| Records |
| Author |
Vermeulen, M.; Janssens, K.; Sanyova, J.; Rahemi, V.; McGlinchey, C.; De Wael, K. |
| Title |
Assessing the stability of arsenic sulfide pigments and influence of the binding media on their degradation by means of spectroscopic and electrochemical techniques |
Type |
A1 Journal article |
| Year |
2018 |
Publication |
Microchemical journal |
Abbreviated Journal |
Microchem J |
| Volume |
138 |
Issue |
138 |
Pages |
82-91 |
| Keywords |
A1 Journal article; AXES (Antwerp X-ray Analysis, Electrochemistry and Speciation) |
| Abstract |
In this paper, we used the semiconducting and lightfastness properties of synthetic and mineral arsenic sulfide pigments to study their stability by means of electrochemical and microfadometric techniques. A combination of these techniques shows that in the early stage of the degradation process, amorphous arsenic sulfides are more stable than both crystalline forms, while upon longer exposure time, amorphous pigments will fade more than both mineral pigments, making it less suitable. While the stability study was carried out on unbound pigments, the influence of the organic binder on the relative degradation of the arsenic sulfide pigments was investigated through a multi-analytical approach on pigment/binder mock-up paint samples. For this purpose, the formation of arsenic trioxide was assessed by micro Fourier transform infrared (μ-FTIR) spectroscopy while the influence of the binder on the formation of sulfates was studied by means of synchrotron radiation X-ray near edge structure (μ-XANES). Both techniques elucidate a higher stability of all pigments in gum arabic while the use of egg yolk as binder leads to the most degradation, most likely due to its sulfur-rich composition. In the context of the degradation of arsenic sulfide pigments, other binders such as animal glue, egg white or linseed oil show an intermediate impact. |
| Address |
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| Corporate Author |
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Thesis |
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| Publisher |
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Place of Publication |
|
Editor |
|
| Language |
|
Wos |
000428103000010 |
Publication Date |
2018-01-06 |
| Series Editor |
|
Series Title |
|
Abbreviated Series Title |
|
| Series Volume |
|
Series Issue |
|
Edition |
|
| ISSN |
0026-265x; 0026-265x |
ISBN |
|
Additional Links |
UA library record; WoS full record; WoS citing articles |
| Impact Factor |
3.034 |
Times cited |
4 |
Open Access |
|
| Notes |
; This research is made possible with the support of the Belgian Science Policy Office (BELSPO, Brussels) through the research program Science for a Sustainable Development – SDD, “Long-term role and fate of metal-sulfides in painted works of art – S2ART” (grant number SD/RI/04A). We gratefully acknowledge Megane Willems (Institut Paul-Lambin) for her help with mu-FFIR analyses and realization of the mock-up paint samples. We acknowledge the Paul Scherrer Institut, Villigen, Switzerland for provision of synchrotron radiation beamtime at beamline Phoenix of the SLS. ; |
Approved |
Most recent IF: 3.034 |
| Call Number |
UA @ admin @ c:irua:150149 |
Serial  |
5482 |
| Permanent link to this record |
| |
|
| |
| Author |
Pilehvar, S.; Mehta, J.; Dardenne, F.; Robbens, J.; Blust, R.; De Wael, K. |
| Title |
Aptasensing of chloramphenicol in the presence of its analogues : reaching the maximum residue limit |
Type |
A1 Journal article |
| Year |
2012 |
Publication |
Analytical chemistry |
Abbreviated Journal |
Anal Chem |
| Volume |
84 |
Issue |
15 |
Pages |
6753-6758 |
| Keywords |
A1 Journal article; AXES (Antwerp X-ray Analysis, Electrochemistry and Speciation) |
| Abstract |
A novel label-free folding induced aptamer-based electrochemical biosensor for the detection of chloramphenicol (CAP) in the presence of its analogues has been developed. CAP is a broad-spectrum antibiotic which has lost its favor due to its serious adverse toxic effects on human health. Aptamers are artificial nucleic acid ligands (ssDNA or RNA) able to specifically recognize a target such as CAP. In this article, the aptamers are fixed onto a gold electrode surface by a self-assembly approach. In the presence of CAP, the unfolded ssDNA on the electrode surface changes to a hairpin structure bringing the target molecules close to the surface and trigger electron transfer. Detection limits were determined to be 1.6×10-9 mol L-1. In addition, thiamphenicol (TAP) and florfenicol (FF), antibiotics with a similar structure to CAP, did not influence the performance of the aptasensor, suggesting a good selectivity of the CAP-aptasensor. Simplicity and lower detection limit (because of the home-selected aptamers) make that the electrochemical aptasensor is suitable for practical use in the detection of CAP in milk samples. |
