“Study of medieval glass fragments from Savona (Italy) and their relation with the glass produced in Altare”. Cagno S, Badano MB, Mathis F, Strivay D, Janssens K, Journal of archaeological science 39, 2191 (2012). http://doi.org/10.1016/J.JAS.2012.03.013
Abstract: Altare was in the medieval and post-medieval period an important glassmaking center in the Liguria region in Northern Italy. The first historical evidence of glassmaking in Altare is dated to the twelfth century. In spite of that, due to the continuity of glassmaking up to the present time and the contemporaneous intensive urbanization of the territory, no medieval glass from Altare or its immediate vicinity has been analyzed up to now. In this work, glass from archaeological excavations in the center of Savona, city with close ties with the glassmaking center, was studied. Glass fragments, dated from the tenth to the sixteenth century were selected from the collections of the Archaeological Museum in Savona and non-destructively analyzed with quantitative PIXE-PIGE. The resulting compositions, compared with known glass productions of the same time and evaluated on the basis of historical documents, offer an interesting panorama on the variety of glass circulation in Liguria. (C) 2012 Elsevier Ltd. All rights reserved.
Keywords: A1 Journal article; AXES (Antwerp X-ray Analysis, Electrochemistry and Speciation)
Impact Factor: 2.602
Times cited: 21
DOI: 10.1016/J.JAS.2012.03.013
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“Catalytic impact of RuOx clusters to high ammonia sensitivity of tin dioxide”. Marikutsa A, Krivetskiy V, Yashina L, Rumyantseva M, Konstantinova E, Ponzoni A, Comini E, Abakumov A, Gaskov A, Sensors and actuators : B : chemical
T2 –, 25th Eurosensors Conference, SEP 04-07, 2011, Athens, GREECE 175, 186 (2012). http://doi.org/10.1016/j.snb.2012.03.003
Abstract: A comparative study of NH3-sensing performance of blank and modified nanocrystal line SnO2 was performed. Tin dioxide modified by ruthenium displayed the highest ammonia sensitivity with a maximum signal at 200 degrees C. The modifier was shown by XPS and EPR to occur in a mixed valence state of oxidized ruthenium distributed between the surface and bulk of tin dioxide nanocrystals. RuOx clustering on SnO2 surface was detected by means of electron microscopy assisted EDX-mapping. The effect of RuOx on tin dioxide interaction with ammonia was studied by temperature-programmed NH3 desorption, simultaneous Kelvin probe and DC-resistance measurements, EPR spectroscopy and analyses of the gas-solid interaction products. The modifier was shown to promote the materials reactivity to NH3 due to the catalytic activity of RuOx. The interaction with ammonia resulted in dipoles formation on the oxide surface along with reducing the grains net surface charge, established from the electron affinity increase and resistance decrease during NH3 exposure. The RuOx-catalyzed gas-solid interaction was deduced to proceed deeper than in the case of non-modified SnO2 and to yield nitrogen oxides (e.g. NO2), as was suggested by the oxidative character of gaseous products of NH3 interaction with RuOx-modified tin dioxide at 200 degrees C. (C) 2012 Elsevier B.V. All rights reserved.
Keywords: A1 Journal article; Electron microscopy for materials research (EMAT)
Impact Factor: 5.401
Times cited: 20
DOI: 10.1016/j.snb.2012.03.003
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“Establishing uniform acceptance in force biased Monte Carlo simulations”. Neyts EC, Thijsse BJ, Mees MJ, Bal KM, Pourtois G, Journal of chemical theory and computation 8, 1865 (2012). http://doi.org/10.1021/ct2008268
Abstract: Uniform acceptance force biased Monte Carlo (UFMC) simulations have previously been shown to be a powerful tool to simulate atomic scale processes, enabling one to follow the dynamical path during the simulation. In this contribution, we present a simple proof to demonstrate that this uniform acceptance still complies with the condition of detailed balance, on the condition that the characteristic parameter lambda = 1/2 and that the maximum allowed step size is chosen to be sufficiently small. Furthermore, the relation to Metropolis Monte Carlo (MMC) is also established, and it is shown that UFMC reduces to MMC by choosing the characteristic parameter lambda = 0 [Rao, M. et al. Mol. Phys. 1979, 37, 1773]. Finally, a simple example compares the UFMC and MMC methods.
Keywords: A1 Journal article; Plasma Lab for Applications in Sustainability and Medicine – Antwerp (PLASMANT)
Impact Factor: 5.245
Times cited: 20
DOI: 10.1021/ct2008268
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“Separate control between geometrical and electrical asymmetry effects in capacitively coupled plasmas”. Zhang Q-Z, Zhao S-X, Jiang W, Wang Y-N, Journal of physics: D: applied physics 45, 305203 (2012). http://doi.org/10.1088/0022-3727/45/30/305203
Abstract: Both geometrical and electrical asymmetry effects in capacitive argon discharges are investigated using a two-dimensional particle-in-cell coupled with Monte Carlo collision model. When changing the ratio of the top and bottom electrode surface areas and the phase shift between the two applied harmonics, the induced self-bias was found to develop separately. By adjusting the ratio between the high and low harmonic amplitudes, the electrical asymmetry effect at a fixed phase shift can be substantially optimized. However, the self-bias caused by the geometrical asymmetry hardly changed. Moreover, the separate control of these two asymmetry effects can also be demonstrated from their power absorption profiles. Both the axial and radial plasma density distributions can be modulated by the electrical asymmetry effect.
