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The effect of low molecular weight chelators on iron chelation and free radical generation as studied by ESR measurement
2000 - IRG/WP 00-10367
The focus of this work was to improve our current knowledge of the non-enzymatic mechanisms involved in brown-rot decay. Electron Spin Resonance (ESR), also known as Electron Paramagnetic Resonance (EPR), is an attractive technique for the identification and study of chemical species containing unpaired electrons (such as radicals and certain transition metal species). ESR spin-trapping techniques are also commonly used to study very reactive and short-lived free radical species. It has been proposed that low MW chelators as well as Fenton reagents are involved in wood brown-rot decay, at least in early non-enzymatic stages. In this work, the binding between a chelator model compound and ferric iron was studied by ESR spectroscopy. The effects of the chelator model compound, Fenton reagents, as well as the reaction conditions on free radical generation were also studied using ESR spin-trapping techniques. The results indicate: 1. The relative amount of ferric iron bound to chelators is directly related to the chelator / iron ratio in the system. The relative quantity of the chelator-iron complex can be determined by measuring the intensities of the characteristic g4.3 ESR signal. 2. The effects of the chelator/iron ratio, the pH, and other reaction parameters on the hydroxyl radical generation in a Fenton type system could be determined using ESR spin-trapping techniques. 3. Data support the hypothesis that superoxide radicals are involved in the chelator mediated Fenton processes.
Yuhui Qian, B Goodell


An electron spin resonance study of manganese changes in wood decayed by the brown-rot fungus, Postia placenta
1988 - IRG/WP 1359
Electron spin resonance (ESR) spectrometry was used to examine wood decay by the brown-rot fungus, Postia placenta. Wood slivers of Douglas-fir, white fir, redwood, sweetgum and yellow poplar were incubated for 4 weeks in custom-made quartz ESR tubes with or without Postia placenta. In all wood species without fungus, a weak partially resolved signal (about g=2, presumably due to manganese) was detected. No manganese-like signal was found in aerial hyphae of the fungus. Wood slivers with fungus had a smooth, well-resolved manganese signal with a larger amplitude than wood without fungus, indicating a larger amount of paramagnetic manganese. The ratio of amplitudes for slivers with and without fungus increased with incubation time, reflecting an accumulation of paramagnetic manganese during decay. Due to the nature of this closed system without culture media, the accumulation of paramagnetic manganese is most likely due to the change of wood manganese by the fungus.
B Illman, D C Meinholtz, T L Highley


The effect of a chelator mediated fenton system on activation of TMP fibres and decolorization of synthesized dyes
2004 - IRG/WP 04-50223
The purpose of this work is to improve our current knowledge of the non-enzymatic mechanisms involved in the brown rot degradation of wood, but also to study the potential applications of a chelator-mediated Fenton system in activation of wood fibers and decolorization of synthesized dyes. In this work, Electron Spin Resonance (ESR) spin-trapping techniques were used to study the generation of hydroxyl radicals in a mediated Fenton system. The activation of Thermal Mechanical Pulp (TMP) fibers was also evaluated by ESR measurement of free phenoxy radical generation on solid fibers. The results indicate that low molecular weight chelators can improve Fenton reactions, thus in turn stimulating the free radical activation of TMP fibers. However, the data also show that excessive and prolonged free radical treatment may cause the destruction of fiber phenoxy radicals. A mediated Fenton system was evaluated for decolorization of several types of synthesized dyes as well. The results show that, compared to a neat Fenton process, the mediated Fenton process increased the production of .OH species to increase the decolorization efficiency. The color of a dilute liquid dyes (Carta Yellow RW, Carta Yellow G, or Cartasol Red 2GF) was effectively reduced to a colorless level after 90 minutes of treatment at room temperature by a mediated Fenton process. In conclusion, this study demonstrates the potential for application, but also the complexity of free radical chemistry in biological materials, especially with regard to the chelation of transition metals and the interaction between free radicals. The complexity of the dyes is similar to that of some organic wood preservatives and may provide a means for remediation of preservative contaminants in soils.
Yuhui Qian, B Goodell, J Jellison


