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Buck, D., Wallentén, P., Sehlstedt-Persson, M. & Öhman, M. (2023). Moisture- and mould-resistance: multi-modal modelling leveraging X-ray tomography in edge-sealed cross-laminated timber. Materials & design, 230, Article ID 111967.
Open this publication in new window or tab >>Moisture- and mould-resistance: multi-modal modelling leveraging X-ray tomography in edge-sealed cross-laminated timber
2023 (English)In: Materials & design, ISSN 0264-1275, E-ISSN 1873-4197, Vol. 230, article id 111967Article in journal (Refereed) Published
Abstract [en]

Edge-sealing, which involves treating the edges of wood products, improves water resistance. This study investigated the feasibility of edge-sealed cross-laminated timber (CLT) panels to reduce capillary water uptake, thereby resisting mould formation. The water and vapour permeabilities of ten characteristically different single-layer sealant coating systems were systematically determined. Multi-modal assessment leveraged by computed tomography (CT) scanning methodology was used to enhance detection of material characteristics beyond the standard coating permeability assessment. Moisture content was observed to change during the specimens’ absorption and desorption depending on the sealant system applied. The results revealed different characteristics of coatings during the water absorption and desorption stages. Findings from this study were used to develop recommendations regarding the water resistance of coating systems, curing time, susceptibility to mould formation, and industrial applicability. Results suggest that edge-sealed CLT could minimise the risk of mould formation, which can occur at worksites with minimal weather protection. The method developed in this study provides a basis to evaluate new coating systems and determine which use case is the best for a particular coating type. This study also incorporates insights from industry to identify future research orientations, which may pave the way for new designs and assessment techniques.

Place, publisher, year, edition, pages
Elsevier, 2023
Keywords
CT scan, Full-field data, Image processing, Moisture simulation, Mould estimation, Multivariate modelling
National Category
Wood Science
Research subject
Wood Science and Engineering
Identifiers
urn:nbn:se:ltu:diva-97626 (URN)10.1016/j.matdes.2023.111967 (DOI)2-s2.0-85159149308 (Scopus ID)
Note

Validerad;2023;Nivå 2;2023-05-29 (joosat);

Funder: TräCentrum Norr (TCN), [grant number 239268, 239278]; FORMAS project: Experimental Studies of Capillary Phenomena in Bio-based Materials [grant number 942-2016-64]

Licens fulltext: CC BY License

Available from: 2023-05-29 Created: 2023-05-29 Last updated: 2023-10-11Bibliographically approved
Degerman, M. & Öhman, M. (2023). Photobiomodulation on hard to heal ulcers: influence of diabetes mellitus on treatment time to healing in frail elderly patients. In: Ann Liebert; Jeri-Anne Lyons; James D. Carroll (Ed.), Mechanisms of Photobiomodulation Therapy XVII: Proceedings of SPIE. Paper presented at Mechanisms of Photobiomodulation Therapy XVII (SPIE BIOS), San Francisco, United States, January 28, 2023. SPIE, Article ID 1236202.
Open this publication in new window or tab >>Photobiomodulation on hard to heal ulcers: influence of diabetes mellitus on treatment time to healing in frail elderly patients
2023 (English)In: Mechanisms of Photobiomodulation Therapy XVII: Proceedings of SPIE / [ed] Ann Liebert; Jeri-Anne Lyons; James D. Carroll, SPIE , 2023, article id 1236202Conference paper, Published paper (Refereed)
Place, publisher, year, edition, pages
SPIE, 2023
Series
Proceedings of SPIE. Progress in biomedical optics and imaging., ISSN 1605-7422 ; 12362
National Category
Endocrinology and Diabetes Nursing
Research subject
Wood Science and Engineering
Identifiers
urn:nbn:se:ltu:diva-103498 (URN)10.1117/12.2646997 (DOI)2-s2.0-85159782557 (Scopus ID)
Conference
Mechanisms of Photobiomodulation Therapy XVII (SPIE BIOS), San Francisco, United States, January 28, 2023
Note

