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An insight into brown rot decay of timber as revealed by 13C CP/MAS NMR
1985 - IRG/WP 1259
L E Leightley

Effect of wood polymers degradation during heat treatment on extracellular enzymatic activities involved in beech degradation by Trametes versicolor
2008 - IRG/WP 08-40392
Effect of heat treatment on extracellular enzymes involved in wood degradation by Trametes versicolor was investigated. Heat-treated and untreated beech blocks were exposed to T. versicolor on malt agar medium and extracellular enzymatic activities investigated. A strong ABTS oxidizing activity has been detected during the first stage of colonization in both cases, while cellulase activities are mainly detected in the case of untreated beech wood. Further investigations carried out on holocellulose, isolated using sodium chlorite delignification procedure, either on untreated beech wood or heat treated one, indicate that commercially available cellulases are able to hydrolyse totally holocellulose from untreated sawdust, while hollocellulose from heat treated one was only partially hydrolysed. CP/MAS 13C NMR analysis of heat treated beech wood but also its lignin and holocellulose fractions obtained after acidic hydrolysis of polysaccharides or delignification with sodium chlorite indicates an important modification of hollocellulose showing degradation of hemicelluloses as generally described in the literature, but also formation of carbonaceous materials within the wood structure. All these data suggest that chemical modifications of wood components during heat treatment disturb enzymatic system involved in wood degradation.
S Lekounougou, G Nguila Inari, M Pétrissans, S Dumarçay, J P Jacquot, E Gelhaye, P Gérardin

Characterisation and evaluation of various chitosan oligomers, and decay resistance
2011 - IRG/WP 11-30562
Chitosan, a polymer of D-glucosamine, is known for its antimicrobial activity. However, the physicochemical properties of chitosan depend upon three principal factors, i.e. source of raw material, molecular weight and degree of deacetylation. Here, we report synthesis and characterization of chitosan oligomers prepared by deaminative depolymerization of chitosan (s) obtained from Sigma Aldrich and China (industrial grade). Subsequently their antifungal activies were evaluated using both agar nutrient medium and wood decay bioassays. The nutrient medium bioassay results showed that chitosan(s) and chitosan oligomers affected mycelial growth to different magnitudes. Nevertheless, two of the low-MW chitosan oligomers completely inhibited the growth of all the tested fungi as compared to high-MW chitosan oligomers. However, the work presented in this paper, depicts that antifungal activity increases by decreasing the degree of polymerization of chitosan oligomers, which is a contrary to the reported literature. The wood decay trial confirmed the antifungal activity of chitosan oligmers against basidiomycetes but highlighted the leachability of chitosan when exposed to water.
I Hussain, C Chittenden, T Singh

The use of C CP/MAS NMR in the chemical identification of decayed and undecayed, tropical timber species
1984 - IRG/WP 1224
13C CP/MAS NMR was found to be an extremely powerful tool for elucidating the chemical composition of Eucalyptus maculata, Pinus elliottii and Alstonia scholaris. The differences in lignin composition were different for each timber and discussed in relation to decay caused by soft-rot and white rot fungi. In particular the presence of syringyl and guaiacyl lignin types are discussed.
L E Leightley

Analysis of D-glucose metabolism of wood decay fungi using 13C-NMR and 13C-labeled substrates
2003 - IRG/WP 03-10475
D-Glucose metabolism is thought to be important during wood decay by fungi, not only for anabolic and catabolic purposes of central metabolism, but also as a potential source of peroxide required by extracellular peroxidases. There has been some confusion in the literature as to whether this peroxide-generating activity is of the glucose 1-oxidase or pyranose 2-oxidase (glucose 2-oxidase) type with various fungi or even within the same fungal species. Definitive classification requires accurate identification of the enzymatic products D-glucono-1,5-lactone and D-arabino-2-hexosulose (glucosone) with glucose 1-oxidase and pyranose 2-oxidase, respectively. We used 13C-NMR to distinguish these reactions starting with 13C-labeled glucose. The use of labeled substrates simplifies analysis and greatly increases detection sensitivity without requiring the isolation or derivatization of metabolites. We synthesized 13C-1-glucosone to study subsequent metabolism with crude enzyme preparations. Preliminary results with Phanerochaete chrysosporium are presented.
T H de Koker, M D Mozuch, P J Kersten

