morphology of two ginkgo cultivars”. Tian F, Wang Y, Sandhu HS, Gielis J, Shi P, Journal Of Forestry Research 31, 751 (2020). http://doi.org/10.1007/S11676-018-0770-Y
Abstract: Ginkgo biloba L. is a precious relic tree species with important economic value. Seeds, as a vital reproductive organ of plants, can be used to distinguish cultivars of the species. We chose 400 seeds from two cultivars of ginkgo (Fozhi and Maling; 200 seeds for each cultivar) as the study material and used the Gielis equation to fit the projected shape of these seeds. The coefficients of variation (CV) in root mean squared errors (RMSE) obtained from the fitted data were used to compare the level of inter-cultivar variations in seed shape. We also used the covariance analysis to compare the allometric relationships between seed weights and projected areas of these two cultivars. The Gielis equation fitted well the seed shapes of two ginkgo cultivars. The lower CV in RMSE of cultivar Fozhi than Maling indicated a less symmetrical seed shape in the latter than the former. The bootstrap percentile method showed that the seed shape differences between the two cultivars were significant. However, there was no significant difference in the exponents between the seed weights and the projected areas of these two cultivars. Overall, the significant differences in shapes between the seeds of two ginkgo cultivars were well explained by the Gielis equation; this model can be further extended to compare morphological differences in other ginkgo cultivars, and even for plant seeds or animal eggs that have similar oval shapes.
Keywords: A1 Journal article; Engineering sciences. Technology; Sustainable Energy, Air and Water Technology (DuEL)
Impact Factor: 3
Times cited: 3
DOI: 10.1007/S11676-018-0770-Y
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“Heating of liquid foods in cans: Effects of can geometry, orientation, and food rheology”. Borah R, Gupta S, Mishra L, Chhabra RP, Journal Of Food Process Engineering , e13420 (2020). http://doi.org/10.1111/JFPE.13420
Abstract: In this work, the effect of geometry and orientation of food cans on the heating characteristics of processed liquid foods and the resulting lethality target values as a function of the processing times have been investigated. For this purpose, the governing differential equations have been solved numerically for elliptical and cylindrical cans of varying aspect ratios in different orientations in order to delineate their effect on the heating rate (especially of the slowest heating zone [SHZ]) and lethality values over wide ranges of rheological features including shear thinning (n < 1), Newtonian (n = 1), and shear thickening (n > 1) behaviors. The flow and heat transfer characteristics were analyzed with the help of velocity vectors, isotherm contours, average Nusselt number, SHZ temperature and heat penetration parameters, and lethality target values. Also, comparisons were made in terms of the sterilization time and heat penetration parameters to identify the preferable geometries and orientations of food cans for effective heating of non-Newtonian foodstuffs. Finally, favorable conditions in terms of the shape and orientation of the can and the rheological properties have been delineated which lead to superior heating characteristics. Practical Applications Processed foodstuffs are produced in various forms ranging from that in solid, liquid, or as heterogeneous mixtures. Often such liquid and heterogeneous suspensions products are viscous non-Newtonian in character and their thermal processing (including pasteurization, sterilization, etc.) tends to be much more challenging than that of their Newtonian counterparts like air and water. This work explores heating of non-Newtonian liquid foodstuffs in cans of various shapes, geometries and in different orientations in the free convection regime. The results show that depending upon the rheological properties of the products, some orientations and/or geometries offer potential advantages in terms of shorter processing times and lethality values. This information can be of great potential in customizing the design of containers for different food products as well as of different rheological properties.
Keywords: A1 Journal article; Pharmacology. Therapy; Sustainable Energy, Air and Water Technology (DuEL)
Impact Factor: 3
Times cited: 2
DOI: 10.1111/JFPE.13420
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“Identification of nano-width variants in a fully monoclinic martensitic Ni50Ti50 alloy by scanning electron microscope-based transmission Kikuchi diffraction and improved groupoid structure approach”. Zhao ZX, Ma X, Cao S, Li YY, Zeng CY, Wang DX, Yao X, Deng ZJ, Zhang XP, Materials Letters 281, 128624 (2020). http://doi.org/10.1016/J.MATLET.2020.128624
Abstract: Nano-width martensite plates in a fully martensitic Ni50Ti50 alloy are indexed successfully by using the off-axis transmission Kikuchi diffraction in scanning electron microscope (i.e., SEM-based TKD). The data obtained by SEM-TKD are effectively interpreted using an improved approach based on the framework of the theoretical groupoid structure method, where the equivalent variants transformed from the monoclinic variants are introduced to calculate all theoretical axis/angle pairs of rotation, and to formulate a complete list of source martensite to target martensite pairs. Consequently, B19' monoclinic martensite variants in NiTi alloys are identified unambiguously, by using numerical comparison between the experimental and theoretical rotation components, without the reference of retained parent phase. (C) 2020 Elsevier B.V. All rights reserved.