ISBN for host publication: 9781510658295

Available from: 2024-01-09 Created: 2024-01-09 Last updated: 2024-02-08Bibliographically approved
Livas, C., Ekevad, M. & Öhman, M. (2022). Experimental analysis of passively and actively reinforced glued-laminated timber with focus on ductility. Wood Material Science & Engineering, 17(2), 129-137
Open this publication in new window or tab >>Experimental analysis of passively and actively reinforced glued-laminated timber with focus on ductility
2022 (English)In: Wood Material Science & Engineering, ISSN 1748-0272, E-ISSN 1748-0280, Vol. 17, no 2, p. 129-137Article in journal (Refereed) Published
Abstract [en]

When glued-laminated timber are subjected to bending moment, they usually fail in a brittle way in the tension zone before the compressive zone reaches the compressive strength of wood. This means that the compression strength of wood is not fully exploited. By reinforcing the tension zone, the failure mode of glued-laminated timber can be changed from tensile to compressive. As a result, by utilizing the higher compressive strength, reinforced glued-laminated timber become stronger and the failure mode becomes compressive and ductile. This paper presents experimental results of the effect of steel reinforcements in the tension zone of glued-laminated timber. Four passively reinforced beams, four actively reinforced beams, and seven unreinforced beams were tested to failure in four-point bending tests. The experimental results confirmed the brittle tension failure in the unreinforced beams as well as the ductile and compressive failure in the reinforced beams. Furthermore, the experiments revealed the increase of the passively and the actively reinforced glued-laminated timber relative to the reference beams for strengths (26% and 39%) and stiffnesses (30% and 11%). Ductilities were increased from 7.7% for the reference beams to 90% and 75% for the passively and the actively reinforced glued-laminated timber, respectively.

Place, publisher, year, edition, pages
Taylor & Francis, 2022
Keywords
Glulam, reinforcement, ductility, bending test
National Category
Wood Science
Research subject
Wood Science and Engineering
Identifiers
urn:nbn:se:ltu:diva-82331 (URN)10.1080/17480272.2020.1869998 (DOI)000606904400001 ()2-s2.0-85099340355 (Scopus ID)
Note

Validerad;2022;Nivå 2;2022-04-13 (sofila)

Available from: 2021-01-13 Created: 2021-01-13 Last updated: 2022-04-13Bibliographically approved
Degerman, M., Öhman, M. & Bertilson, B. C. (2022). Photobiomodulation, as additional treatment to traditional dressing of hard-to-heal venous leg ulcers, in frail elderly with municipality home healthcare. PLOS ONE, 17(9), Article ID e0274023.
Open this publication in new window or tab >>Photobiomodulation, as additional treatment to traditional dressing of hard-to-heal venous leg ulcers, in frail elderly with municipality home healthcare
2022 (English)In: PLOS ONE, E-ISSN 1932-6203, Vol. 17, no 9, article id e0274023Article in journal (Refereed) Published
Abstract [en]

The main objectives of the study were to explore whether laser Photobiomodulation (PBM) in addition to traditional dressing of hard-to-heal venous leg ulcer, reduced healing time of the ulcer and if the duration of the ulcer before PBM impacted the treatment time with PBM to healing. The intervention group was frail, elderly patients with home healthcare in the municipality of Skellefteå, registered in the Swedish quality registry RiksSar for ulcer treatment with hard-to-heal venous leg ulcer. The control group with equivalent physical conditions was obtained from the same quality registry. Definition of hard-to-heal ulcer was six weeks duration or more. The PBM was performed two times per week with laser type infrared GaAs, 904nm, 60mW, and 700Hz, targeting lymphatic area and ulcer area. Laser type red visible, GaAllnp, 635nm, 75mW and 250Hz, targeting ulcer area. The intervention group treated with PBM in addition to traditional dressing healed significantly faster than the control group with a mean of 123 days (p = 0.0001). Duration of the ulcer before PBM did not impact the healing time. To conclude, the findings indicate that using PBM in addition to dressing may have multiple benefits on hard-to-heal venous leg ulcer, saving valuable time and resources for patients, healthcare providers, and institutions.

