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Author |
Gielis, J.; Grigolia, R. |
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Title |
Lamé curves and Rvachev's R-functions |
Type |
A3 Journal article |
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Year |
2022 |
Publication |
Sn – 1512-0066 |
Abbreviated Journal |
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Volume |
37 |
Issue |
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Pages |
1-4 |
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Keywords |
A3 Journal article; Sustainable Energy, Air and Water Technology (DuEL) |
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Abstract  |
Gielis transformations are a generalization of Lame curves. To combine domains, we can make use of the natural alliance between Lame's work and Rvachev's R-functions. A logical next step is the extension to n-valued logic dening dierent partitions. |
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Most recent IF: NA |
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Call Number |
UA @ admin @ c:irua:189316 |
Serial |
7178 |
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Author |
Gielis, J.; Caratelli, D.; Fougerolle, Y.; Ricci, P.E.; Tavkelidze, I.; Gerats, T. |
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Title |
Universal natural shapes : from unifying shape description to simple methods for shape analysis and boundary value problems |
Type |
A1 Journal article |
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Year |
2012 |
Publication |
PLoS ONE |
Abbreviated Journal |
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Volume |
7 |
Issue |
9 |
Pages |
e29324-11 |
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Keywords |
A1 Journal article; Engineering sciences. Technology; Sustainable Energy, Air and Water Technology (DuEL) |
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Abstract |
Gielis curves and surfaces can describe a wide range of natural shapes and they have been used in various studies in biology and physics as descriptive tool. This has stimulated the generalization of widely used computational methods. Here we show that proper normalization of the Levenberg-Marquardt algorithm allows for efficient and robust reconstruction of Gielis curves, including self-intersecting and asymmetric curves, without increasing the overall complexity of the algorithm. Then, we show how complex curves of k-type can be constructed and how solutions to the Dirichlet problem for the Laplace equation on these complex domains can be derived using a semi-Fourier method. In all three methods, descriptive and computational power and efficiency is obtained in a surprisingly simple way. |
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000309517500001 |
Publication Date |
2012-09-30 |
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ISSN |
1932-6203 |
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UA library record; WoS full record; WoS citing articles |
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Call Number |
UA @ admin @ c:irua:102202 |
Serial |
8711 |
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Author |
Fougerolle, Y.D.; Truchetet, F.; Demonceaux, C.; Gielis, J. |
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Title |
A robust evolutionary algorithm for the recovery of rational Gielis curves |
Type |
A1 Journal article |
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Year |
2013 |
Publication |
Pattern recognition |
Abbreviated Journal |
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Volume |
46 |
Issue |
8 |
Pages |
2078-2091 |
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Keywords |
A1 Journal article; Engineering sciences. Technology; Sustainable Energy, Air and Water Technology (DuEL) |
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Abstract |
Gielis curves (GC) can represent a wide range of shapes and patterns ranging from star shapes to symmetric and asymmetric polygons, and even self intersecting curves. Such patterns appear in natural objects or phenomena, such as flowers, crystals, pollen structures, animals, or even wave propagation. Gielis curves and surfaces are an extension of Lamé curves and surfaces (superquadrics) which have benefited in the last two decades of extensive researches to retrieve their parameters from various data types, such as range images, 2D and 3D point clouds, etc. Unfortunately, the most efficient techniques for superquadrics recovery, based on deterministic methods, cannot directly be adapted to Gielis curves. Indeed, the different nature of their parameters forbids the use of a unified gradient descent approach, which requires initial pre-processings, such as the symmetry detection, and a reliable pose and scale estimation. Furthermore, even the most recent algorithms in the literature remain extremely sensitive to initialization and often fall into local minima in the presence of large missing data. We present a simple evolutionary algorithm which overcomes most of these issues and unifies all of the required operations into a single though efficient approach. The key ideas in this paper are the replacement of the potential fields used for the cost function (closed form) by the shortest Euclidean distance (SED, iterative approach), the construction of cost functions which minimize the shortest distance as well as the curve length using R-functions, and slight modifications of the evolutionary operators. We show that the proposed cost function based on SED and R-function offers the best compromise in terms of accuracy, robustness to noise, and missing data. |
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Wos |
000317944800002 |
Publication Date |
2013-01-29 |
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ISSN |
0031-3203 |
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UA library record; WoS full record; WoS citing articles |
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no |
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Call Number |
UA @ admin @ c:irua:107181 |
Serial |
8485 |
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Author |
Gielis, J.; Tavkhelidze, I.; Ricci, P.E. |
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Title |
Generalized Möbius-Listing bodies and the heart |
Type |
A3 Journal article |
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Year |
2023 |
Publication |
Sn – 2247-689x |
Abbreviated Journal |
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Volume |
13 |
Issue |
2 |
Pages |
58-70 |
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Keywords |
A3 Journal article; Sustainable Energy, Air and Water Technology (DuEL) |
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Abstract |
Generalized Möbius-Listing surfaces and bodies generalize Möbius bands, and this research was motivated originally by solutions of boundary value problems. Analogous to cutting of the original Möbius band, for this class of surfaces and bodies, results have been obtained when cutting such bodies or surfaces. The results can be applied in a wide range of fields in the natural science, and here we propose how they can serve as a model for the heart and the circulatory system. |
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http://rjm-cs.ro/2023v13i2_7.pdf#page=1 |
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UA library record; http://rjm-cs.ro/2023v13i2_7.pdf#page=1 |
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Most recent IF: NA |
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Call Number |
UA @ admin @ c:irua:200773 |
Serial |
9043 |
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Author |
Gielis, J.; Tavkhelidze, I. |
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Title |
A note on Generalized Möbius-Listing Bodies |
Type |
P1 Proceeding |
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Year |
2023 |
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Pages |
31-39
T2 - Proceedings of the 1st International Sy |
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Keywords |
P1 Proceeding; Sustainable Energy, Air and Water Technology (DuEL) |
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Abstract |
Generalized Möbius-Listing surfaces and bodies generalize Möbius bands, and this research was motivated originally by solutions of boundary value problems. Analogous to cutting of the original Möbius band, for this class of surfaces and bodies, results have been obtained when cutting such bodies or surfaces. In general, cutting leads to interlinked and intertwined different surfaces or bodies, resulting in very complex systems. However, under certain conditions, the result of cutting can be a single surface or body, which reduces complexity considerably. These conditions are based on congruence and rotational symmetry of the resulting cross sections after cutting, and on the knife cutting the origin |
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Publication Date |
2023-11-29 |
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978-90-833839-0-3 |
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UA library record |
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Most recent IF: NA |
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Call Number |
UA @ admin @ c:irua:201047 |
Serial |
9063 |
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Author |
Potgieter-Vermaak, S.S.; Mmari, A.; Van Grieken, R.; McCrindle, R.I.; Potgieter, J.H. |
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Title |
Degradation of galvanised iron roofing material in Tanzania by atmospheric corrosion |
Type |
A1 Journal article |
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Year |
2011 |
Publication |
Corrosion engineering science and technology |
Abbreviated Journal |
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Volume |
46 |
Issue |
5 |
Pages |
642-650 |
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Keywords |
A1 Journal article; AXES (Antwerp X-ray Analysis, Electrochemistry and Speciation) |
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Abstract |
Galvanised iron is popular in many applications, particular as a roofing material. However, just like other materials, especially metallic ones, it is prone to degradation by corrosion. In this particular study, the degradation of galvanised roof sheets was investigated at a coastal, urban and rural site in Tanzania, Africa. Samples were exposed to various outdoor environments over a period of 3 years. In addition, some accelerated laboratory investigations were conducted in different simulated air pollution environments in an artificial corrosion chamber constructed for this purpose to supplement the outdoor exposure tests. It was found that the combination of the tropical climate and increasing air pollution due to industrial development in the capital Dar-es-Salaam resulted in substantial atmospheric corrosion of the roof sheets, which eventually leads to failure and the necessity for replacement. The rural site had the lowest degree of atmospheric corrosion as expected. A combination of different corrosion products was identified as a result of the atmospheric corrosion by Raman and EDX analyses. The information gained from this investigation could be utilised to construct more durable structures requiring less frequent replacement and maintenance in future. |
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000294421100008 |
Publication Date |
2010-04-12 |
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Edition |
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ISSN |
1478-422x |
ISBN |
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UA library record; WoS full record; WoS citing articles |
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Call Number |
UA @ admin @ c:irua:92094 |
Serial |
7758 |
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Author |
Lenaerts, S.; Honoré, M.; Huyberechts, G.; Roggen, J.; Maes, G. |
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Title |
In situ infrared and electrical characterization of tin dioxide gas sensors in nitrogen/oxygen mixtures at temperatures up to 720 K |