Keywords: A1 Journal article; Electron microscopy for materials research (EMAT)
Impact Factor: 3
DOI: 10.1016/J.MATLET.2020.128624
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“Electroactivity of superoxide anion in aqueous phosphate buffers analyzed with platinized microelectrodes”. Lefrancois P, Girard-Sahun F, Badets V, Clement F, Arbault S, Electroanalysis (2020). http://doi.org/10.1002/ELAN.202060456
Abstract: The reactivity of platinized ultramicroelectrodes (Pt-black UMEs) towards superoxide anion O-2(.-), an unstable Reactive Oxygen Species (ROS), and its relatives, H2O2 and O-2, was studied. Voltammetric studies in PBS demonstrate that Pt-black UMEs provide: i) a well-resolved reversible redox signature for O-2(.-) detected in both alkaline and physiological buffers (pH 12 and 7.4); ii) irreversible oxidation and reduction waves for H2O2 at pH 7.4. The oxygen reduction reaction (ORR) at Pt-black surfaces solely yields H2O2 (2 electrons/2 H+) at physiological pH. Consequently, Pt-black UMEs allow to sense different ROS including superoxide anion for future biomedical or physico-chemical investigations.
Keywords: A1 Journal article; Plasma Lab for Applications in Sustainability and Medicine – Antwerp (PLASMANT)
Impact Factor: 3
DOI: 10.1002/ELAN.202060456
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“Photothermal heating of Au nanorods and nanospheres : temperature characteristics and strength of convective forces”. Borah R, Kumar A, Samantaray M, Desai A, Tseng F-G, Plasmonics 18, 1449 (2023). http://doi.org/10.1007/S11468-023-01855-4
Abstract: The nanoscale photothermal effect and the optofluidic convection around plasmonic nanoparticles drive the application of such nanoparticles in micro-environment. In this work, heat transfer and fluid flow around Au nanospheres and nanorods in water medium under continuous and pulsed wave laser irradiance was investigated using an FEM based numerical framework. Au nanospheres of a wide range of diameter: 40 nm = Diameter (D) = 180 nm and relatively large nanorods (diameter: 50 nm) with varying aspect ratio (1 = Aspect ratio (A) = 5) and orientation (0 degrees = ? = 90 degrees, ? = 0 degrees, 90 degrees) with respect to the incident EM radiation were investigated for continuous wave (CW) and pulsed wave laser. It was found that although nanorods can attain much higher temperature than nanospheres, orientation of a nanorod is an important factor to be carefully considered in applications. In micro-scale spherical and hemispherical confinements (diameter < 14.4 p.m), the convective velocity fields around nanoparticles is in the order of 10-9 m/s, with only a weak effect of the slip or no-slip boundary condition on the confining walls. Importantly, the size of the confinement has a strong effect leading to an order of magnitude stronger convection for 14.4 p.m (diameter) spherical confinement as compared to 3.6 p.m confinement. Additionally close proximity of the nanoparticles to the confining walls strongly reduces (by an order of magnitude) the convective currents. The results reported herein provides important insights for the use of photothermal nanoparticles in microscale confined space (e.g. cellular environment) for applications such as optical tweezers, photoporation, etc.