Place, publisher, year, edition, pages
Public Library of Science (PLoS), 2022
National Category
Other Medical Engineering Geriatrics
Research subject
Wood Science and Engineering
Identifiers
urn:nbn:se:ltu:diva-93245 (URN)10.1371/journal.pone.0274023 (DOI)000892087100040 ()36107964 (PubMedID)2-s2.0-85137871095 (Scopus ID)
Note

Validerad;2022;Nivå 2;2022-09-26 (joosat);

2022-10-04: Dubblettpost PID: 1700859 har raderats. (sofila)

Available from: 2022-09-26 Created: 2022-09-26 Last updated: 2023-02-28Bibliographically approved
Buck, D., Wallentén, P., Sehlstedt-Persson, M. & Öhman, M. (2021). Impregnation of Wood / End Grain Treatment. In: : . Paper presented at Fuktcentrums informationsdag "Nio nyanser av fukt", Lund, Sweden [Hybrid], November 25, 2021. Lund University
Open this publication in new window or tab >>Impregnation of Wood / End Grain Treatment
2021 (English)Conference paper, Oral presentation with published abstract (Other academic)
Abstract [en]

This research presents the findings of a study conducted by Luleå University of Technology (LTU) and Lund University (LTH) on the effect of edge treatment on the end grain of cross-laminated timber (CLT) elements. The objective of the study was to identify whether edge treatment influences the moisture performance and mould risk of CLT.The investigation was conducted through controlled laboratory studies, utilising standardised procedures. Specifically, the end grain of the CLT specimens was exposed to moisture by placing them in contact with a free water surface for 96 hours. Following this exposure, the specimens were dried under controlled conditions. X-ray computed tomography (CT) scanning was used to estimate the moisture content of the specimens and provide detailed spatial information about the moisture distribution within the wood.To further evaluate the effectiveness of edge treatment, the experimental moisture content assessments were compared to values by WUFI simulations. Additionally, annual data for the simulations were conducted using climate data from three different locations: Lund, Stockholm, and Borlänge. These simulations assessed the theoretical impact of edge treatment on mould risk under different climatic conditions.Results revealed that edge treatment has potential to reduce moisture content and mitigate mould risk in CLT elements. Experimentally assessed moisture content values were consistently lower in edge-treated specimens compared to untreated specimens. The calculations and simulations supported these findings, showing a distinct reduction in moisture accumulation and mould risk in edge-treated CLT elements.This study provides insights into the effect of edge treatment on the moisture performance and mould risk in CLT elements. The findings suggest that implementing appropriate edge treatment techniques can enhance the durability of CLT structures, particularly for worksites in regions where climatic conditions fluctuate over the course of construction. Further research and testing are warranted to explore additional factors influencing the effectiveness of edge treatment in CLT applications.

Place, publisher, year, edition, pages
Lund University, 2021
National Category
Building Technologies
Research subject
Wood Science and Engineering
Identifiers
urn:nbn:se:ltu:diva-98005 (URN)
Conference
Fuktcentrums informationsdag "Nio nyanser av fukt", Lund, Sweden [Hybrid], November 25, 2021
Available from: 2023-06-08 Created: 2023-06-08 Last updated: 2023-09-05Bibliographically approved
Myronycheva, O., Karlsson, O., Sehlstedt-Persson, M., Öhman, M. & Sandberg, D. (2019). Portable microNIR sensor for the evaluation of mould contamination on wooden surfaces. In: Susan LeVan-Green (Ed.), Proceedings of the 2019 Society of Wood Science and Technology International Convention: Convention Theme: Renewable Materials and the Wood-based Bioeconomy. Paper presented at 62nd International Convention of Society of Wood Science and Technology, 20-25 October, 2019, Yosemite, California (pp. 120-125). Society of Wood Science and Technology (SWST)
Open this publication in new window or tab >>Portable microNIR sensor for the evaluation of mould contamination on wooden surfaces
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2019 (English)In: 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, p. 120-125Conference paper, Published paper (Refereed)
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.

Place, publisher, year, edition, pages
Society of Wood Science and Technology (SWST), 2019
Keywords
mould fungi, microNIR, wood, naturally seasoned, kiln-dried, multivariate model
National Category
Other Mechanical Engineering
Research subject
Wood Science and Engineering
Identifiers
urn:nbn:se:ltu:diva-76467 (URN)
Conference
62nd International Convention of Society of Wood Science and Technology, 20-25 October, 2019, Yosemite, California
Note

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

Available from: 2019-10-22 Created: 2019-10-22 Last updated: 2023-09-05Bibliographically approved
Myronycheva, O., Karlsson, O., Sehlstedt-Persson, M., Öhman, M. & Sandberg, D. (2018). Distribution of low-molecular lipophilic extractives beneath the surface of air- and kiln-dried Scots pine sapwood boards. PLOS ONE, 13(10), Article ID e0204212.
Open this publication in new window or tab >>Distribution of low-molecular lipophilic extractives beneath the surface of air- and kiln-dried Scots pine sapwood boards
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2018 (English)In: PLOS ONE, E-ISSN 1932-6203, Vol. 13, no 10, article id e0204212Article in journal (Refereed) Published
Abstract [en]