| Address |
|
| Corporate Author |
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Thesis |
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| Publisher |
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Place of Publication |
|
Editor |
|
| Language |
|
Wos |
000307159200069 |
Publication Date |
2012-06-20 |
| Series Editor |
|
Series Title |
|
Abbreviated Series Title |
|
| Series Volume |
|
Series Issue |
|
Edition |
|
| ISSN |
0003-2700; 5206-882x |
ISBN |
|
Additional Links |
UA library record; WoS full record; WoS citing articles |
| Impact Factor |
6.32 |
Times cited |
68 |
Open Access |
|
| Notes |
; ; |
Approved |
Most recent IF: 6.32; 2012 IF: 5.695 |
| Call Number |
UA @ admin @ c:irua:98816 |
Serial |
5477 |
| Permanent link to this record |
| |
|
| |
| Author |
Cuypers, B.; Vermeylen, S.; Hammerschmid, D.; Trashin, S.; Rahemi, V.; Konijnenberg, A.; De Schutter, A.; Cheng, C.-H.C.; Giordano, D.; Verde, C.; De Wael, K.; Sobott, F.; Dewilde, S.; Van Doorslaer, S. |
| Title |
Antarctic fish versus human cytoglobins : the same but yet so different |
Type |
A1 Journal article |
| Year |
2017 |
Publication |
Journal of inorganic biochemistry |
Abbreviated Journal |
J Inorg Biochem |
| Volume |
173 |
Issue |
|
Pages |
66-78 |
| Keywords |
A1 Journal article; AXES (Antwerp X-ray Analysis, Electrochemistry and Speciation) |
| Abstract |
The cytoglobins of the Antarctic fish Chaenocephalus aceratus and Dissostichus mawsoni have many features in common with human cytoglobin. These cytoglobins are heme proteins in which the ferric and ferrous forms have a characteristic hexacoordination of the heme iron, i.e. axial ligation of two endogenous histidine residues, as confirmed by electron paramagnetic resonance, resonance Raman and optical absorption spectroscopy. The combined spectroscopic analysis revealed only small variations in the heme-pocket structure, in line with the small variations observed for the redox potential. Nevertheless, some striking differences were also discovered. Resonance Raman spectroscopy showed that the stabilization of an exogenous heme ligand, such as CO, occurs differently in human cytoglobin in comparison with Antarctic fish cytoglobins. Furthermore, while it has been extensively reported that human cytoglobin is essentially monomeric and can form an intramolecular disulfide bridge that can influence the ligand binding kinetics, 3D modeling of the Antarctic fish cytoglobins indicates that the cysteine residues are too far apart to form such an intramolecular bridge. Moreover, gel filtration and mass spectrometry reveal the occurrence of non-covalent multimers (up to pentamers) in the Antarctic fish cytoglobins that are formed at low concentrations. Stabilization of these oligomers by disulfide-bridge formation is possible, but not essential. If intermolecular disulfide bridges are formed, they influence the heme-pocket structure, as is shown by EPR measurements. |
| Address |
|
| Corporate Author |
|
Thesis |
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| Publisher |
|
Place of Publication |
|
Editor |
|
| Language |
|
Wos |
000405159600007 |
Publication Date |
2017-04-28 |
| Series Editor |
|
Series Title |
|
Abbreviated Series Title |
|
| Series Volume |
|
Series Issue |
|
Edition |
|
| ISSN |
0162-0134 |
ISBN |
|
Additional Links |
UA library record; WoS full record; WoS citing articles |
| Impact Factor |
3.348 |
Times cited |
7 |
Open Access |
|
| Notes |
; The authors acknowledge the support of the University of Antwerp GOA-BOF funding (28312), FWO funding (G.0687.13) and the Hercules foundation for funding of the Synapt G2 instrument. This study was carried out in the framework of the SCAR program “Antarctic Thresholds – Ecosystem Resilience and Adaptation” (AnT-ERA). It was financially supported by the Italian National Program for Antarctic Research (PNRA). Research of A. De Schutter is funded by a PhD grant of the Agency for Innovation by Science and Technology (121339) (IWT, Belgium). C-H C. Cheng acknowledges funding support from US National Science Foundation Polar Programs (ANT-1142158). ; |
Approved |
Most recent IF: 3.348 |
| Call Number |
UA @ admin @ c:irua:144826 |
Serial |
5474 |
| Permanent link to this record |
| |
|
| |
| Author |
Hamidi-Asl, E.; Dardenne, F.; Blust, R.; De Wael, K. |
| Title |