Effect of fungal degradation on the chemical composition of acetylated beech wood
2003 - IRG/WP 03-40267
This study investigated the impact of fungal attack on the chemical composition of acetylated wood. Beech wood acetylated to different degrees was exposed to decay by the white-rot fungus Trametes versicolor under solid-state fermentation conditions. Laboratory soil-bed assays were also conducted to study the degradation of acetylated wood by soft rot fungi and other soil-inhabiting microorganisms. Changes in the chemical composition of untreated wood and acetylated wood following exposure to fungal attack were examined by wet chemical analysis, as well as FT-IR and CP/MAS 13C-NMR spectral methods.
H Militz, Dong-won Son, L Gómez-Hernández, R Sierra-Alvarez

Tannin resin-boron associations: Leaching and biological resistance
2012 - IRG/WP 12-30587
The easy leaching of boron in wood preservation formulations has allowed to use this fungicide only for short term applications. The recently discovered adduct with flavonoids allows boron to resist longer periods of time within wood and consequently extend its life. Two different leaching treatments were compared and the fungal and termite decay was examined. The biological tests have shown extremely high resistance of the leached samples against both, fungus (Coriolus versicolor and Coniophora puteana). The resistance towards termites (Reticulitermes flavipes ex. santonensis) was also evaluated. A threshold concentration for the efficacy of boron as wood preservative was determined. Furthermore, the solid state 13C-NMR analysis of the tannin resin has permitted to prove the anchorage of boron to flavonoids.
G Tondi, S Wieland, N Lemenager, A Petutschnigg, A Pizzi, M-F Thevenon

Effect of acetylation on decay resistance of wood against brown-rot, white-rot and soft-rot fungi
1989 - IRG/WP 3540
Effect of acetylation on decay resistance of wood was investigated using wood blocks of Cryptomeria japonica, Pinus densiflora, Albizia falcata and Fagus crenata. Blocks were treated with uncatalyzed acetic anhydride for different lengths of time and exposed to Tyromyces palustris, Serpula lacrymans, Coriolus versicolor and unsterilized soil. The action of OH-radical on acetylated wood was also examined using Fenton's reagent. The enhancement of decay resistance by acetylation was revealed clearly for all cases of exposures but varying with fungal and wood species used. For a brown-rot fungus Tyromyces palustris, the weight loss reached almost nil in all woods at 20 WPG (weight percent gain) of acetylation, after the striking decrease from 10 to 15 WPG. For a white-rot fungus Coriolus versicolor, it was counted until 12-15 WPG in the perishable hardwoods used, but not in a softwood Cryptomeria japonica, even at 6 WPG. In cases of another brown-rotter Serpula lacrymans and soil burial, effect of acetylation was intermediate between Tyromyces palustris and Coriolus versicolor. Anti-degradation mechanism by acetylation was discussed, from these weight loss - weight gain relationships, and the IR-and 13C-NMR spectral analyses of fungus-exposed wood.
M Takahashi, Y Imamura, M Tanahashi

Preliminary study of the fungicidal and structural variability in copper naphthenates and naphthenic acids
1996 - IRG/WP 96-30114
Copper naphthenates, an oil-borne wood preservative listed by the American Wood-Preservers' Association (AWPA), is manufactured by complexing copper(II) with naphthenic acids. Prior to AWPA listing as a wood preservative, field experiments showed that copper naphthenates generally had good stability and were active against wood-destroying organisms. Recently, however, there have been reports of some copper naphthenate-treated poles rapidly failing. One possible explanation for the varying effectiveness could be that the structure, and resulting biological activity, of the naphthenic acids used to make copper naphthenate may vary. To test this hypothesis several naphthenic acids and copper naphenates were obtained and their fungicidal activity against three wood-destroying fungi measured. In addition, the chemical structure of the naphthenic acids were examined by proton- and carbon- NMR. Different activities were observed, especially against a copper-tolerant fungus. Some apparent correlations were seen between the fungicidal activity and chemical structures for the few samples studied.
T Schultz, D D Nicholas, L L Ingram Jr, T H Fisher

