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Records |
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Author |
Török, S.; Labar, J.; Schmeling, M.; Van Grieken, R. |
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Title |
X-ray spectrometry |
Type |
A1 Journal article |
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Year |
1998 |
Publication |
Analytical chemistry |
Abbreviated Journal |
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Volume |
70 |
Issue  |
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Pages |
495r-517r |
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Keywords |
A1 Journal article; AXES (Antwerp X-ray Analysis, Electrochemistry and Speciation) |
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000074161100020 |
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ISSN |
0003-2700; 5206-882x |
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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:20967 |
Serial |
8776 |
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Author |
Török, S.B.; Labar, J.; Injuk, J.; Van Grieken, R.E. |
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Title |
X-ray spectrometry |
Type |
A1 Journal article |
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Year |
1996 |
Publication |
Analytical chemistry |
Abbreviated Journal |
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Volume |
R68 |
Issue |
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Pages |
467-485 |
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Keywords |
A1 Journal article; AXES (Antwerp X-ray Analysis, Electrochemistry and Speciation) |
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0003-2700; 5206-882x |
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no |
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Call Number |
UA @ admin @ c:irua:14650 |
Serial |
8777 |
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Author |
Török, S.B.; Van Grieken, R.E. |
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Title |
X-ray spectrometry |
Type |
A1 Journal article |
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Year |
1992 |
Publication |
Analytical chemistry |
Abbreviated Journal |
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Volume |
64r |
Issue |
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Pages |
180-196 |
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Keywords |
A1 Journal article; AXES (Antwerp X-ray Analysis, Electrochemistry and Speciation) |
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Wos |
A1992HZ51800011 |
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0003-2700; 5206-882x |
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UA library record; WoS full record; WoS citing articles |
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Call Number |
UA @ admin @ c:irua:2823 |
Serial |
8778 |
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Author |
Markowicz, A.A.; Van Grieken, R.E. |
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Title |
X-ray spectrometry |
Type |
A1 Journal article |
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Year |
1984 |
Publication |
Reviews in analytical chemistry |
Abbreviated Journal |
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Volume |
56 |
Issue |
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Pages |
241r-250r |
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Keywords |
A1 Journal article; AXES (Antwerp X-ray Analysis, Electrochemistry and Speciation) |
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Series Volume |
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ISSN |
0048-752x |
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UA library record |
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no |
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Call Number |
UA @ admin @ c:irua:116709 |
Serial |
8782 |
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Author |
Van Grieken, R.; Delalieux, F. |
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Title |
X-ray spectrometry for air pollution and cultural heritage research |
Type |
P3 Proceeding |
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Year |
2004 |
Publication |
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Abbreviated Journal |
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Volume |
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Issue |
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Pages |
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Keywords |
P3 Proceeding; AXES (Antwerp X-ray Analysis, Electrochemistry and Speciation) |
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no |
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Call Number |
UA @ admin @ c:irua:51259 |
Serial |
8783 |
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Author |
Van Grieken, R.; Makarovska, Y.; van Meel, K.; Worobiec, A. |
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Title |
X-ray spectrometry for analysis of atmospheric particulate matter: detection limits versus legal levels |
Type |
H3 Book chapter |
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Year |
2007 |
Publication |
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Abbreviated Journal |
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Volume |
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Issue |
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Pages |
153-161
T2 - Topics in X-ray spectrometry / Vázque |
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Keywords |
H3 Book chapter; AXES (Antwerp X-ray Analysis, Electrochemistry and Speciation); Laboratory Experimental Medicine and Pediatrics (LEMP) |
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no |
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Call Number |
UA @ admin @ c:irua:64402 |
Serial |
8784 |
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Author |
Tsuji, K.; Injuk, J.; Van Grieken, R. |
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Title |
X-ray spectrometry: recent technological advances |
Type |
ME1 Book as editor or co-editor |
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Year |
2004 |
Publication |
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Abbreviated Journal |
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Volume |
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Issue |
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Pages |
616 p. |
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Keywords |
ME1 Book as editor or co-editor; AXES (Antwerp X-ray Analysis, Electrochemistry and Speciation) |
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ISBN |
0-471-48640-x |
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UA library record |
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Approved |
no |
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Call Number |
UA @ admin @ c:irua:43876 |
Serial |
8786 |
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Author |
Van Alsenoy, W.; Bernard, P.; Van Grieken, R. |
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Title |
Zware metalen in Noordzee- en Schelde-sedimenten |
Type |
A3 Journal article |
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Year |
1990 |
Publication |
Wtare |
Abbreviated Journal |
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Volume |
5 |
Issue |
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Pages |
113-121 |
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Keywords |
A3 Journal article; AXES (Antwerp X-ray Analysis, Electrochemistry and Speciation) |
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no |
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Call Number |
UA @ admin @ c:irua:116829 |
Serial |
8787 |
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Author |
Parrilla, M.; Vanhooydonck, A.; Johns, M.; Watts, R.; De Wael, K. |
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Title |
3D-printed microneedle-based potentiometric sensor for pH monitoring in skin interstitial fluid |
Type |
A1 Journal article |
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Year |
2023 |
Publication |
Sensors and actuators : B : chemical |
Abbreviated Journal |
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Volume |
378 |
Issue |
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Pages |
133159-10 |
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Keywords |
A1 Journal article; Engineering sciences. Technology; Internet Data Lab (IDLab); Product development; Antwerp Electrochemical and Analytical Sciences Lab (A-Sense Lab) |
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Abstract |
