Your search resulted in 13 documents.
Imaging fungal deterioration of wood using x-ray microtomography
1997 - IRG/WP 97-10240
Nondestructive tomographic images of solid Southern yellow pine (SYP) wood and SYP during deterioration by wood decay fungi were obtained by using a new class of synchrotron X-ray computed microtomography (CMT). The CMT images will provide information about spatial relationship between degrading fungi and wood structures. Wood samples were scanned with synchrotron-generated X-rays at high resolution (3 microns) using Charge Coupled Device (CCD) area detectors. The CCD detector array optimizes reconstruction algorithms with 329 x 259 small pixels where 1 row of pixels constitutes a single 2-dimensional slice of a specimen. A total of 500 horizontal slices comprising each data set were stacked to reconstruct a 3-dimensional volume of the specimen. Color images were computer-generated in 2-dimension to portray single slices of select cross or tangential sections and 3-dimensional volumes of the wood. Reconstructed volumes can be viewed on 3-dimensional video by fiber optic link to a 3-dimensional stereo viewing theater. The CMT model developed in this work will provide needed information about the chronology and location of structural damage to wood and aid in determining the chemical mechanisms of lignocellulose degradation.
B Illman, B A Dowd
Use of fluorescent-coupled lectins as probes for studying fungal degradation of wood
1986 - IRG/WP 1288
The ability of the fluorescent-coupled lectins wheat germ agglutin (WGA) and Concanavalin A (Con A) to react with selected Basidiomycetes, Ascomycetes, and Fungi Imperfecti was evaluated using pure cultures of 35 fungi grown on malt extract agar. WGA, which binds specifically to the n-acetylglucosamine residues found in fungal chitin, reacted with nearly all hyaline fungal structures but did not react with dematiaceous (dark) structures. Several reasons are suggested for this variation. Con A, which is specific for a-D-mannosyl and a-D-glucosyl residues, reacted with about one half of the fungi that reacted with WGA. This variation in reactivity may be useful for studying simultaneous degradation by morphologically similar fungi having different lectin specificities. The results indicate that WGA is a useful probe for studying fungal degradation by non-dematiaceous fungi particularly at the early stages of decay.
J J Morrell, R L Krahmer, L C Lin
A standardised procedure for the treatment of timber with test chemicals
1986 - IRG/WP 2257
A procedure is described which allows the standardisation of sample handling and data manipulation during trials invastigating the treatability of timber with test chemicals. The use of computer software allows the data to be handled efficiently.
J Norton, A Zosars, L E Leightley
A comparison of inductively coupled plasma spectroscopy and neutron activity analysis for the determination of concentrations in wood
1993 - IRG/WP 93-10048
As wood decays the ionic composition changes, with increases often being seen in the concentrations of Ca, Mg, Fe, Mn and sometimes K. The concentration of eight cations in red spruce sapwood and heartwood samples was determined independently by inductively coupled plasma spectroscopy (ICP) and by neutron activation analysis (NAA) as part of an effort to standardize our analytical procedures and create a uniform wood standard for use by multiple researchers. Preliminary studies indicate a difference in the values of Ca and K as estimated by ICP and NAA, possibly due to a loss of these elements due to volatilization during ashing.
J Jellison, J Connolly, K C Smith, W T Shortle
A novel device for detecting internal defects in wooden poles
1989 - IRG/WP 2329
The diagnosis of internal defects caused by termites and decay in hardwood transmission poles has been investigated using a novel Automatic Feed Drill (AFD) pole testing device. Internal defects were recognised by changes in drill feed-rate as the automatic air-driven drill traversed its 100 mm working stroke. The instrument is portable, simple to operate and recognises defects instantaneously. Tests carried out on pole material in the laboratory and the field showed that the instrument gives quick and accurate measurements of internal collapse and weakness in wood at the groundline zone.