Keywords: A1 Journal article; Plasma Lab for Applications in Sustainability and Medicine – Antwerp (PLASMANT)
Impact Factor: 2.588
Times cited: 20
DOI: 10.1088/0022-3727/45/30/305203
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“Snake states and Klein tunneling in a graphene Hall bar with a pn-junction”. Barbier M, Papp G, Peeters FM, Applied physics letters 100, 163121 (2012). http://doi.org/10.1063/1.4704667
Abstract: The Hall (R-H) and bend (R-B) resistances of a graphene Hall bar structure containing a pn-junction are calculated when in the ballistic regime. The simulations are done using the billiard model. Introducing a pn-junction-dividing the Hall bar geometry in two regions-leads to two distinct regimes exhibiting very different physics: (1) both regions are of n-type and (2) one region is n-type and the other p-type. In regime (1), a “Hall plateau”-an enhancement of the resistance-appears for R-H. On the other hand, in regime (2), we found a negative R-H, which approaches zero for large B. The bend resistance is highly asymmetric in regime (2) and the resistance increases with increasing magnetic field B in one direction while it reduces to zero in the other direction. (C) 2012 American Institute of Physics. [http://dx.doi.org/10.1063/1.4704667]
Keywords: A1 Journal article; Condensed Matter Theory (CMT)
Impact Factor: 3.411
Times cited: 20
DOI: 10.1063/1.4704667
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“Thermally induced structural and morphological changes of CdSe/CdS octapods”. Goris B, van Huis MA, Bals S, Zandbergen HW, Manna L, Van Tendeloo G, Small 8, 937 (2012). http://doi.org/10.1002/smll.201101897
Abstract: Branched nanostructures are of great interest because of their promising optical and electronic properties. For successful and reliable integration in applications such as photovoltaic devices, the thermal stability of the nanostructures is of major importance. Here the different domains (CdSe cores, CdS pods) of the heterogeneous octapods are shown to have different thermal stabilities, and heating is shown to induce specific shape changes. The octapods are heated from room temperature to 700 °C, and investigated using (analytical and tomographic) transmission electron microscopy (TEM). At low annealing temperatures, pure Cd segregates in droplets at the outside of the octapods, indicating non-stochiometric composition of the octapods. Furthermore, the tips of the pods lose their faceting and become rounded. Further heating to temperatures just below the sublimation temperature induces growth of the zinc blende core at the expense of the wurtzite pods. At higher temperatures, (500700 °C), sublimation of the octapods is observed in real time in the TEM. Three-dimensional tomographic reconstructions reveal that the four pods pointing into the vacuum have a lower thermal stability than the four pods that are in contact with the support.
Keywords: A1 Journal article; Engineering sciences. Technology; Electron microscopy for materials research (EMAT)
Impact Factor: 8.643
Times cited: 20
DOI: 10.1002/smll.201101897
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“Defect controlled room temperature ferromagnetism in Co-doped barium titanate nanocrystals”. Ray S, Kolen'ko YV, Kovnir KA, Lebedev OI, Turner S, Chakraborty T, Erni R, Watanabe T, Van Tendeloo G, Yoshimura M, Itoh M, Nanotechnology 23, 025702 (2012). http://doi.org/10.1088/0957-4484/23/2/025702
Abstract: Defect mediated high temperature ferromagnetism in oxide nanocrystallites is the central feature of this work. Here, we report the development of room temperature ferromagnetism in nanosized Co-doped barium titanate particles with a size of around 14 nm, synthesized by a solvothermal drying method. A combination of x-ray diffraction with state-of-the-art electron microscopy techniques confirms the intrinsic doping of Co into BaTiO3. The development of the room temperature ferromagnetism was tracked down to the different donor defects, namely hydroxyl groups at the oxygen site (\mathrm {OH}\mathrm {(O)}
Keywords: A1 Journal article; Electron microscopy for materials research (EMAT)
Impact Factor: 3.44
Times cited: 19
DOI: 10.1088/0957-4484/23/2/025702
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“Electron-phonon bound states in graphene in a perpendicular magnetic field”. Zhu J, Badalyan SM, Peeters FM, Physical review letters 109, 256602 (2012). http://doi.org/10.1103/PhysRevLett.109.256602
Abstract: The spectrum of electron-phonon complexes in monolayer graphene is investigated in the presence of a perpendicular quantizing magnetic field. Despite the small electron-phonon coupling, usual perturbation theory is inapplicable for the calculation of the scattering amplitude near the threshold of optical phonon emission. Our findings, beyond perturbation theory, show that the true spectrum near the phonon-emission threshold is completely governed by new branches, corresponding to bound states of an electron and an optical phonon with a binding energy of the order of alpha omega(0), where alpha is the electron-phonon coupling and omega(0) the phonon energy. DOI: 10.1103/PhysRevLett.109.256602
Keywords: A1 Journal article; Condensed Matter Theory (CMT)
Impact Factor: 8.462
Times cited: 19
DOI: 10.1103/PhysRevLett.109.256602
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“Magnetodielectric CuCr0.5V0.5O2 : an example of a magnetic and dielectric multiglass”. Singh K, Maignan A, Simon C, Kumar S, Martin C, Lebedev O, Turner S, Van Tendeloo G, Journal of physics : condensed matter 24, 226002 (2012). http://doi.org/10.1088/0953-8984/24/22/226002
Abstract: The complex dielectric susceptibility and spin glass properties of polycrystalline CuCr0.5V 0.5O2 delafossite have been investigated. Electron diffraction, high resolution electron microscopy and electron energy loss spectroscopy show that the Cr3+ and V 3+ magnetic cations are randomly distributed on the triangular network of CdI2-type layers. In contrast to CuCrO2, CuCr0.5V 0.5O2 exhibits two distinctive (magnetic and electric) glassy states evidenced by memory effects in electric and magnetic susceptibilities. A large magnetodielectric coupling is observed at low temperature.