Wearable electrochemical sensors are driven by the user-friendly capability of continuous monitoring of key biomarkers for diagnostic or therapeutic operations. Particularly, microneedle (MN)-based sensors can access the interstitial fluid (ISF) in the dermis layer of skin to carry out on-body transdermal detection of analytes. Interestingly, 3D-printing technology allows for rapid and versatile prototyping reaching micrometer resolution. Herein, for the first time, we explore 3D-printed hollow MN patches (1 mm height x 1 mm base with 0.3 mm hole) which are modified with conductive inks to develop a potentiometric sensor for pH monitoring. First, the piercing capability of 3D-printed MN patches is demonstrated by using the parafilm model and their insertion in porcine skin. Subsequently, the hollow MNs are filled with conductive inks to engineer a set of microelectrodes. Thereafter, the working and reference electrodes are properly modified with polyaniline and polyvinyl butyral, respectively, toward a highly stable potentiometric cell. A full in vitro characterization is performed within a broad range of pH (i.e. pH 4 to pH 9). Besides, the MN sensor is analytically assessed in phantom gel and pierced on porcine skin to evaluate the resilience of the MN sensor. Finally, the MN sensor is pierced on the forearm of a subject and tested for its on-body monitoring capability. Overall, 3D-printed MN-based potentiometric sensing brings a versatile and affordable technology to minimally-invasively monitor key physiological parameters in the body. |
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Wos |
000904590500008 |
Publication Date |
2022-12-12 |
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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 |
0925-4005 |
ISBN |
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Additional Links |
UA library record; WoS full record; WoS citing articles |
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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:192381 |
Serial |
8824 |
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Author |
Neven, L.; Barich, H.; Sleegers, N.; Cánovas, R.; Debruyne, G.; De Wael, K. |
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Title |
Development of a combi-electrosensor for the detection of phenol by combining photoelectrochemistry and square wave voltammetry |
Type |
A1 Journal article |
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Year |
2022 |
Publication |
Analytica chimica acta |
Abbreviated Journal |
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Volume |
1206 |
Issue |
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Pages |
339732 |
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Keywords |
A1 Journal article; Antwerp Electrochemical and Analytical Sciences Lab (A-Sense Lab) |
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Abstract |
The high toxicity, endocrine-disrupting effects and low (bio)degradability commonly attributed to phenolic compounds have promoted their recognition as priority toxic pollutants. For this reason, the monitoring of these compounds in industrial, domestic and agricultural streams is crucial to prevent and decrease their toxicity in our daily life. To confront this relevant environmental issue, we propose the use of a combi-electrosensor which combines singlet oxygen (1O2)-based photoelectrochemistry (PEC) with square wave voltammetry (SWV). The high sensitivity of the PEC sensor (being a faster alternative for traditional COD measurements) ensures the detection of nmol L−1 levels of phenolic compounds while the SWV measurements (being faster than the color test kits) allow the differentiation between phenolic compounds. Herein, we report on the development of such a combi-electrosensor for the sensitive and selective detection of phenol (PHOH) in the presence of related phenolic compounds such as hydroquinone (HQ), bisphenol A (BPA), resorcinol (RC) and catechol (CC). The PEC sensor was able to determine the concentration of PHOH in spiked river samples containing only PHOH with a recovery between 96% and 111%. The SWV measurements elucidated the presence of PHOH, HQ and CC in the spiked samples containing multiple phenol compounds. Finally, the practicality of the combi-electrosensor set-up with a dual SPE containing two working electrodes and shared reference and counter electrodes was demonstrated. As a result, the combination of the two techniques is a powerful and valuable tool in the analysis of phenolic samples, since each technique improves the general performance by overcoming the inherent drawbacks that they display independently. |
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000793070200016 |
Publication Date |
2022-03-16 |
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Edition |
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ISSN |
0003-2670; 1873-4324 |
ISBN |
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Additional Links |
UA library record; WoS full record; WoS citing articles |
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OpenAccess |
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Call Number |
UA @ admin @ c:irua:187499 |
Serial |
8848 |
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Author |
Mendonça Verbinnen, C.D. |
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Title |
Development of semiconductor-based photoelectrochemical sensing strategies for phenolic compounds in natural and supply water |
Type |
Doctoral thesis |
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Year |
2022 |
Publication |
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Abbreviated Journal |
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Volume |
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Issue |
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Pages |
152 p. |
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Keywords |
Doctoral thesis; Engineering sciences. Technology; Antwerp Electrochemical and Analytical Sciences Lab (A-Sense Lab) |
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Abstract |
A wide variety of organic and inorganic compounds have been frequently released into the environment without control by industries and agricultural activities. This has caused significant impact on the development and health of living organisms, and biodiversity. Therefore, the challenge of monitoring and/or remediation of these contaminants remains. This thesis presents the development of three sensing strategies based on photoelectrochemical sensors to monitor phenolic contaminants. The well-known semiconductors TiO2 and ZnO were used for building novel setups for nM analysis of phenolic compounds in water. The setups employing TiO2-based photosensors were integrated into a photoelectrochemical flow cell. The flow system favored higher sensitivity of the method by periodic wash sequences of the electrode, significantly reducing the electrode fouling. Firstly, a straightforward method was developed based on the immobilization of TiO2 on screen printed graphite electrodes. Under UV light, the developed photosensor presented high performance for the detection of 4- aminophenol. A second study was developed by impregnating gold nanoparticles into TiO2 structure. The incorporation of gold nanoparticles can broaden the light absorption region of TiO2 and improve its photocatalytic activity for the detection of hydroquinone under visible light. In both systems, the detection was possible due to the presence of reactive oxygen species at the surface of TiO2 upon light, which participate in the oxidation process of the analyte. By applying a reductive potential, the oxidized form of the analyte gets reduced and a measurable amperometric response proportional to the initial analyte concentration is recorded. The third proposed setup is a ZnO-based photosensor for the quantification of 4-nitrophenol under UVA light. Nanostructured ZnO was electrochemically synthesized on FTO glass without the use of catalysts or seed layer. A post-growth annealing treatment significantly improved ZnO nanorods physicochemical properties. Subsequent modification of ZnO nanorods with a photosensitizer (perylene acid) increased the photocurrent response and the sensitivity. In this system, the detection mechanism is based on the decrease of the photocurrent response at the presence of an electron harvesting molecule, such as 4-nitrophenol. The decrease in photocurrent is proportional to the increase of 4-nitrophenol concentration in the solution. The applicability of the photoelectrochemical semiconductor-based sensing setups was verified to analyze phenolic compounds in natural and supply water samples. The proposed robust and sensitive approaches were designed for the on-site monitoring of phenolic compounds. The encouraging results confirm the potential of these photosensors as promising tools for tracelevel sensing purposes. |
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Call Number |
UA @ admin @ c:irua:186763 |
Serial |
8850 |
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Author |
Vizarim, N.P. |
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Title |
Dynamic behavior of Skyrmions under the influence of periodic pinning in chiral magnetic infinite thin films |
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 |
212 p. |
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Keywords |
Doctoral thesis; Condensed Matter Theory (CMT) |
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Abstract |