R A Eaton, R S Johnstone
Ability of an acoustic inspection device to detect internal voids
in untreated pole sections
2002 - IRG/WP 02-20246
Detecting deterioration before substantial losses in material properties occur poses a major challenge to most wood users. While physical inspection techniques such as drilling or coring are useful, these methods can miss small pockets of damage and they lack the ability to detect early or incipient decay. The development of sonic test methodologies has created the potential for detecting changes in material properties at relatively early stages of attack, but these technologies have suffered from an inability to separate normal wood characteristics from changes associated with degradation. One aspect of these methods that might prove useful, however, is their ability to detect small voids such as those caused by termites or beetles. This ability would be especially useful for assessing termite infestations in large structures. There is little data on the ability of many commercial devices to quantify termite damage. We assessed the ability of one device, the PURL-1, to detect increasing levels of simulated insect voids in Douglas-fir pole sections. The device was capable of detecting damage when as little as 1% of the cross section was removed. While the device was less successful at precisely quantifying the cross sectional area loss, the results suggest that this device has promise for early detection of small voids.
J J Morrell, R G Rhatigan
Kinetics of the dissociation of Cr, Cu, and As in fixed CCA-treated wood
2001 - IRG/WP 01-50168
The results of an experiment showing the kinetics of the dissociation of CCA compo-nents in water within treated wood samples are presented. Dry red pine (Pinus resinosa Ait.) samples were simultaneously vacuum-treated with water, then expressed to re-move the water at successive time intervals. The expressate was then analyzed for Cr, Cu, and As concentration by inductively coupled plasma (ICP). Dissolved ion concen-trations increased for approximately 24 hours then reached relatively high equilibrium values which did not seem to depend on CCA loading in the wood. This detailed kinetic information is essential to understanding and predicting the leaching of fixed CCA.
L Waldron, P A Cooper
Effectiveness of sol-gel treatments coupled with copper and boron against subterranean termites
2009 - IRG/WP 09-30493
Wood modification by sol-gel treatments shows many positive features, like antimicrobial properties. Wood was also successfully modified with alkoxysilanes enhancing its resistance against soil micro-organisms. Silver, copper, zinc compounds, boric acid or organic biocides such as alkylammonium compounds may be added to the sol-gel to enhance its biocidal properties. Nevertheless, if some of these active ingredients and compounds are not fixed into wood by chemical reactions, they can be easily leached out by water. To overcome this limitation, a system based on silica sol-gel material starting from alkoxysilanes has been functionalized with organic groups having copper linking function. Sol-gel was also coupled with boric acid. As preliminary tests against the brown rot agent Coniophora puteana (Schumacher ex Fries) gave good results, the sol-gel formulations were also tested for their efficacy against subterranean termites. A no-choice test was set up, in two different time scales. Results show that though the sol-gel treatments act in very different ways, all of them are efficacy against subterranean termites. The total mortality occurred in the longer test suggested that active ingredients may be added in lower quantity.
E Feci, L Nunes, S Palanti, S Duarte, G Predieri, F Vignali
Classification of wood materials using Fourier Transform Near Infrared Spectroscopy and multivariate analysis
2011 - IRG/WP 11-20471
A distinction between preservative-treated wood and non-treated wood can be demonstrated by the combination of Fourier Transform-Near Infrared Spectroscopy (FT-NIRS) and Multivariate Analysis (MVA). This technique is non-destructive, quick, easy to use and can be portable. The calibration models for different heavy metals are set up using principal component analysis (PCA) to classify species of treated wood as well as wood contaminated by organic or inorganic substances. The actual heavy metal contamination levels of the wood samples was determined by ICP-AES (Induction Coupled Plasma- Atomic Emission Spectroscopy).
M A Bouslamti, M A Irle, C Belloncle, V Salvador, S Hulot, B Caron, E M Qannan
Utilization of thermodesorption coupled to GC-MS to study kinetics of thermodegradation of different wood species
2011 - IRG/WP 11-40559
Thermdesorption coupled to Gas Chromatography coupled to Mass Spectroscopy (TD-GC-MS) has been investigated to identify volatile degradation products generated during wood heat treatment by mild pyrolysis. For this purpose, wood samples of different softwood and hardwood species have been heat treated under nitrogen for different temperatures comprised between 180 and 230°C during 15 min. in the glass thermal desorption tube of the thermodesorber and the volatile wood degradation products trapped. The trapped products were then thermodesorbed and analysed by GC-MS. Chromatograms of the different samples indicated the formation of different products resulting from degradation of lignin and hemicelluloses. The important formation of acetic acid is concomitant with the formation of most degradation products and at the origin of the difference of reactivity observed between softwoods and hardwoods.