Keywords: A1 Journal article; Electron microscopy for materials research (EMAT)
Impact Factor: 2.649
Times cited: 19
DOI: 10.1088/0953-8984/24/22/226002
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“Texture-dependent twin formation in nanocrystalline thin Pd films”. Wang B, Idrissi H, Shi H, Colla MS, Michotte S, Raskin JP, Pardoen T, Schryvers D, Scripta materialia 66, 866 (2012). http://doi.org/10.1016/j.scriptamat.2012.01.038
Abstract: Nanocrystalline Pd films were produced by electron-beam evaporation and sputter deposition. The electron-beam-evaporated films reveal randomly oriented nanograins with a relatively high density of growth twins, unexpected in view of the high stacking fault energy of Pd. In contrast, sputter-deposited films show a clear 〈1 1 1〉 crystallographic textured nanostructure without twins. These results provide insightful information to guide the generation of microstructures with enhanced strength/ductility balance in high stacking fault energy nanocrystalline metallic thin films.
Keywords: A1 Journal article; Engineering sciences. Technology; Electron microscopy for materials research (EMAT)
Impact Factor: 3.747
Times cited: 19
DOI: 10.1016/j.scriptamat.2012.01.038
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“Copper(II)-binding ability of stereoisomeric cis- and trans-2-aminocyclohexanecarboxylic acidl-phenylalanine dipeptides : a combined CW/pulsed EPR and DFT study”. Nagy NV, Van Doorslaer S, Szabó-Plánka T, Van Rompaey S, Hamza A, Fülöp F, Tóth GK, Rockenbauer A, Inorganic chemistry 51, 1386 (2012). http://doi.org/10.1021/ic2016116
Abstract: With the aim of an improved understanding of the metal-complexation properties of alicyclic β-amino acid stereoisomers, and their peptides, the complex equilibria and modes of coordination with copper(II) of l-phenylalanine (F) derivatives of cis/trans-2-aminocyclohexanecarboxylic acid (c/tACHC), i.e. the dipeptides F-c/tACHC and c/tACHC-F, were investigated by a combination of CW and pulsed EPR methods. For the interpretation of the experimental data, DFT quantum-chemical calculations were carried out. Simulation of a pH-dependent series of room-temperature CW-EPR spectra revealed the presence of EPR-active complexes ([Cu(aqua)]2+, [CuL]+, [CuLH1], [CuLH2]−, and [CuL2H1]−), and an EPR-inactive species ([Cu2L2H3]−) in aqueous solutions for all studied cases. [CuLH]2+ was included in the equilibrium model for the c/tACHC-Fcopper(II) systems, and [CuL2], together with two coordination isomers of [CuL2H1]−, were also identified in the F-tACHCcopper(II) system. Comparison of the complexation properties of the diastereomeric ligand pair F-(1S,2R)-ACHC and F-(1R,2S)-ACHC did not reveal significant differences. Considerably lower formation constants were obtained for the trans than for the cis isomers for both the F-c/tACHC and the c/tACHC-F pairs in the case of [CuLH1] involving tridentate coordination by the amino, the deprotonated peptide, and the carboxylate groups. A detailed structural analysis by pulsed EPR methods and DFT calculations indicated that there was no significant destabilization for the complexes of the trans isomers. The lower stability of their complexes was explained by the limitation that only the conformer with donor groups in equatorialequatorial ring positions can bind to copper(II), whereas both equatorial-axial conformers of the cis isomers are capable of binding. From a consideration of the proton couplings obtained with X-band 1H HYSCORE, 2H exchange experiments, and DFT, the thermodynamically most stable cyclohexane ring conformer was assigned for all four [CuLH1] complexes. For the F-cACHC case, the conformer did not match the most stable conformer of the free ligand.