Studies of the mechanism of chromated-copper preservative. Fixation using electron spin resonance
1992 - IRG/WP 92-3701
Two softwoods and one hardwood species were treated with chromium trioxide, copper sulphate, chromated-copper wood preservative (CCA). The treated wood samples were analyzed during fixation by electron spin resonance (ESR). ESR spectra indicated that more than one Cr(V) species was generated from Cr(VI) soon after CCA treatment. The Cr(V) signal became strong within increased several hours followed by the gradual decay of Cr(V) accompanying with generation of single broad Cr(III) species. Cr(V) signal still remained at least up to six months after the treatment. ESR spectral parameters from Cu(II) signal consisted of a quadruplet at lower field with a unresolved absorption of higher field, suggesting a evidence of a dX²-Y² ground state of Cu2+ ions bound in inner-sphare complexes with "O4" ("O6") ligands arranged in square planar cordination (distorted octahedral) cordination. Cu(II) signal did not change significantly during fixation.
K Yamamoto, J N R Ruddick


The examination of preservative-treated radiata pine using electron spin resonance spectroscopy
1987 - IRG/WP 3423
Electron spin resonance spectroscopy (ESR) may be used to characterise the molecular environment of chemical species containing unpaired electrons. These species include free radicals, bi-radicals, point defects in solids, localised crystal imperfections and many transition metal ions. ESR has previously been applied to the examination of wood weathering or wood pyrolysis and now FRI and Massey University are collaborating on the use of ESR to characterise CCA-treated radiata pine. Samples examined to date have included Tanalith C-, Tanalith NCA-, and CuSO4-treated radiata pine. ESR spectra of treated wood give signals indicative of hydrated Cu2+ ions regardless of whether samples are examined in whole splinters or in ground form at room temperature or at -160°C. Comparison of the ESR spectrum of CuSO4-treated lignin with that of CuSO4-treated wood provided no evidence for copper complexation with lignin in treated wood.
D V Plackett, E W Ainscough, A M Brodie


Direct estimation of the durability of high-pressure steam modified wood by ESR-spectroscopy
2010 - IRG/WP 10-40508
Heat generated persistent free radicals have been detected by electron spin resonance measurement of thermally modified wood, prepared by high pressure superheated steam treatment. The specific density of these radicals have been correlated with the durability against basidiomycetes, as measured by the European standard EN113 test. In the lower range of specific radical densities, the found correlation has revealed non-specificity for six different wood species, for two different treatment intensities and within different tree zones. This result promises a great potential for electron spin resonance to estimate the durability of high pressure steam modified wood. It also provides evidence for an antioxidant mechanism, responsible for the durability enhancement in heat treated wood.
W Willems, A Tausch, H Militz


Biological test, AAS and EPR study of copper monoethanolamine complex with quaternary ammonium compounds as a wood preservative
2003 - IRG/WP 03-30321
Experiments were carried out on the wood preservative with a strong fungicidal activity based on Cu(II) carbonate, 2-aminoethanol (monoethanolamine) and quaternary ammonium compound (QAC). The object of the performed investigations was sapwood of Scots pine (Pinus sylvestris L.) treated with Cu-EA-QAC formulation. Mycological investigations were carried out according to EN 113 and EN 84 standards. The retention of the copper ions in the wood grows nonlinearly with concentration (in %) of the impregnating solution from 0,25 kg/m3 at 0.03% to 1,55 kg/m3 at 0.21% (i.e. nearly 6 times) whereas the copper leachability decreases 2,5 times from 15% to 6% in the same range. These results indicate good fixation of the copper to the wood and high leaching resistance. EPR results and computer simulations of the observed EPR spectra shows that in Cu-EA aqueous solution the Cu(EA)2(H2O)2 complexes exist and the main coordination plane is not destroyed in impregnating solution and in the wood. In Cu-EA-QAC-BA solution the Cu(EA)2(QAC)2 complexes appear whereas EPR spectra of the treated wood indicate coexistence of a few types of Cu-complexes. We have identified strongly fixed Cu(EA)2O2 and Cu(EA)2O complexes with oxygens atoms from wood functional groups.
B Mazela, I Polus, S K Hoffmann, J Goslar


Examination of preservative-treated Pinus sylvestris using electron paramagnetic resonance
1992 - IRG/WP 92-3710
EPR is currently being used to help elucidate the nature and extent of the chemical reactions occurring between wood and copper based timber preservatives. In the work reported here treated Scots pine samples were examined at room temperature and in the frozen state. Plots of the electronic parameters A|| vs. g|| were found to be a useful index of the electronic properties of the various formulations. Those containing copper bound to nitrogen could clearly be distinguished from chromated-copper and other nitrogen-free systems and the technique was extremely useful in the interpretation of spectra where a formulation generated more than one copper signal. In two of the nitrogen containing systems one of the forms of copper, identified as being bound to nitrogen was well fixed whereas the other form, not bound to nitrogen, was more leachable. In the chromated-copper formulations tested (CC and CCA) a small amount of the chromium was identified as a stable concentration dependent Cr(V) species (g = 1.974 - 1.978) which presumably disproportionates during leaching into Cr(III) and Cr(VI). In general, chromated copper formulations gave poor quality spectra in comparison to copper only formulations and this should allow the newer, chromium free preservatives to be more widely studied by EPR.
A S Hughes, R J Murphy, J F Gibson, A J Cornfield