Type |
A1 Journal article |
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Year |
1994 |
Publication |
Sensors and actuators : B : chemical |
Abbreviated Journal |
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Volume |
19 |
Issue |
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Pages |
478-482 |
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Keywords |
A1 Journal article |
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Abstract |
FT-IR spectroscopy and impedance measurements of tin dioxide sensor materials at working temperatures up to 450 °C in atmospheres with varying O2/N2 ratio are used as an in situ probe to study the interactions at the surface of the semiconducting oxide. Every diminution in the oxygen content above the sample induces a broad IR absorption band (X-band) between 2300700 cm−1 with a few small peaks in the 1400850 cm−1 region of the spectrum superimposed on it. The X-band results from the enchanced electron concentration in the bulk of the tin dioxide domain. The fine structure is due to the absorption of several kinds of surface oxygen species associated vibration modes. The porous tin dioxide consists of domains were the outward shell is depleted of electrons by the formation of adsorbed O− species on oxygen surface sites, SO(O− species. In our proposed model for the impedance data this gives rise to a parallel RpCp circuit for the domain boundary characteristics and to an Rs parameter for the intradomain resistance. The evolution of these IR and impedance spectroscopic effects with temperature and oxygen content is used to set up, to confirm and refine a physicochemical operation model of tin dioxide gas sensor. This model consists of a sensitizing reaction sequence in the presence of oxygen and a gas-detection reaction sequence when a reducing gas is present. Based on this model, the principal disadvantages of this type of gas sensor become clear. Every factor that influences the concentration of SO(O−) species, causes a conductance modification. If we can control and direct the nature, the number and the arrangement of the tin dioxide domains, a directed development and improvement of the sensor characteristics is possible. |
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Wos |
A1994NN90000040 |
Publication Date |
2002-07-25 |
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Series Issue |
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Edition |
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ISSN |
0925-4005 |
ISBN |
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UA library record; WoS full record; WoS citing articles |
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no |
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Call Number |
UA @ admin @ c:irua:82014 |
Serial |
5962 |
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Author |
Cabal, A.; Schalm, O.; Eyskens, P.; Willems, P.; Harth, A.; van Espen, P. |
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Title |
Comparison of x-ray absorption and emission techniques for the investigation of paintings |
Type |
A1 Journal article |
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Year |
2015 |
Publication |
X-ray spectrometry |
Abbreviated Journal |
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Volume |
44 |
Issue |
3 |
Pages |
141-148 |
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Keywords |
A1 Journal article; AXES (Antwerp X-ray Analysis, Electrochemistry and Speciation); Antwerp Cultural Heritage Sciences (ARCHES) |
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Abstract |
Four x-ray techniques: computed radiography, emission radiography, energy-resolved radiography and imaging x-ray fluorescence were compared using four mock-up panel paintings. The paintings have different stratigraphy and pigments and are representative for different historical periods. One of the paintings has a hidden underlying painting. The type of pigments used mainly influences the information obtained by both the emission and absorption measurements; high-Z white pigment and high-Z color pigments giving the best contrast. Each of the techniques revealed interesting aspects of the paintings, but none of them could reveal the hidden painting to a satisfactory level. Due to the statistical quality of the spectral data, x-ray fluorescence gives elemental images with high contrast. The radiographic images are better to reveal the internal structure. Imaging x-ray fluorescence and energy-resolved radiography measurements can be done simultaneously, and the combination has the highest potential for the study of complex multilayer paintings. Copyright (c) 2015 John Wiley & Sons, Ltd. |
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000353644500010 |
Publication Date |
2015-02-05 |
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ISSN |
0049-8246 |
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UA library record; WoS full record; WoS citing articles |
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Call Number |
UA @ admin @ c:irua:126016 |
Serial |
7698 |
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Author |
Vos, L.; Van Grieken, R. |
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Title |
Preparation of conducting electrodes from biological samples for multi-element trace analysis by spark-source mass spectrometry or emission spectrometry |
Type |
A1 Journal article |
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Year |
1984 |
Publication |
Analytica chimica acta |
Abbreviated Journal |
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Volume |
164 |
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Pages |
83-90 |
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Keywords |
A1 Journal article; AXES (Antwerp X-ray Analysis, Electrochemistry and Speciation) |
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Abstract |
Four decomposition procedures frequently used for biological material (dry ashing, open wet digestion, wet digestion in a teflon bomb and low-temperature ashing) are optimized for the conversion of biological samples to conducting electrodes suitable for multi-element trace determinations by spark-source mass spectrometry or emission spectrometry. The optimized procedures are evaluated with respect to contamination, retention and preconcentration of the trace elements, homogeneity of the electrodes and precision of the final results. Both dry-ashing methods are prone to losses by volatilization; simple dry ashing suffers from contamination problems during electrode preparation. Wet digestion gives better precision; digestion with nitric/sulfuric acids in an open flask is the method of choice for most elements being simpler and giving lower blanks than the bomb method. |
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A1984ABC2700007 |
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2002-07-25 |
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ISSN |
0003-2670; 1873-4324 |
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UA library record; WoS full record; WoS citing articles |
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Call Number |
UA @ admin @ c:irua:116443 |
Serial |
8411 |
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Author |
Kabsch-Korbutowicz, M.; Krupinska, B. |
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Title |
Removal of natural organic matter from water by using ion-exchange resins |
Type |
A1 Journal article |
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Year |
2008 |
Publication |
Przemysl chemiczny
T2 – Scientific and Technical Conference on Water and Wastewater Basis for, Environmental Protection (School of Quality Water 2008), MAY 28-30, 2008, Kolobrzeg, POLAND |
Abbreviated Journal |
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Volume |
87 |
Issue |
5 |
Pages |
473-475 |
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Keywords |
A1 Journal article; AXES (Antwerp X-ray Analysis, Electrochemistry and Speciation) |
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Abstract |
Four aq. solns. contg. natural peat components and the water from Odra river were treated with 3 anion-exchange resins (2.5 to 15 cm(3) of resin per 1 dm(3) of the sample) for 5-60 min to remove the org. matter. The process efficiency was detd. by UV absorbance (254 nm) and colour intensity measurements. The treatment resulted in discoloration of the solns. A resin with weak alky, was the most efficient. The degree of removal increased with increasing the resin dose and contact time. The presence of inorg. anions in the soins. contributed to a decrease of process effectivity. |
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000257179000020 |
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ISSN |
0033-2496 |
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Additional Links |
UA library record; WoS full record; WoS citing articles |
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Call Number |
UA @ admin @ c:irua:102617 |
Serial |
8471 |
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Author |
Ma, X.; Pavlidis, G.; Dillon, E.; Beltran, V.; Schwartz, J.J.; Thoury, M.; Borondics, F.; Sandt, C.; Kjoller, K.; Berrie, B.H.; Centrone, A. |
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Title |
Micro to nano : multiscale IR analyses reveal zinc soap heterogeneity in a 19th-century painting by Corot |
Type |
A1 Journal article |
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Year |
2022 |
Publication |
Analytical chemistry |
Abbreviated Journal |
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Volume |
94 |
Issue |
7 |
Pages |
3103-3110 |
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Keywords |
A1 Journal article; Antwerp Electrochemical and Analytical Sciences Lab (A-Sense Lab) |
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Abstract |
Formation and aggregation of metal carboxylates (metal soaps) can degrade the appearance and integrity of oil paints, challenging efforts to conserve painted works of art. Endeavors to understand the root cause of metal soap formation have been hampered by the limited spatial resolution of Fourier transform infrared microscopy (mu-FTIR). We overcome this limitation using optical photothermal infrared spectroscopy (O-PTIR) and photothermal-induced resonance (PTIR), two novel methods that provide IR spectra with approximate to 500 and approximate to 10 nm spatial resolutions, respectively. The distribution of chemical phases in thin sections from the top layer of a 19th-century painting is investigated at multiple scales (mu-FTIR approximate to 10(2) mu m(3), O-PTIR approximate to 10(-1) mu m(3), PTIR approximate to 10(-5) mu m(3)). The paint samples analyzed here are found to be mixtures of pigments (cobalt green, lead white), cured oil, and a rich array of intermixed, small (often << 0.1 mu m(3)) zinc soap domains. We identify Zn stearate and Zn oleate crystalline soaps with characteristic narrow IR peaks (approximate to 1530-1558 cm(-1)) and a heterogeneous, disordered, water-permeable, tetrahedral zinc soap phase, with a characteristic broad peak centered at approximate to 1596 cm(-1). We show that the high signal-to-noise ratio and spatial resolution afforded by O-PTIR are ideal for identifying phase-separated (or locally concentrated) species with low average concentration, while PTIR provides an unprecedented nanoscale view of distributions and associations of species in paint. This newly accessible nanocompositional information will advance our knowledge of chemical processes in oil paint and will stimulate new art conservation practices. |
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Wos |
000766206700011 |
Publication Date |
2022-02-09 |
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Edition |
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ISSN |
0003-2700; 5206-882x |
ISBN |
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Additional Links |
UA library record; WoS full record; WoS full record; WoS citing articles |