Keywords: A1 Journal article; Electron microscopy for materials research (EMAT)
Impact Factor: 4.857
Times cited: 18
DOI: 10.1021/ic2016116
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“Effect of a mass spectrometer interface on inductively coupled plasma characteristics : a computational study”. Aghaei M, Lindner H, Bogaerts A, Journal of analytical atomic spectrometry 27, 604 (2012). http://doi.org/10.1039/c2ja10341a
Abstract: An inductively coupled plasma connected to a mass spectrometer interface (sampling cone) is computationally investigated. Typical plasma characteristics, such as gas flow velocity, plasma temperature and electron density, are calculated in two dimensions (cylindrical symmetry) and compared with and without a mass spectrometer sampling interface. The results obtained from our model compare favorably with experimental data reported in the literature. A dramatic increase in the plasma velocity is reported in the region close to the interface. Furthermore, a cooled metal interface lowers the plasma temperature and electron density on the axial channel very close to the sampling cone but the corresponding values in the off axial regions are increased. Therefore, the effect of the interface strongly depends on the measurement position. It is shown that even a small shift from the actual position of the sampler leads to a considerable change of the results.
Keywords: A1 Journal article; Plasma Lab for Applications in Sustainability and Medicine – Antwerp (PLASMANT)
Impact Factor: 3.379
Times cited: 18
DOI: 10.1039/c2ja10341a
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“Effect of grain boundary on the buckling of graphene nanoribbons”. Neek-Amal M, Peeters FM, Applied physics letters 100, 101905 (2012). http://doi.org/10.1063/1.3692573
Abstract: The buckling of graphene nano-ribbons containing a grain boundary is studied using atomistic simulations where free and supported boundary conditions are invoked. We consider the buckling transition of two kinds of grain boundaries with special symmetry. When graphene contains a large angle grain boundary with theta = 21.8 degrees, the buckling strains are larger than those of perfect graphene when the ribbons with free (supported) boundary condition are subjected to compressive tension parallel (perpendicular) to the grain boundary. This is opposite for the results of theta = 32.2 degrees. The shape of the deformations of the buckled graphene nanoribbons depends on the boundary conditions, the presence of the particular used grain boundaries, and the direction of applied in-plane compressive tension. (C) 2012 American Institute of Physics. [http://dx.doi.org/10.1063/1.3692573]
Keywords: A1 Journal article; Condensed Matter Theory (CMT)
Impact Factor: 3.411
Times cited: 18
DOI: 10.1063/1.3692573
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“Impact of Dresselhaus versus Rashba spin-orbit coupling on the Holstein polaron”. Li Z, Covaci L, Marsiglio F, Physical review : B : condensed matter and materials physics 85, 205112 (2012). http://doi.org/10.1103/PhysRevB.85.205112
Abstract: We utilize an exact variational numerical procedure to calculate the ground-state properties of a polaron in the presence of Rashba and linear Dresselhaus spin-orbit coupling. We find that when the linear Dresselhaus spin-orbit coupling approaches the Rashba spin-orbit coupling, the Van Hove singularity in the density of states will be shifted away from the bottom of the band and finally disappear when the two spin-orbit couplings are tuned to be equal. The effective mass will be suppressed; the trend will become more significant for low phonon frequency. The presence of two dominant spin-orbit couplings will make it possible to tune the effective mass with more varied observables.
Keywords: A1 Journal article; Condensed Matter Theory (CMT)
Impact Factor: 3.836
Times cited: 18
DOI: 10.1103/PhysRevB.85.205112
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“Optimization of operating parameters for inductively coupled plasma mass spectrometry : a computational study”. Aghaei M, Lindner H, Bogaerts A, Spectrochimica acta: part B : atomic spectroscopy 76, 56 (2012). http://doi.org/10.1016/j.sab.2012.06.006
Abstract: An inductively coupled plasma, connected to a mass spectrometer interface, is computationally investigated. The effect of pressure behind the sampler, injector gas flow rate, auxiliary gas flow rate, and applied power is studied. There seems to be an optimum range of injector gas flow rate for each setup which guaranties the presence and also a proper length of the central channel in the torch. Moreover, our modeling results show that for any specific purpose, it is possible to control that either only the central gas flow passes through the sampler orifice or that it is accompanied by the auxiliary gas flow. It was also found that depending on geometry, the variation of outgoing gas flow rate is much less than the variation of the injector gas flow rate and this causes a slightly higher pressure inside the torch. The general effect of increasing the applied power is a rise in the plasma temperature, which results in a higher ionization in the coil region. However, the negative effect is reducing the length of the cool central channel which is important to transfer the sample substances to the sampler. Using a proper applied power can enhance the efficiency of the system. Indeed, by changing the gas path lines, the power can control which flow (i.e., only from injector gas or also from the auxiliary gas) goes to the sampler orifice. Finally, as also reported from experiments in literature, the pressure behind the sampler has no dramatic effect on the plasma characteristics.