Keywords: A1 Journal article; Engineering sciences. Technology; Sustainable Energy, Air and Water Technology (DuEL)
Impact Factor: 3
DOI: 10.1007/S11468-023-01855-4
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“New indices to balance α-diversity against tree size inequality”. Zhang L, Quinn BK, Hui C, Lian M, Gielis J, Gao J, Shi P, Journal of forestry research 35, 31 (2024). http://doi.org/10.1007/S11676-023-01686-3
Abstract: The number and composition of species in a community can be quantified with alpha-diversity indices, including species richness (R), Simpson's index (D), and the Shannon-Wiener index (HGREEK TONOS). In forest communities, there are large variations in tree size among species and individuals of the same species, which result in differences in ecological processes and ecosystem functions. However, tree size inequality (TSI) has been largely neglected in studies using the available diversity indices. The TSI in the diameter at breast height (DBH) data for each of 999 20 m x 20 m forest census quadrats was quantified using the Gini index (GI), a measure of the inequality of size distribution. The generalized performance equation was used to describe the rotated and right-shifted Lorenz curve of the cumulative proportion of DBH and the cumulative proportion of number of trees per quadrat. We also examined the relationships of alpha-diversity indices with the GI using correlation tests. The generalized performance equation effectively described the rotated and right-shifted Lorenz curve of DBH distributions, with most root-mean-square errors (990 out of 999 quadrats) being < 0.0030. There were significant positive correlations between each of three alpha-diversity indices (i.e., R, D, and H') and the GI. Nevertheless, the total abundance of trees in each quadrat did not significantly influence the GI. This means that the TSI increased with increasing species diversity. Thus, two new indices are proposed that can balance alpha-diversity against the extent of TSI in the community: (1 – GI) x D, and (1 – GI) x H'. These new indices were significantly correlated with the original D and HGREEK TONOS, and did not increase the extent of variation within each group of indices. This study presents a useful tool for quantifying both species diversity and the variation in tree sizes in forest communities, especially in the face of cumulative species loss under global climate change.
Keywords: A1 Journal article; Sustainable Energy, Air and Water Technology (DuEL)
Impact Factor: 3
DOI: 10.1007/S11676-023-01686-3
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“The crystal and defect structures of polar KBiNb2O7”. Mallick S, Zhang W, Batuk M, Gibbs AS, Hadermann J, Halasyamani PS, Hayward MA, Journal of the Chemical Society : Dalton transactions 51, 1866 (2022). http://doi.org/10.1039/D1DT04064B
Abstract: KBiNb2O7 was prepared from RbBiNb2O7 by a sequence of cation exchange reactions which first convert RbBiNb2O7 to LiBiNb2O7, before KBiNb2O7 is formed by a further K-for-Li cation exchange. A combination of neutron, synchrotron X-ray and electron diffraction data reveal that KBiNb2O7 adopts a polar, layered, perovskite structure (space group A11m) in which the BiNb2O7 layers are stacked in a (0, ½, z) arrangement, with the K+ cations located in half of the available 10-coordinate interlayer cation sites. The inversion symmetry of the phase is broken by a large displacement of the Bi3+ cations parallel to the y-axis. HAADF-STEM images reveal that KBiNb2O7 exhibits frequent stacking faults which convert the (0. ½, z) layer stacking to (½, 0, z) stacking and vice versa, essentially switching the x- and y-axes of the material. By fitting the complex diffraction peak shape of the SXRD data collected from KBiNb2O7 it is estimated that each layer has approximately an ~11% chance of being defective – a high level which is attributed to the lack of cooperative NbO6 tilting in the material, which limits the lattice strain associated with each fault.
Keywords: A1 Journal article; Electron microscopy for materials research (EMAT)
Impact Factor: 4
DOI: 10.1039/D1DT04064B
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“Overcoming contrast reversals in focused probe ptychography of thick materials: An optimal pipeline for efficiently determining local atomic structure in materials science”. Gao C, Hofer C, Jannis D, Béché, A, Verbeeck J, Pennycook TJ, Applied physics letters 121, 081906 (2022). http://doi.org/10.1063/5.0101895
Abstract: Ptychography provides highly efficient imaging in scanning transmission electron microscopy (STEM), but questions have remained over its applicability to strongly scattering samples such as those most commonly seen in materials science. Although contrast reversals can appear in ptychographic phase images as the projected potentials of the sample increase, we show here how these can be easily overcome by a small amount of defocus. The amount of defocus is small enough that it not only can exist naturally when focusing using the annular dark field (ADF) signal but can also be adjusted post acquisition. The ptychographic images of strongly scattering materials are clearer at finite doses than other STEM techniques and can better reveal light atomic columns within heavy lattices. In addition, data for ptychography can now be collected simultaneously with the fastest of ADF scans. This combination of sensitivity and interpretability presents an ideal workflow for materials science.