The miniaturization of transistors for application in new processors and logic devices poses a significant challenge in the field of materials. Spintronics, which relies on controlled movement of magnetic nanostructures, offers a promising solution. Among the candidates, magnetic skyrmions are considered one of the most promising. These chiral spin structures, characterized by topological protection and enhanced stability compared to vortices or magnetic bubbles, have been extensively studied. To advance in the control of skyrmion motion, essential for practical applications, we investigated their dynamic behavior in a two-dimensional chiral magnet at zero temperature. Our study focused on the influence of periodic arrays of pinning centers. The simulations considered skyrmions as point-like particles considering the following interactions: skyrmion-skyrmion interactions, interactions with pinning center arrays, a current of polarized spins, and the Magnus force. We conducted calculations for scenarios involving a single skyrmion as well as different skyrmion density values in the material. The aim was to explore possibilities for controlled skyrmion motion, investigate different dynamic regimes, and examine collective effects. The results demonstrate that by adjusting the size, strength, and density of the pinning centers, we can effectively control the motion of individual skyrmions and manage the flow of multiple skyrmions. Furthermore, we discovered that periodic arrays of pinning centers can facilitate topological selection when different species of skyrmions with distinct Magnus components are present. Employing alternating currents, we observed the significant role of the ratchet effect in the skyrmion dynamics. By fine-tuning the amplitudes of the alternating currents, we achieved direct and controlled motion of skyrmions in specific directions. These findings hold potential for advancing our understanding of skyrmion dynamics and can inspire future technological applications involving these quasi-particles. Overall, we anticipate that our results will be valuable to the scientific community, contributing to a deeper comprehension of skyrmion dynamics and paving the way for future technological applications. |
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Most recent IF: NA |
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Call Number |
UA @ admin @ c:irua:198101 |
Serial |
8852 |
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Author |
Montiel, F.N.; Parrilla, M.; Sleegers, N.; Van Durme, F.; van Nuijs, A.L.N.; De Wael, K. |
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Title |
Electrochemical sensing of amphetamine-type stimulants (pre)-precursors to fight against the illicit production of synthetic drugs |
Type |
A1 Journal article |
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Year |
2022 |
Publication |
Electrochimica acta |
Abbreviated Journal |
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Volume |
436 |
Issue |
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Pages |
141446-11 |
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Keywords |
A1 Journal article; Engineering sciences. Technology; Toxicological Centre; Antwerp Electrochemical and Analytical Sciences Lab (A-Sense Lab) |
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Abstract |
The illicit drug precursor market for the manufacture of amphetamine-type stimulants (ATS), mainly amphetamine, methamphetamine and methylenedioxymethamphetamine (MDMA), has emerged quickly in the last years. The evidence of a more complex and sophisticated drug market underlines the pressing need for new on-site methods to quickly detect precursors of synthetic drugs, with electrochemical analysis as a promising technique. Herein, the electrochemical fingerprints of ten common ATS precursors-3-oxo-2-phenylbutanenitrile (APAAN), 3-oxo-2-phenylbutanamide (APAA), methyl 3-oxo-2-phenylbutanoate (MAPA), benzyl methyl ketone (BMK), 1-(1,3-benzodioxol-5-yl)propan-2-one (PMK), ephedrine, pseudoephedrine, safrole, sassafras oil and piperonal- are reported for the first time. The electrochemical screening disclosed the redox inactivity of BMK, which is an essential starting material for the production of ATS. Therefore, the local derivatization of BMK at an electrode surface by reductive amination is presented as a feasible solution to enrich its electrochemical fingerprint. To prove that, the resulting mixture was analyzed using a set of chromatographic techniques to understand the reaction mechanism and to identify possible electrochemical active products. Two reaction products (i.e. methamphetamine and 1-phenylpropan-2-ol) were found and characterized using mass spectrometry and electrochemical methods. Subsequently, the optimization of the reaction parameters was carefully addressed to set the portable electrochemical sensing strategy. Ultimately, the analysis concept was validated for the qualitative identification of ATS precursors in seizures from a forensic institute. Overall, the electrochemical approach demonstrates to be a useful and affordable analytical tool for the early identification of ATS precursors to prevent trafficking and drug manufacture in clandestine laboratories. |
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000914833800003 |
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2022-10-27 |
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0013-4686 |
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UA library record; WoS full record |
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UA @ admin @ c:irua:191622 |
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8858 |
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Author |
Hassani, H. |
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Title |
First-principles study of polarons in WO₃ |
Type |
Doctoral thesis |
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Year |
2023 |
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Pages |
181 p. |
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Doctoral thesis; Condensed Matter Theory (CMT) |
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Abstract |
Polarons are quasiparticles emerging in materials from the interaction of extra charge carriers with the surrounding atomic lattice. They appear in a wide va- riety of compounds and can have a profound impact on their properties, making the concept of a polaron a central and ubiquitous topic in material science. Al- though the concept is known for about 75 years, the origin of polarons is not yet fully elucidated. This thesis focuses on WO 3 as a well-known prototypical system for studying polarons, which inherent polaronic nature is linked to its remark- able electrical and chromic properties. The primary objective of this research is to provide a comprehensive atomistic description and understanding of polaron formation in WO 3 using first-principles density functional theory (DFT) calcula- tions. Additionally, the investigation explores the interactions between polarons and the possibility of bipolaron formation. Following a systematic strategy, we first extensively analyze the dielectric and lattice dynamical properties of WO 3 in both the room-temperature P 2 1 /n and ground-state P 2 1 /c phases. Our specific focus is on characterizing the zone-center phonons, which serve as the founda- tion for identifying the phonon modes involved in the polaron formation and charge localization process. Subsequently, we examine the impact of structural distortions on the electronic structure of WO 3 to elucidate the interplay between structural distortions and electronic properties, thereby laying the groundwork for understanding electron-phonon couplings. By incorporating these critical fac- tors, we address our primary research goals. The most common explanation for the polaron formation is associated with the electrostatic screening of the extra charge by the polarizable lattice. Here, we show that, even in ionic crystals, this is not necessarily the case. We demonstrate that polarons in this compound arise primarily from non-polar atomic distortions. We then unveil that this unexpected behavior originates from the undoing of distortive atomic motions, which lowers the bandgap. As such, we coin the name of anti-distortive polaron and validate its appearance through a simple quantum-dot model, in which charge localization is the result of balancing structural, electronic, and confinement energy costs. Then, we also study the polaron-polaron interaction and present the formation of the antiferromagnetic W 4+ bipolaronic state with relatively large formation energy. Our analysis of the W 4+ bipolaronic distortions on the global structure reveals the same behavior as in experiments where the highly distorted monoclinic phase transforms into a tetragonal phase as a function of doping. Additionally, leveraging our previous findings on asymmetric polaronic distortion and examin- ing different merging orientations, we stabilize the antiferromagnetic W 5+ -W 5+ bipolaronic state with an energy lower than the W 4+ state. This thesis clari- fies the formation of unusual medium-size 2D polarons and bipolarons in WO3,which might be relevant to the whole family of ABO 3 perovskites, to which WO 3 is closely related. The simplicity of the concept provides also obvious guidelines for tracking similar behavior in other families of compounds. |
