Your search resulted in 192 documents. Displaying 25 entries per page.
Copper nanoparticles in southern pine wood treated with a micronised preservative: Can nanoparticles penetrate the cell walls of tracheids and ray parenchyma?
2010 - IRG/WP 10-30547
This study tests the hypothesis that copper nanoparticles can penetrate the cell walls of southern pine wood treated with a micronised preservative. We examined the nanodistribution of particles in tracheid and ray parenchyma cell walls using state-of-the-art HR (High Resolution)-TEM and HR-STEM (Scanning Transmission Electron Microscope)-EDX. These devices are capable of atomic-scale resolution. FIB (Focused Ion Beam) processing was used to make ultra-thin sections for electron microscopy. Our results show that FIB sectioning in combination with HR-TEM and HR-STEM is a powerful tool for observing the penetration of wood cell walls by nanoparticles or clusters of metal atoms. HR-STEM with a Cs corrector revealed that copper carbonate nanoparticles could not penetrate the cell walls of tracheids. Copper, however, is present in cell walls of tracheids as atoms or ions. In contrast, small copper nanoparticles (2.5 nm in diameter) were able to penetrate ray parenchyma cell walls. These particles were identified as copper carbonate by HR-TEM lattice image analysis. We conclude that the cell walls of unlignified ray parenchyma tissue in southern pine are accessible to copper nanoparticles whereas nanoparticles are excluded from lignified tracheid walls.
H Matsunaga, Y Kataoka, M Kiguchi, P Evans
Accessibility of Wood Cell Walls to Well-defined Platinum Nanoparticles
2012 - IRG/WP 12-20494
Copper nanoparticles are found in the walls of parenchyma cells in southern pine sapwood treated with a micronised wood preservative, but they are absent from tracheid walls. Hence, we hypothesized that small nanoparticles can penetrate the walls of unlignified parenchyma cells, but are excluded from lignified tracheid walls. This paper tests this hypothesis by treating pine sapwood with an aqueous emulsion of coated, inert, platinum nanoparticles (2-4 nm). A focused ion beam was used to make ultra-thin sections of the cell wall layers of earlywood tracheid and ray parenchyma cells excised from treated southern pine sapwood. High resolution transmission electron microscopy and high-angle annular dark-field scanning transmission electron microscopy in combination with energy dispersive analysis of x-rays were used to examine the penetration of cell walls by platinum nanoparticles. Platinum nanoparticles were only deposited on the wall adjacent to the cell lumen of tracheids and were not detected in the cell wall. In contrast, platinum nanoparticles penetrated ray parenchyma cell walls. These particles were identified as crystalline (metallic) platinum by lattice image analysis in high resolution transmission electron microscopy. Therefore we conclude that small nanoparticles (2-4 nm) are able to penetrate ray parenchyma cell walls, but are excluded from lignified tracheid walls.
H Matsunaga, Y Kataoka, M Kiguchi, P D Evans
SEM of wood dust particles
1997 - IRG/WP 97-50084
Dust particles from beech and oak trees have been classified in Germany as being "working materials which are definitely carcinogenic to humans". All other wood dusts, including those from softwoods, are classified as being materials "with reasonable suspicion of carcinogenic potential". The carcinogenic principle of action continues to remain unclear. The mechanical irritation is one of a number of possible triggering principles. In this connection the morphology of the dust particles is of decisive importance. With the aid of a scanning electron microscope this study characterises the dust from spruce, Scots pine, beech and oak. With regard to shape and size the dust particles of all sample collections were divided into 5 groups with principle structural similarity. Therefore a different particle morphology with correspondingly different mechanical irritation in the nose can not be the main principle of action. When compared to asbestos fibers, the small amount of fibrous dust particles as one of the five groups could be clearly distinguished by their structure and dimensions. Mechanical irritation as the main principle of action in the formation of malignant nasal tumors is also contradicted by the findings of different working groups which have established a strong association between hardwood dust and adenocarcinomas of the nasal cavity and paranasal sinuses, and a connection between softwood dust and other types of nasal carcinoma.