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


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
J Bech-Andersen


Electron microscopic detection and chemical analysis of three-lamellar structures in wood-destroying fungi
1984 - IRG/WP 1240
In the course of transmission electron microscopical investigations of pine wood decay by various brown- and white-rot fungi extracellular three-lamellar structures (TLS) formed by the fungi were found in specimens stained with ruthenium red. These structures occured in the lumen of the wood cell surrounding the hypha at the outermost layer of the fungal cell wall. In the course of the investigations these structures were also detected in fungi cultivated with glucose on a rotary shaker, where they showed forms similar to tubuli and vesicles. The three-lamellar structures formed by the white-rot fungus Sporotrichum pulverulentum, which were contained in the outermost cell wall layer, were isolated by disintegration of the fungal pellet and subsequent digestion of the fungal cell wall by snail enzyme. It was found that these structures are resistant to the enzymatic digestion and are composed of 80 to 90% carbohydrates, mainly consisting of glucose monomeres, 5 to 10% proteins, containing 5 fractions with molecular weights between 30000 and 200000, and finally 5 to 10% lipids which do not contain any phospholipid.
R Foisner, K Messner, H Stachelberger, M Röhr


Comparative studies on the distribution of lignin and CCA elements in birch using electron microscopic X-ray microanalysis
1987 - IRG/WP 1328
The microdistribution of metal preservatives in treated wood has received considerable research over the last two decades. Despite this, little effort seems to have been made to try and correlate the distribution of CCA elements with respect to naturally occurring wood cell wall components in wood. In the present preliminary study an attempt is made to relate the distribution of lignin in-situ with that of CCA elements. For the study matched samples of Betula verrucosa were first either mercurized to specifically label the lignin or vacuum impregnated with a commercial 2% K33 CCA preservative solution. Thereafter using SEM-EDXA, the relative distribution of labelled lignin and CCA elements were compared for both different cell types and cell wall regions. Results showed the relative microdistribution of CCA to follow closely that of the lignin distribution. Regions showing high lignin levels showed high CCA levels and vice-versa. Highest CCA and lignin levels were recorded in the vessel, fibre and ray middle lamella cell corners regions while the lowest levels were detected in the fibre (S2) secondary walls. Both the low lignin level (and syringyl type) and CCA uptake in fibre S2 walls would seem in close agreement with the known high susceptibility of these elements to soft rot attack in both treated and untreated birch. Comparisons made between the lignin content of the S2 layer for birch fibres and other known soft rot resistant species (e.g. Alstonia scholaris) showed great differences, with the latter showing much higher lignin (ca 3x) levels.
G F Daniel, T Nilsson


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


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


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 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


Novel observations on the micromorphology of soft rot attack of wood
1996 - IRG/WP 96-10176
Electron microscopic examinations of decaying Pinus radiata horticultural posts which had been treated with CCA preservative prior to being placed in service about nine years ago showed the presence of soft rot fungi and tunnelling bacteria. Some novel observations on the micromorphology of the soft-rotted areas of tracheid walls are described here. The micromorphology of soft-rotted areas was highly variable. In some areas soft rot cavities were associated with little or no dense residues, whereas in other areas a considerable amount of dense residues was seen around cavities. The dense soft-rotted regions appeared regular in some cases but irregular in others, depending upon the extent to which the tracheid wall around soft rot cavities had been modified. The observed morphological appearance of soft-rotted zones suggests that the initial fungal activities during soft rot attacks of wood cell walls may involve production of molecules small enough to diffuse through the microcapillaries of lignified walls, and in this respect some types of soft rot attack appears to be similar to brown rot attack.
A P Singh, R N Wakeling


EELS (Electron Energy Loss Spectroscopy) - a technique for quantification of nitrogen and other light elements in the cell wall
1999 - IRG/WP 99-20163
A literature survey was performed to find progress in techniques for monitoring penetration of synthetic resins in wood cell walls. Electron energy loss spectroscopy (EELS) in combination with transmission electron microscopy (TEM) was successfully applied for the high resolution examination of the distribution of a partly methylated hydroxymethyl melamine resin in Norway spruce (Picea abies Karst.) earlywood cell walls. The nitrogen of the resin was found as clearly detectable signals in all layers of the lignified cell wall, thus allowing the quantification of resin which had penetrated into the different layers.
A O Rapp, H Bestgen, W Adam, R-D Peek