An improved electrochemical aptasensor for chloramphenicol detection based on aptamer incorporated gelatine |
Type |
A1 Journal article |
| Year |
2015 |
Publication |
Sensors |
Abbreviated Journal |
Sensors-Basel |
| Volume |
15 |
Issue |
4 |
Pages |
7605-7618 |
| Keywords |
A1 Journal article; AXES (Antwerp X-ray Analysis, Electrochemistry and Speciation) |
| Abstract |
Because of the biocompatible properties of gelatine and the good affinity of aptamers for their targets, the combination of aptamer and gelatine type B is reported as promising for the development of biosensing devices. Here, an aptamer for chloramphenicol (CAP) is mixed with different types of gelatine and dropped on the surface of disposable gold screen printed electrodes. The signal of the CAP reduction is investigated using differential pulse voltammetry. The diagnostic performance of the sensor is described and a detection limit of 1.83 x 10(-10) M is found. The selectivity and the stability of the aptasensor are studied and compared to those of other CAP sensors described in literature. |
| Address |
|
| Corporate Author |
|
Thesis |
|
| Publisher |
|
Place of Publication |
|
Editor |
|
| Language |
|
Wos |
000354236100025 |
Publication Date |
2015-03-27 |
| Series Editor |
|
Series Title |
|
Abbreviated Series Title |
|
| Series Volume |
|
Series Issue |
|
Edition |
|
| ISSN |
1424-8220 |
ISBN |
|
Additional Links |
UA library record; WoS full record; WoS citing articles |
| Impact Factor |
2.677 |
Times cited |
21 |
Open Access |
|
| Notes |
; Ezat Hamidi-Asl was financially supported by IOF-POC (University of Antwerp). ; |
Approved |
Most recent IF: 2.677; 2015 IF: 2.245 |
| Call Number |
UA @ admin @ c:irua:126071 |
Serial |
5464 |
| Permanent link to this record |
| |
|
| |
| Author |
Rahemi, V.; Trashin, S.; Hafideddine, Z.; Van Doorslaer, S.; Meynen, V.; Gorton, L.; De Wael, K. |
| Title |
Amperometric flow-injection analysis of phenols induced by reactive oxygen species generated under daylight irradiation of titania impregnated with horseradish peroxidase |
Type |
A1 Journal article |
| Year |
2020 |
Publication |
Analytical Chemistry |
Abbreviated Journal |
Anal Chem |
| Volume |
92 |
Issue |
92 |
Pages |
3643-3649 |
| Keywords |
A1 Journal article; Laboratory of adsorption and catalysis (LADCA); AXES (Antwerp X-ray Analysis, Electrochemistry and Speciation) |
| Abstract |
Titanium dioxide (TiO2) is a unique material for biosensing applications due to its capability of hosting enzymes. For the first time, we show that TiO2 can accumulate reactive oxygen species (ROS) under daylight irradiation and can support the catalytic cycle of horseradish peroxidase (HRP) without the need of H2O2 to be present in the solution. Phenolic compounds, such as hydroquinone (HQ) and 4-aminophenol (4-AP), were detected amperometrically in flow-injection analysis (FIA) mode via the use of an electrode modified with TiO2 impregnated with HRP. In contrast to the conventional detection scheme, no H2O2 was added to the analyte solution. Basically, the inherited ability of TiO2 to generate reactive oxygen species is used as a strategy to avoid adding H2O2 in the solution during the detection of phenolic compounds. Electron paramagnetic resonance (EPR) spectroscopy indicates the presence of ROS on titania which, in interaction with HRP, initiate the electrocatalysis toward phenolic compounds. The amperometric response to 4-AP was linear in the concentration range between 0.05 and 2 μM. The sensitivity was 0.51 A M–1 cm–2, and the limit of detection (LOD) 26 nM. The proposed sensor design opens new opportunities for the detection of phenolic traces by HRP-based electrochemical biosensors, yet in a more straightforward and sensitive way following green chemistry principles of avoiding the use of reactive and harmful chemical, such as H2O2. |
| Address |
|
| Corporate Author |
|
Thesis |
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| Publisher |
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Place of Publication |
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Editor |
|
| Language |
|
Wos |
000518234700023 |
Publication Date |
2020-01-27 |
| Series Editor |
|
Series Title |
|
Abbreviated Series Title |
|
| Series Volume |
|
Series Issue |
|
Edition |
|
| ISSN |
0003-2700; 5206-882x |
ISBN |
|
Additional Links |
UA library record; WoS full record; WoS citing articles |
| Impact Factor |
7.4 |
Times cited |
3 |
Open Access |
|
| Notes |
; The authors thank Scientific Reseatch-Flanders (F-WO) (grant 12T4219N) for funding. ; |
Approved |
Most recent IF: 7.4; 2020 IF: 6.32 |
| Call Number |