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Most recent IF: NA |
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Call Number |
UA @ admin @ c:irua:198169 |
Serial |
8868 |
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Moro, G.; Foumthuim, C.J.D.; Spinaci, M.; Martini, E.; Cimino, D.; Balliana, E.; Lieberzeit, P.; Romano, F.; Giacometti, A.; Campos, R.; De Wael, K.; Moretto, L.M. |
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Title |
How perfluoroalkyl substances modify fluorinated self-assembled monolayer architectures : an electrochemical and computational study |
Type |
A1 Journal article |
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Year |
2022 |
Publication |
Analytica chimica acta |
Abbreviated Journal |
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Volume |
1204 |
Issue |
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Pages |
339740-12 |
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Keywords |
A1 Journal article; Antwerp Electrochemical and Analytical Sciences Lab (A-Sense Lab) |
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Abstract |
There is an urgent need for sensing strategies to screen perfluoroalkyl substances (PFAS) in aqueous matrices. These strategies must be applicable in large-scale monitoring plans to face the ubiquitous use of PFAS, their wide global spread, and their fast evolution towards short-chain, branched molecules. To this aim, the changes in fluorinated self-assembled monolayers (SAM) with different architectures (pinholes/defects-free and with randomized pinholes/defects) were studied upon exposure to both long and short-chain PFAS. The applicability of fluorinated SAM in PFAS sensing was evaluated. Changes in the SAM structures were characterised combining electrochemical impedance spectroscopy and voltam-metric techniques. The experimental data interpretation was supported by molecular dynamics simu-lations to gain a more in-depth understanding of the interaction mechanisms involved. Pinhole/defect-free fluorinated SAM were found to be applicable to long-chain PFAS screening within switch-on sensing strategy, while a switch-off sensing strategy was reported for screening of both short/long-chain PFAS. These strategies confirmed the possibility to play on fluorophilic interactions when designing PFAS screening methods.(c) 2022 Elsevier B.V. All rights reserved. |
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000789493000010 |
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2022-03-17 |
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0003-2670; 1873-4324 |
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UA library record; WoS full record; WoS citing articles |
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Not_Open_Access |
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no |
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Call Number |
UA @ admin @ c:irua:188658 |
Serial |
8880 |
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Author |
Wittner, N. |
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Title |
Improving and characterising solid-state fungal pretreatment by Phanerochaete chrysosporium for sugar production from poplar wood |
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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Pages |
206 p. |
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Keywords |
Doctoral thesis; Engineering sciences. Technology; Sustainable Energy, Air and Water Technology (DuEL); Biochemical Wastewater Valorization & Engineering (BioWaVE) |
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Abstract |
Pretreatment is a critical step in the conversion of lignocellulose into biofuels and biochemicals. During pretreatment, the recalcitrance of lignocellulose is reduced, e.g. by removing lignin, thereby making the carbohydrates more accessible for enzymatic saccharification. Fungal delignification by white-rot fungi is a biotechnological alternative to chemical/physicochemical methods, which is carried out in solid-state fermentation with mild reaction conditions and without the formation of microbial inhibitors. However, fungal pretreatment presents some challenges, such as long pretreatment time, non-selective and low delignification, low enzymatic digestibility and feedstock sterilisation requirement, making its commercial implementation challenging compared to conventional methods. This study investigates the possibility of improving and characterising the solid-state fungal pretreatment of poplar wood by Phanerochaete chrysosporium. The individual and combined effects of MnSO4 and CuSO4 supplements on the delignification of sterilised wood are investigated using response surface methodology to improve the degree and selectivity of fungal delignification. Spore-inoculated solid-state fermentations are carried out for 4 weeks in sterile vented bottles. The mechanism of the concerted action of the metal ions on lignin degradation is then elucidated by relating fungal growth and ligninolytic enzyme activities to lignocellulose degradation as a function of pretreatment time. The optimised metal-supplemented system is then applied to the pretreatment of non-sterilised wood using different inoculation techniques (spores and pre-colonised substrate), nutrients (metal ions with or without glucose and sodium nitrate) and cultivation environments (sterile aerated bottles and open trays). The fermentations are then characterised using infrared spectroscopy, in particular NIR and ATR-FTIR spectroscopy, with the aim of developing rapid lignin quantification methods as an alternative to conventional wet chemical methods. Finally, the feasibility of producing fermentable sugars from sterilised and non-sterilised poplar wood using fungal pretreatment is evaluated through a techno-economic analysis. Supplementing the pretreatment system with 2.01 µmol CuSO4 and 0.77 µmol MnSO4 g-1 wood resulted in 1.9-fold higher lignin degradation, 2.3-fold higher delignification selectivity value and 2.9-fold higher glucose yield. The improved delignification could be explained by the concerted action of Mn2+ and Cu2+ ions, with Mn2+ ions inducing and Cu2+ prolonging manganese peroxidase production responsible for delignification. Fungal pretreatment at non-sterile conditions was obtained using trays in a simple solid-state fermentation set-up without sterile aeration. A 1:3 ratio of pre-colonised and untreated wood was applied for inoculation and only Cu2+, Mn2+ and sodium nitrate as supplements. Remarkably, this technology resulted in a comparably high glucose yield (28.51 ± 0.28%) to the traditional method using sterilised wood, sterile aeration and spores as inoculum, while reducing the amount of wood to be sterilised by 71.2%. Infrared spectroscopy-based methods with high coefficients of determination (R_CV |
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Most recent IF: NA |
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Call Number |
UA @ admin @ c:irua:197185 |
Serial |
8883 |
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Author |
Van Putte, N. |
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Title |
Improving groundwater dynamics : a key factor for successful tidal marsh restoration |
Type |
Doctoral thesis |
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Year |
2023 |
Publication |
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Abbreviated Journal |
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Pages |
166 p. |
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Doctoral thesis; Sustainable Energy, Air and Water Technology (DuEL); Ecosphere |
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Tidal marshes take up and release certain elements from and to the river water. Hence, they act as a filter, improving the estuarine water quality. This filtering function depends on the interaction between the marsh soil and water that infiltrates into the marsh platform at high tide and seeps out of the creek banks at low tide. In the past centuries, many tidal marshes disappeared due to large scale land reclamations, together with their associated ecosystem services. Nowadays, tidal marshes are increasingly restored on formerly embanked agricultural areas to regain these ecosystem services. Here, we studied the effect of historical agricultural land use on the contribution of restored tidal marshes to water quality improvement, and we investigated several solutions to stimulate the water quality improving function in newly restored tidal marshes. In restored tidal marshes, the soil is often compacted due to the historical agricultural land use, leading to a reduced organic matter content and micro- and macroporosity. In this compacted soil, groundwater flow is hindered, leading to a more waterlogged soil and reduced groundwater dynamics in the restored marsh as compared to a natural marsh. The depth of groundwater drainage and the groundwater flow velocity have important implications for the processes that contribute to water quality improvement, e.g. removal of nitrogen, phosphorus retention and silica cycling. Where groundwater drains deeper, i.e. in the vicinity of tidal creeks and in a more porous soil, these processes are promoted. We suggest that, in newly restored tidal marshes, the soil porosity can be increased by amending the soil (e.g. with organic matter), and the distance to the nearest tidal creek can be reduced by creek excavation. Numerical modelling showed that the largest gain in groundwater dynamics and seepage was attained when both measures were applied together. The effect of organic soil amendments on groundwater dynamics and nutrient cycling was further explored in a large scale in situ mesocosm experiment. Where the soil was amended, groundwater drained deeper and nitrogen removal increased. For new tidal marsh restoration projects, we advise to conduct an explorative soil study. When the soil is heavily compacted, design measures, such as creek initiation and organic soil amendments can be applied to jumpstart the contribution to water quality improvement of newly restored tidal marshes. |