Keywords: A1 Journal article; Electron microscopy for materials research (EMAT)
Impact Factor: 4
Times cited: 9
DOI: 10.1063/5.0101895
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“Two-dimensional semimetal states in transition metal trichlorides : a first-principles study”. Yu Y, Xie X, Liu X, Li J, Peeters FM, Li L, Applied physics letters 121, 112405 (2022). http://doi.org/10.1063/5.0105605
Abstract: The two-dimensional (2D) transition metal trihalide (TMX3, X = Cl, Br, I) family has attracted considerable attention in recent years due to the realization of CrCl3, CrBr3, and CrI3 monolayers. Up to now, the main focus of the theoretically predicted TMX3 monolayers has been on the Chern insulator states, which can realize the quantum anomalous Hall effect. Here, using first-principles calculations, we theoretically demonstrate that the stable OsCl3 monolayer has a ferromagnetic ground state and a spin-polarized Dirac point without spin-orbit coupling (SOC), which disappears in the band structure of a Janus OsBr1.5Cl1.5 monolayer. We find that OsCl3 exhibits in-plane magnetization when SOC is included. By manipulating the magnetization direction along the C-2 symmetry axis of the OsCl3 structure, a gapless half-Dirac semimetal state with SOC can be achieved, which is different from the gapped Chern insulator state. Both semimetal states of OsCl3 monolayer without and with SOC exhibit a linear half-Dirac point (twofold degenerate) with high Fermi velocities. The achievement of the 2D semimetal state with SOC is expected to be found in other TMX3 monolayers, and we confirm it in a TiCl3 monolayer. This provides a different perspective to study the band structure with SOC of the 2D TMX3 family.
Keywords: A1 Journal article; Condensed Matter Theory (CMT)
Impact Factor: 4
Times cited: 4
DOI: 10.1063/5.0105605
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“The lock-in effect and the greening of automotive cooling systems in the European Union”. Bjornavold A, Van Passel S, Journal Of Environmental Management 203, 1199 (2017). http://doi.org/10.1016/J.JENVMAN.2017.06.010
Abstract: As of 2017, the sale and use of the refrigerants most commonly used in automotive cooling systems – hydrofluorocarbons – are entirely banned in all new vehicles placed on the market in the European Union. These refrigerants have been recognised as potent greenhouse gases and, therefore, direct contributors to climate change. It is within this regulation-driven market that the technologies for a sustainable solution have been developed. However, this paper argues that the market for automotive cooling systems has been 'locked-in', which means that competing technologies, operating under dynamic increasing returns, will allow for one – potentially inferior technology – to dominate the market. Whilst such a situation is not uncommon, this paper discusses the way that regulation has reinforced a patented monopoly in 'picking winners': to the advantage of a synthetic chemical, R-1234yf, as opposed to the natural solution, which is CO2. By developing a generic conceptual framework of path dependence and lock-in, the presented evidence seeks to show how a snowballing effect has led to the intensification of differences in market share. We also argue that the automotive industry is potentially promoting short-term fixes, rather than long-term, sustainable and economically viable solutions. (C) 2017 Elsevier Ltd. All rights reserved.
Keywords: A1 Journal article; Engineering Management (ENM)
Impact Factor: 4.01
Times cited: 5
DOI: 10.1016/J.JENVMAN.2017.06.010
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“Optimal timing of multiple investment decisions in a wood value chain : a real options approach”. Tschulkow M, Compernolle T, Van Passel S, Journal Of Environmental Management 290, 112590 (2021). http://doi.org/10.1016/J.JENVMAN.2021.112590
Abstract: A new reductive catalytic fractionation biorefinery process (RCF) is currently being developed transforming wood into high-value end-products. RCF is considered to be in the pilot stage with a technology readiness level of 5–6. Apart from the RCF-process characteristics, the economic feasibility also depends on the investment decisions that are made upstream and downstream within the wood value chain, increasing the level of uncertainty. Two investment options within the value chain are considered: an option to invest in harvesting equipment and an option to invest in the RCF. To understand the impact of multiple sources of uncertainty on the decision to invest in an innovative RCF-driven wood value chain, an analytical two-factor real options model is presented, accounting for correlated cost and price uncertainties. Two different scenarios, separated and united investments in harvesting equipment and RCF, are analyzed. In both scenarios, market uncertainty postpones investment in comparison to the traditional NPV approach. When both investments are considered separately, the investment in RCF is expected to be earlier than the investment in harvesting equipment. When both investment decisions are united, the probability of investment increases. The study reveals that RCF has the potential to stimulate investments from different investors, –upstream and midstream–, within the wood value chain. Besides, the introduced real options model proofs its ability to assess the economic feasibility of innovative technologies (e.g RCF) individually or within the value chain, taking into account multiple sources of uncertainty.