Keywords: A1 Journal article; Plasma Lab for Applications in Sustainability and Medicine – Antwerp (PLASMANT)
Impact Factor: 3.241
Times cited: 18
DOI: 10.1016/j.sab.2012.06.006
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“Stability and crystal structures of iron carbides : a comparison between the semi-empirical modified embedded atom method and quantum-mechanical DFT calculations”. Fang CM, van Huis MA, Thijsse BJ, Zandbergen HW, Physical review : B : condensed matter and materials physics 85, 054116 (2012). http://doi.org/10.1103/PhysRevB.85.054116
Abstract: Iron carbides play a crucial role in steel manufacturing and processing and to a large extent determine the physical properties of steel products. The modified embedded atom method (MEAM) in combination with Lee's Fe-C potential is a good candidate for molecular dynamics simulations on larger Fe-C systems. Here, we investigate the stability and crystal structures of pure iron and binary iron carbides using MEAM and compare them with the experimental data and quantum-mechanical density functional theory calculations. The analysis shows that the Fe-C potential gives reasonable results for the relative stability of iron and iron carbides. The performance of MEAM for the prediction of the potential energy and the calculated lattice parameters at elevated temperature for pure iron phases and cementite are investigated as well. The conclusion is that Lee's MEAM Fe-C potential provides a promising basis for further molecular dynamics simulations of Fe-C alloys and steels at lower temperatures (up to 800 K).
Keywords: A1 Journal article; Electron microscopy for materials research (EMAT)
Impact Factor: 3.836
Times cited: 18
DOI: 10.1103/PhysRevB.85.054116
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“Stability and structures of the CFCC-TmC phases : a first-principles study”. Fang CM, van Huis MA, Zandbergen HW, Computational materials science 51, 146 (2012). http://doi.org/10.1016/j.commatsci.2011.07.017
Abstract: The η-M6C, γ-M23C6, and π-M11C2 phases (M = Cr, Mn and Fe) have complex cubic lattices with lattice parameters of approximately 1.0 nm. They belong to the CFCC-TmC family (complex face-centered cubic transition metal carbides), display a rich variety of crystal structures, and play in important role in iron alloys and steels. Here we show that first-principles calculations predict high stability for the γ-M23C6 and η-M6C phases, and instability for the π-M11C2 phases, taking into account various compositional and structural possibilities. The calculations also show a wide variety in magnetic properties. The Cr-containing phases were found to be non-magnetic and the Fe-phases to be ferromagnetic, while the Mn-containing phases were found to be either ferrimagnetic or non-magnetic. Details of the local atomic structures, and the formation and stability of these precipitates in alloys are discussed.
Keywords: A1 Journal article; Electron microscopy for materials research (EMAT)
Impact Factor: 2.292
Times cited: 18
DOI: 10.1016/j.commatsci.2011.07.017
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“Crystal structure of a lightweight borohydride from submicrometer crystallites by precession electron diffraction”. Hadermann J, Abakumov A, Van Rompaey S, Perkisas T, Filinchuk Y, Van Tendeloo G, Chemistry of materials 24, 3401 (2012). http://doi.org/10.1021/cm301548k
Abstract: We demonstrate that precession electron diffraction at low-dose conditions can be successfully applied for structure analysis of extremely electron-beam-sensitive materials. Using LiBH4 as a test material, complete structural information, including the location of the H atoms, was obtained from submicrometer-sized crystallites. This demonstrates for the first time that, where conventional transmission electron microscopy techniques fail, quantitative precession electron diffraction can provide structural information from submicrometer particles of such extremely electron-beam-sensitive materials as complex lightweight hydrides. We expect the precession electron diffraction technique to be a useful tool for nanoscale investigations of thermally unstable lightweight hydrogen-storage materials.
Keywords: A1 Journal article; Electron microscopy for materials research (EMAT)
Impact Factor: 9.466
Times cited: 17
DOI: 10.1021/cm301548k
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“Prussian blue analogues of reduced dimensionality”. Gengler RYN, Toma LM, Pardo E, Lloret F, Ke X, Van Tendeloo G, Gournis D, Rudolf P, Small 8, 2532 (2012). http://doi.org/10.1002/smll.201200517
Abstract: Mixed-valence polycyanides (Prussian Blue analogues) possess a rich palette of properties spanning from room-temperature ferromagnetism to zero thermal expansion, which can be tuned by chemical modifications or the application of external stimuli (temperature, pressure, light irradiation). While molecule-based materials can combine physical and chemical properties associated with molecular-scale building blocks, their successful integration into real devices depends primarily on higher-order properties such as crystal size, shape, morphology, and organization. Herein a study of a new reduced-dimensionality system based on Prussian Blue analogues (PBAs) is presented. The system is built up by means of a modified Langmuir-Blodgett technique, where the PBA is synthesized from precursors in a self-limited reaction on a clay mineral surface. The focus of this work is understanding the magnetic properties of the PBAs in different periodic, low-dimensional arrangements, and the influence of the “on surface” synthesis on the final properties and dimensionality of the system.