UA @ admin @ c:irua:166241 |
Serial |
5463 |
| Permanent link to this record |
| |
|
| |
| Author |
Krupińska, B.; Van Grieken, R.; De Wael, K. |
| Title |
Air quality monitoring in a museum for preventive conservation : results of a three-year study in the Plantin-Moretus Museum in Antwerp, Belgium |
Type |
A1 Journal article |
| Year |
2013 |
Publication |
Microchemical journal |
Abbreviated Journal |
Microchem J |
| Volume |
110 |
Issue |
|
Pages |
350-360 |
| Keywords |
A1 Journal article; AXES (Antwerp X-ray Analysis, Electrochemistry and Speciation) |
| Abstract |
Through different research projects on air quality in museums, researcher and conservators try identifying various risks of air pollution on materials. The conclusions may be later translated into specific actions for a maximum preservation of the museum collections, a process known as preventive conservation. Air pollution is a particular problem in historical buildings such as museums, because they were not originally built to exhibit and protect art objects in a sustainable way. This article reports on the data and results that were obtained during 10 sampling campaigns, in the period between November 2008 and February 2012 in a museum in Antwerp (Belgium), i.e. Plantin-Moretus Museum/Print Room. Different pollutants were measured inside and outside the museum such as inorganic gases, particulate matter and black carbon. The report specifically addresses environmental factors that may be responsible for damage to the collections present in museums. Thanks to the knowledge about the current situation in the museum, accurate solutions regarding preventive conservation, in general, are suggested. |
| Address |
|
| Corporate Author |
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Thesis |
|
| Publisher |
|
Place of Publication |
|
Editor |
|
| Language |
|
Wos |
000326851200051 |
Publication Date |
2013-05-21 |
| Series Editor |
|
Series Title |
|
Abbreviated Series Title |
|
| Series Volume |
|
Series Issue |
|
Edition |
|
| ISSN |
0026-265x; 0026-265x |
ISBN |
|
Additional Links |
UA library record; WoS full record; WoS citing articles |
| Impact Factor |
3.034 |
Times cited |
46 |
Open Access |
|
| Notes |
; The presented work was realised in the frame of the project Preventive conservation/preservation in the museum Plantin-Moretus/Prentenkabinet, Antwerp, financed by the Flemish Government. Special thanks are due to Mrs Hanne Moris and Mrs Elke van Herck and all the staff of the Museum Plantin-Moretus/Print Room in Antwerp for their sincere interest in this work and their eager assistance during all the sampling campaigns. VMM and Dr. Edward Roekens is acknowledged for sharing the black carbon measurements. Barbara Krupinska is supported as PhD student by the Flemish Fund for Scientific Research (FWO, Belgium). ; |
Approved |
Most recent IF: 3.034; 2013 IF: 3.583 |
| Call Number |
UA @ admin @ c:irua:108402 |
Serial |
5460 |
| Permanent link to this record |
| |
|
| |
| Author |
Rahemi, V.; Trashin, S.; Meynen, V.; De Wael, K. |
| Title |
An adhesive conducting electrode material based on commercial mesoporous titanium dioxide as a support for Horseradish peroxidase for bioelectrochemical applications |
Type |
A1 Journal article |
| Year |
2016 |
Publication |
Talanta : the international journal of pure and applied analytical chemistry |
Abbreviated Journal |
Talanta |
| Volume |
146 |
Issue |
|
Pages |
689-693 |
| Keywords |
A1 Journal article; Laboratory of adsorption and catalysis (LADCA); AXES (Antwerp X-ray Analysis, Electrochemistry and Speciation) |
| Abstract |
An adhesive conducting electrode material containing of graphite, biocompatible ion exchange polymer nafion® and commercial mesoporous TiO2 impregnated with horseradish peroxidase (HRP) is prepared and characterized by amperometric, UVvis and N2 sorption methods. The factors influencing the performance of the resulting biosensor are studied in detail. The optimal electrode material consists of 45% graphite, 50% impregnated HRPTiO2 and 5% nafion®. The optimum conditions for H2O2 reduction are an applied potential of 0.3 V and 0.1 mM hydroquinone. Sensitivity and limit of detection in the optimum conditions are 1 A M−1 cm−2 and 1 µM correspondingly. The N2 sorption results show that the pore volume of TiO2 decreases sharply upon adsorption of HRP. The preparation process of the proposed enzyme electrode is straightforward and potentially can be used for preparation of carbon paste electrodes for bioelectrochemical detections. |
| Address |
|
| Corporate Author |
|
Thesis |
|
| Publisher |
|
Place of Publication |
|