An investigation into the stability of TBTO in LOSP-treated radiata pine
1987 - IRG/WP 3459
Nuclear magnetic resonance (NMR) spectroscopy and reverse phase paper chromatography were used to characterise the organotin compounds found in radiata pine treated with bis (tri-n-butyl) tin oxide (TBTO). Preliminary results indicate that the preservative is remarkably unstable in wood after light organic solvent preservative (LOSP) treatment. Significant decomposition of TBTO occurs in a matter of hours. White crystalline material observed on the surface of treated wood was identified as tributyltin acetate (TBTA). Other tributyltin esters, dibutyltin ethers, and butyltin chlorides were also identified.
K J Archer, R Meder

The formation of organotin carboxylates in bis(tributyltin) oxide - treated Pinus sylvestris sapwood
1990 - IRG/WP 3618
Tributyltin compounds have been successfully used for many years as wood preservatives, although their chemical nature in timber have not been fully elucidated. This study by 119Sn and 13C NMR spectroscopy has shown that, on impregnation into Pinus sylvestris sapwood, bis(tributyltin) oxide, (Bu3Sn)2O, is rapidly converted to tributyltin carboxylates, Bu3SnOCO·R, via reaction with components of the wood resin. It is further suggested that the formation of these species is a prerequisite for the known disproportionation reaction which occurs in (Bu3Sn)2O - treated timber.
S J Blunden, R Hill

Extracellular layers of wood decay fungi and copper tolerance
1983 - IRG/WP 1180
Extracellular layers around the hyphae of brown, white and soft rot fungi have been examined using electron microscopy. These layers were isolated for identification. Particular interest was directed towards the extracellular layers of copper-tolerant soft rot fungi.
D M Francis, L E Leightley

The chemical analysis and biological evaluation of wood extractives as potential timber preservatives
1995 - IRG/WP 95-30090
Work involved the biological performance of water and organic solvent soluble extractives of four naturally durable wood species, namely; Matumi, Tamboti, Sneezewood and the Turpentine tree. These timber species are known to be naturally durable against termites and fungi (±25 to 35 years). The extractives were evaluated against termites and fungi using impregnated pine pencil stakes in field tests and soil burial trials over a 2 year period. C13NMR analysis of extractives isolated from the wood was carried out to try and identify the key chemical components which might impart durability with a view to prediction of new potential wood preservative formulations.
P Turner, D Conradie

The chemical nature of bis(tributyltin) oxide in Pinus sylvestris sapwood
1989 - IRG/WP 3508
Tributyltin compounds have been used for many years as wood preservatives. This study has provided, for the first time, an explanation for the previously reported dealkylation and/or volatilisation of the tributyltin species in, and from, Scots pine (Pinus sylvestris) sapwood. Thus, 119 Sn nuclear magnetic resonance studies have shown that, on impregnation into this timber, bis(tributyltin) oxide is rapidly converted to other tributyltin species, Bu3SnOX, and that these subsequently undergo disproportionation to Bu4Sn and Bu2Sn(OX)2 compounds. We have additionally demonstrated that Bu4Sn, so produced, is not substantive in Pinus sylvestris and is lost by volatilisation. Since the rate of disproportionation of the Bu3SnOX species should be dependent upon the nature of the X group, it should be possible to significantly affect, if not stop, this process by the use of alternative tributyltin fungicides, e.g. tris(tributyltin) phosphate or tributyltin methanesulphonate. However, tributyltin fungicides have been used successfully in wood preservation for at least 25 years. Therefore, it must be concluded that, even after disproportionation in timber, in service, sufficient preservative action is retained to prevent decay of wood under the conditions of natural exposure. Nevertheless, it is becoming evident from this work and from previous studies of the compatibility of tributyltin fungicides with synthetic pyrethroid insecticides, that, on chemical grounds, (Bu3Sn)2O should not be the preferred tributyltin preservative.
S J Blunden, R Hill