U Schmitt, R-D Peek, A O Rapp
The Relationship of Fiber Cell Wall Ultrastructure to Soft Rot Decay in Kempas (Koompassia malaccensis) Heartwoo
2004 - IRG/WP 04-10541
The ultrastructure of fiber walls in kempas (koompassia malaccensis) heartwood was examined in relation to soft rot cavity formation. The fibers consisted of middle lamella and thick secondary wall. The secondary wall was differentiated in to a S1 layer, and a unique multi-lamellar S2 layer. Two distinct forms of lamellae were recognisable, one type being considerably thicker than the other. They also differed in their electron density, the thin lamellae being much denser than the thick lamellae. It was not possible to determine whether a S3 layer also existed, because of the presence of a dense material coating the lumen wall, which obscured the definition of this region of the fiber wall. The resistance to soft rot varied with different regions of the fiber wall, middle lamella being completely resistant and the thick S2 lamellae least resistant. The observed relationship between the ultrastructure of these fiber wall regions and the degree of their resistance/susceptibility to soft rot cavity formation is discussed.
A P Singh, A H H Wong, Yoon Soo Kim, Seung-Gon Wi
Termite and fungal resistance of in situ polymerized tributyltin acrylate and acetylated Indonesian and USA wood
2000 - IRG/WP 00-30219
Wood [Indonesian pine (IP), Indonesian Jabon (IJ) and USA southern yellow pine (USP)] was either in situ polymerized with tributyltin acrylate (TBTA) or acetylated and then exposed to termite and fungal degradation both in laboratory tests and field exposure. The TBTA woods had an average weight percent gain (WPG) of 11% for IP, 12% for IJ, and 10% for USP. The acetylated woods had a WPG of 15-27% for IP, 16% for IJ, and 12-21% for USP. All levels of TBTA and acetylation treatments were effective against the brown-rot fungus Tyromyces palustris and the white-rot fungus Coriolus versicolor in laboratory testing. Resistance to subterranean termites [Coptotermes gestroi (Wasmann)] and dry wood termites [Cryptotermes cynocephalus (Light)] was shown in laboratory tests with all treatments. After one year of field testing in Indonesia (AWPA Standard E7-93), TBTA treated specimens gave a grade number of 8 for all 3 woods compared to 0 for the untreated controls (based on a 10 - point scale.) The acetylated specimens gave a grade number of 4 for IP, 8 for IJ, and 6 for USP. Scanning electron microscopy (SEM) showed polymer located in the lumen of the earlywood and latewood of selected TBTA treated specimens, but at low overall polymer weight gain the lumens were not evenly filled. Termite field testing continues on all treated wood specimens.
R E Ibach, Y S Hadi, D Nandika, S Yusuf, Y Indrayani
Studies of the ray parenchyma cell ends on the radial flow of Sitka spruce (Picea sitchensis)
2000 - IRG/WP 00-40164
It is widely accepted that either ray tracheids or ray parenchyma cells offer the major flow pathways radially for the impregnation of softwood with preservative chemicals. It is now generally recognised that, if radial flow does occur through ray parenchyma cells, the cross-field pits play a dominating role for the liquid movement in the radial direction. In this case, the radial flow of fluid is through the ray parenchyma cells to the longitudinal tracheids across cross-field pit apertures and then back again to the other ray parenchyma cells. It is in this context that cross-field pits which favours flow in the radial direction via a longitudinal route, and thus gives a long path length for radial flow. However, the presence of small channels (i.e. simple pits) between the two ray parenchyma cells may also have a recognisable influence on the radial flow, and exceed the continuous pathway for liquid movement. In this study, therefore, the anatomical structure (the end platform angle, the number of the simple pits per ray parenchyma cell end, their dimensions and the changes in dimensions across growth rings) of the ray parenchyma cell ends have been examined by scanning electron microscope (and microscopic images were then analysed by image analyser) to explain the differences in radial permeability between the extremes in the radial treatment data.