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Call Number |
UA @ admin @ c:irua:196965 |
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8884 |
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Drăgan, A.-M. |
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Investigation of the electrochemical behaviour of illicit substances and their redox pathways in the development of nanomaterial-modified platforms for decentralized analysis |
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Doctoral thesis |
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2023 |
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169 p. |
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Doctoral thesis; Pharmacology. Therapy; Engineering sciences. Technology; Antwerp Electrochemical and Analytical Sciences Lab (A-Sense Lab) |
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Most recent IF: NA |
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Call Number |
UA @ admin @ c:irua:199086 |
Serial |
8892 |
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Shi, P.; Gielis, J.; Niklas, K.J.; Niinemets, Ü.; Schrader, J. |
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Title |
Leaf functional traits : ecological and evolutionary implications |
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ME3 Book as editor |
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2023 |
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185 p. |
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ME3 Book as editor; Sustainable Energy, Air and Water Technology (DuEL) |
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2023-04-14 |
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978-2-8325-2086-4; 1664-8714 |
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UA @ admin @ c:irua:198002 |
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8894 |
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De Meyer, S. |
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Macroscopic X-ray powder diffraction in reflection mode : a new technique for chemical imaging of artworks |
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Doctoral thesis |
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2023 |
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285 p. |
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Doctoral thesis; Engineering sciences. Technology; Art; Antwerp X-ray Imaging and Spectroscopy (AXIS) |
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Scientific research into cultural heritage has significantly grown in importance over the past decades. The growing popularity of macroscopic imaging techniques such as X-ray fluorescence or Fourier transform infrared now means that conservators and restorers have access to highly objective information on the chemical composition of a painting without the necessity for destructive sampling. As many works of art are heterogeneous on the macroscopic scale, it is clear that solely relying on microscopic samples does not provide sufficiently representative information on the condition of a painting and that macroscopic imaging techniques should be considered a crucial part of the analytical toolkit for conservation science. The goal of this research has been to investigate the added value of reflection-mode macroscopic X-ray powder diffraction (MA-XRPD) for scientific and art historical investigations of cultural heritage artefacts. A prototype scanner was developed after careful consideration of the individual components. This mobile instrument allows for the analysis of flat objects such as oil paintings with reflection MA-XRPD. In this manner images can be obtained that show the distribution of crystalline components present at the surface of the stratigraphy. These crystalline materials can originate from different sources and include original pigments and non-original pigments. MA-XRPD offers novel insights into original pigments such as ultramarine, copper sulfates and lead white. In Girl with a Pearl Earring by Vermeer the MA-XRPD instrument was used to prove that Vermeer used multiple subtypes of lead white to achieve subtle optical effects while in the painting The Night Watch by Rembrandt the lead white composition was studied in detail; multiple rare lead-based compounds were identified that could be linked to the usage of specific driers in the oil paint. By investigating the presence of degradation products, MA-XRPD can be used to assess the conservation state of an artwork. Secondary alteration products were identified in paintings by Nellius and Mignon, explaining why the paintings had visually deteriorated over time. MA-XRPD registered the presence of lead arsenates which were formed from the original yellow arsenic-based orpiment. By combining microscopic and macroscopic analysis, a chemical degradation pathway for the conversion of the unstable orpiment pigment was proposed. In this manner, MA-XRPD can also be used to provide highly valuable information for conservators and restorers by pinpointing areas that have undergone degradation and to guide sampling campaigns. |
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Most recent IF: NA |
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Call Number |
UA @ admin @ c:irua:198766 |
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8896 |
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Ysebaert, T. |
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Modelling and experimental validation of deposition on vegetation to facilitate urban particulate matter mitigation |
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Doctoral thesis |
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2023 |
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xxvi, 234 p. |
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Doctoral thesis; Engineering sciences. Technology; Sustainable Energy, Air and Water Technology (DuEL) |
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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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UA @ admin @ c:irua:199439 |
Serial |
8900 |
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Neven, L.; Barich, H.; Rutten, R.; De Wael, K. |
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Title |
Novel (photo)electrochemical analysis of aqueous industrial samples containing phenols |
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A1 Journal article |
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Year |
2022 |
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Microchemical journal |
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181 |
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107778-11 |
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A1 Journal article; Engineering sciences. Technology; Antwerp Electrochemical and Analytical Sciences Lab (A-Sense Lab) |
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Phenols are considered as toxic pollutants and their discharge into the environment by industries is regulated by a concentration limit. As these limits are in the low mg L−1 to µg L−1-range, sensitive methods are necessary to detect these phenols. Here, aqueous industrial phenolic samples throughout a cleaning process were analyzed by two novel electrochemical sensors. Both the photoelectrochemical (PEC) sensor and the square wave voltammetric (SWV) sensor could successfully follow the decrease of the concentration of phenols along the industrial cleaning process. The discharge sample (μg L−1) could only be analyzed by the PEC sensor and not by the SWV sensor, as the phenolic concentration was close to the LOD of the latter. With HPLC-diode array detector (DAD) measurements, classical phenols such as phenol (PHOH), hydroquinone, resorcinol and o-cresol could be identified in the industrial samples, and their presence could be linked to the electrochemical responses. At last, the performance of the PEC and SWV sensors were compared with commercial colorimetric and chemical oxygen demand (COD) test kits. This comparison demonstrated the high sensitivity of the PEC sensor in the μg L−1 concentrated phenolic samples. Together with the identification of the redox peaks through HPLC-DAD analysis, the SWV sensor can be a powerful tool in the qualitative analysis of mg L−1 concentrated phenolic samples due to its speed, simplicity and absence of laborious sample pre-treatment steps. |