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Open Access |
OpenAccess |
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Call Number |
UA @ admin @ c:irua:187380 |
Serial |
8897 |
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Author |
Vanderborght, B.M.; Van Grieken, R.E. |
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| |
Title |
Water analysis by spark-source mass-spectrometry after preconcentration on activated carbon |
Type |
A1 Journal article |
| |
Year |
1980 |
Publication |
Talanta : the international journal of pure and applied analytical chemistry |
Abbreviated Journal |
|
|
| |
Volume |
27 |
Issue |
5 |
Pages |
417-422 |
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| |
Keywords |
A1 Journal article; AXES (Antwerp X-ray Analysis, Electrochemistry and Speciation) |
|
| |
Abstract |
For trace analyses of environmental waters, spark-source mass-spectrometry has been combined with a preconcentration procedure involving chelation of the dissolved trace elements with oxine and subsequent adsorption of the oxinates and naturally occurring organic and colloidal metal species onto activated carbon. The activated carbon is filtered off and ashed at low temperature. The residue is dissolved, an internal standard and pure graphite are added and, after drying, the electrodes are prepared. The photographically recorded mass spectrum is evaluated by a suitable computer routine. The error of the procedure is around 30%. While this preconcentration and analysis procedure is capable of measuring about 40 elements quantitatively, in practice 1025 trace elements are determined simultaneously above the 0.1-μg/l. detection limit, as is illustrated by analyses of drinking water, surface and ground water samples. Although a sophisticated technique, SSMS can be considered for regular panoramic survey analyses. |
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Corporate Author |
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Thesis |
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Publisher |
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Place of Publication |
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Editor |
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Language |
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Wos |
A1980JR07800006 |
Publication Date |
2002-07-25 |
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Series Editor |
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Series Title |
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Abbreviated Series Title |
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| |
Series Volume |
|
Series Issue |
|
Edition |
|
|
| |
ISSN |
0039-9140; 1873-3573 |
ISBN |
|
Additional Links |
UA library record; WoS full record; WoS citing articles |
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Impact Factor |
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Times cited |
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Open Access |
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| |
Notes |
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Approved |
no |
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| |
Call Number |
UA @ admin @ c:irua:116557 |
Serial |
8746 |
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| Permanent link to this record |
| |
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| |
|
Author |
Krata, A.; Kontozova-Deutsch, V.; Bencs, L.; Deutsch, F.; Van Grieken, R. |
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| |
Title |
Single-run ion chromatographic separation of inorganic and low-molecular-mass organic anions under isocratic elution: application to environmental samples |
Type |
A1 Journal article |
| |
Year |
2009 |
Publication |
Talanta : the international journal of pure and applied analytical chemistry |
Abbreviated Journal |
|
|
| |
Volume |
79 |
Issue |
1 |
Pages |
16-21 |
|
| |
Keywords |
A1 Journal article; AXES (Antwerp X-ray Analysis, Electrochemistry and Speciation) |
|
| |
Abstract |
For the isocratic ion chromatography (IC) separation of low-molecular-mass organic acids and inorganic anions three different anion-exchange columns were studied: IonPac AS14 (9 ìm particle size), Allsep A-2 (7 ìm particle size), and IC SI-50 4E (5 ìm particle size). A complete baseline separation for all analyzed anions (i.e., F−, acetate, formate, Cl−, NO2−, Br−, NO3−, HPO42− and SO42−) in one analytical cycle of shorter than 17 min was achieved on the IC SI-50 4E column, using an eluent mixture of 3.2 mM Na2CO3 and 1.0 mM NaHCO3 with a flow rate of 1.0 mL min−1. On the IonPac AS14 column, it was possible to separate acetate from inorganic anions in one run (i.e., less than 9 min), but not formate, under the following conditions: 3.5 mM Na2CO3 plus 1.0 mM NaHCO3 with a flow rate of 1.2 mL min−1. Therefore, it was necessary to adapt a second run with a 2.0 mM Na2B4O7 solution as an eluent under a flow rate of 0.8 mL min−1 for the separation of organic ions, which considerably enlarged the analysis time. For the Allsep A-2 column, using an eluent mixture of 1.2 mM Na2CO3 plus 1.5 mM NaHCO3 with a flow rate of 1.6 mL min−1, it was possible to separate almost all anions in one run within 25 min, except the fluoride-acetate critical pair. A Certified Multianion Standard Solution PRIMUS for IC was used for the validation of the analytical methods. The lowest RSDs (less than 1%) and the best LODs (0.02, 0.2, 0.16, 0.11, 0.06, 0.05, 0.04, 0.14 and 0.09 mg L−1 for F−, Ac−, For−, Cl−, NO2−, Br−, NO3−, HPO42− and SO42−, respectively) were achieved using the IC SI-50 4E column. This column was applied for the separation of concerned ions in environmental precipitation samples such as snow, hail and rainwater. |
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Corporate Author |
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Thesis |
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Publisher |
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Place of Publication |
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Editor |
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| |
Language |
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Wos |
000266187600004 |
Publication Date |
2009-03-06 |
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Series Editor |
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Series Title |
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Abbreviated Series Title |
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| |
Series Volume |
|
Series Issue |
|
Edition |
|
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| |
ISSN |
0039-9140; 1873-3573 |
ISBN |
|
Additional Links |
UA library record; WoS full record; WoS citing articles |
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| |
Impact Factor |
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Times cited |
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Open Access |
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| |
Notes |
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Approved |
no |
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| |
Call Number |
UA @ admin @ c:irua:75475 |
Serial |
8542 |
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| Permanent link to this record |
| |
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| |
|
Author |
Sankaran, K.; Swerts, J.; Carpenter, R.; Couet, S.; Garello, K.; Evans, R.F.L.; Rao, S.; Kim, W.; Kundu, S.; Crotti, D.; Kar, G.S.; Pourtois, G. |
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| |
Title |
Evidence of magnetostrictive effects on STT-MRAM performance by atomistic and spin modeling |
Type |
P1 Proceeding |
| |
Year |
2018 |
Publication |
2018 Ieee International Electron Devices Meeting (iedm) |
Abbreviated Journal |
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|
| |
Volume |
|
Issue |
|
Pages |
|
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| |
Keywords |
P1 Proceeding; Plasma Lab for Applications in Sustainability and Medicine – Antwerp (PLASMANT) |
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| |
Abstract |
For the first time, we demonstrate, using an atomistic description of a 30nm diameter spin-transfer-torque magnetic random access memories (STT-MRAM), that the difference in mechanical properties of its sub-nanometer layers induces a high compressive strain in the magnetic tunnel junction (MTJ) and leads to a detrimental magnetostrictive effect. Our model explains the issues met in engineering the electrical and magnetic performances in scaled STT-MRAM devices. The resulting high compressive strain built in the stack, particularly in the MgO tunnel barrier (t-MgO), and its associated non-uniform atomic displacements, impacts on the quality of the MTJ interface and leads to strain relieve mechanisms such as surface roughness and adhesion issues. We illustrate that the strain gradient induced by the different materials and their thicknesses in the stacks has a negative impact on the tunnel magneto-resistance (TMR), on the magnetic nucleation process and on the STT-MRAM performance. |
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Address |
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Corporate Author |
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Thesis |
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Place of Publication |
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Language |
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Wos |
000459882300147 |
Publication Date |
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Series Editor |
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Series Title |
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Abbreviated Series Title |
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Series Volume |
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Series Issue |
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Edition |
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| |
ISSN |
978-1-72811-987-8; 978-1-72811-987-8 |
ISBN |
|
Additional Links |
UA library record; WoS full record; WoS citing articles |
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Impact Factor |
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Times cited |
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Open Access |
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|
| |
Notes |
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Approved |
no |
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| |
Call Number |
UA @ admin @ c:irua:158694 |
Serial |
7942 |
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| Permanent link to this record |
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| |
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Author |
Vos, L.; Robberecht, H.; Van Dyck, P.; Van Grieken, R. |
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| |
Title |
Multi-element analysis of urine by energy-dispersive x-ray fluorescence spectrometry |
Type |
A1 Journal article |
| |
Year |
1981 |
Publication |
Analytica chimica acta |
Abbreviated Journal |
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|
| |
Volume |
130 |
Issue |
1 |
Pages |
167-175 |
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| |
Keywords |
A1 Journal article; AXES (Antwerp X-ray Analysis, Electrochemistry and Speciation) |
|
| |
Abstract |
For multi-element analysis of human urine, 25-ml samples doped with yttrium as internal standard are evaporated gently and then ashed up to 460°C overnight. The residue is pelletized and analysed by energy-dispersive x-ray fluorescence. Acid addition to facilitate the digestion is not mandatory. Recoveries are nearly quantitative for traces of Fe, Ni, Cu, Zn and Sr, to a lesser extent for lead, but not for arsenic or selenium. The standard deviation per measurement is typically around 6%. The detection limits are such that some 10 elements can be determined simultaneously in normal urine, and possibly more in cases of importance to toxicology or industrial hygiene. |
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Address |