Keywords: A1 Journal article; Engineering sciences. Technology; Electron microscopy for materials research (EMAT)
Impact Factor: 8.643
Times cited: 17
DOI: 10.1002/smll.201200517
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“Beyond the environmentalist's paradox and the debate on weak versus strong sustainability”. Ang F, Van Passel S, Bioscience 62, 251 (2012). http://doi.org/10.1525/BIO.2012.62.3.6
Abstract: Environmentalists generally argue that ecological damage will (eventually) lead to declines in human well-being. From this perspective, the recent introduction of the “environmentalist's paradox” in BioScience by Raudsepp-Hearne and colleagues (2010) is particularly significant. In essence, Raudsepp-Hearne and colleagues (2010) claimed that although ecosystem services have been degraded, human well-being-paradoxically-has increased. In this article, we show that this debate is in fact rooted in a broader discussion on weak sustainability versus strong sustainability (the substitutability of human-made capital for natural capital). We warn against the reductive nature of focusing only on a stock flow framework in which a natural-capital stock produces ecosystem services. Concretely, we recommend a holistic approach in which the complexity, irreversibility, uncertainty, and ethical predicaments intrinsic to the natural environment and its connections to humanity are also considered.
Keywords: A1 Journal article; Economics; Engineering Management (ENM)
Impact Factor: 5.378
Times cited: 17
DOI: 10.1525/BIO.2012.62.3.6
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“Analytical TEM study of CVD diamond growth on TiO2 sol-gel layers”. Lu Y-G, Verbeeck J, Turner S, Hardy A, Janssens SD, De Dobbelaere C, Wagner P, Van Bael MK, Van Tendeloo G, Diamond and related materials 23, 93 (2012). http://doi.org/10.1016/j.diamond.2012.01.022
Abstract: The early growth stages of chemical vapor deposition (CVD) diamond on a solgel TiO2 film with buried ultra dispersed diamond seeds (UDD) have been studied. In order to investigate the diamond growth mechanism and understand the role of the TiO2 layer in the growth process, high resolution transmission electron microscopy (HRTEM), energy-filtered TEM and electron energy loss spectroscopy (EELS) techniques were applied to cross sectional diamond film samples. We find evidence for the formation of TiC crystallites inside the TiO2 layer at different diamond growth stages. However, there is no evidence that diamond nucleation starts from these crystallites. Carbon diffusion into the TiO2 layer and the chemical bonding state of carbon (sp2/sp3) were both extensively investigated. We provide evidence that carbon diffuses through the TiO2 layer and that the diamond seeds partially convert to amorphous carbon during growth. This carbon diffusion and diamond to amorphous carbon conversion make the seed areas below the TiO2 layer grow and bend the TiO2 layer upwards to form the nucleation center of the diamond film. In some of the protuberances a core of diamond seed remains, covered by amorphous carbon. It is however unlikely that the remaining seeds are still active during the growth process.
Keywords: A1 Journal article; Electron microscopy for materials research (EMAT)
Impact Factor: 2.561
Times cited: 16
DOI: 10.1016/j.diamond.2012.01.022
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“Preparation, microstructure characterization and catalytic performance of Cu/ZnO and ZnO/Cu composite nanoparticles for liquid phase methanol synthesis”. Sliem MA, Turner S, Heeskens D, Kalidindi SB, Van Tendeloo G, Muhler M, Fischer RA, Physical chemistry, chemical physics 14, 8170 (2012). http://doi.org/10.1039/c2cp40482f
Abstract: Stearate@Cu/ZnO nanocomposite particles with molar ratios of ZnO ∶ Cu = 2 and 5 are synthesized by reduction of the metalorganic Cu precursor [Cu{(OCH(CH3)CH2N(CH3)2)}2] in the presence of stearate@ZnO nanoparticles. In the case of ZnO ∶ Cu = 5, high-angle annular dark field-scanning transmission electron microscopy (HAADF-STEM) combined with electron-energy-loss-spectroscopy (EELS) as well as attenuated total reflection Fourier transform infrared (ATR-IR) spectroscopy are used to localize the small amount of Cu deposited on the surface of 35 nm sized stearate@ZnO particles. For ZnO ∶ Cu = 2, the microstructure of the nanocomposites after catalytic activity testing is characterized by HAADF-STEM techniques. This reveals the construction of large Cu nanoparticles (2050 nm) decorated by small ZnO nanoparticles (35 nm). The catalytic activity of both composites for the synthesis of methanol from syn gas is evaluated.
Keywords: A1 Journal article; Electron microscopy for materials research (EMAT)
Impact Factor: 4.123
Times cited: 16
DOI: 10.1039/c2cp40482f
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“The electronic properties of graphene and graphene ribbons under simple shear strain”. Sena SHR, Pereira JM, Farias GA, Peeters FM, Costa Filho RN, Journal of physics : condensed matter 24, 375301 (2012). http://doi.org/10.1088/0953-8984/24/37/375301
Abstract: A tight-binding model is used to study the energy band of graphene and graphene ribbon under simple shear strain. The ribbon consists of lines of carbon atoms in an armchair or zigzag orientation where a simple shear strain is applied in the x-direction keeping the atomic distances in the y-direction unchanged. Such modification in the lattice gives an energy band that differs in several aspects from the one without any shear and with pure shear. The changes in the spectrum depend on the line displacement of the ribbon, and also on the modified hopping parameter. It is also shown that this simple shear strain tunes the electronic properties of both graphene and graphene ribbon, opening and closing energy gaps for different displacements of the system. The modified density of states is also shown.