Micro-Distribution of Metals in Wood Treated with a Nano-Copper Wood Preservative
2007 - IRG/WP 07-40360
The microdistribution of copper in southern pine treated with a newly-developed nano-copper wood preservative was examined to determine if it differed from that reported for wood treated with conventional copper-based wood preservatives. Field Emission Scanning Electron Microscopy (FE-SEM) in combination with x-ray microanalysis (EDX) revealed the presence of nano-sized copper and iron particles in treated wood. These particles ranged in size from 10 to 700 nm and were abundantly present in pit chambers and on tertiary wall layers adjacent to the lumens of tracheids and ray parenchyma cells. FE-SEM and EDX clarified that copper and iron was mainly present as separate particles. Copper was also found in wood cell walls where its concentration was slightly higher in the middle lamella than in the secondary wall layer. In this respect the microdistribution of copper in wood treated with nano-copper resembles that observed in wood treated with conventional copper-based wood preservatives. However, the presence of numerous particulate deposits of copper in voids within the wood creates a different microdistribution pattern for copper in wood treated with the nano-copper preservative compared to that observed in wood treated with current copper-based wood preservatives.
H Matsunaga, M Kiguchi, P Evans
Micro-Distribution of Micronized Copper in Southern Pine
2008 - IRG/WP 08-30479
For copper-based preservatives to be used in ground contact, penetration of copper into the cell wall is believed to be important to protect the wood from soft rot fungi. Preservatives containing soluble copper are known to do this. It is not known whether preservatives containing particulate copper will also migrate into the cell wall in sufficient quantities to control soft rot decay. An AWPA standard E11 leaching test found that leachate from southern pine blocks treated with a preservative containing particulate copper (Micronized copper quat) contained copper ions, suggesting that copper-containing particles in the treated wood slowly release mobile copper. Southern pine sapwood samples treated with wood preservatives containing soluble (ACQ-D) and particulate copper (Micronized copper quat), as well as untreated southern pine sapwood, were analyzed by Environmental Scanning Electron Microscopy (ESEM) and Energy Dispersive X-Ray Spectrometry (EDS). Copper was detected in the lumens of wood treated with both preservatives, and not in the untreated control. Moreover, the presence of small amounts of copper in the cell walls of samples treated with Micronized copper quat and ACQ-D was indicated by ESEM and EDS. This was further supported by the results of a fungal cellar test and a field stake test which demonstrated that wood treated with Micronized copper quat is resistant to soft rot attack. Future work will investigate copper mobility from particles lodged in the lumens.
R Stirling, J Drummond, Jun Zhang, R J Ziobro
Re-Distribution of Copper in the Cell Walls of Wood Treated with Micronized Copper Quat
2009 - IRG/WP 09-30506
Wood treated with copper-based preservatives to be used in ground contact may fail to inhibit soft rot fungi if penetration of copper into the cell wall is insufficient. Preservatives containing soluble copper are known to penetrate the cell wall; however, it is not known whether preservatives containing particulate copper will also migrate into the cell wall in sufficient quantities to control soft rot decay. A method was developed to accelerate and detect re-distribution of copper into the cell wall. Copper was found to re-distribute into the cell wall, presumably from cell lumen deposits, in both ACQ- and micronized copper quat-treated samples after exposure to high temperature and relative humidity. In a non-accelerated test, copper was not found to re-distribute into the cell wall in either ACQ- or micronized copper quat-treated samples after exposure in soil at 15°C for eight weeks.