Keywords: A1 Journal article; Economics; Engineering Management (ENM)
Impact Factor: 4.01
DOI: 10.1016/J.JENVMAN.2021.112590
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“An integrated assessment of environmental, economic, social and technological parameters of source separated and conventional sanitation concepts : a contribution to sustainability analysis”. Firmansyah I, Carsjens GJ, de Ruijter FJ, Zeeman G, Spiller M, Journal Of Environmental Management 295, 113131 (2021). http://doi.org/10.1016/J.JENVMAN.2021.113131
Abstract: Resource recovery and reuse from domestic wastewater has become an important subject for the current development of sanitation technologies and infrastructures. Different technologies are available and combined into sanitation concepts, with different performances. This study provides a methodological approach to evaluate the sustainability of these sanitation concepts with focus on resource recovery and reuse. St. Eustatius, a small tropical island in the Caribbean, was used as a case study for the evaluation. Three source separation-communityon-site and two combined sewerage island-scale concepts were selected and compared in terms of environmental (net energy use, nutrient recovery/reuse, BOD/COD, pathogens, and GHG emission, land use), economic (CAPEX and OPEX), social cultural (acceptance, required competences and education), and technological (flexibility/ adaptability, reliability/continuity of service) indicators. The best performing concept, is the application of Upflow Anaerobic Sludge Bed (UASB) and Trickling Filter (TF) at island level for combined domestic wastewater treatment with subsequent reuse in agriculture. Its overall average normalised score across the four categories (i. e., average of average per category) is about 15% (0.85) higher than the values of the remaining systems and with a score of 0.73 (conventional activated sludge – centralised level), 0.77 (UASB-septic tank (ST)), 0.76 (UASB-TF – community level), and 0.75 (ST – household level). The higher score of the UASB-TF at community level is mainly due to much better performance in the environmental and economic categories. In conclusion, the case study provides a methodological approach that can support urban planning and decision-making in selecting more sustainable sanitation concepts, allowing resource recovery and reuse in small island context or in other contexts.
Keywords: A1 Journal article; Sustainable Energy, Air and Water Technology (DuEL)
Impact Factor: 4.01
DOI: 10.1016/J.JENVMAN.2021.113131
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“Towards harmonization of water quality management : a comparison of chemical drinking water and surface water quality standards around the globe”. Van Winckel T, Cools J, Vlaeminck SE, Joos P, Van Meenen E, Borregán-Ochando E, Van Den Steen K, Geerts R, Vandermoere F, Blust R, Journal Of Environmental Management 298, 113447 (2021). http://doi.org/10.1016/J.JENVMAN.2021.113447
Abstract: Water quality standards (WQS) set the legal definition for safe and desirable water. WQS impose regulatory concentration limits to act as a jurisdiction-specific legislative risk-management tool. Despite its importance in shaping a universal definition of safe, clean water, little information exists with respect to (dis)similarity of chemical WQS worldwide. Therefore, this paper compares chemical WQS for drinking and surface water matrices in eight jurisdictions representing a global geographic distribution: Australia, Brazil, Canada, China, the European Union, the region of Flanders in Belgium, the United States of America, and South Africa. The World Health Organization's list is used as a reference for drinking water standards. Sørensen–Dice indices (SDI) showed little qualitative similarity in the compounds that are regulated in drinking water (median SDI = 40%) and surface water (median SDI = 33%), indicating that the heterogeneity within a matrix is substantial at the level of the standard. Quantitative similarity for matching standards was higher than the qualitative per Kendall correlation (median = 0.73 and 0.58 for drinking water and surface water respectively), yet variance observed within standards remained inexplicably high for organic compounds. Variations in WQS were more pronounced for organic compounds. Most differences cannot be easily explained from a toxicological or risk-based point-of-view. Historical development, ease of measurement, and (toxicological) knowledge gaps on the risk of a vast number of organic compounds are theorized to be the drivers. Therefore, this study argues for a more tailored, risk-based approach in which standards incorporated into water safety plans are dynamically set for compounds that are persistent and could pose a risk for human health and/or aquatic ecosystems. Global variations in WQS should therefore not necessarily be avoided but rather globally harmonized with enough flexibility to ensure a global, up-to-date definition of safe and desirable water everywhere.