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Corporate Author |
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Thesis |
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Publisher |
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Place of Publication |
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Editor |
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| |
Language |
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Wos |
A1981ME98900017 |
Publication Date |
2002-07-25 |
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Series Editor |
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Series Title |
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Abbreviated Series Title |
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| |
Series Volume |
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Series Issue |
|
Edition |
|
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| |
ISSN |
0003-2670; 1873-4324 |
ISBN |
|
Additional Links |
UA library record; WoS full record; WoS citing articles |
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Impact Factor |
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Times cited |
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Open Access |
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Notes |
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Approved |
no |
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| |
Call Number |
UA @ admin @ c:irua:116439 |
Serial |
8285 |
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| Permanent link to this record |
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Author |
Van Grieken, R.E.; Adams, F.C. |
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| |
Title |
Folding of aerosol loaded filters during X-ray fluorescence analysis |
Type |
A1 Journal article |
| |
Year |
1976 |
Publication |
X-ray spectrometry |
Abbreviated Journal |
|
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| |
Volume |
5 |
Issue |
2 |
Pages |
61-67 |
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| |
Keywords |
A1 Journal article; AXES (Antwerp X-ray Analysis, Electrochemistry and Speciation) |
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| |
Abstract |
Folding aerosol loaded filters in two with the loaded side inwards during the X-ray analysis not only reduces possible filter heterogeneity effects and improves sample protection, but also increases the sensitivity and renders filter paper absorption corrections simple and more accurate in many instances. It is shown that folding an aerosol loaded Whatman filter paper during Kα X-rays counting leads to an increased sensitivity for all elements up from calcium, scandium or titanium (depending on the sensitivity definition and on the aerosol load) and for all elements up from phosphorus, sulphur or chlorine in the case of the Nuclepore filter. Although the absorption by the filter, into which the aerosol penetrates to some extent, is always more important in the sandwich than in the usual geometry, the dependence of the absorption correction on the usually unknown average deposition depth is less pronounced. Assuming all the aerosol material to be collected at the very surface of the filter and hence being present in the centre of the sandwich to be analysed, leads to an extremely simple filter paper absorption correction which is less prone to uncertainties than more sophisticated corrections in the usual geometry requiring additional measurements. This is the case for all elements up from potassium on Whatman filters and up from phosphorus on Nuclepore filters. |
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Address |
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Corporate Author |
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Thesis |
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Publisher |
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Place of Publication |
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Editor |
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Language |
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Wos |
A1976BM95300002 |
Publication Date |
2005-05-28 |
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Series Editor |
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Series Title |
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Abbreviated Series Title |
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| |
Series Volume |
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Series Issue |
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Edition |
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| |
ISSN |
0049-8246 |
ISBN |
|
Additional Links |
UA library record; WoS full record; WoS citing articles |
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Impact Factor |
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Times cited |
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Open Access |
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| |
Notes |
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Approved |
no |
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| |
Call Number |
UA @ admin @ c:irua:116480 |
Serial |
7976 |
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| Permanent link to this record |
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Author |
Ma, J.; Duong, T.H.; Smits, M.; Verstraete, W.; Carballa, M. |
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| |
Title |
Enhanced biomethanation of kitchen waste by different pre-treatments |
Type |
A1 Journal article |
| |
Year |
2011 |
Publication |
Bioresource technology |
Abbreviated Journal |
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| |
Volume |
102 |
Issue |
2 |
Pages |
592-599 |
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Keywords |
A1 Journal article; Engineering sciences. Technology; Sustainable Energy, Air and Water Technology (DuEL) |
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| |
Abstract |
Five different pre-treatments were investigated to enhance the solubilisation and anaerobic biodegradability of kitchen waste (
KW) in thermophilic batch and continuous tests. In the batch solubilisation tests, the highest and the lowest solubilisation efficiency were achieved with the thermo-acid and the pressuredepressure pre-treatments, respectively. However, in the batch biodegradability tests, the highest cumulative biogas production was obtained with the pressuredepressure method. In the continuous tests, the best performance in terms of an acceptable biogas production efficiency of 60% and stable in-reactor CODs and VFA concentrations corresponded to the pressuredepressure reactor, followed by freezethaw, acid, thermo-acid, thermo and control. The maximum OLR (5 g COD L−1 d−1) applied in the pressuredepressure and freezethaw reactors almost doubled the control reactor. From the overall analysis, the freezethaw pre-treatment was the most profitable process with a net potential profit of around 11.5 ton−1 KW. |
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Corporate Author |
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Thesis |
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Place of Publication |
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Editor |
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Language |
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Wos |
000286782700022 |
Publication Date |
2010-08-12 |
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Series Editor |
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Series Title |
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Abbreviated Series Title |
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Series Volume |
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Series Issue |
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Edition |
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| |
ISSN |
0960-8524 |
ISBN |
|
Additional Links |
UA library record; WoS full record; WoS citing articles |
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Impact Factor |
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Times cited |
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Open Access |
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Notes |
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Approved |
no |
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| |
Call Number |
UA @ admin @ c:irua:85249 |
Serial |
7910 |
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| Permanent link to this record |
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Author |
Rezaei, M.; Saey, T.; Seuntjens, P.; Joris, I.; Boenne, W.; Van Meirvenne, M.; Cornelis, W. |
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Title |
Predicting saturated hydraulic conductivity in a sandy grassland using proximally sensed apparent electrical conductivity |
Type |
A1 Journal article |
| |
Year |
2016 |
Publication |
Journal of applied geophysics |
Abbreviated Journal |
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Volume |
126 |
Issue |
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Pages |
35-41 |
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Keywords |
A1 Journal article; Sustainable Energy, Air and Water Technology (DuEL) |
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Abstract |
Finding a correspondence between soil hydraulic properties, such as saturated hydraulic conductivity (Ks) and apparent electrical conductivity (ECa) as an easily measurable parameter, may be a way forward to estimate the spatial distribution of hydraulic properties at the field scale. In this study, the spatial distributions of Ks, of soil ECa measured by a DUALEM-21S sensor and of soil physical properties were investigated in a sandy grassland. To predict field scale Ks, the statistical relationship between co-located soil Ks, and EMI-ECa was evaluated. Results demonstrated the large spatial variability of all studied properties with Ks being the most variable one (CV = 86.21%) followed by ECa (CV >= 53.77%). A significant negative correlation was found between In-transformed Ks and ECa (r = 0.83; P <= 0.01) at two depths of exploration (0-50 and 0-100 cm). This site specific relation between In Ks and ECa was used to predict saturated hydraulic conductivity over 0-50 cm depth for the whole field. The empirical relation was validated using an independent dataset of measured Ks. The statistical results demonstrate the robustness of this empirical relation with mean estimation error MEE = 0.46 (cm h(-1)), root-mean-square estimation errors RMSEE = 0.74 (cm h(-1)), coefficient of determination r(2) = 0.67 and coefficient of model efficiency Ce = 0.64. The relationship was then used to produce a detailed map of Ks for the whole field. The result will allow model predictions of spatially distributed water content in view of irrigation management. (C) 2016 Elsevier B.V. All rights reserved. |
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Address |
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Corporate Author |
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Thesis |
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Publisher |
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Place of Publication |
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Editor |
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Language |
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Wos |
000371361200004 |
Publication Date |
2016-01-17 |
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Series Editor |
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Series Title |
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Abbreviated Series Title |
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Series Volume |
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Series Issue |
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Edition |
|
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| |
ISSN |
0926-9851 |
ISBN |
|
Additional Links |
UA library record; WoS full record; WoS citing articles |