R Stirling, J Drummond
Study of Microscopy Properties of Modified Wood During Weathering Process
2010 - IRG/WP 10-40517
In this study spruce (Picea excelsa) and Beech (Fagus orientalis) wood acetylated and has been subjected of artificial weathering in difference times (0, 50,150&300 h), then wood surface analyzed using Scanning Electron Microscopy (SEM). The SEM results shown that the surface of wood exposed to weathering undergoes distinct physical changes and the surface degradation appears to be directly proportional to the time of exposure to the weathering conditions. Changes were minor in samples weathered after 50 h. Physical changes after weathering in acetylated samples lower than un treated samples. SEM observation visualized the formation of the large surface check along the fiber lengths in the un treated specimens, but checks were dispersed over the surface with small sizes in the treated ones. The changes observed in the SEM of the surfaces after acetylated Beech and Spruce wood samples were subjected to 150 and 300h weathering are minor compared with untreated wood samples. physical changes (surface checks and color) in Beech wood is lower than spruce wood. Acetylation of the wood servers to protect the surface from the weathering effect of light and water.
Decay resistance of a commercial pistachio twig-plastic composite
2011 - IRG/WP 11-40553
In this research, the decay resistance of commercial extruded pistachio twig flour-plastic composite was investigated against the white-rot fungi Trametes versicolor and the brown-rot fungus Coniophora puteana. The composite specimens containing 60% pistachio twig flour were exposed to a decay test according to modified ASTM standard for 3 months. The results showed that the composite could be decayed by the fungi. The weight loss of the composite due to decay by C.puteana was noticeably higher than that for T.versicolor. By employing scanning electron microscopic (SEM) studies, cracks and voids in the control (unexposed samples), and hyphae penetration in the sample decayed by C.puteana were shown.
M R M Farahani, M Safarzadeh
Use of Variable Pressure Scanning Electron Microscopy for in situ Observation of Degradation of Wood Surfaces during Artificial Weathering
2012 - IRG/WP 12-20489
Variable pressure scanning electron microscopy (VPSEM) is capable of observing electrically non-conductive materials like wood without the need to render the surface conductive by applying a coating of gold, platinum or carbon. Hence, there is the possibility that VPSEM could be used to non-destructively follow the structural changes occurring at wood surfaces during weathering, because specimens can be observed initially (before weathering), and then re-examined after exposure to the weather. This study uses VPSEM to examine the time-dependent micro-structural changes occurring at untreated and treated wood surfaces exposed to artificial weathering. Cryptomeria japonica (sugi) sapwood was treated by grafting a UV absorber (UVA) to the wood. We compared the micro-checking of bordered and half-bordered pits at treated (grafted) and untreated wood surfaces exposed to weathering. We hypothesised that the grafting treatment would restrict micro-checking of pits. VPSEM revealed significant micro-checking of pits at untreated surfaces exposed to artificial weathering for only 30 h. The dimensions of pit micro-checks increased when untreated samples were exposed to weathering for an additional 30 h. Pit micro-checking occurred more slowly in sugi sapwood treated with a UV absorber. We conclude that pit micro-checking at wood surfaces exposed to artificial weathering is restricted by grafting a UVA to the wood. We further conclude that VPSEM is a valuable tool to follow the time-dependent micro-structural changes occurring at wood surfaces exposed to weathering.
F Hatae, Y Kataoka, M Kiguchi, H Matsunaga, J Matsumura
Scanning Transmission X-ray Microscopy as a tool for examining chemical changes in wood cell walls due to enzymatic activity
2014 - IRG/WP 14-20556
As development of techniques for examining enzymatic activity on solid, complex biological materials, is considered to be an important factor in further development of enzyme applications and for understanding the decay of plant materials, this study explores applicability of Scanning Transmission X-ray Microscope (STXM) for determining chemical changes in enzymatically treated samples at the cell wall level. STXM was an instrument of choice for the study due to its capability to differentiate organic compounds at a spatial resolution comparable to an electron microscope. By treating aspen slivers with solutions of either individual or mixtures of enzymes, we confirm the synergistic activity of laccase and xylanase enzymes, and indicate possibility of penetration of small enzymes into the cell wall structures.