Keywords: A1 Journal article; Engineering sciences. Technology; Sustainable Energy, Air and Water Technology (DuEL); Centre for Research on Environmental and Social Change
Impact Factor: 4.01
DOI: 10.1016/J.JENVMAN.2021.113447
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“Sustainable value assessment of farms using frontier efficiency benchmarks”. Van Passel S, Van Huylenbroeck G, Lauwers L, Mathijs E, Journal Of Environmental Management 90, 3057 (2009). http://doi.org/10.1016/J.JENVMAN.2009.04.009
Abstract: Appropriate assessment of firm sustainability facilitates actor-driven processes towards sustainable development. The methodology in this paper builds further on two proven methodologies for the assessment of sustainability performance: it combines the sustainable value approach with frontier efficiency benchmarks. The sustainable value methodology tries to relate firm performance to the use of different resources. This approach assesses contributions to corporate sustainability by comparing firm resource productivity with the resource productivity of a benchmark, and this for all resources considered. The efficiency is calculated by estimating the production frontier indicating the maximum feasible production possibilities. In this research, the sustainable value approach is combined with efficiency analysis methods to benchmark sustainability assessment. In this way, the production theoretical underpinnings of efficiency analysis enrich the sustainable value approach. The methodology is presented using two different functional forms: the CobbDouglas and the translog functional forms. The simplicity of the CobbDouglas functional form as benchmark is very attractive but it lacks flexibility. The translog functional form is more flexible but has the disadvantage that it requires a lot of data to avoid estimation problems. Using frontier methods for deriving firm specific benchmarks has the advantage that the particular situation of each company is taken into account when assessing sustainability. Finally, we showed that the methodology can be used as an integrative sustainability assessment tool for policy measures.
Keywords: A1 Journal article; Economics
Impact Factor: 4.01
Times cited: 41
DOI: 10.1016/J.JENVMAN.2009.04.009
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“Bioremediation : how to deal with removal efficiency uncertainty? An economic application”. Compernolle T, Van Passel S, Lebbe L, Journal Of Environmental Management 127, 77 (2013). http://doi.org/10.1016/J.JENVMAN.2013.04.016
Abstract: Bioremediation is a remediation strategy, which has considerable strength but also certain limitations. Complex and uncertain relationships among biomass, contaminants, and nutrients lead to an uncertain level of removal efficiency. The uncertainty inherent to a bioremediation strategy should be addressed in the remediation selection process. In order to evaluate the bioremediation strategy economically, this study takes into account the reversibility of a decision. A decision tree structures the different remediation strategies, thus giving the possible courses of action open to the decision maker. The option value indicates the importance of having the possibility to reverse a previously made decision. Compared with conventional economic evaluation tools, more information to ground the selection made is revealed.
Keywords: A1 Journal article; Economics
Impact Factor: 4.01
Times cited: 1
DOI: 10.1016/J.JENVMAN.2013.04.016
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“A pseudo-tetragonal tungsten bronze superstructure: a combined solution of the crystal structure of K6.4(Nb,Ta)36.3O94 with advanced transmission electron microscopy and neutron diffraction”. Paria Sena R, Babaryk AA, Khainakov S, Garcia-Granda S, Slobodyanik NS, Van Tendeloo G, Abakumov AM, Hadermann J, Journal of the Chemical Society : Dalton transactions 45, 973 (2016). http://doi.org/10.1039/c5dt03479e
Abstract: The crystal structure of the K6.4Nb28.2Ta8.1O94 pseudo-tetragonal tungsten bronze-type oxide was determined using a combination of X-ray powder diffraction, neutron diffraction and transmission electron microscopy techniques, including electron diffraction, high angle annular dark field scanning transmission electron microscopy (HAADF-STEM), annular bright field STEM (ABF-STEM) and energy-dispersive X-ray compositional mapping (STEM-EDX). The compound crystallizes in the space group Pbam with unit cell parameters a = 37.468(9) A, b = 12.493(3) A, c = 3.95333(15) A. The structure consists of corner sharing (Nb,Ta)O6 octahedra forming trigonal, tetragonal and pentagonal tunnels. All tetragonal tunnels are occupied by K(+) ions, while 1/3 of the pentagonal tunnels are preferentially occupied by Nb(5+)/Ta(5+) and 2/3 are occupied by K(+) in a regular pattern. A fractional substitution of K(+) in the pentagonal tunnels by Nb(5+)/Ta(5+) is suggested by the analysis of the HAADF-STEM images. In contrast to similar structures, such as K2Nb8O21, also parts of the trigonal tunnels are fractionally occupied by K(+) cations.
Keywords: A1 Journal article; Electron microscopy for materials research (EMAT)
Impact Factor: 4.029
Times cited: 6
DOI: 10.1039/c5dt03479e
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