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Impact Factor |
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Times cited |
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Open Access |
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Notes |
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Approved |
no |
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| |
Call Number |
UA @ admin @ c:irua:132349 |
Serial |
8403 |
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| Permanent link to this record |
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Author |
Rezaei, M.; Seuntjens, P.; Shahidi, R.; Joris, I.; Boenne, W.; Al-Barri, B.; Cornelis, W. |
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Title |
The relevance of in-situ and laboratory characterization of sandy soil hydraulic properties for soil water simulations |
Type |
A1 Journal article |
| |
Year |
2016 |
Publication |
Journal of hydrology |
Abbreviated Journal |
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Volume |
534 |
Issue |
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Pages |
251-265 |
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Keywords |
A1 Journal article; Sustainable Energy, Air and Water Technology (DuEL) |
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Abstract |
Field water flow processes can be precisely delineated with proper sets of soil hydraulic properties derived from in situ and/or laboratory experiments. In this study we analyzed and compared soil hydraulic properties obtained by traditional laboratory experiments and inverse optimization tension infiltrometer data along the vertical direction within two typical Podzol profiles with sand texture in a potato field. The main goal was to identify proper sets of hydraulic parameters and to evaluate their relevance on hydrological model performance for irrigation management purposes. Tension disc infiltration experiments were carried out at four and five different depths for both profiles at consecutive negative pressure heads of 12, 6, 3 and 0.1 cm. At the same locations and depths undisturbed samples were taken to determine Mualem-van Genuchten (MVG) hydraulic parameters (theta(r), residual water content, theta(s), saturated water content, alpha and n, shape parameters and K-ls, saturated hydraulic conductivity) in the laboratory. Results demonstrated horizontal differences and vertical variability of hydraulic properties. The tension disc infiltration data fitted well in inverse modeling using Hydrus 2D/3D in combination with final water content at the end of the experiment, theta(f). Four MVG parameters (theta(s), alpha, n and field saturated hydraulic conductivity K-fs) were estimated (theta(r) set to zero), with estimated K-ls and alpha values being relatively similar to values from Wooding's solution which used as initial value and estimated theta(s) corresponded to (effective) field saturated water content, theta(f). The laboratory measurement of K-ls yielded 2-30 times higher values than the field method K-fs from top to subsoil layers, while there was a significant correlation between both K-s values (r = 0.75). We found significant differences of MVG parameters theta(s), n and alpha values between laboratory and field measurements, but again a significant correlation was observed between laboratory and field MVG parameters namely K-s, n, theta(s) (r >= 0.59). Assessment of the parameter relevance in 1-D model simulations, illustrated that the model over predicted and under predicted top soil-water content using laboratory and field experiments data sets respectively. The field MVG parameter data set resulted in better agreement to observed soil-water content as compared to the laboratory data set at nodes 10 and 20 cm. However, better simulation results were achieved using the laboratory data set at 30-60 cm depths. Results of our study do not confirm whether laboratory or field experiments data sets are most appropriate to predict soil water fluctuations in a complete soil profile, while field experiments are preferred in many studies. (C) 2016 Elsevier B.V. All rights reserved. |
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Place of Publication |
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Wos |
000371940900022 |
Publication Date |
2016-01-11 |
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Series Editor |
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Series Title |
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Abbreviated Series Title |
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Series Volume |
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Series Issue |
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Edition |
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ISSN |
0022-1694 |
ISBN |
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Additional Links |
UA library record; WoS full record; WoS citing articles |
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Impact Factor |
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Times cited |
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Open Access |
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Notes |
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Approved |
no |
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Call Number |
UA @ admin @ c:irua:133161 |
Serial |
8657 |
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| Permanent link to this record |
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Author |
Gielis, J. |
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Title |
Phi-bonacci in Ancient Greece |
Type |
A1 Journal article |
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Year |
2021 |
Publication |
Symmetry : culture and science |
Abbreviated Journal |
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Volume |
32 |
Issue |
1 |
Pages |
25-40 |
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Keywords |
A1 Journal article; Sustainable Energy, Air and Water Technology (DuEL) |
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Abstract |
Fibonacci numbers are a very popular subject in mathematics, culture and science. A major open question is why the ancient Greeks overlooked this series, while they were very familiar with the golden mean and division in extreme and mean ratio. Furthermore, they could compute the square root of five to a high degree of precision using Theon 's ladder. This fact is based on tables built with side and diagonal numbers, and it is a simple and incredibly efficient method to compute roots of integers, though it is little known even now among most of the experts. The biologist D 'Arcy Wentworth Thompson showed that the same method could be used to generate the Fibonacci series using a simple shift in the computation of the tables. He argues, quite convincingly, that the ancient Greeks could not have overlooked this. Actually, the same method can be used to generate all possible regular phyllotaxis patterns. |
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Place of Publication |
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Language |
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Wos |
000643822700002 |
Publication Date |
2021-03-30 |
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Series Editor |
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Series Title |
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Abbreviated Series Title |
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Series Volume |
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Series Issue |
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Edition |
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ISSN |
0865-4824 |
ISBN |
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Additional Links |
UA library record; WoS full record |
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Impact Factor |
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Times cited |
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Open Access |
OpenAccess |
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Notes |
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Approved |
Most recent IF: NA |
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Call Number |
UA @ admin @ c:irua:178322 |
Serial |
8376 |
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Author |
Peeters, B.; Safdar, S.; Carlier, B.; Spasic, D.; Daems, D.; Lammertyn, J. |
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Title |
PCR amplified DNAzyme-amplicons for generic solid-phase antimicrobial resistance screening |
Type |
P1 Proceeding |
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Year |
2019 |
Publication |
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Abbreviated Journal |
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Volume |
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Issue |
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Pages |
971-974
T2 - Transducers 2019 : Eurosensors XXXIII |
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Keywords |
P1 Proceeding; Engineering sciences. Technology; AXES (Antwerp X-ray Analysis, Electrochemistry and Speciation) |
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Abstract |
Fiber optic surface plasmon resonance (FO-SPR) has shown its potential for the detection of nucleic acids and more recently the technology has been combined with catalytic active strands such as DNAzymes. In this work, an innovative, generic solid-phase DNA sensor concept is presented, based on FO-SPR and PCR amplified DNAzyme activity. Improved levels of specificity and sensitivity were obtained down to picomolar concentrations. Moreover, the FO-SPR sensor concept enables AuNP amplified DNA target detection, independent of the target sequence length. The FO-SPR sensor was demonstrated for the screening of the mobile colistin resistance (MCR-2) gene, a gene important for the antimicrobial resistance in Gram-negative species such as E. Coli. |
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Wos |
000539487000245 |
Publication Date |
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Series Editor |
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Abbreviated Series Title |
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Series Volume |
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Series Issue |
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Edition |
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ISSN |
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ISBN |
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Additional Links |
UA library record; WoS full record |
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Impact Factor |
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Times cited |
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Open Access |
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Notes |
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Approved |
no |
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Call Number |
UA @ admin @ c:irua:166108 |
Serial |
8367 |
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| Permanent link to this record |
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Author |
Van Grieken, R.; Van 't dack, L.; Costa Dantas, C.; Moura de Amorim, W.; Maenhaut, W. |
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Title |
Elemental constituents of atmospheric aerosols in Recife, North-East Brazil |
Type |
A3 Journal article |
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Year |
1982 |
Publication |
Environmental pollution: series B : chemical and physical |
Abbreviated Journal |
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Volume |
4 |
Issue |
2 |
Pages |
143-163 |
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Keywords |
A3 Journal article; AXES (Antwerp X-ray Analysis, Electrochemistry and Speciation) |
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Abstract |