During industrial wood drying, extractives migrate towards the wood surfaces and make the material more susceptible to photo/biodegradation. The present work provides information about the distribution, quantity and nature of lipophilic substances beneath the surface in air- and kiln-dried Scots pine (Pinus sylvestris L.) sapwood boards. Samples were taken from knot-free sapwood surfaces and the composition of lipophilic extractives, phenols and low-molecular fatty/resin acids layers at different nominal depths below the surface was studied gravimetrically, by UV-spectrometry and by gas chromatography-mass spectrometry (GC-MS). 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. The scatter in the values for the lipophilic extractives was high in both drying types, being highest for linoleic acid and slightly lower for palmitic, oleic and stearic acids. The amount of fatty acids was low in kiln-dried boards, probably due to a stronger degradation due to the high temperature employed. The most abundant resin acid was dehydroabietic acid followed by pimaric, isopimaric, and abietic acids in both drying types. It is concluded that during kiln-drying a migration front is created at a depth of 0.25 mm with a thickness of about 0.5 mm.

Place, publisher, year, edition, pages
PLOS, 2018
National Category
Wood Science Other Mechanical Engineering
Research subject
Wood Science and Engineering
Identifiers
urn:nbn:se:ltu:diva-71200 (URN)10.1371/journal.pone.0204212 (DOI)000446921100033 ()30303988 (PubMedID)2-s2.0-85054716404 (Scopus ID)
Projects
Experimental studies of capillary phenomena in bio-based materialsFungal growth on modified wood-based products under subarctic conditionsModWoodLifeUnderstanding wood modification through an integrated scientific and environmental impact approach
Funder
Swedish Research Council
Note

Validerad;2018;Nivå 2;2018-10-29 (svasva)

Available from: 2018-10-13 Created: 2018-10-13 Last updated: 2023-09-05Bibliographically approved
Karlsson, O., Myronycheva, O., Sehlstedt-Persson, M., Öhman, M. & Sandberg, D. (2017). Multivariate modeling of mould growth in relation to extractives in dried Scots pine sapwood. In: Proceedings IRG Annual Meetin: . Paper presented at 48th Conference of the International Research Group on Wood Protection, IRG48, Ghent, Belgium, 4-8 Jun 2017. , Article ID 17-20629.
Open this publication in new window or tab >>Multivariate modeling of mould growth in relation to extractives in dried Scots pine sapwood
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2017 (English)In: Proceedings IRG Annual Meetin, 2017, article id 17-20629Conference paper, Poster (with or without abstract) (Refereed)
Abstract [en]

Influence of extractives on mould growth on Scots pine sapwood dried in air or in kiln was studied. Boards were sprayed with water mixtures of spores of the fungal species Penicillium sp., Aspergillus sp., Mucor sp., Paecilomyces sp., Trichoderma sp., treated at a temperature of 22ºC at 90% RH, classified into a percentage of covered area. Acetone and water extracts were isolated and analyzed for sugars, nitrogen, ash, resin/fatty acids, glycerol, and phenols. A multivariate Orthogonal Partial Least Squares (OPLS) regression model was developed to study relations between the extent of mould coverage of boards and chemical content. The model describes 51% variability in X and 69% in Y with prediction power of 55%. The results indicated that total acetone soluble extractives and sugars like glucose contributed to increased mould growth whereas fatty acids prevent mould growth.

Keywords
Multivariate analysis, sapwood, fungi
National Category
Materials Engineering Other Mechanical Engineering
Research subject
Wood Science and Engineering
Identifiers
urn:nbn:se:ltu:diva-63985 (URN)
Conference
48th Conference of the International Research Group on Wood Protection, IRG48, Ghent, Belgium, 4-8 Jun 2017
Available from: 2017-06-14 Created: 2017-06-14 Last updated: 2023-09-05Bibliographically approved
Ekevad, M., Berg, S., Öhman, M. & Guo, X. (2017). Potential Yield Increase with Reduced Saw Kerf Deviations when Curve Sawing. In: : . Paper presented at 23rd International Wood Machining Seminar (IWMS-23), Warsaw, Poland, May 28-31, 2017.
Open this publication in new window or tab >>Potential Yield Increase with Reduced Saw Kerf Deviations when Curve Sawing
2017 (English)Conference paper, Oral presentation with published abstract (Refereed)
Abstract [en]