Keywords: A1 Journal article; Condensed Matter Theory (CMT)
Impact Factor: 2.649
Times cited: 15
DOI: 10.1088/0953-8984/24/37/375301
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“Experimental validation of edge strength model for glass with polished and cut edge finishing”. Vandebroek M, Belis J, Louter C, Van Tendeloo G, Engineering fracture mechanics 96, 480 (2012). http://doi.org/10.1016/j.engfracmech.2012.08.019
Abstract: In literature, the experimental validation of a glass edge strength model is lacking. Therefore, in this study, an edge strength model was established and validated. The short-term parameters of the edge strength model, i.e. the flaw geometry and depth, were determined by means of testing at a high stress rate. This was done for polished and cut edges. Next, the strength model, including subcritical crack growth, was established. Finally, the edge strength model was validated by the test results at a low stress rate. The assessed model was found to be slightly conservative, compared to the test results.
Keywords: A1 Journal article; Engineering sciences. Technology; Electron microscopy for materials research (EMAT)
Impact Factor: 2.151
Times cited: 15
DOI: 10.1016/j.engfracmech.2012.08.019
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“Fluid simulation of the phase-shift effect in hydrogen capacitively coupled plasmas: 2 : radial uniformity of the plasma characteristics”. Zhang Y-R, Xu X, Bogaerts A, Wang Y-N, Journal of physics: D: applied physics 45, 015203 (2012). http://doi.org/10.1088/0022-3727/45/1/015203
Abstract: A two-dimensional fluid model, including the full set of Maxwell equations, has been developed and applied to investigate the effect of a phase shift between two power sources on the radial uniformity of several plasma characteristics in a hydrogen capacitively coupled plasma. This study was carried out at various frequencies in the range 13.56200 MHz. When the frequency is low, at 13.56 MHz, the plasma density is characterized by an off-axis peak when both power sources are in-phase (phgr = 0), and the best radial uniformity is obtained at phgr = π. This trend can be explained because the radial nonuniformity caused by the electrostatic edge effect can be effectively suppressed by the phase-shift effect at a phase difference equal to π. When the frequency rises to 60 MHz, the plasma density profiles shift smoothly from edge-peaked over uniform to centre-peaked as the phase difference increases, due to the pronounced standing-wave effect, and the best radial uniformity is reached at phgr = 0.3π. At a frequency of 100 MHz, a similar behaviour is observed, except that the maximum of the plasma density moves again towards the radial edge at the reverse-phase case (phgr = π), because of the dominant skin effect. When the frequency is 200 MHz, the bulk plasma density increases significantly with increasing phase-shift values, and a better uniformity is obtained at phgr = 0.4π. This is because the density in the centre increases faster than at the radial edge as the phase difference rises, due to the increasing power deposition Pz in the centre and the decreasing power density Pr at the radial edge. As the phase difference increases to π, the maximum near the radial edge becomes obvious again. This is because the skin effect has a predominant influence on the plasma density under this condition, resulting in a high density at the radial edge. Moreover, the axial ion flux increases monotonically with phase difference, and exhibits similar profiles to the plasma density. The calculation results illustrate that the radial uniformity of the various plasma characteristics is strongly dependent on the applied frequency and the phase shift between both power sources, which is important to realize, for controlling the uniformity of the plasma etch and deposition processes.
Keywords: A1 Journal article; Plasma Lab for Applications in Sustainability and Medicine – Antwerp (PLASMANT)
Impact Factor: 2.588
Times cited: 15
DOI: 10.1088/0022-3727/45/1/015203
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“Fully automated measurement of the modulation transfer function of charge-coupled devices above the Nyquist frequency”. van den Broek W, Van Aert S, van Dyck D, Microscopy and microanalysis 18, 336 (2012). http://doi.org/10.1017/S1431927611012633
Abstract: The charge-coupled devices used in electron microscopy are coated with a scintillating crystal that gives rise to a severe modulation transfer function (MTF). Exact knowledge of the MTF is imperative for a good correspondence between image simulation and experiment. We present a practical method to measure the MTF above the Nyquist frequency from the beam blocker's shadow image. The image processing has been fully automated and the program is made public. The method is successfully tested on three cameras with various beam blocker shapes.