Few data are available on the inorganic atmospheric pollution in the rapidly expanding cities of South America, like Recife, on the Atlantic Coast of North-east Brazil. Therefore, the elemental composition of atmospheric aerosols was investigated for nine sites in the Recife conurbation and a fairly remote site in the area. Total aerosol samples were collected on cellulose filters for analysis by energy dispersive X-ray fluorescence and cascade impactors were used to collect the aerosols as a function of particle size for subsequent analysis by proton-induced X-ray emission. Local soil aliquots were also analysed. About eighteen elements were quantified in all cases. The average total atmospheric concentrations appeared to be well above natural levels but usually lower than, or comparable with, those of North American and European cities. Dispersal of sea spray and of local soil (often contaminated with, for example, Cu, Zn and Pb from industrial sources) contributes predominantly to the total atmospheric load in Recife. However, the particle size fraction results also indicated strong excesses in the small particle mode for S, K, V, Mn, Ni, Cu, Zn, Br and Pb, mainly in the downtown area. Again, the corresponding enrichment factors were only moderate in comparison with other published urban data. |
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Wos |
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Publication Date |
2003-09-11 |
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ISSN |
0143-148x; 1878-0695 |
ISBN |
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UA library record |
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Impact Factor |
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Times cited |
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no |
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Call Number |
UA @ admin @ c:irua:111437 |
Serial |
7894 |
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Author |
Gupta, A.; Baron, G.V.; Perreault, P.; Lenaerts, S.; Ciocarlan, R.-G.; Cool, P.; Mileo, P.G.M.; Rogge, S.; Van Speybroeck, V.; Watson, G.; Van Der Voort, P.; Houlleberghs, M.; Breynaert, E.; Martens, J.; Denayer, J.F.M. |
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Title |
Hydrogen clathrates : next generation hydrogen storage materials |
Type |
A1 Journal article |
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Year |
2021 |
Publication |
Energy Storage Materials |
Abbreviated Journal |
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Volume |
41 |
Issue |
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Pages |
69-107 |
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Keywords |
A1 Journal article; Engineering sciences. Technology; Laboratory of adsorption and catalysis (LADCA); Sustainable Energy, Air and Water Technology (DuEL) |
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Abstract |
Extensive research has been carried on the molecular adsorption in high surface area materials such as carbonaceous materials and MOFs as well as atomic bonded hydrogen in metals and alloys. Clathrates stand among the ones to be recently suggested for hydrogen storage. Although, the simulations predict lower capacity than the expected by the DOE norms, the additional benefits of clathrates such as low production and operational cost, fully reversible reaction, environmentally benign nature, low risk of flammability make them one of the most promising materials to be explored in the next decade. The inherent ability to tailor the properties of clathrates using techniques such as addition of promoter molecules, use of porous supports and formation of novel reverse micelles morphology provide immense scope customisation and growth. As rapidly evolving materials, clathrates promise to get as close as possible in the search of “holy grail” of hydrogen storage. This review aims to provide the audience with the background of the current developments in the solid-state hydrogen storage materials, with a special focus on the hydrogen clathrates. The in-depth analysis of the hydrogen clathrates will be provided beginning from their discovery, various additives utilised to enhance their thermodynamic and kinetic properties, challenges in the characterisation of hydrogen in clathrates, theoretical developments to justify the experimental findings and the upscaling opportunities presented by this system. The review will present state of the art in the field and also provide a global picture for the path forward. |
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000685118300009 |
Publication Date |
2021-06-08 |
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Abbreviated Series Title |
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Series Issue |
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Edition |
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ISSN |
2405-8297 |
ISBN |
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Additional Links |
UA library record; WoS full record; WoS citing articles |
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Times cited |
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Open Access |
OpenAccess |
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Notes |
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Approved |
Most recent IF: NA |
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Call Number |
UA @ admin @ c:irua:178744 |
Serial |
8045 |
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Author |
Van Dyck, P.; Markowicz, A.; Van Grieken, R. |
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Title |
Influence of sample thickness, excitation energy and geometry on particle size effects in XRF |
Type |
A1 Journal article |
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Year |
1985 |
Publication |
X-ray spectrometry |
Abbreviated Journal |
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Volume |
14 |
Issue |
4 |
Pages |
183-187 |
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Keywords |
A1 Journal article; AXES (Antwerp X-ray Analysis, Electrochemistry and Speciation) |
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Abstract |
Expressions are presented for calculating the matrix effect and the pure particle size effect in the XRF analysis of particulate samples with a discrete particle size. The equations are based on the absorption-weighted radiometric diameter concept. Two excitationdetection geometries are considered, with the angles between the sample plane and both the incident and emerging radiation being either 90° (π geometry) or 45° (π/2 geometry). Calculations were made for different sample loadings and exciting radiation energies. The influence of these parameters on the matrix and pure particle size effects is shown. From the results, it is possible to predict the performances of alternative experimental correction procedures for the particle size effect, involving dual measurements at different excitation energies or in different excitationdetection geometries. |
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Wos |
A1985ATB6100007 |
Publication Date |
2005-05-28 |
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Abbreviated Series Title |
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Series Volume |
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Series Issue |
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ISSN |
0049-8246 |
ISBN |
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Additional Links |
UA library record; WoS full record; WoS citing articles |
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Impact Factor |
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Times cited |
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no |
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Call Number |
UA @ admin @ c:irua:116486 |
Serial |
8097 |
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Author |
Roegiers, J. |
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Title |
Development of combined photocatalytic and active carbon fiber technology for indoor air purification based on Multiphysics models |
Type |
Doctoral thesis |
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Year |
2021 |
Publication |
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Abbreviated Journal |
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Volume |
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Issue |
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Pages |
XXX, 197 p. |
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Keywords |
Doctoral thesis; Engineering sciences. Technology; Electron microscopy for materials research (EMAT); Sustainable Energy, Air and Water Technology (DuEL) |
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Abstract |
Exposure to volatile organic compounds (VOCs) remains a major public health concern. Indoor VOC concentrations typically far exceed outdoor levels due to a variety of emission sources and the stringent insulation measures that are imposed today. Many attempts have been made to use photocatalysis for indoor air purification. In an ideal situation, photocatalysis is capable of complete mineralization of VOCs to H2O and CO2, without any byproduct formation. Moreover, the process can take place at standard atmospheric conditions, i.e. ambient temperature and atmospheric pressure. However, successful exploitation is still impeded due to low conversion efficiency, significant pressure loss (and hence a high energy consumption) and byproduct formation. In the first part of this thesis an attempt was made to tackles these problems by designing a novel type of photocatalytic (PCO) reactor. The PCO device consists of a cylindrical vessel filled with TiO2-coated glass tubes and equipped with UV fluorescence lamps. It was investigated in terms of fluid dynamics, coating properties, UV-light distribution and photocatalytic activity. Experimental data was later used to develop and calibrate a Multiphysics model. The model proved to be a useful tool for designing and upscaling the PCO reactor. Consequently, an optimized prototype reactor was constructed and tested according the CEN-EN-16846-1 standard for VOC removal. Although the prototype showed promising results for lab-scale conditions, it struggled with byproduct formation when purifying ppb-level VOCs. In the second part of this thesis, activated carbon adsorption was investigated in order to combine it with photocatalysis. Activated carbon fiber was opted for its fast kinetics, high adsorption capacity and thermo-electrical regeneration. The filter was studied in detail regarding the adsorption of polar and apolar VOCs at indoor air concentration levels and regeneration capabilities. Experimental data was used to develop a Multiphysics model for activated carbon adsorption as well. Consequently, a novel type of ACF filter was developed using the Multiphysics model, which was equipped with electrodes in the tips of the pleats for effective thermal regeneration. In the last part, the combination of both ACF and PCO was studied using a realistic case study. Based on the Multiphysics model, the feasibility of a so-called hybrid air purification device could be investigated. The Multiphysics model shows promising results for this hybrid PCO-ACF system and hence, a demo setup was constructed for future research. |
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Additional Links |
UA library record |
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Impact Factor |
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Times cited |
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Open Access |
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Notes |
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Approved |
Most recent IF: NA |
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Call Number |
UA @ admin @ c:irua:181137 |
Serial |
6860 |
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Author |
Ysebaert, T. |
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Title |
Modelling and experimental validation of deposition on vegetation to facilitate urban particulate matter mitigation |
Type |
Doctoral thesis |