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000837838400003 |
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2022-07-20 |
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0026-265x; 0026-265x |
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UA @ admin @ c:irua:189428 |
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8906 |
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Faust, V.; Boon, N.; Ganigué, R.; Vlaeminck, S.E.; Udert, K.M. |
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Title |
Optimizing control strategies for urine nitrification : narrow pH control band enhances process stability and reduces nitrous oxide emissions |
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A1 Journal article |
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2023 |
Publication |
Frontiers in environmental science |
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11 |
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1275152-14 |
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A1 Journal article; Engineering sciences. Technology; Sustainable Energy, Air and Water Technology (DuEL) |
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Nitrification is well-suited for urine stabilization. No base dosage is required if the pH is controlled within an appropriate operating range by urine feeding, producing an ammonium-nitrate fertilizer. However, the process is highly dependent on the selected pH set-points and is susceptible to process failures such as nitrite accumulation or the growth of acid-tolerant ammonia-oxidizing bacteria. To address the need for a robust and reliable process in decentralized applications, two different strategies were tested: operating a two-position pH controller (inflow on/off) with a narrow pH control band at 6.20/6.25 (∆pH = 0.05, narrow-pH) vs. a wider pH control band at 6.00/6.50 (∆pH = 0.50, wide-pH). These variations in pH also cause variations in the chemical speciation of ammonia and nitrite and, as shown, the microbial production of nitrite. It was hypothesized that the higher fluctuations would result in greater microbial diversity and, thus, a more robust process. The diversity of nitrifiers was higher in the wide-pH reactor, while the diversity of the entire microbiome was similar in both systems. However, the wide-pH reactor was more susceptible to tested process disturbances caused by increasing pH or temperature, decreasing dissolved oxygen, or an influent stop. In addition, with an emission factor of 0.47%, the nitrous oxide (N2O) emissions from the wide-pH reactor were twice as high as the N2O emissions from the narrow-pH reactor, most likely due to the nitrite fluctuations. Based on these results, a narrow control band is recommended for pH control in urine nitrification. |
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001087861500001 |
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2023-10-10 |
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2296-665x |
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UA library record; WoS full record; WoS citing articles |
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OpenAccess |
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Most recent IF: NA |
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UA @ admin @ c:irua:199585 |
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8909 |
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Schram, J.; Parrilla, M.; Slosse, A.; Van Durme, F.; Åberg, J.; Björk, K.; Bijvoets, S.M.; Sap, S.; Heerschop, M.W.J.; De Wael, K. |
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Paraformaldehyde-coated electrochemical sensor for improved on-site detection of amphetamine in street samples |
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A1 Journal article |
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2022 |
Publication |
Microchemical journal |
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179 |
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107518-107519 |
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A1 Journal article; Antwerp Electrochemical and Analytical Sciences Lab (A-Sense Lab) |
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The increasing illicit production, distribution and abuse of amphetamine (AMP) poses a challenge for law enforcement worldwide. To effectively combat this issue, fast and portable tools for the on-site screening of suspicious samples are required. Electrochemical profile (EP)-based sensing of illicit drugs has proven to be a viable option for this purpose as it allows rapid voltammetric measurements via the use of disposable and low-cost graphite screen-printed electrodes (SPEs). In this work, a highly practical paraformaldehyde (PFA)-coated sensor, which unlocks the detectability of primary amines through derivatization, is developed for the on-site detection of AMP in seized drug samples. A potential interval was defined at the sole AMP peak (which is used for identification of the target analyte) to account for potential shifts due to fluctuations in concentration and temperature, which are relevant factors for on-site use. Importantly, it was found that AMP detection was not hindered by the presence of common diluents and adulterants such as caffeine, even when present in high amounts. When inter-drug differentiation is desired, a simultaneous second test with the same solution on an unmodified electrode is introduced to provide the required additional electrochemical information. Finally, the concept was validated by analyzing 30 seized AMP samples (reaching a sensitivity of 96.7 %) and comparing its performance to that of commercially available Raman and Fourier Transform Infrared (FTIR) devices. |
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000809675500010 |
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2022-04-26 |
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0026-265x; 0026-265x |
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UA library record; WoS full record; WoS citing articles |
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UA @ admin @ c:irua:188454 |
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8910 |
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Friedrich, T. |
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Quantifying atomic structures using neural networks from 4D scanning transmission electron microscopy (STEM) datasets |
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Doctoral thesis |
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2023 |
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127 p. |
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Doctoral thesis; Electron microscopy for materials research (EMAT) |
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Nanoscience and nanotechnologies are of immense importance across many fields of science and for numerous practical applications. In this context, scanning transmission electron microscopy (STEM) and 4D-STEM are among the most powerful characterization methods at the atomic scale. Annular dark-field (ADF)-STEM can be used to quantify atomic structures in 3D by counting atoms based on a single projection image. In 4D-STEM a full diffraction pattern is recorded at each scan step, which enables more dose efficient imaging and the utilization of various advanced imaging modalities, which can however be complex and slow. Both, STEM and 4D-STEM suffer from noise and distortions. In the first section of this work the most important of these distortions are discussed and it is shown how image restoration with a dedicated convolutional neural network (CNN) can be beneficial for atomic structure quantifications in ADF-STEM. In the second part, a new 4D-STEM imaging method real-time-integrated-centre-of-mass (riCOM) is introduced, which is a very dose-efficient and fast algorithm that enables unprecedented live-imaging capabilities for 4D-STEM. It is based on the integrated centre-of-mass approach, but is reformulated with variable integration ranges and optional filters, which allows for a tunable contrast transfer function. This enables the imaging of light and heavy elements simultaneously at very low doses. In the third part another new 4D-STEM method, coined AIRPI (AI-assisted rapid phase imaging) is introduced, which uses a CNN to retrieve a patch of the specimen's phase image for each scan position, based on the diffraction patterns in the probe's immediate surroundings. This allows also live imaging in principle and surpasses comparable state-of-the-art algorithms in terms of resolution also at low doses. Different atomic columns can be reliably distinguished over a wide range of atomic numbers, enabling a very good image interpretability. Further, AIRPI can recover low frequency image components, which preserves thickness information. This is a unique and important feature which could make quantitative 4D-STEM feasible. |