Solid state NMR study on pine wood degraded by brown rot fungus Gloeophyllum trabeum
1994 - IRG/WP 94-10067
Blocks of Pinus koraiensis wood were degraded by Gloeophyllum trabeum and examined by solid-state 13C NMR spectroscopy. Chemical compositions were estimated from relative signal aras. There was no evidence for preferential degradation of the noncrystalline cellulose which accounted for about 4% by weight of the wood. Loss of partly ordered cellulose on crystal surfaces exceeded the loss of crystal-interior cellulose. The proportion of the monoclinic ¦-beta crystalline form increased. The results were interpreted in terms of preferential degradation of crystallites with widths > 3 nm, mostly of the triclinic ¦-alpha form. The spectra showed evidence for loss of hemicellulose, particulary those associated with relatively sharp NMR signals suggesting some degree of molecular ordering, e.g., imposed by proximity to cellulose microfibrils. There was no detectable loss of lignin in the brown-rotted wood samples.
Yoon Soo Kim, R Newman

NMR T1 relaxation time as a non-destructive method for the study of decay in wood
1992 - IRG/WP 92-2406
The NMR spectroscopic technique of measuring the T1 spin-lattice relaxation times has been investigated for its potential in the detection of microbial decay in wood. The T1 NMR analyses were carried out on samples of Scots pine and European beech that had been exposed to decay and non-decay fungi representing each of the important groups colonising wood. Decay in the test material was also assessed by conventional weight loss methods for direct comparison with the NMR results. The results indicate that this NMR technique may provide a useful tool for the non-destructive evaluation of the molecular changes in wood resulting from fungal decay. Significant differences existed between the results obtained with decay and non-decay organisms allowing the two groups to be differentiated. The T1 relaxation results obtained for beech were more variable with greater scatter in the data groups than those for pine, this probably being due to the greater variation in tissue types in the beech. Further work is in progress on a larger population of material and to extend the study to include a related NMR spin-spin relaxation parameter T2.
P W McCormack, A E G Cass, R J Murphy

Preliminary observations on tributyltin treated Scots pine sapwood using 119Sn (Mössbauer and NMR) spectroscopic techniques
1984 - IRG/WP 3312
119mSn Mössbauer data are presented for bis(tributyltin) oxide, tributyltin ethanesulphonate, bis(tributyltin) carbonate and tris(tributyltin) phosphate, both in the pure form and in Scots pine sapwood. The structures proposed for these compounds, in the solid state, are supported by 119Sn nuclear magnetic resonance spectroscopy.
R Hill

An unusual soft-rot decay pattern caused by the Ascomycete Hypoxylon mediterraneum (de Not.) J Miller
1984 - IRG/WP 1222
A distinct pattern of soft-rot decay has been observed for the fungus Hypoxylan mediterraneum (de Not.) J. Miller. This fungus also produced decay patterns typical of brown and white rot decay. The production of characteristic cavities by Hypoxylan mediterraneum was prolific in the hardwoods Eucalyptus maculata and Eucalyptus regnans, but infrequent in the softwoods, Pinus elliottii and Pinus radiata. The chemistry of this decay was investigated using carbon-13 nuclear magnetic resonance (13C-NMR). This technique produced results valuable to the understanding of the timber decay activities of Hypoxylan mediterraneum.
D M Francis, L E Leightley