Editor |
|
| Language |
|
Wos |
000363815600093 |
Publication Date |
2015-06-24 |
| Series Editor |
|
Series Title |
|
Abbreviated Series Title |
|
| Series Volume |
|
Series Issue |
|
Edition |
|
| ISSN |
0039-9140; 1873-3573 |
ISBN |
|
Additional Links |
UA library record; WoS full record; WoS citing articles |
| Impact Factor |
4.162 |
Times cited |
7 |
Open Access |
|
| Notes |
; The authors thank the Fund for Scientific Research – Flanders (FWO) (Grant G.0687.13), the GOA-BOF UA 2013-2016 (project-ID 28312) for funding and Ward Huybrechts of the University of Antwerp, Laboratory of Adsorption and Catalysis (LADCA) for help with the N<INF>2</INF> sorption. ; |
Approved |
Most recent IF: 4.162 |
| Call Number |
UA @ admin @ c:irua:126495 |
Serial |
5458 |
| Permanent link to this record |
| |
|
| |
| Author |
Wuyts, K.; Hofman, J.; van Wittenberghe, S.; Nuyts, G.; De Wael, K.; Samson, R. |
| Title |
A new opportunity for biomagnetic monitoring of particulate pollution in an urban environment using tree branches |
Type |
A1 Journal article |
| Year |
2018 |
Publication |
Atmospheric environment : an international journal |
Abbreviated Journal |
Atmos Environ |
| Volume |
190 |
Issue |
190 |
Pages |
177-187 |
| Keywords |
A1 Journal article; AXES (Antwerp X-ray Analysis, Electrochemistry and Speciation) |
| Abstract |
Environmental magnetism, and the magnetic leaf signal in particular, is amply investigated and applied as proxy for atmospheric particulate matter pollution. In this study, we investigated the magnetic signal of annual segments of tree branches, and the composition of particles deposited hereon. Branches are, contrary to leaves of deciduous trees, available during leaf-off seasons and exposed to air pollution year-round. We examined the intra- and inter-tree variation in saturation isothermal remanent magnetization (SIRM) of branch internodes of London plane (Platanus x aeerifolia Willd.) trees in an urban environment. The branch SIRM, normalized by surface area, ranged from 18 to 650 x 10(-6) angstrom; the median amounted to 106 x 10(-6) angstrom. Most of the branch magnetic signal was attributed to the epidermis or bark, and the presence of metal-containing particles on the branch surfaces was confirmed by SEM-EDX. The location of the trees and the height, the depth in the crown and the age of the branches significantly influenced the branch SIRM. The median branch SIRM was up to 135% higher near a busy ring road than in quiet environments (city park and quiet street canyon), and was linked to the presence of Fe-rich particles with co-occurrence of trace metals such as Cr, Cu, Zn and Mn on the branch surface. Within the tree crowns, the branch SIRM generally decreased with increasing height, and was 22% higher in the interior than at the periphery of the crowns. Within the branches, the SIRM increased with each year of exposure, but did not relate to year-to-year variation in particle concentrations due to branch surface changes (epidermis shedding). Our results provide indications that branches can be a valuable alternative for biomagnetic monitoring of particulate pollution, but intra-tree variability in branch SIRM can be substantial due to the branch's location in the tree and branch age. |
| Address |
|
| Corporate Author |
|
Thesis |
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| Publisher |
|
Place of Publication |
|
Editor |
|
| Language |
|
Wos |
000444659400017 |
Publication Date |
2018-07-11 |
| Series Editor |
|
Series Title |
|
Abbreviated Series Title |
|
| Series Volume |
|
Series Issue |
|
Edition |
|
| ISSN |
1352-2310 |
ISBN |
|
Additional Links |
UA library record; WoS full record; WoS citing articles |
| Impact Factor |
3.629 |
Times cited |
3 |
Open Access |
|
| Notes |
; We would like to thank the city council services of the city of Antwerp for their logistical support. We are grateful to Ana Castanheiro and Leen Van Ham for laboratory and SEM assistance. JH is supported as postdoctoral fellow of the Research Foundation Flanders (FWO; 12I4816N) and SVW is supported by a Marie Sklodowska-Curie Individual Fellowship under the grant agreement no 701815 FLUOPHOT. ; |
Approved |
Most recent IF: 3.629 |
| Call Number |
UA @ admin @ c:irua:153607 |
Serial |
5454 |
| Permanent link to this record |
| |
|
| |
| Author |
Meysman, F.J.R.; Cornelissen, R.; Trashin, S.; Bonne, R.; Hidalgo-Martinez, S.; van der Veen, J.; Blom, C.J.; Karman, C.; Hou, J.-L.; Eachambadi, R.T.; Geelhoed, J.S.; De Wael, K.; Beaumont, H.J.E.; Cleuren, B.; Valcke, R.; van der Zant, H.S.J.; Boschker, H.T.S.; Manca, J.V. |
| Title |