D Jeremic, R Goacher, R Yan, C Karunakaran, E R Master
Modern Instrumental Methods to Investigate the Mechanism of Biological Decay in Wood Plastic Composites
2014 - IRG/WP 14-40674
Various instrumental techniques were used to study the fungal decay process in wood plastic composite (WPC) boards. Commercial boards exposed near Hilo, Hawaii (HI) for eight years in both sun and shadow locations were inspected and tested periodically. After eight years of exposure, both boards were evaluated using magnetic resonance imaging (MRI), while a selected area of the board exposed in shadow was additionally tested using microscopy and micro x-ray computed tomography (CT). Experimental boards exposed to either exterior conditions in Vancouver, British Columbia (BC) or a laboratory decay process were used for verification of MRI and CT results obtained from the commercial board. MRI detected the presence of free water and its distribution in the exposed commercial board samples tested. Fibre saturation in the experimental board was found to be about 22%, in comparison to 27 – 30% present in most wood species. There was good correlation between the detection of free water by MRI and by destructive testing. Reconstructed volumes from CT scans of the tested boards allowed for the WPC microstructure to be observed in various planes of view and for void analysis of the material to be conducted. A significantly higher average percentage volume of voids was detected in the exposed sample compared to its reference unexposed counterpart. CT scans and subsequent void analysis of the experimental soil block culture test samples of known weight loss in wood demonstrated this technique to be reasonably accurate in the detection of voids created due to biological decay. No obvious relationship was established between the presence of free water detected by MRI and the average volume of voids detected by CT. Scanning electron microscopy (SEM) confirmed the presence of fungal mycelia in the exposed commercial board cross-section imaged by both MRI and CT. It was confirmed that both MRI and micro CT could be used for non-destructive evaluations of WPC materials, including their decay process. This work also found that many different decay fungi species could colonize and internally damage WPC, and that fungal decay in WPC seems to be a self-propagating process requiring an initiation time period where no obvious decay damage is observed.
G Sun, R Ibach, M Gnatowski, J Glaeser, M Leung, J Haight
Development of a new characterization method to analyse Cypermethrin penetration in wood material by immunolabelling
2015 - IRG/WP 15-30674
The preservative efficacy of organic biocides is strongly related to their capacity of penetration and retention within wood tissues. The specific detection of the pyrethroid insecticide cypermethrin is currently obtained after extraction followed by chemical analysis by chromatography techniques. However visualizing the insecticide molecule within the wood structure requires specific probes together with microscopy techniques. Therefore, the aim of the present work was to apply a new methodology based on antibody-antigen recognition and electronic microscopy to visualize directly cypermethrin in wood material. A polyclonal antibody directed against cypermethrin was developed and implement it on Pinus sylvestris wood samples coated with technical cypermethrin. The antibody was tested on cypermethrin-impregnated wood and the specific recognition of the insecticide was visualized in transmission electron microscopy (TEM). The immunogold-TEM assay evidenced the capacity of the synthetic biocide to penetrate in the wood. The depth of penetration was measured on sections taken at increasing distances from the coated surface of the wood. In the present conditions of application, cypermethrin was shown to penetrate up to the 6-9 mm zone below the surface. Such results correlated with chemical analyses carried out by GC-ECD after extraction. In addition, the immuno-TEM investigation allowed visualizing, for the first time at the ultrastructure scale of resolution, that cypermethrin was able to diffuse within the secondary wood cell walls. The scarce labeling of the compound middle lamella shows that the chemical does not diffuse freely in this part of the cell walls. The results suggest that the adsorption within the cell walls is an essential factor of the retention of cypermethrin and of its permanence in wood-treated materials and products.