An investigation of organotin compounds in treated wood using Mössbauer spectroscopy
1983 - IRG/WP 3249
The influence of sample preparation on the 119mSn Mössbauer spectrum of tributyltin chloride in ponderosa pine was investigated. Initial studies with sawdust and compressed discs concluded that the latter were clearly superior. Further studies showed that compressed discs prepared from 0.4 g of treated wood and 0.1 g of cellulose were robust and gave excellent Mössbauer spectra. The possibility of improving the Mössbauer resonance by increasing the solution concentration was evaluated, and found to be beneficial, with no change in the fixation process being evident at least up to 6.9% solution strength. Wooden cores were assessed as alternative test material since they are less prone to disintegration. The Mössbauer spectrum of tributyltin chloride in wood was obtained and analyzed with the aid of point charge calculations. It was concluded that when impregnated into wood, tributyltin chloride either remains polymeric with bridging chlorides or adopts a mer-trigonal bipyramidal geometry with hydroxyl donor bonding from the cellulose. Investigation of tributyltin-, dibutyltin- and monobutyltin-chlorides following impregnation into wood suggested that, while the monobutyltin-derivative may be easily identified when present, it is doubtful whether the tributyltin- and dibutyltin- complexes will be distinguishable using simple Mössbauer spectroscopy. Modifications were therefore proposed for the technique which would allow the triorgano- and diorganotin species to be identified when present as mixtures in wood.
J N R Ruddick, J K Ingram


The compatability of tributyltin fungicides and synthetic pyrethroid insecticides as wood preservatives
1987 - IRG/WP 3414
The stability of three synthetic pyrethroids, cypermethrin, deltamethrin and permethrin, to selected tributyltin compounds, Bu3SnX {where X = OSnBu3, Cl, 02CC6H5, O2C (Naphthenyl), OSO2Et}, (Bu3SnO)3PO and {NBu4} {Bu3SnCl2}, in toluene solution was investigated by infra-red spectroscopy over a six month period. It was found that only (Bu3Sn)2O reacted with the pyrethroids and that their order of reactivity was cypermethrin > deltamethrin > permethrin. An attempt was made to elucidate the reaction mechanism(s) occurring between (Bu3Sn)2O and the pyrethroids by studying mixtures of this tributyltin fungicide with simple model compounds, R1CO2R2 where R1 = CH3; R2 = CH2C6H5 and R1 = cyclo - C3H5 and R2 = CH2C6H5.
S J Blunden, R Hill


A light and electron microscopic study of decayed CCA-treated radiata pine (Pinus radiata) wood from a cooling tower
1994 - IRG/WP 94-10056
An inspection of an industrial cooling tower in New Zealand showed surface decay of 12 year old Pinus radiata wood panels treated with CCA preservative to a retention of around 15 kg/m³ of salt. Wood decay micromorphology typical of that caused by soft rot fungi, white rot fungi, 'stripy' and 'v-shaped' erosion bacteria and cavitation bacteria were all commonly seen using a light microscope (LM). Some evidence of the presence of tunnelling bacteria was also seen but was not as common. Soft rot was largely absent from the wettest regions sampled such as spray-line supports and side panels in close proximity to the spray lines, and erosion bacteria attack was the predominant type in these areas. Transmission electron microscopy (TEM) showed that unusual patterns largely consisting of troughs, depression and granulations in wood cell walls, were in most instances, almost certainly caused by erosion bacteria, but in others, tunnelling bacteria were also present. Several decay patterns seen under light microscope as matrices of fine troughs parallel and perpendicular to the cellulose microfibres were difficult to characterise in terms of previous classification but were also thought to have been caused by erosion bacteria. The distinction made by previous classification between patternms formed by erosion and cavitation bacteria needed to be questioned on the basis of observations made. Whilst the TEM showed that erosion and tunnelling bacteria were often present in close association within the wood cell walls, light microscopy suggested that, in the majority of section examined, all the types seen were clearly seperated by regions of undegraded cell wall. The observations underscore the importance of erosion bacteria in wood decay under the conditions of a cooling tower where in-service timbers are kept constantly wet by the spray from water sprinklers. Also of significance is the great diversity of decay types seen, in particular the presence of cavitation bacteria and white rot fungi has not previously been recorded for high retention CCA treated cooling tower timbers.
A P Singh, R N Wakeling, D R Page


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


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