K Candelier, M Chaouch, S Dumarçay, A Pétrissans, M Pétrissans, P Gérardin
Utilization of thermodesorption coupled to GC-MS to characterize volatiles formation kinetics during wood thermodegradation
2012 - IRG/WP 12-40587
Identification of volatile degradation products produced during wood mild pyrolysis is important to have better insight on thermodegradation mechanisms. Previous studies have shown that thermodesorption coupled to GC-MS is an attractive tool to characterize and quantify products formed during wood thermodegradation indicating an higher susceptibility of hardwoods to thermodegradation compare to softwoods. The aim of this study is to give better insights on wood thermodegradation pathways during wood heat treatment with special emphasis on the kinetics of thermodegradation. For this purpose, one hardwood species (beech) and one softwood species (Sylver fir) have been subjected to thermal treatment directly in the thermal desorption glass tube of the thermodesorber under helium at temperatures of 210 and 230°C for different times ranging from 10 to 80 minutes and volatiles compounds formed analysed by gas chromatography coupled to mass spectroscopy. Starting from these results, it’s was possible to visualize the different products formed as a function of time allowing determination of the kinetic curves of formation of the main degradation products. Making the assumption that acetic acid is representative of hemicelluloses degradation and vanillin representative of lignin degradation, it was possible using Arrhenius equation to determine a mean activation energy of formation of this two products leading to indirect informations on lignin and hemicelluloses stability for each wood species.
K Candelier, S Dumarçay, A Pétrissans, M Pétrissans, P Kamdem, P Gérardin
Study on Nailed Joint with Iron Contamination. Part2: Elucidation of the Occurrence Condition of Iron Contamination
2019 - IRG/WP 19-50350
In recent years, efforts towards wooden buildings are progressing in Japan. And many woods are used in various places. However, various problems have also occurred in wooden buildings. One of the problems is iron contamination which appears when wood and metal chemically react. At present, tree species that are prone to iron contamination and components that cause iron contamination are clarified. However, the actual weather conditions under which iron contamination occurs are unknown. In this study, conditions of occurrence of iron contamination verified seven test methods. The test method is difference in water quality, difference in temperature, the influence of water entering from the butt end of plywood, the amount of rainfall and iron contamination occurrence time, the difference between sapwood and heartwood, the difference in the distance the butt end and the comparison of how to hit nails. By the results of this test, the water quality and water temperature had little effect on the occurrence of iron contamination within the conditions of this test. However, when the temperature of the environment to be dried was low, the occurrence of iron contamination remarkably decreased. The colour intensity and extent of iron contamination change with rainfall amount. Iron contamination spreads up to the top 10 mm of the nail. The state of the nail after driving the nail into the occurrence of iron contamination does not affect. However, iron contamination did not appear on the surface of the nail implanted deeply into the plywood.
D Nakano, R Nakano, H Ishiyama
Significance of the thermal design and the sorption isotherm shape in hygroscopic wood moisture dynamics and service life
2022 - IRG/WP 22-20682
Moisture dynamics are considered important for predicting the service performance of wood in exterior applications. Above a critical moisture content, water acts a softener on the structural polymer matrix of the wood cell wall, enabling the necessary diffusion of molecular species involved in the fungal degradation mechanism of wood. Water may enter solid wood in either liquid form or in vapor form, whereas it can only leave in vapor form. In exterior applications with prolonged exposure to rainwater, wood moisture may quickly accumulate to the critical moisture content for fungal degradation. On the other hand, moisture loss during dry weather conditions proceeds by relatively slow vapor transfer, leaving wood vulnerable to fungal decay for extended periods of time. This conference contribution addresses the latest scientific work, showing the role of heat transfer - associated with moisture changes in wood - as a major physical cause for the slow moisture content change rates in a humid ambient. The results from this work may guide the wood technologist to improve the service performance of wood through thermal detailing in the application design and/or by wood modification of the moisture sorption isotherm.