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Year |
2023 |
Publication |
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Abbreviated Journal |
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Volume |
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Issue |
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Pages |
xxvi, 234 p. |
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Keywords |
Doctoral thesis; Engineering sciences. Technology; Sustainable Energy, Air and Water Technology (DuEL) |
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Abstract |
Exposure to air pollution, such as particulate matter (PM), causes adverse health effects, particularly to the respiratory tract and cardiovascular system. PM is the collective name for all kinds of particles ranging from small particles and liquid droplets, which contain organic compounds, acids and metals, to soil or dust particles. One distinguishes PM10, PM2.5 and PM0.1, which have aerodynamic particle sizes smaller than 10, 2.5 and 0.1 µm, respectively. It is mainly the latter that is the most harmful, as PM0.1 penetrates deep into the respiratory system and carries relatively more toxic substances than the other PM fractions. Over a 15-year period, PM concentrations in European member states have fallen by about 30%. Nevertheless, the World Health Organisation (WHO) air quality guidelines, which became stricter in 2021, are exceeded in most places around the world. Particularly in cities, excessive levels of PM are measured and it is here that PM mitigation should be investigated. For this, the implementation of urban green infrastructure, including trees, shrubs, green roofs and green walls, is being looked at. Plants hinder airflow and remove PM from the air by deposition on their leaves and branches. This process is known as dry deposition. Plants can capture PM very efficiently, due to their complex structure of leaves and branches. Green walls offer significant advantages over other types of urban green infrastructure because they can grow on the huge available wall area and, because they do not hinder air circulation, as we sometimes see with trees. Green walls are believed to have a much greater, untapped potential to reduce PM pollution. However, a literature review showed that we do not know the quantitative impact of green walls and lack the tools and/or general methodology to do so. The objective of this thesis is therefore to develop a method for assessing PM removal by green walls, based on predictive models and based on relevant parameters that are experimentally determined. Computational fluid dynamics (CFD) is a numerical method to simulate airflow in complex environments such as cities. These models can also simulate the vegetation-wind interaction in detail and are interesting tools to assess the effect of green walls on PM concentrations in real environments. It is important to first study the aerodynamic effect of green walls and parameterise it correctly in CFD models. Plants decrease the wind speed and create turbulence through a combination of viscous and form drag, which are determined by the permeability (K) and drag coefficient (Cd), respectively. Wind tunnel experiments were conducted with three commonly found climbers (Hedera helix, Parthenocissus tricuspidata and Parthenocissus quinquefolia) and the variation of leaf area density was investigated for two of them. It was observed that the air resistance depended on plant species, leaf area density and wind speed. The difference between the plant species was assigned to the functional leaf size (FLS), the ratio of the largest circle within the boundaries of the leaf to the total leaf area. FLS is likely associated with other morphological characteristics of plants that, when considered collectively, provide a more comprehensive representation of leaf complexity. The pressure and velocity measurements obtained were used to optimise the permeability and drag coefficient in a CFD model. At wind speeds below 0.6 m s-1, the resistance was mainly determined by viscous drag and a larger leaf size resulted in a higher viscous drag. At wind speeds above 1.5 m s-1, form drag was dominant and the parameterised Cd decreased with increasing wind speed due to the sheltering effect of successive plant elements. The leaf area density had a significant effect on K and Cd and, is therefore an important plant parameters in CFD models. The main conclusion here is that the common practice of using a constant Cd to model the influence of plants on the air flow leads to deviations from reality. Wind tunnels are highly suitable to study the impact of green walls on PM concentration under controlled environmental conditions. For this purpose, a new wind tunnel setup was built and great attention was paid to obtaining a uniform air flow. Thus, based on CFD models, appropriate flow controllers were chosen, consisting of honeycombs and screens with different mesh sizes. New PM generation devices and measuring equipment were installed and set up appropriately. Devices were available for generating and measuring ultrafine dust (<0.1 µm, i.e. PM0.1) and fine dust (<0.3 µm, i.e. PM0.3) consisting of soot particles, and, on the other hand, fine dust with particle sizes smaller than 2.5 (PM2.5) and 10 µm (PM10) consisting of 'Arizona fine test dust'. With the new wind tunnel setup, it was possible to measure the influence of Hedera helix (common ivy), grown in a planter against a climbing aid, on the PM concentration and this was expressed by a collection efficiency, i.e. the difference in concentration in front and behind the plants normalised for the incoming concentration. The collection efficiency of H. helix depended on the particle size of the PM and wind speed. The collection efficiency decreased when the particle size increased from 0.02 to 0.2 µm and increased again for particle sizes above 0.3 µm. The collection efficiency also increased with increasing wind speed, especially for particle sizes > 0.03 µm. On the other hand, relative humidity and the type of PM (soot or dust) did not significantly affect the collection efficiency. The main objective of this study was to obtain an optimised size-resolved deposition model. Dry deposition occurs through several mechanisms, in particular gravity, diffusion, impaction and interception, and the subsequent resuspension of deposited PM back to the environment. The modelling of these mechanisms was described by \citet{Zhang2001} and \citet{Petroff2010}. The data obtained from the wind tunnel experiments allowed validating these deposition models. It was for the first time that deposition of real PM on green walls was studied. The different PM deposition mechanisms were found to be strongly dependent on particle size and wind speed. The models of \citet{Zhang2001} and \citet{Petroff2010} each matched PM concentration measurements for only certain particle sizes. Therefore, a combination of the two models was investigated and the root mean square error was lower by on average 3.5% (PM < 0.03 µm) and 46% (PM > 0.03 µm) compared to the original models at wind speeds greater than 1.5 m s-1. For wind speeds less than 1.5 m s-1, the optimised model did not differ from the original models. The optimised model was able to meet the imposed criteria for air quality models, where a correct model exhibits low deviation from measurements ('normalised mean square error' < 1.5), low bias ('fractional bias' between -0.3 and 0.3) and high R2. In comparison, the R$2$ of the optimised model was 0.57, while that of Zhang et al. (2001) and Petroff et al. (2010) was 0.23 and 0.31, respectively. The optimised model was however characterised by a high scatter, with the fraction of modeled results located within a factor of two of the measurements being lower than 50. A model study with a green façade oriented parallel to the incoming airflow showed that deposition by interception and impaction reduced remarkably, but that the orientation had no effect on deposition by Brownian diffusion. A promising green wall form for PM mitigation is the living wall system (LWS). LWS consist of supporting structures with substrate to grow plants in and can be planted with a variety of plant species. This allows to select plant species with optimal characteristics to achieve PM deposition. These characteristics refer to the macro- and microstructure of the leaves, and research has been conducted mainly on these. On the other hand, the influence of the supporting structure and substrate on PM concentrations has rarely been studied. With the new wind tunnel setup, LWS from different manufacturers were tested for their ability to capture PM. The setups were subjected for three hours to an air flow with a low PM concentration (resuspension phase) and then for three hours to an air flow to which additional PM was added (deposition phase). Some setups were able to decrease the PM concentration during both phases, while others just caused the concentration to increase. Some systems were able to reduce particulate matter concentration during both phases, namely LWS consisting of planters (-2% and -4% for PM0.1 and PM2.5, respectively) and textile cloths (-23% and -5% for PM0.1 and PM2.5, respectively). While other systems actually resulted in an increase in concentration especially LWS existing textile fabrics consisting of geotextiles (+11% for both PM fractions) and with moss as substrate (+2% and +5% for PM0.1 and PM2.5, respectively). This highlights the importance of careful selection of suspension systems to reduce particulate matter concentrations. Further research is therefore needed on the materials used in these systems in relation to their particulate content, as well as on plant development in these systems. In addition to air measurements, measurements were taken of the amount of PM deposited on the leaves and suspension system of LWS. This allowed the difference in PM resuspension and deposition between plant species to be investigated. The amount of deposited particulate matter was determined based on 'saturation isothermal remanent magnetisation' (SIRM), a measure of magnetisable particulate matter. This was possible because the added 'Arizona fine test dust' contained iron oxide. However, no significant difference was observed between the SIRM values measured before the wind tunnel experiment, after resuspension and after deposition. This suggested that the iron oxide content in the Arizona fine test dust was too low to measure a significant difference in the SIRM values on leaves after three hours. The plant species did give rise to different SIRM values ranging between 5 and 260 µ A. In particular, SIRM values above 26 µ A were observed for the plant species that were grouped due to their significantly higher accumulation of PM. 'Specific leaf area' (SLA), specifically the ratio of the one-sided 'fresh' leaf area to its dry mass, was the significant leaf characteristic. SLA correlated with leaf complexity. In particular, plant species with elongated leaves were characterized by low SLA, high FLS and high complexity and showed significantly higher SIRM values. Finally, the optimised size-resolved deposition model was also tested in an urban model to get an idea of the impact of a green wall on PM concentrations in a so-called 'street canyon'. These are narrow streets with high buildings on both sides, making air pollution more persistent. To this end, an ideal scenario was tested in which a green wall was introduced along both sides of the street over a length of about 270 m. The model result showed a decrease in PM2.5 and PM10 of 46 ± 12% and 52 ± 14%. This result is of course for a very optimal scenario where the green wall covers the entire building façades. Since this is not feasible in reality, other ways of promoting contact between green walls and polluted air can be explored. The insights obtained illustrate that the use of climbing plants can be a cost-effective and environmentally friendly solution to reduce PM concentrations. Moreover, the findings showed that models can be used to investigate the impact of green walls on PM levels. These findings fit within the broader context of designing healthy and sustainable urban environments and developing innovative solutions based on solid scientific knowledge. |