S Tapin-Lingua, K Ruel, J-P Joseleau, D Messaoudi, O Fahy, M Jequel, M Petit-Conil
Investigation of enzymatic effect on pit membranes by light and scanning electron microscopy
2016 - IRG/WP 16-40721
Spruce wood, one of the refractory wood species has pit membranes, which has an influence on the permeability of wood providing liquid flow between the wood cells. However, these membranes tend to close under the fiber saturated point (FSD), which makes impregnation more difficult. In this study spruce sapwood samples were treated with two different commercial enzymes to improve the permeability of spruce sapwood. Bioprep 3000 L and Viscozyme L, which are mostly used in the textile industry, are alkaline pectinase enzymes as well as acidic pectinase enzymes, respectively. Following enzymatic treatment, wood samples were analyzed under by light microscopy (LM) and scanning electron microscopy (SEM). Primarily, all enzyme treated and untreated wood samples were stained with toluidine blue. The pectin material was coloured red with toluidine blue stain. However, enzymatic treatment caused red coloration loss along with expansion and rupturing of pit membranes. According to these results, pit membranes are known to be destroyed. As expected, the acidic pectinase enzyme degraded torus more so than the alkaline enzyme.
S Durmaz, Ü C Yildiz, M Öztürk, B Serdar
Environmentally Friendly Wood Modification based on Tannin-Furfuryl alcohol - Effect on stabilisation, mechanical properties and decay durability
2022 - IRG/WP 22-40929
Furfurylation is a well-known wood modification technology. This paper studied the effect of tannin addition on the wood furfurylation. Three kinds of dicarboxylic acids, adipic acid, succinic acid, and tartaric acid, as well as glyoxal as a comparing agent, were used to catalyse the polymerisation of furanic or tannin-furanic solutions during wood modification. Impregnation of furanic or tannin-furanic solution at a certain concentration into the wood followed with curing at 103°C for a specific duration was performed for the wood modification. Different properties of the modified woods like dimensional stability, resistance of treatment to leaching, mechanical properties, decay durability against white-rot (Coriolus versicolor, Pycnoporus sanguineus) and brown-rot (Coniophora puteana) as well as their chemical and anatomical characteristics were evaluated. Results revealed that the partial substitution of FA by the tannins improved the fixation of the chemicals impregnated in wood. Further, dimensional stability, leaching resistance, Brinell hardness, modulus of elasticity/modulus of rupture, and decay durability properties of the furfurylated wood were also improved in the presence of tannins. Scanning electron microscopy revealed the polymerisation of the polymer in the wood lumen cells and in the wood cell walls.
M Mubarok, E Azadeh, F O Akong, S Dumarçay, A Pizzi, C Charbonnier-Gérardin, P Gérardin
Confocal laser scanning microscopy of a novel decay in preservative treated radiata pine in wet acidic soils
1997 - IRG/WP 97-10215
Light microscopy of radiata pine (Pinus radiata D. Don) field test stakes (20x20x500mm3) exposed in wet acidic (pH 3-4) soil for 12 - 24 months showed predominance of an unusual type of decay characte-rised by tunnelling attack of wood cell walls. After two years decay was moderate to severe in wood treated to ground contact CCA specifications and also equivalent retentions of creosote, and a number of new generation preservatives. Relative to other New Zealand temperate test sites and also an Australian tropical site, the New Zealand acidic soil test site was very aggressive. Correlative scanning electron microscopy (SEM) and confocal laser scanning microscopy (CLSM) were used to elucidate the micromorphology of this attack. Tunnels of diameter 0.2-5 µm were present throughout all layers of the cell wall, and their orientation was not related to cellulose microfibril orientation. They also showed no preference for particular cell wall layers, indicating a lignin degrading capability. CLSM images showed that living, connecting fungal hyphae were present in the cell lumina and tunnels. This type of attack was predominant in wood that was highly saturated with water whereas wood that was less moist was predominantly attacked by classical white rot. Ongoing isolation and incubation studies in conjunction with further microscopy should enable identification of the fungal species involved.