Curve sawing with circular saw blades introduces saw kerf deviations due to the combination of the flat sawblade and the curvature of the saw kerf in log or cant direction. Deviations for a double arbor resaw used for curve sawing, are that the saw kerf becomes wider at top and bottom and that the desired rectangular cross sections of the boards become distorted. The yield loss due to the saw kerf deviation in practice for a sawmill was of interest in this study. Earlier and very approximate guesses and simple estimates have been indicating that the loss of income for a sawmill in Sweden producing 200’ m3 of sawn timber may be about 2 MSEK/year (0.22 Meuro/year). In this study calculations were based on true log data and assumed sawing conditions for a sawmill. A true mixed input log assortment (78458 spruce and pine logs taken into the log yard of a sawmill in northern part of Sweden) was used as basis. Individual curvature of these logs was taken into consideration but the calculation was still approximate because not all facts about sawing patterns, log classes etc. for an actual sawmill were known. Instead one single sawing class was used for the calculation of saw kerf deviation.

 

Results show that the direct yield loss given the assumed input data was 0.61 %-units. This corresponds roughly to the income loss 0.2 Meuro/year mentioned above. Besides from the yield increase there are other advantages gained if the saw kerf deviation can be reduced.

Keywords
Curve sawing, ripsawing, saw kerf deviation, sawing yield, sawmill
National Category
Engineering and Technology Other Mechanical Engineering
Research subject
Wood Science and Engineering
Identifiers
urn:nbn:se:ltu:diva-63068 (URN)
Conference
23rd International Wood Machining Seminar (IWMS-23), Warsaw, Poland, May 28-31, 2017
Available from: 2017-04-19 Created: 2017-04-19 Last updated: 2017-11-24Bibliographically approved
Ekevad, M., Guo, X., Li, R. & Öhman, M. (2016). Curve sawing effects on board dimensions when rip-sawing with a circular saw blade (ed.). Wood Material Science & Engineering, 11(3), 135-141
Open this publication in new window or tab >>Curve sawing effects on board dimensions when rip-sawing with a circular saw blade
2016 (English)In: Wood Material Science & Engineering, ISSN 1748-0272, E-ISSN 1748-0280, Vol. 11, no 3, p. 135-141Article in journal (Refereed) Published
Abstract [en]

Curve sawing means advantages for yield and quality of sawn boards. However, for circular saw machinery deviations of saw kerfs give losses of valuable board volume. Deviations give thinner boards but also slight cupping of the cross sections. Theoretical calculations show that even with moderate (large) curve radii, these saw kerf deviations are typically 0.2–0.6 mm for normal circular saw machinery and Swedish log material. The test sawing reported here was made in order to give experimental values that can be compared to theoretical values. Fifty normal logs and 50 curved with top diameter 236–248 mm were cut with sawing pattern 3X with center boards 51 × 149 mm. The average curve radius of the curved cants that were cut in the resaw was 132 m (bow height 19 mm) and the theoretical saw kerf deviation for this radius is 0.31 mm. The experimental results show that the thickness reduction at the measuring points for curve sawn boards compared to straight sawn boards was in average 0.19 mm to be compared with the theoretical value of 0.20 mm. Cupping was more difficult to measure but results seem to agree well between theory and experiments.

National Category
Other Mechanical Engineering
Research subject
Wood Science and Engineering
Identifiers
urn:nbn:se:ltu:diva-31222 (URN)10.1080/17480272.2016.1150342 (DOI)000375935000003 ()2-s2.0-84961218673 (Scopus ID)55774805-e94c-4e3e-b19f-bbb674543cdb (Local ID)55774805-e94c-4e3e-b19f-bbb674543cdb (Archive number)55774805-e94c-4e3e-b19f-bbb674543cdb (OAI)
Note

Validerad; 2016; Nivå 1; 20160510 (andbra); Konferensartikel i tidskrift

Available from: 2016-09-30 Created: 2016-09-30 Last updated: 2018-07-10Bibliographically approved
Organisations
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ORCID iD: ORCID iD iconorcid.org/0000-0003-2247-674x

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