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Author |
Cabal Rodríguez, A.E.; Leyva Pernia, D.; Schalm, O.; van Espen, P.J.M. |
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Title |
Possibilities of energy-resolved X-ray radiography for the investigation of paintings |
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A1 Journal article |
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Year |
2012 |
Publication |
Analytical and bioanalytical chemistry |
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Volume |
402 |
Issue |
4 |
Pages |
1471-1480 |
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Keywords |
A1 Journal article; AXES (Antwerp X-ray Analysis, Electrochemistry and Speciation) |
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Abstract |
X-ray radiographic images of paintings often show little or no contrast. In order to increase the contrast in radiographic images we measured the X-ray spectrum of a low power X-ray tube, after passing through the painting, with a high energy-resolution SDD detector. To obtain images, the detector is collimated with a 400 mu m diameter pinhole and the painting was moved through the beam in the x and y-direction using a dwell time of a few seconds per pixel. The data obtained consists of a data cube of, typically, 200 x 200 pixels and a 512-channel X-ray spectrum for each pixel, spanning the energy range from 0 to 40 keV. Having the absorbance spectrum available for each pixel, we are able, a posteriori, to produce images by edge subtraction for any given element. In this way high contrast, element-specific, images can be obtained. Because of the high energy-resolution a much simpler edge subtraction algorithm can be applied. We also used principal-component imaging to obtain, in a more automated way, images with high contrast. Some of these images can easily be attributed to specific elements. It turns out that preprocessing of the spectral data is crucial for the success of the multivariate image processing. |
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Wos |
000299842000008 |
Publication Date |
2011-07-14 |
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ISSN |
1618-2642; 1618-2650 |
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Additional Links |
UA library record; WoS full record; WoS citing articles |
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Open Access |
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Approved |
no |
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Call Number |
UA @ admin @ c:irua:96200 |
Serial |
8394 |
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Author |
Schalm, O.; Nuyts, G.; Janssens, K. |
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Title |
Some critical observations about the degradation of glass : the formation of lamellae explained |
Type |
A1 Journal article |
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Year |
2021 |
Publication |
Journal Of Non-Crystalline Solids |
Abbreviated Journal |
J Non-Cryst Solids |
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Volume |
569 |
Issue |
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Pages |
120984 |
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Keywords |
A1 Journal article; AXES (Antwerp X-ray Analysis, Electrochemistry and Speciation) |
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Abstract |
This study demonstrates that the mechanism responsible for the transformation of glass into a degradation layer is pH-dependent. In acid conditions, the transformed glass is homogeneous and brittle. In mild alkaline conditions, transformed glass is heterogeneous due to the presence of lamellae composed of silica nanoparticles and the occurrence of Ca-rich inclusions. The fundamental difference between acid and alkaline conditions cannot be explained by the currently accepted degradation mechanism based on ion exchange. To explain this critical observation, we propose a refined degradation mechanism based on existing knowledge that involves several inwardly moving reaction fronts. The fronts responsible for the transformation of the silicate network into amorphous silica are also responsible for the morphology of the transformed glass. We have identified the feedback mechanism that explains the formation of lamellae in alkaline conditions. |
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Wos |
000674487200009 |
Publication Date |
2021-06-20 |
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ISSN |
0022-3093 |
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Additional Links |
UA library record; WoS full record; WoS citing articles |
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Impact Factor |
2.124 |
Times cited |
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Open Access |
OpenAccess |
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Approved |
Most recent IF: 2.124 |
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Call Number |
UA @ admin @ c:irua:179835 |
Serial |
8551 |
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Author |
Anaf, W.; Leyva Pernia, D.; Schalm, O. |
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Title |
Standardized indoor air quality assessments as a tool to prepare heritage guardians for changing preservation conditions due to climate change |
Type |
A1 Journal article |
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Year |
2018 |
Publication |
Geosciences |
Abbreviated Journal |
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Volume |
8 |
Issue |
8 |
Pages |
Unsp 276-14 |
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Keywords |
A1 Journal article; Engineering sciences. Technology; Antwerp Systems and software Modelling (AnSyMo); AXES (Antwerp X-ray Analysis, Electrochemistry and Speciation); Antwerp Cultural Heritage Sciences (ARCHES) |
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Abstract |
Climate change will affect the preservation conditions of our cultural heritage. Therefore, well-considered mitigation actions should be implemented to safeguard our heritage for future generations. Environmental monitoring is essential to follow up the change in preservation conditions and to evaluate the effectiveness of performed mitigation actions. To support heritage guardians in the processing and evaluation of monitored data, an indoor air quality (IAQ) index for heritage applications is introduced. The index is calculated for each measured point in time and is visualized in a user-friendly and intuitive way. The current paper describes the backbone of the IAQ-calculating algorithm. The algorithm is subsequently applied on a case study in which a mitigation action is implemented in a church. |
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Wos |
000443254500006 |
Publication Date |
2018-07-27 |
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Series Issue |
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Edition |
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ISSN |
2076-3263 |
ISBN |
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Additional Links |
UA library record; WoS full record; WoS citing articles |
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Impact Factor |
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Times cited |
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Open Access |
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Notes |
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Approved |
no |
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Call Number |
UA @ admin @ c:irua:152329 |
Serial |
8578 |
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