A highly conductive fibre network enables centimetre-scale electron transport in multicellular cable bacteria |
Type |
A1 Journal article |
| Year |
2019 |
Publication |
Nature communications |
Abbreviated Journal |
Nat Commun |
| Volume |
10 |
Issue |
10 |
Pages |
4120 |
| Keywords |
A1 Journal article; Engineering sciences. Technology; AXES (Antwerp X-ray Analysis, Electrochemistry and Speciation) |
| Abstract |
Biological electron transport is classically thought to occur over nanometre distances, yet recent studies suggest that electrical currents can run along centimetre-long cable bacteria. The phenomenon remains elusive, however, as currents have not been directly measured, nor have the conductive structures been identified. Here we demonstrate that cable bacteria conduct electrons over centimetre distances via highly conductive fibres embedded in the cell envelope. Direct electrode measurements reveal nanoampere currents in intact filaments up to 10.1 mm long (>2000 adjacent cells). A network of parallel periplasmic fibres displays a high conductivity (up to 79 S cm(-1)), explaining currents measured through intact filaments. Conductance rapidly declines upon exposure to air, but remains stable under vacuum, demonstrating that charge transfer is electronic rather than ionic. Our finding of a biological structure that efficiently guides electrical currents over long distances greatly expands the paradigm of biological charge transport and could enable new bio-electronic applications. |
| Address |
|
| Corporate Author |
|
Thesis |
|
| Publisher |
|
Place of Publication |
|
Editor |
|
| Language |
|
Wos |
000485216900006 |
Publication Date |
2019-09-11 |
| Series Editor |
|
Series Title |
|
Abbreviated Series Title |
|
| Series Volume |
|
Series Issue |
|
Edition |
|
| ISSN |
2041-1723 |
ISBN |
|
Additional Links |
UA library record; WoS full record; WoS citing articles |
| Impact Factor |
12.124 |
Times cited |
10 |
Open Access |
|
| Notes |
; This research was financially supported by the European Research Council under the European Union's Seventh Framework Programme (FP/2007-2013) through ERC Grant 306933 (F.J.R.M.), the Research Foundation Flanders (FWO project grant G031416N), and the Netherlands Organisation for Scientific Research (VICI grant 016.VICI.170.072 to F.J.R.M.). H.J.E.B., C.J.B. and H.S.J.Z. were supported by the Netherlands Organisation for Scientific Research (NWO/OCW), as part of the Frontiers of Nanoscience program. R.B. is supported by an 'aspirant' grant from Research Foundation Flanders (FWO). We thank Laurine Burdorf (UAntwerpen) for help with Thiothrix cultivation, Marlies Nijemeisland (Faculty of Aerospace, TU Delft) for assistance with Raman microscopy, and Jan D'Haen (UHasselt) and Renaat Dasseville (UGent) for help with EM imaging. ; |
Approved |
Most recent IF: 12.124 |
| Call Number |
UA @ admin @ c:irua:162795 |
Serial |
5451 |
| Permanent link to this record |
| |
|
| |
| Author |
Rahemi, V.; Sarmadian, N.; Anaf, W.; Janssens, K.; Lamoen, D.; Partoens, B.; De Wael, K. |
| Title |
Unique opto-electronic structure and photo reduction properties of sulfur doped lead chromates explaining their instability in paintings |
Type |
A1 Journal article |
| Year |
2017 |
Publication |
Analytical chemistry |
Abbreviated Journal |
Anal Chem |
| Volume |
89 |
Issue |
89 |
Pages |
3326-3334 |
| Keywords |
A1 Journal article; Electron microscopy for materials research (EMAT); Condensed Matter Theory (CMT); AXES (Antwerp X-ray Analysis, Electrochemistry and Speciation) |
| Abstract |
Chrome yellow refers to a group of synthetic inorganic pigments that became popular as an artists material from the second quarter of the 19th century. The color of the pigment, in which the chromate ion acts as a chromophore, is related to its chemical composition (PbCr1-xSxO4, with 0≤x≤0.8) and crystalline structure (monoclinic/orthorhombic). Their shades range from the yellow-orange to the paler yellow tones with increasing sulfate amount. These pigments show remarkable signs of degradation after limited time periods. Pure PbCrO4 (crocoite in its natural form) has a deep yellow color and is relatively stable, while the co-precipitate with lead sulfate (PbCr1-xSxO4) has a paler shade and seems to degrade faster. This degradation is assumed to be related to the reduction of Cr(VI) to Cr(III). We show that on increasing the sulfur(S)-content in chrome yellow, the band gap increases. Typically, when increasing the band gap, one might assume that a decrease in photo activity is the result. However, the photo activity relative to the Cr content, and thus Cr