R N Wakeling, Ying Xiao, A P Singh
Resistance of Alstonia scholaris vestures to degradation by tunnelling bacteria
1992 - IRG/WP 92-1547
Electron microscopic examination of vessels and fibre-tracheids in the wood of Alstonia scholaris exposed to tunnelling bacteria (TB) in a liquid culture showed degradation of all areas of the secondary wall. The highly lignified middle lamella was also degraded in advanced stages of TB attack. However, vestured pit membranes and vestures appeared to be resistant to degradation by TB even when other wall areas in Alstonia scholaris wood cells were severely degraded. The size comparison indicated vestures to be considerably smaller than TB, and we suspect that this may primarily be the reason why vestures in Alstonia scholaris wood were found to be resistant to degradation by TB.
A P Singh, T Nilsson, G F Daniel
The dry rot fungus and other fungi in houses. Part 2
1993 - IRG/WP 93-10001
Ultrastructural observations on wood-degrading erosion bacteria
1986 - IRG/WP 1283
G F Daniel, T Nilsson
Spatial arrangement of lignin peroxidase in pine decayed by Phanerochaete chrysosporium and Fomitopsis pinicola
1988 - IRG/WP 1343
By applying immunoelectronmicroscopic methods, lignin peroxidase of the white rot fungus Phanerochaete chrysosporium has been localized in the cytoplasm of hyphae, close to the plasmalemma and on the plasmalemma. Infiltration of wood specimen with culture filtrates, concentrated 300-fold, gave clear information on the penetration of the enzyme into the wood cell wall. Penetration was restricted to superficial areas. No diffusion of enzymes into the cell wall took place in white rot. Likewise, infiltration of wood. degraded by the brown rot fungus Fomitopsis pinicola, did not indicate free diffusion of the enzyme within the cell wall. This was taken as a proof of non-ezymatic cell wall degradation in brown rot.
E Srebotnik, K Messner
Occurrence of manganese deposits in test stakes exposed in groung contact situations
1996 - IRG/WP 96-10182
Dark spots and flecks were frequently recognized on the surface and within non-preservative treated hard- and softwood test stakes placed in soil contact. Energy dispersive X-ray microanalysis in conjunction with electron microscopy showed the flecks to be composed primarily of manganese dioxide. Detailed transmission electron microscopy observations indicated intrusion of manganese into the wood cell lumena and into areas of erosion, cavity formation and decayed middle lamella regions in wood cells attacked by fungi and/or bacteria. Distinct zones of apparent delignification were also noted in the secondary cell walls and middle lamella regions of attacked cells. Manganese is thought to play a major regulating role in both lignin depolymerization and minerialization in the presence of organic acids and has been reported previously in white rotted wood removed from standing trees. Present observations also suggest the uptake of manganese into wood stakes during microbial degradation results from biotic activity. Soil type appears to be of major significance.
G F Daniel, T Nilsson, J Volc
Importance of bacteria in the deterioration of archaeological woods
1995 - IRG/WP 95-10122
An electron microscopic study of archaeological woods from different sites and of different ages revealed that the woods had been attacked by erosion bacteria, tunnelling bacteria and soft rot fungi. Bacterial erosion appeared to be most widespread, and was present independently as well as together with tunnelling and soft rot attacks. Thus, in many instances bacterial erosion was the only type of microbial attack present. This work recognizes the important role bacteria play generally, and erosion bacteria particularly, in the deterioration of waterlogged archaeological woods.
Yoon Soo Kim, A P Singh, T Nilsson
The use of immunofluorescence labelling for detecting Ophiostoma piceae in radiata pine
1998 - IRG/WP 98-10268
The primary objective of the current investigation is to understand fungal interactions of dominant sapstaining fungi in radiata pine using confocal laser scanning microscopy (CLSM). In the current paper, an immunofluorescence labelling technique was developed for detection of Ophiostoma piceae using a monoclonal antibody. The primary antibody was labelled with Oregon green 514 Goat anti-mouse IgG fluorescent dye before examining with CLSM. The study showed that immunofluoresence labelling was achieved satisfactorily for detecting fungal hyphae of Ophiostoma piceae but not for some other important sapstaining fungi that occur in radiata pine.
Ying Xiao, B Kreber, C Breuil