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Portable microNIR sensor for the evaluation of mould contamination on wooden surfaces
Luleå tekniska universitet, Institutionen för teknikvetenskap och matematik, Träteknik.ORCID-id: 0000-0001-7864-8091
Luleå tekniska universitet, Institutionen för teknikvetenskap och matematik, Träteknik.ORCID-id: 0000-0002-7711-9267
Luleå tekniska universitet, Institutionen för teknikvetenskap och matematik, Träteknik.ORCID-id: 0000-0002-3544-8716
Luleå tekniska universitet, Institutionen för teknikvetenskap och matematik, Träteknik.ORCID-id: 0000-0003-2247-674x
Vise andre og tillknytning
2019 (engelsk)Inngår i: Proceedings of the 2019 Society of Wood Science and Technology International Convention: Convention Theme: Renewable Materials and the Wood-based Bioeconomy / [ed] Susan LeVan-Green, Society of Wood Science and Technology (SWST) , 2019, s. 120-125Konferansepaper, Publicerat paper (Fagfellevurdert)
Abstract [en]

The traditional assessment of mould growth is sometimes subjective and can differ from person to person. By applying spectroscopic tools, it is possible to create an individual fingerprint of a wooden material and create databases for obtaining more objective information related to the chemical and biological composition. Side-boards (the flat-sawn sapwood part of the log) of Scots pine were single stacked on stickers and naturally dried indoors at 20°C to an average moisture content (MC) of 4.6%. Another ten side-boards were dried in a small-scale laboratory air-circulation kiln to an average MC of 14%. Another group of side-boards were double-stacked with the bark-side surfaces of each pair turned outwards in order to get a high extractive concentration on these surfaces, and less concentration on opposite surfaces. The different flat-side surfaces were planed according to a planing-depth scheme : 0 mm (unplanned), 0.25, 0.75, and 1.75 mm depth from the surface, and the residual wood particles were collected for further analysis. The planned surfaces were exposed to a mould test, performed by spraying a spore suspension of five mould fungi on the wood surfaces followed by incubation at the temperature of 24°C and 95±3%RH for 35 days. Thereafter, the surfaces were graded according to mould growth. A portable microNIR sensor (wave-length range 900-1670 nm, step 6 nm) was used for NIRspectra detection on the surfaces after mould test, and a data matrix was created. Multivariate analysis of obtained spectra was performed. The results show that the principal component analysis (PCA) can describe and predict 99.7% of the spectroscopic data obtained. No influence of the drying method or planned depth was discovered during classification. Two mould-classes could, however, be clearly separated; no mould, and with mould growth respectively, and the separation could be detected on a 93.4% level.

The study demonstrates that mould growth on the wooden surface could be evaluated by portable MicroNIR spectrometer, which is sensitive enough to detect chemical differences caused by fungal contamination.

sted, utgiver, år, opplag, sider
Society of Wood Science and Technology (SWST) , 2019. s. 120-125
Emneord [en]
mould fungi, microNIR, wood, naturally seasoned, kiln-dried, multivariate model
HSV kategori
Forskningsprogram
Träteknik
Identifikatorer
URN: urn:nbn:se:ltu:diva-76467OAI: oai:DiVA.org:ltu-76467DiVA, id: diva2:1362884
Konferanse
62nd International Convention of Society of Wood Science and Technology, 20-25 October, 2019, Yosemite, California
Merknad

ISBN för värdpublikation: 978-0-9817876-9-5

Tilgjengelig fra: 2019-10-22 Laget: 2019-10-22 Sist oppdatert: 2023-09-05bibliografisk kontrollert
Inngår i avhandling
1. Effectiveness and Evaluation of Wood Protection against Biological Deterioration Caused by Filamentous Fungi
Åpne denne publikasjonen i ny fane eller vindu >>Effectiveness and Evaluation of Wood Protection against Biological Deterioration Caused by Filamentous Fungi
2021 (engelsk)Doktoravhandling, med artikler (Annet vitenskapelig)
Abstract [en]

Developing a holistic understanding of the biological deterioration of wooden material by fungi in the laboratory and outdoor conditions requires the development of new assessment procedures and tools that allow describing the process with maximum precision and accuracy. Environmental biodeterioration is a complex process including a combination of physical, chemical and biological changes, with many uncertainties limiting the predictability and effectiveness of selected preservatives after laboratory tests. Therefore, in the current thesis, the investigation of the effectiveness of selected wood process parameters and protection systems against fungal growth and evaluation of the applicability of near-infrared spectroscopy for wooden surfaces assessment under fungal attack were accomplished.  The mould attack on copper impregnated Scots pine sapwood regulated to a greater extent by planing depth than by the infection method. Air-borne contaminants can heavily occupy the unplaned surfaces, but the extent of such occupation could be reduced with planing and impregnation solutions. Despite the vulnerability of the differently planed and copper-impregnated wood towards mould fungi, mass loss of that wood degraded by white-rot Trametes versicolor was less than 5%. The distribution, quantity, and nature of lipophilic substances beneath the surface in the air- and kiln-dried Scots pine sapwood boards significantly influenced mould fungi attack. It was found that the concentration of total extractives was significantly higher in kiln-dried than in air-dried samples and was higher close to the surface than in the layers beneath. During kiln-drying, a migration front is created at a depth of 0.25 mm with a thickness of about 0.5 mm. The evidence from the previous study is committed to understanding the influence of extractives and other migrating compounds on the unplanned surface and, consequently, on mould growth on that surface of Scots pine sapwood subjected to air and kiln drying. Therefore, a multivariate regression model was developed.  The thermal modification at different temperatures of exotic African wood influenced the chemistry. Iroko wood demonstrated stabilisation of pH and different patterns of chemical changes compared to padouk.  The open process of wood treatment like heating-and-cooling (i.e. fully soaking heated wood in cold liquor allowing the liquor to penetrate wood partially) can improve wood performance by developing a protective layer beneath the surface on heat-induced curing. However, the applied methacrylic resin demonstrated effectiveness during laboratory testing for biodeterioration but did not perform efficiently during outdoor tests.  The test of available commercially of generally recognised as safe (GRAS) compounds and biocidal treatment in laboratory conditions revealed a moderate inhibition effect on protection against biodeterioration.  Hyperspectral imaging in the NIR region could be applied to classify thermally modified wood but not for air/kiln-dried Scots pine wood. The use of a portable microNIR spectrometer efficiently demonstrated the separation of no mould and mould specimens in laboratory tests of Scots pine and allowed classifying boards treated with commercial biocides after outdoor weathering. 

sted, utgiver, år, opplag, sider
Luleå: Luleå University of Technology, 2021
Serie
Doctoral thesis / Luleå University of Technology 1 jan 1997 → …, ISSN 1402-1544
HSV kategori
Forskningsprogram
Träteknik
Identifikatorer
urn:nbn:se:ltu:diva-87553 (URN)978-91-7790-960-6 (ISBN)978-91-7790-961-3 (ISBN)
Disputas
2021-12-17, A193, Skelleftea, 00:00 (engelsk)
Opponent
Veileder
Tilgjengelig fra: 2021-10-19 Laget: 2021-10-19 Sist oppdatert: 2021-11-26bibliografisk kontrollert

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Myronycheva, OlenaKarlsson, OlovSehlstedt-Persson, MargotÖhman, MicaelSandberg, Dick

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