Keywords: A1 Journal article; Electron microscopy for materials research (EMAT); Vision lab
Impact Factor: 1.891
Times cited: 15
DOI: 10.1017/S1431927611012633
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“Oxidation of the GaAs(001) surface : insights from first-principles calculations”. Scarrozza M, Pourtois G, Houssa M, Heyns M, Stesmans A, Physical review : B : condensed matter and materials physics 85, 195307 (2012). http://doi.org/10.1103/PhysRevB.85.195307
Abstract: We performed a detailed investigation of the oxidation of the technologically relevant GaAs(001)-beta 2(2x4) surface via density functional calculations. The purpose is to gain insights on the atomistic mechanisms and local bondings that underlie the degradation of the surface properties once exposed to oxygen. The study comprises the adsorption of single O atoms, through the sampling of several adsorption sites, and the subsequent formation of the O adsorbate at increasing coverage by taking into account multiple-atom adsorption. Based on the evaluation of the energetics and the structural properties of the atomistic models generated, the results here reported delineate a consistent picture of the initial stage of the surface oxidation: (i) at low coverage, in the limit of single O insertions, oxygen is incorporated on the surface forming a twofold-bridging Ga-O-As bond; (ii) at increasing coverage, as multiple O atoms are involved, this is accompanied by the formation of a threefold-coordinated bond (with two Ga and one As atoms); (iii) the latter has important implications regarding the electronic properties of the adsorbate since this O bonding may result in the formation of As dangling bonds. Moreover, a clear trend of increased energy gain for the incorporation of neighboring O atoms compared to single O insertions indicates that the formation of oxide clusters is favored over a regime of uniform oxidation. Our findings provide a detailed description of the O bonding and stress the importance of modeling the adsorption of multiple O atoms for an accurate description of the surface oxidation.
Keywords: A1 Journal article; Plasma Lab for Applications in Sustainability and Medicine – Antwerp (PLASMANT)
Impact Factor: 3.836
Times cited: 15
DOI: 10.1103/PhysRevB.85.195307
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“X-ray absorption spectroscopy by full-field X-ray microscopy of a thin graphite flake: Imaging and electronic structure via the carbon K-edge”. Bittencourt C, Hitchock AP, Ke X, Van Tendeloo G, Ewels CP, Guttmann P, Beilstein journal of nanotechnology 3, 345 (2012). http://doi.org/10.3762/bjnano.3.39
Abstract: We demonstrate that near-edge X-ray-absorption fine-structure spectra combined with full-field transmission X-ray microscopy can be used to study the electronic structure of graphite flakes consisting of a few graphene layers. The flake was produced by exfoliation using sodium cholate and then isolated by means of density-gradient ultracentrifugation. An image sequence around the carbon K-edge, analyzed by using reference spectra for the in-plane and out-of-plane regions of the sample, is used to map and spectrally characterize the flat and folded regions of the flake. Additional spectral features in both π and σ regions are observed, which may be related to the presence of topological defects. Doping by metal impurities that were present in the original exfoliated graphite is indicated by the presence of a pre-edge signal at 284.2 eV.
Keywords: A1 Journal article; Engineering sciences. Technology; Electron microscopy for materials research (EMAT)
Impact Factor: 3.127
Times cited: 15
DOI: 10.3762/bjnano.3.39
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“Concept and validation of a fully automated photocatalytic test setup”. Tytgat T, Hauchecorne B, Smits M, Verbruggen S, Lenaerts S, Journal of laboratory automation 17, 134 (2012). http://doi.org/10.1177/2211068211424554
Abstract: Photocatalytic activity can be studied by several methods, each with its own strengths and weaknesses. To study photocatalytic activity in an easy, user-friendly, and realistic way, a completely new setup has been built. The setup is modularly constructed around Fourier transform infrared spectroscopy (FTIR) spectroscopy at the heart of it, resulting in great versatility. Complementary software has been written for automatic control of the setup and for processing the generated data. Two pollutants, oil and n-octane, are tested to validate the performance of the setup. These validation experiments confirm the usefulness and added value of the setup in general and of the FTIR detection methodology as well. It becomes clear that a system of online measurements with good repeatability, accuracy, and user-friendliness has been created.
Keywords: A1 Journal article; Engineering sciences. Technology; Sustainable Energy, Air and Water Technology (DuEL)
Impact Factor: 2.85
Times cited: 15
DOI: 10.1177/2211068211424554
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“Flux-quantum-discretized dynamics of magnetic flux entry, exit, and annihilation in current-driven mesoscopic type-I superconductors”. Berdiyorov GR, Hernández-Nieves AD, Milošević, MV, Peeters FM, Dominguez D, Physical review : B : condensed matter and materials physics 85, 092502 (2012). http://doi.org/10.1103/PhysRevB.85.092502
Abstract: We study nonlinear flux dynamics in a current-carrying type-I superconductor. The stray magnetic field of the current induces the intermediate state, where nucleation of flux domains is discretized to a single fluxoid at a time, while their final shape (tubular or laminar), size, and nucleation rate depend on applied current and edge conditions. The current induces opposite flux domains on opposite sides of the sample, and subsequently drives them to annihilation-which is also discretized, as a sequence of vortex-antivortex pairs. The discretization of both nucleation and annihilation leaves measurable traces in the voltage across the sample and in locally probed magnetization. The reported dynamic phenomena thus provide an unambiguous proof of a flux quantum being the smallest building block of the intermediate state in type-I superconductors.
Keywords: A1 Journal article; Condensed Matter Theory (CMT)
Impact Factor: 3.836
Times cited: 14
DOI: 10.1103/PhysRevB.85.092502
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