reduction, of sulfur-rich PbCr1-xSxO4 is found to be much higher compared to the sulfur-poor or non-doped lead chromates. This discrepancy can be explained by the evolution of the crystal and electronic structure as function of the sulfur content: first-principles density functional theory calculations show that both the absorption coefficient and reflection coefficients of the lead chromates change as a result of the sulfate doping in such a way that the generation of electron-hole pairs under illumination relative to the total Cr content increases. These changes in the material properties explain why paler shade yellow colors of this pigment are more prone to discoloration. The electronic structure calculations also demonstrate that lead chromate and its co-precipitates are p-type semiconductors, which explains the observed reduction reaction. As understanding this phenomenon is valuable in the field of cultural heritage, this study is the first joint action of photo-electrochemical measurements and first-principles calculations to approve the higher tendency of sulfur-rich lead chromates to darken. |
| Address |
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| Corporate Author |
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Thesis |
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| Publisher |
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Place of Publication |
Washington, D.C. |
Editor |
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| Language |
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Wos |
000397478300015 |
Publication Date |
2017-02-23 |
| 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 |
0003-2700 |
ISBN |
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Additional Links |
UA library record; WoS full record; WoS citing articles |
| Impact Factor |
6.32 |
Times cited |
7 |
Open Access |
OpenAccess |
| Notes |
; The computational resources and services used in this work were provided by the VSC (Flemish Supercomputer Center) and the HPC infrastructure of the University of Antwerp (CalcUA), both funded by the Hercules Foundation and the Flemish Government, department EWI. The BOF-GOA action SOLARPAINT of the University of Antwerp Research Council is acknowledged for financial support. W.A. acknowledges support from BELSPO project S2-ART. Dr. L. Monico and Dr. C. Miliani (ISTM, Perugia) are gratefully acknowledged for helpful discussions and for providing some of the initial batches of the materials studied. ; |
Approved |
Most recent IF: 6.32 |
| Call Number |
UA @ lucian @ c:irua:140886 |
Serial |
4451 |
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| Author |
Janssens, K.; van der Snickt, G.; Vanmeert, F.; Legrand, S.; Nuyts, G.; Alfeld, M.; Monico, L.; Anaf, W.; de Nolf, W.; Vermeulen, M.; Verbeeck, J.; De Wael, K. |
| Title |
Non-invasive and non-destructive examination of artistic pigments, paints, and paintings by means of X-Ray methods |
Type |
A1 Journal article |
| Year |
2016 |
Publication |
Topics in Current Chemistry |
Abbreviated Journal |
Topics Curr Chem |
| Volume |
374 |
Issue |
374 |
Pages |
81 |
| Keywords |
A1 Journal article; Electron microscopy for materials research (EMAT); AXES (Antwerp X-ray Analysis, Electrochemistry and Speciation) |
| Abstract |
Recent studies are concisely reviewed, in which X-ray beams of (sub)micrometre to millimetre dimensions have been used for non-destructive analysis and characterization of pigments, minute paint samples, and/or entire paintings from the seventeenth to the early twentieth century painters. The overview presented encompasses the use of laboratory and synchrotron radiation-based instrumentation and deals with the use of several variants of X-ray fluorescence (XRF) as a method of elemental analysis and imaging, as well as with the combined use of X-ray diffraction (XRD) and X-ray absorption spectroscopy (XAS). Microscopic XRF is a variant of the method that is well suited to visualize the elemental distribution of key elements, mostly metals, present in paint multi-layers, on the length scale from 1 to 100 μm inside micro-samples taken from paintings. In the context of the characterization of artists pigments subjected to natural degradation, the use of methods limited to elemental analysis or imaging usually is not sufficient to elucidate the chemical transformations that have taken place. However, at synchrotron facilities, combinations of μ-XRF with related methods such as μ-XAS and μ-XRD have proven themselves to be very suitable for such studies. Their use is often combined with microscopic Fourier transform infra-red spectroscopy and/or Raman microscopy since these methods deliver complementary information of high molecular specificity at more or less the same length scale as the X-ray microprobe techniques. Since microscopic investigation of a relatively limited number of minute paint samples, taken from a given work of art, may not yield representative information about the entire artefact, several methods for macroscopic, non-invasive imaging have recently been developed. Those based on XRF scanning and full-field hyperspectral imaging appear very promising; some recent published results are discussed. |