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Most recent IF: NA |
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Call Number |
UA @ admin @ c:irua:199439 |
Serial |
8900 |
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Author |
Conti, S.; Saberi-Pouya, S.; Perali, A.; Virgilio, M.; Peeters, F.M.; Hamilton, A.R.; Scappucci, G.; Neilson, D. |
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Title |
Electron-hole superfluidity in strained Si/Ge type II heterojunctions |
Type |
A1 Journal article |
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Year |
2021 |
Publication |
npj Quantum Materials |
Abbreviated Journal |
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Volume |
6 |
Issue |
1 |
Pages |
41 |
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Keywords |
A1 Journal article; Condensed Matter Theory (CMT) |
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Abstract |
Excitons are promising candidates for generating superfluidity and Bose-Einstein condensation (BEC) in solid-state devices, but an enabling material platform with in-built band structure advantages and scaling compatibility with industrial semiconductor technology is lacking. Here we predict that spatially indirect excitons in a lattice-matched strained Si/Ge bilayer embedded into a germanium-rich SiGe crystal would lead to observable mass-imbalanced electron-hole superfluidity and BEC. Holes would be confined in a compressively strained Ge quantum well and electrons in a lattice-matched tensile strained Si quantum well. We envision a device architecture that does not require an insulating barrier at the Si/Ge interface, since this interface offers a type II band alignment. Thus the electrons and holes can be kept very close but strictly separate, strengthening the electron-hole pairing attraction while preventing fast electron-hole recombination. The band alignment also allows a one-step procedure for making independent contacts to the electron and hole layers, overcoming a significant obstacle to device fabrication. We predict superfluidity at experimentally accessible temperatures of a few Kelvin and carrier densities up to similar to 6 x 10(10) cm(-2), while the large imbalance of the electron and hole effective masses can lead to exotic superfluid phases. |
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000642904200001 |
Publication Date |
2021-04-23 |
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ISSN |
2397-4648 |
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Additional Links |
UA library record; WoS full record; WoS citing articles |
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Impact Factor |
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Times cited |
9 |
Open Access |
OpenAccess |
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Notes |
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Approved |
Most recent IF: NA |
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Call Number |
UA @ admin @ c:irua:178226 |
Serial |
6984 |
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Author |
Herremans, D.; Cagno, S.; Vincke, A.; Janssens, K.; De Clercq, W. |
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Title |
All crystal clear : 18th-century glass à la façon de Bohème from the cistercian nunnery of Clairefontaine, Belgium |
Type |
A1 Journal article |
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Year |
2013 |
Publication |
Journal of glass studies |
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55 |
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137-+ |
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A1 Journal article; Art; History; AXES (Antwerp X-ray Analysis, Electrochemistry and Speciation) |
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Abstract |
Excavations at the Cistercian nunnery of Clairefontaine, located near Arlon in the south of Belgium, revealed an assemblage of 18th-century colorless glass. The morphology of the vessels and the engraved decoration suggest a central European origin or, at least, stylistic inspiration. The composition of the glass points to a recipe combining silica, lime, and potash: a colorless potash glass a la facon de Boheme. This article considers the technology, morphology, and origin of the vessels. The art-historical analysis is supported by chemical research (scanning electron microscopy energy-dispersive X-ray spectroscopy [SEM-EDX]). The finds are also discussed in light of the emerging northwestern European glass industry, changing consumer practices during the 18th century, and their meaning for the inhabitants of the abbey. |
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0075-4250 |
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UA library record; WoS full record; WoS citing articles |
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; ; |
Approved |
Most recent IF: NA |
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Call Number |
UA @ admin @ c:irua:114603 |
Serial |
5461 |
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Pacquets, L. |
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Title |
Towards stable Cu-Ag bimetallic nanoparticles to boost the electrocatalytic CO2 reduction |
Type |
Doctoral thesis |
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2022 |
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Pages |
xvi, 188 p. |
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Doctoral thesis; Engineering sciences. Technology; Electron microscopy for materials research (EMAT); Applied Electrochemistry & Catalysis (ELCAT) |
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Abstract |
Ever since the industrial revolution, the emission of greenhouse gasses dramatically increased, resulting in high CO2 concentration in the atmosphere. The electrochemical conversion of CO2 to value added products, such as carbon monoxide, formic acid, methane, ethylene and ethanol is a very promising strategy to inhibit CO2 emissions. Nevertheless, at the moment, the electrochemical CO2 reduction (eCO2R) is not yet industrially viable, mainly due to the lack of good electrocatalysts. On the other hand, core-shell nanoparticles (NPs) have emerged over the last couple of years as promising candidates. It is believed that bimetallic enhancement effects are behind the improved performance of these core-shell NPs when compared to the individual metals. Although widely investigated, there are still some remaining issues and/or open questions. Indeed, the development of a robust and straightforward synthesis method along with fundamental insight into their resistance towards electrochemical stress remains absent. A good control over morphology, size and composition is key in determining which properties are beneficial for the eCO2R. Since these catalysts are designed to be implemented in electrolyzers, they have to maintain long-term performance. This makes the design of a reproducible method, unveiling structure-performance relationships the effect of electrochemical stress, a crucial aspect. Exploring and modifying existing synthesis methods, have led to the acquisition of a robust and reproducible synthesis method where thermal decomposition of the Cu core is combined with the galvanic replacement of Ag in organic solvents. The implementation of this method has led to the design of a wide variety of Cu-Ag bimetallic NPs and enabled to investigate their composition-selectivity profile. Introducing Ag on Cu suppressed hydrogen and increased the CO formation. CO production was boosted by using Cu@Ag core-shells and was promoted even more by changing the type of electrolyte. As these nanoparticles suffered from degradation, the 3D mapping of the structural changes of Cu@Ag core-shells under operating conditions led to the hypothesis of a two-step degradation mechanism where initially Cu leaching was observed with the subsequent sintering of the Ag shells. One approach to avoid this electrochemical degradation, investigated in this research, was the application of an ultrathin carbon layer to protect the active layer. This ultrathin carbon layer operated as a protective layer, suppressing hydrogen production and increasing the stability of the electrocatalyst. In conclusion, the product selectivity can be tuned by using different Cu-Ag bimetallic nanoparticles synthesized through a robust method. Their unique degradation pathway of Cu@Ag core-shell nanoparticles has led to the proposition of a more accurate stabilization strategy. These findings can contribute significantly in the quest for improved electrocatalysts for the eCO2R. |
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Most recent IF: NA |
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UA @ admin @ c:irua:190236 |
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7221 |
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Author |
Seuntjens, D.; Han, M.; Kerckhof, F.-M.; Boon, N.; Al-Omari, A.; Takacs, I.; Meerburg, F.; De Mulder, C.; Wett, B.; Bott, C.; Murthy, S.; Carvajal Arroyo, J.M.; De Clippeleir, H.; Vlaeminck, S.E. |
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Pinpointing wastewater and process parameters controlling the AOB to NOB activity ratio in sewage treatment plants |
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A1 Journal article |
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2018 |
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Water research |
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138 |
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37-46 |
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A1 Journal article; Engineering sciences. Technology; Sustainable Energy, Air and Water Technology (DuEL) |
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Even though nitrification/denitrification is a robust technology to remove nitrogen from sewage, economic incentives drive its future replacement by shortcut nitrogen removal processes. The latter necessitates high potential activity ratios of ammonia oxidizing to nitrite oxidizing bacteria (rAOB/rNOB). The goal of this study was to identify which wastewater and process parameters can govern this in reality. Two sewage treatment plants (STP) were chosen based on their inverse rAOB/rNOB values (at 20 °C): 0.6 for Blue Plains (BP, Washington DC, US) and 1.6 for Nieuwveer (NV, Breda, NL). Disproportional and dissimilar relationships between AOB or NOB relative abundances and respective activities pointed towards differences in community and growth/activity limiting parameters. The AOB communities showed to be particularly different. Temperature had no discriminatory effect on the nitrifiers' activities, with similar Arrhenius temperature dependences (ΘAOB = 1.10, ΘNOB = 1.061.07). To uncouple the temperature effect from potential limitations like inorganic carbon, phosphorus and nitrogen, an add-on mechanistic methodology based on kinetic modelling was developed. Results suggest that BP's AOB activity was limited by the concentration of inorganic carbon (not by residual N and P), while NOB experienced less limitation from this. For NV, the sludge-specific nitrogen loading rate seemed to be the most prevalent factor limiting AOB and NOB activities. Altogether, this study shows that bottom-up mechanistic modelling can identify parameters that influence the nitrification performance. Increasing inorganic carbon in BP could invert its rAOB/rNOB value, facilitating its transition to shortcut nitrogen removal. |
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000431747300005 |
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2017-11-24 |
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0043-1354; 1879-2448 |
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UA @ admin @ c:irua:149976 |
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8385 |
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