The action of siderophores isolated from Gloeophyllum trabeum on the structure and crystallinity of cellulose compounds
1991 - IRG/WP 1479
Low molecular weight, high affinity iron-binding compounds (siderophores) were isolated from the brown-rot fungus Gloeophyllum trabeum. The compounds were shown to be inducible by iron starvation and could be purified by ultra-filtration, ethyl acetate extraction, column chromatography and preparative HPLC. The isolated compounds were shown by analytical and immunological techniques to be produced in both culture and in degraded wood. GC-mass spectroscopy and NMR allowed characterization showing their phenolate nature and molecular mass. The chelators are capable of cleaving selected cellulose model compounds and preliminary results suggest siderophores may be able to effect the percent crystallinity of milled poplar wood. Siderophores, together with other non-enzymatic factors, may function as readily diffusible agents catalyzing the initial degradation of wood cell walls.
J Jellison, V Chandhoke, B Goodell, F Fekete, N Hayashi, M Ishihara, K Yamamoto

Quantification of methylene bis thiocyanate in wood and its effect on a sapstain fungus Ophiostoma floccosum
2006 - IRG/WP 06-10591
The mobility and concentrations of MBT at different depths of wood billets (200 mm long, 40 mm in diameter) were determined using NMR spectroscopy and ICP-ASE, and then correlated the effect of wood MBT concentrations on growth of O. floccosum in a bioassay using stereomicroscopy and confocal laser scanning microscopy (CLSM). The 13C NMR spectra showed the presence or absence of MBT in wood but was unable to detect small concentrations. ICP-ASE however, produced quantitative data across the depth (40 mm) of the wood billets tested. Within 7 days of storage, MBT penetrated from surface to pith but showed significantly higher concentrations of MBT in surface wood compared to pith wood. Present study highlighted the benefit of using CLSM for fungal detection in wood. The information obtained from the ICP-ASE and the CLSM analysis suggested that to inhibit growth of O. floccosum, the MBT concentration needs to be greater than 55 ?g/g of dry wood. Due to its high detection capacity, ICP-ASE is identified as an excellent tool for MBT detection and quantification in wood.
T Singh

Discovering anti-fungal agents in New Zealand native plants for use in wood protection
2009 - IRG/WP 09-10692
Extracts from Hinau (Elaeocarpus dentatus) leaves were tested in the laboratory for antifungal activity. In addition, the anatomical structure of the leaf was also examined by a combination of light and scanning electron microscopy. Chemical characterisation of the extracts and investigation into potential use of its components for wood protection is underway. A combination of light microscopy (LM) and scanning electron microscopy (SEM) proved most effective for examining the tissue composition, particularly in differentiating the distribution of lignified tissues relative to non-lignified tissues after staining freshly cut leaf sections with phloroglucinol-HCl stain, which specifically stains lignin in cell walls. In-vitro bioassay results showed antifungal activity of Hinau extracts against two brown rot fungi, Oligoporus placenta and Coniophora puteana. NMR spectra of the Hinau extracts indicated mixtures of aromatic substances, showing chemical shifts consistent with ellagitannins and/or gallotannins with minor contributions consistent with flavonoids. The identity of the bioactive component remains unknown.
C Rickard, T Singh, A Singh, R Newman

New insights from NMR, FTIR, X-ray diffraction and physical chemistry into digestive processes in the wood-boring marine crustacean Limnoria quadripunctata
2010 - IRG/WP 10-10732
This paper summarises preliminary findings of a multi-technique exploration of the degradation of lignocellulose in the marine isopod Limnoria quadripunctata. Scanning electron microscopy revealed connections between the digestive gland and the hindgut that would permit the exchange of fluids between the two organs while the food mass is retained in place within the hindgut. This enables enzymes to be delivered to the substrate and breakdown products to be absorbed. FTIR and X-ray diffraction were used to show changes in wood chemistry during digestion. Cellulose crystallinity appears reduced after digestion, but lignin structure appeared little changed. NMR spectroscopy of animals under various feeding regimes measured the generation of breakdown products and levels of metabolites. Glucose was detected as a direct result of the animals feeding on 13C-labelled straw. This is the first direct evidence of total cellulose breakdown to the monomer. The importance of oxygen levels during digestion was shown by direct measurement with microelectrodes and indirectly by observing feeding on substrates impregnated with anti-oxidants. The hindgut lumen was found to be relatively anoxic. The antioxidant BHT significantly reduces feeding rates under laboratory conditions. These findings taken together give a picture of the effects of the activity of the recently described suite of digestive enzymes on their substrate.
G P Malyon, S LaBarre, N Kervarec, P Carey, J McGeehan, X Xie, A Klüppel, S M Cragg