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Thesis |
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| Publisher |
Springer international publishing ag |
Place of Publication |
Cham |
Editor |
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| Language |
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Wos |
000391178900006 |
Publication Date |
2016-11-21 |
| 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 |
2365-0869;2364-8961; |
ISBN |
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Additional Links |
UA library record; WoS full record; WoS citing articles |
| Impact Factor |
4.033 |
Times cited |
50 |
Open Access |
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| Notes |
; ; |
Approved |
Most recent IF: 4.033 |
| Call Number |
UA @ lucian @ c:irua:139930UA @ admin @ c:irua:139930 |
Serial |
4443 |
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| Author |
Horemans, B.; Van Holsbeke, C.; Vos, W.; Darchuk, L.; Novakovic, V.; Fontan, A.C.; de Backer, J.; van Grieken, R.; de Backer, W.; De Wael, K. |
| Title |
Particle deposition in airways of chronic respiratory patients exposed to an urban aerosol |
Type |
A1 Journal article |
| Year |
2012 |
Publication |
Environmental science and technology |
Abbreviated Journal |
Environ Sci Technol |
| Volume |
46 |
Issue |
21 |
Pages |
12162-12169 |
| Keywords |
A1 Journal article; AXES (Antwerp X-ray Analysis, Electrochemistry and Speciation); Laboratory Experimental Medicine and Pediatrics (LEMP) |
| Abstract |
Urban atmospheres in modern cities carry characteristic mixtures of particulate pollution which are potentially aggravating for chronic respiratory patients (CRP). Although air quality surveys can be detailed, the obtained information is not always useful to evaluate human health effects. This paper presents a novel approach to estimate particle deposition rates in airways of CRP, based on real air pollution data. By combining computational fluid dynamics with physical-chemical characteristics of particulate pollution, deposition rates are estimated for particles of different toxicological relevance, that is, minerals, iron oxides, sea salts, ammonium salts, and carbonaceous particles. Also, it enables some qualitative evaluation of the spatial, temporal, and patient specific effects on the particle dose upon exposure to the urban atmosphere. Results show how heavy traffic conditions increases the deposition of anthropogenic particles in the trachea and lungs of respiratory patients (here, +0.28 and +1.5 μg·h1, respectively). In addition, local and synoptic meteorological conditions were found to have a strong effect on the overall dose. However, the pathology and age of the patient was found to be more crucial, with highest deposition rates for toxic particles in adults with a mild anomaly, followed by mild asthmatic children and adults with severe respiratory dysfunctions (7, 5, and 3 μg·h1, respectively). |
| Address |
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Thesis |
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| Publisher |
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Place of Publication |
Easton, Pa |
Editor |
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| Language |
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Wos |
000310665000082 |
Publication Date |
2012-10-04 |
| 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 |
0013-936X;1520-5851; |
ISBN |
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Additional Links |
UA library record; WoS full record; WoS citing articles |
| Impact Factor |
6.198 |
Times cited |
5 |
Open Access |
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| Notes |
; We are grateful for the financial support of n.v. Vooruitzicht. Furthermore, co-workers at the environmental analysis research group are acknowledged for their help in the fieldwork. ; |
Approved |
Most recent IF: 6.198; 2012 IF: 5.257 |
| Call Number |
UA @ lucian @ c:irua:101411 |
Serial |
2557 |
| Permanent link to this record |