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Most recent IF: NA |
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UA @ admin @ c:irua:196826 |
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8919 |
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Ortiz-Aguayo, D.; Ceto, X.; De Wael, K.; del Valle, M. |
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Resolution of opiate illicit drugs signals in the presence of some cutting agents with use of a voltammetric sensor array and machine learning strategies |
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A1 Journal article |
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2022 |
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Sensors and actuators : B : chemical |
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357 |
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131345 |
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A1 Journal article; Antwerp Electrochemical and Analytical Sciences Lab (A-Sense Lab) |
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In the present work, the resolution and quantification of mixtures of different opiate compounds in the presence of common cutting agents using an electronic tongue (ET) is evaluated. More specifically, ternary mixtures of heroin, morphine and codeine were resolved in the presence of caffeine and paracetamol. To this aim, an array of three carbon screen-printed electrodes were modified with different ink-like solutions of graphite, cobalt (II) phthalocyanine and palladium, and their responses towards the different drugs were characterized by means of square wave voltammetry (SWV). Developed sensors showed a good performance with good linearity at the mu M level, LODs between 1.8 and 5.3 mu M for the 3 actual drugs, and relative standard deviation (RSD) ca. 2% for over 50 consecutive measurements. Next, a quantitative model that allowed the identification and quantification of the individual substances from the overlapped voltammograms was built using partial least squares regression (PLS) as the modeling tool. With this approach, quantification of the different drugs was achieved at the mu M level, with a total normalized root mean square error (NRMSE) of 0.084 for the test subset. |
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000745113900003 |
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2021-12-31 |
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0925-4005 |
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UA @ admin @ c:irua:185446 |
Serial |
8922 |
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Zhang, K. |
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Revealing the correlation between titania support properties and propylphosphonic acid modification by in-depth characterization |
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Doctoral thesis |
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2023 |
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XVI, 262 p. |
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Doctoral thesis; Laboratory of adsorption and catalysis (LADCA) |
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Grafting organophosphonic acids modification (PAs) on metal oxides has shown to be a flexible technology to tune the surface properties of metal oxides for various applications. Nevertheless, there are still puzzles that need to be addressed, such as the correlations between metal oxides properties (types of surface reactive sites) and the modification (modification degree), the correlations between metal oxides properties and the properties of modified surfaces. Moreover, the currently used liquid-phase method for the grafting has associated impeding effects of solvent on tailoring the modification degrees, and also causes the formation of metal phosphonate side products. The solid-phase method can induce the unwanted changes in crystal phase of supports. Based on these questions, the three titania supports with divergent surface properties were selected as the metal oxides supports investigated, propylphosphonic acid (3PA) modification was carried out under the same synthesis conditions: four different concentrations, two solvents (water or toluene), and one reaction time (4 h) and temperature (90 ). MeOH chemisorption was introduced to probe the surface (un)reactive sites for 3PA modification. On the other hand, MeOH chemisorption and inverse gas chromatography (IGC) were combined to characterize the changes in surface polarity and acidic properties induced by the modification. Next, a solid-phase method, manual grinding, was proposed to graft 3PA on titania, avoiding the impeding effects of solvent on improving modification degree and the formation of the titania phosphonate side products, as well as preserving the crystal phase. The results indicate that methanol chemisorption can qualitatively analyze the surface active sites that are consumed by 3PA modification, its chemisorption capacity shows the consistent trend with the maximum modification degree, hereby revealing the kinds of interactions that are important in controlling surface coverage. Titania supports is found to play an important role in changes in surface polarity and acidic properties by charactering the three modified titania samples at a similar modification degree using the methanol chemisorption coupled with in-situ infrared and thermogravimetric-mass spectrometer, and the IGC. Moreover, IGC provides additional information about the changes in binding modes. Furthermore, grafting 3PA modification on titania was achieved by manual grinding. Compared to the liquid-phase method, the maximum modification degree obtained by the manual grinding is 25 % higher while using 83.3 % or 75.0% lower amounts of expensive 3PA and limiting the formation of titania phosphonate side products. Compared to the reactive milling method, the proposed manual grinding method preserves the crystal phase(s) of titania. |
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Most recent IF: NA |
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UA @ admin @ c:irua:198726 |
Serial |
8924 |
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Derks, K. |
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Scanning Michael Sweerts and Michaelina Wautier : uncovering the working methods of 17th-century Brussels artists by means of MA-XRF examination |
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Doctoral thesis |
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2023 |
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634 p. |
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Doctoral thesis; Art; Antwerp Cultural Heritage Sciences (ARCHES); Antwerp X-ray Imaging and Spectroscopy (AXIS) |
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This dissertation focuses on the materials and techniques used by the Brussels artists Michael Sweerts (1618-1664) and Michaelina Wautier (1614-1689). It tries to answer the following research questions: 1.Did 17th-century Brussels-based artists use idiosyncratic painting materials and techniques, and can their work be distinguished from paintings created in other artistic centers based on these materials and techniques? 2.How did Sweerts and Wautier influence each other’s work? In order to answer the research questions, a selection of relevant and representative paintings from Sweerts’ and Wautier’s oeuvre has been studied with MA-XRF scanning and microscopic examination. The results are discussed in volume 2 of this dissertation, and form the basis upon which the chapters in volume 1 are built. MA-XRF scanning is a non-destructive imaging technique based on the technique of X-ray fluorescence (XRF). The technique allows for the collection of elemental information about the materials present in a work of art. The work presented in this dissertation has shed more light on the working methods of Sweerts and Wautier. It has shown they both showed an openness and willingness to continue learning and developing as an artist. Wautier did not feel constrained to work only in one genre and apparently carried on developing her skills throughout her career, as evidenced by Flower Garland with Butterfly. She might have trained with a specialized artist to master their idiosyncratic working methods and this diverse genre. This suggests that Wautier had an interest in art education. Sweerts too had a passion for art education: he was involved in the drawing academy of Camillo Pamphilj in Rome, and later established his own academy for life drawing in Brussels. Sweerts’ work clearly shows the influence of his Italian contemporaries. Whilst living in Rome, he adapted his working methods to local customs such as working on brightly colored grounds. Wautier’s oeuvre shows that she was open to explore different genres and that she took inspiration from her contemporaries, including Theodoor van Loon and Daniël Seghers. In doing so, she furthered the development of different genres as she added original elements to her compositions. It is the conclusion of this dissertation that Michaelina Wautier can thus be considered one of the innovative artists of mid-17th-century Flemish painting, who inspired other artists in the Low Countries, including Michael Sweerts. |