Measurement of Cell Wall Moisture in Acetylated Radiata Pine Using Low-Field Nuclear Magnetic Resonance
2016 - IRG/WP 16-20583
Understanding the interaction of water with acetylated wood is necessary to explain how the protective mechanism of acetylation functions. Low-field nuclear magnetic resonance is one technique for assessing water in wood. Pinus radiata earlywood sapwood samples were acetylated to various weight percentage gains and then analysed with this method. Increased levels of acetylation showed significantly increased T2 relaxation times for free water, indicating that the free water is less restricted. This can be explained by the increase in hydrophobicity of the acetylated cell wall. The fiber saturation point (FSP) was determined using the signal from the cell wall water. The FSP of unmodified samples was 43 ± 2% moisture content and increased levels of acetylation significantly decreased FSP. At high weight percentage gain (~22%) the FSP was 16%, below the 20% threshold for fungal degradation to occur.
H G Beck, C A S Hill

Effect of Particle Size on Wax Distribution in Paraffin Wax Emulsion Impregnated Wood
2017 - IRG/WP 17-40779
Paraffin wax emulsion impregnation has been a common eco-friendly approach for improving water repellency of wood. In this study, southern pine (Pinus spp.) and Scots pine (Pinus sylvesteris L.) samples were impregnated with paraffin wax emulsions of different solid contents and particle sizes, and then the time domain nuclear magnetic resonance (TD-NMR) was used to elucidate the influence of particle size on wax distribution and penetration in treated wood. The linear relationship between mass and T2 relaxation peak area of the weight of paraffin wax was built, demonstrating a good correlation (R2=0.9808) between wax content determined by TD-NMR and weight percent gain (WPG) determined by gravimetric method, which confirmed that the TD-NMR analysis was an efficient method for reliable determination of wax content in different parts of wax treated wood. According to wax loading and distribution, southern pine samples showed much better permeability than Scots pine samples. With the decrease of particle size, the penetration of wax emulsion increased for both species. The water contact angles on the surface at different depth of wood were also determined, and the result was consistent with the wax distribution investigated by the TD-NMR analysis. The paraffin wax emulsions with small particle size (smaller than 320nm) mentioned in this study were suitable to improve the hydrophobicity of southern pine. However, wax emulsions with further smaller particle size should be developed for Scots pine modification.
Wang Wang, Jinzhen Cao, Yiheng Huang

Water interactions in wood polyesterified with sorbitol and citric acid
2020 - IRG/WP 20-40888
Polyesterifcation of wood with sorbitol and citric acid seems to be a promising chemical wood modification technique that is both low-cost and produced from bio-based chemicals. An interesting aspect of the modification is the interaction of water with the polyesterified wood since the relationship with moisture appears to be unique compared to other wood modification systems. This communication paper presents preliminary results from trials assessing the effect of weight percentage gain (WPG) on swelling properties and water saturated low-field NMR (LFNMR) spectra. Bulking coefficients indicated that the sorbitol-citric acid polymer penetrated the cell wall and higher WPGs led to greater bulking coefficients. Surprisingly, anti-swelling efficiency decreased with increasing WPG. This was due to an increase in water saturated volume at high WPG which suggests the modification alters the structure of the cell wall in a way that allows it to swell beyond its original volume. LFNMR spectra showed the development of a new peak with increasing WPG which may be attributed to water associated with the hydrophilic sorbitol-citric acid polymer.
G Beck, A Treu, E Larnøy