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UA @ admin @ c:irua:197182 |
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8927 |
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Thiruvottriyur Shanmugam, S.; Trashin, S.; De Wael, K. |
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Singlet oxygen-based photoelectrochemical detection of DNA |
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A1 Journal article |
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2022 |
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Biosensors and bioelectronics |
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195 |
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113652 |
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A1 Journal article; Engineering sciences. Technology; Antwerp Electrochemical and Analytical Sciences Lab (A-Sense Lab) |
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The current work, designed for the photoelectrochemical detection of DNA, evaluates light-responsive DNA probes carrying molecular photosensitizers generating singlet oxygen (1O2). We take advantage of their chromophore’s ability to produce 1O2 upon photoexcitation and subsequent photocurrent response. Type I, fluorescent and type II photosensitizers were studied using diode lasers at 406 nm blue, 532 nm green and 659 nm red lasers in the presensce and absence of a redox reporter, hydroquinone (HQ). Only type II photosensitizers (producing 1O2) resulted in a noticeable photocurrent in 1–4 nA range upon illumination, in particular, dissolved DNA probes labeled with chlorin e6 and erythrosine were found to give a well-detectable photocurrent response in the presence of HQ. Whereas, Type I photosensitizers and fluorescent chromophores generate negligible photocurrents (<0.15 nA). The analytical performance of the sensing system was evaluated using a magnetic beads-based DNA assay on disposable electrode platforms, with a focus to enhance the sensitivity and robustness of the technique in detecting complementary DNA targets. Amplified photocurrent responses in the range of 70–100 nA were obtained and detection limits of 17 pM and 10 pM were achieved using magnetic beads-captured chlorin e6 and erythrosine labeled DNA probes respectively. The presented novel photoelectrochemical detection can further be optimized and employed in applications for which enzymatic amplification such as polymerase chain reaction (PCR) is not applicable owing to their limitations and as an effective alternative to colorimetric detection when rapid detection of specific nucleic acid targets is required. |
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000705223300003 |
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2021-09-23 |
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UA @ admin @ c:irua:181796 |
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8930 |
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Thiruvottriyur Shanmugam, S. |
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Title |
Singlet oxygen-based photoelectrochemical detection of nucleic acids |
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Doctoral thesis |
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2022 |
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217 p. |
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Doctoral thesis; Engineering sciences. Technology; Antwerp Electrochemical and Analytical Sciences Lab (A-Sense Lab) |
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MicroRNAs (miRNAs) are small oligonucleotides (18-25 bases) that play a key role in epigenetic regulation. Since the discovery of miRNAs in 1993, their role in biological processes has been extensively investigated. By now, it has been evidenced that monitoring and detection of miRNAs can improve (early) disease diagnosis. The existing diagnostic approaches have limitations such as the need for complex multistep protocols for sample preparation, analysis, data interpretation, high cost of equipment, the need for highly qualified personnel, and high laboratory standards. As opposed to this, point-of-care biosensors and chips aim to facilitate the procedure and avoid sending samples into centralized laboratories, which saves time, reduces the chance of sample degradation, and enables analysis of patient samples in remote areas, directly at home or primary and secondary care facilities (i.e. general practitioners and specialists). The latter is essential for therapy assessment and follow-up monitoring of patients with chronic diseases and cancer. Nevertheless, the development of such sensors is lagging compared to the projections of 10 – 20 years ago, mainly due to insufficient sensitivity, poor reproducibility, and the complexity of the sensors’ design reported in the research literature. This motivates the development of new detection strategies and technologies such as photoelectrochemical sensors that combine the best features of different sensing approaches. The primary concern when developing detection technologies for miRNA is the need for a highly sensitive and selective platform. This thesis explores a novel photoelectrochemical (PEC) method that is distinctive owing to its sensitive nature and simple and robust design. Firstly, we focused on the usage of recently emerging commercial gold-sputtered electrode systems for the detection of short nucleic acid with enzymatic amplification. Importantly, cleaning such electrodes is a challenge since the standard procedures known for regular disk electrodes such as polishing cannot be employed here, since it will damage the protective layer on the electrode. However, the electrodes can be washed and pretreated chemically and/or electrochemically. Thus, a procedure to effectively clean and modify the gold-sputtered electrode has been developed, resulting in high-performance gold-sputtered nucleic acid sensors. Next, the usage of molecular photosensitizers as an alternative to enzymatic amplification has been evaluated. We took advantage of the singlet oxygen production by photosensitizers upon photoexcitation, leading to a photocurrent response due to the singlet oxygen-induced (electro)chemical conversions. Following the demonstration of the detection strategy, the analytical performance of the sensing system was evaluated using magnetic beads-based nucleic acid assay on disposable electrode platforms, with a focus to enhance the sensitivity and robustness of the technique in detecting complementary nucleic acid targets. Following the fundamental evaluation of the singlet oxygen-based PEC detection of nucleic acids, we further optimized the assay and measurement parameters and employed the sensing strategy for a polymerase chain reaction-free (PCR-free) quantification of miRNAs related to prostate cancer. By successfully detecting and quantifying low-picomolar range concentrations (< 10 pM) in plasma samples from prostate cancer patients, we successfully showed the applicability of the novel sensing strategy. We have also compared and positioned the performance of our developed PEC strategy with an existing state-of-art technique, i.e. electrochemiluminescence (ECL). Our PEC strategy performed on par with ECL, both yielding low-picomolar detection limits in serum matrices, however quicker and cheaper than ECL. Owing to the versatility of this PEC technique, the final study explored its multiplexing capability. As a starting point in this branch of the research, we have investigated two possible ways for multiplexing. To perform multiple measurements at the same time, constructing calibration plots and quantifying unknown miRNA concentrations in patient samples at the same time, we have developed a high-throughput detection with 96X multi-channel electrode systems and in-house designed and constructed 96XLED illumination sources. Secondly, to detect more than one target miRNA in a single measurement, intra-vial multiplexing where the samples were analyzed for different targets in one vial was also explored. Altogether, this thesis presents the fundamentals, development and application of a novel PEC strategy for detecting short (< 25 bases) nucleic acid sequences, in particular, miRNA. With an aim to serve as a distinctive technique to function as a clinical testing platform without any need for PCR, this work adds value to the development of nucleic acid-based sensors for miRNAs and other short-stranded nucleic acid biomarkers, and benefits in the early detection of diseases like cancer. |
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UA @ admin @ c:irua:191753 |
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8931 |
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