Your search resulted in 79 documents. Displaying 25 entries per page.
Degradation features of waterlogged archaeological compression wood
1998 - IRG/WP 98-10258
The degradation characteristics of waterlogged archaeological compression wood excavated in South Korea were examined by transmission electron microscopy (TEM) and confocal laser scanning microscopy (CLSM). Degradation of Pinus compression wood occurred mainly in the inner part of S2 layer. In contrast, the outer part of S2 layer remained relatively intact. CLSM and TEM showed the erosion type of ...
Yoon Soo Kim, A P Singh
Quantification of wood decay effects by HPLC analysis
1992 - IRG/WP 92-1576
The present work quantified the effects of the white rot basidiomycetes Coriolus versicolor and Phanaerochaete chrysosporium, and also those of the brown rot fungi Coniophora puteana and Lentinus lepideus, on Pinus patula and Eucalyptus grandis. Wood colonisation was quantified by Kjeldahl nitrogen determinations converted to biomass assays, and degradation was quantified by weight losses produced...
V Singh, M Tarin, G D Shelver, A A W Baecker
Ponding of radiata pine (Pinus radiata) - 1. The effect of bacteria on wood
1998 - IRG/WP 98-10265
Radiata pine (Pinus radiata) wood panels which had been ponded for periods ranging from 2 to 12 weeks were examined by light microscopy, confocal laser scanning microscopy (CLSM), scanning electron microscopy (SEM) and transmission electron microscopy (TEM) for bacterial colonisation of wood and degradation of pit membranes. After 2 weeks of ponding bacteria colonised the outer few cells of wood, ...
A P Singh, Y S Kim, U Schmitt, B S Dawson
Confocal Laser Scanning Microscopy (CLSM) of decayed wood
1998 - IRG/WP 98-10273
Confocal laser scanning microscopy (CLSM) is currently being used to examine biodegraded wood and is proving to be a useful new technique in this area of work. Non-invasive optical sectioning within a thick specimen (20 - 50 µm), coupled with post image processing techniques allows manipulation of images and 3-D reconstruction from serial sections.
Glutaraldehyde can cause cell autofluorescence,...
Ying Xiao, R N Wakeling, A P Singh
Bacteria are important degraders of cooling tower timbers: New Zealand experience
1995 - IRG/WP 95-10128
Microscopic examinations of CCA-treated Pinus radiata timbers in industrial cooling towers in New Zealand showed bacteria and soft rot fungi to be primarily responsible for the decay of these timbers. Of these micro-organisms, erosion bacteria appeared to be most widespread, attacking wood cell walls independently as well as together with tunnelling bacteria and soft rot fungi. Tunnelling bacteria...
A P Singh, R N Wakeling
Soft Rot Decay of Cengal (Neobalanocarpus heimii) Heartwood in Ground Contact in Relation to Extractive Microdistribution
2003 - IRG/WP 03-10501
The heartwood of cengal (Neobalanocarpus heimii, fam. Dipterocarpaceae) is naturally durable. A square-sawn utility pole specimen of cengal heartwood, after 30 years in ground contact, showed 10-15 mm surface decay all around the ground line position, accompanied with isolated surface termite attack at the decayed region. Light and transmission electron microscopy (TEM) of the decayed regions prov...
A P Singh, A H H Wong, Yoon Soo Kim, Seung-Gon Wi, Kwang Ho Lee
Advances in understanding the mode of action of methylene bisthiocyanate against Sphaeropsis sapinea
2002 - IRG/WP 02-30284
The importance of arresting sapstain pre-infection in radiata pine in New Zealand, to prevent downstream sapstain in both logs and sawn timbers has been clearly demonstrated. Efforts are being made to improve the efficacy of diffusible antisapstain agents through improved understanding wood/fungicide/fungus interactions. The mechanism of action of methylene bisthiocyanate (MBT) was investigated u...
T Singh, R N Wakeling, B Kreber, A Stewart
Characterisations of the mode of action(s) of Methylene bisthiocyanate (MBT) in Ophiostoma floccosum
2005 - IRG/WP 05-10554
Potassium (K+) leakage, oxygen consumption, glucose depletion and level of ATP formation were determined to elucidate the potential target site(s) of MBT on the sapstain fungus O. floccosum. Treatment of O. floccosum with MBT caused an efflux of intracellular K+ ions from the cells, and the rate of leakage increased with increasing MBT concentrations up to a certain value. This observation sugge...
T Singh, B Kreber, A Stewart, M Jaspers
Destruction of two tropical timbers by marine borers and micro-organisms in Goa waters (India)
1992 - IRG/WP 92-4176
The paper deals with the pattern of microbial attack in relation to marine borer damage of test panels of African rosewood and Brazilian jackwood exposed in Goa waters (Western India) for a period of seven months. The degradation of wood cell walls in both the timber samples occurred due to infestation of soft-rot fungi and tunnelling bacteria. African rosewood, which was severely damaged by tered...
L N Santhakumaran, A P Singh
Premature failure of CCA treated vineyard posts from brown rot
1993 - IRG/WP 93-10016
A survey of CCA (AWPA Type C) treated posts used as grape vine trellis supports, to determine the extent and type of decay was carried out at a terraced vineyard in the Hawkes Bay region of the North Island of New Zealand. Of 357 posts examined out of a total of 970 in the vineyard, 47% had moderate to severe decay or had failed, 20% had established decay, 10% had a trace of decay and 23% had no s...
R N Wakeling, A P Singh
Visualising Bacteria in Wood Using Confocal Laser Scanning Microscopy (CLSM)
1998 - IRG/WP 98-10272
A fluorescent phospholipid probe was used in conjunction with confocal laser scanning microscopy (CLSM), to visualise bacteria which inhabit in radiata pine wood and degrade pit membranes. CLSM has the ability to collect fluorescent images through different emission filters at the same time, so it is possible to distinguish gram-positive and gram-negative bacteria in infected wood by counterstaini...
Ying Xiao, A P Singh, R N Wakeling
Microbial decay in an extremely durable Malaysian hardwood Belian (Eusideroxylon zwageri) - an overview
1997 - IRG/WP 97-10216
The heartwood of Belian (Eusideroxylon zwageri) is highly regarded among the naturally durable Malaysian hardwoods, and is therefore a choice timber for soilcontact use in the humid tropics such as untreated telecommunication poles, fence posts and railway sleepers. The high microbial resistance of the wood is evidenced by the mere superficial degradation observed in some pole samples after 20 yea...
A H H Wong, A P Singh
The high decay resistance in the sapwood of the naturally durable Malaysian hardwood Belian (Eusideroxylon zwageri)
2001 - IRG/WP 01-10410
It has long been assumed that the observed natural durability of the heartwood in certain timbers is perhaps associated with a relatively lower decay susceptibility also of the sapwood of these species. While the heartwood of Belian is reputedly highly decay resistant among the tropical hardwoods of Southeast Asia, laboratory decay tests reported in this paper have also confirmed the high decay re...
A A H Wong, A P Singh
Ponding of radiata pine (Pinus radiata) - 2. The effect of ponding on coating penetration into wood
1998 - IRG/WP 98-10249
Radiata pine (Pinus radiata) wood panels which had been ponded for periods ranging from 2 to 12 weeks, dried and subsequently coated with a primer and examined by light microscopy after staining sections with Sudan IV to enhance the contrast of the primer material.
A correlation between the extent of ponding and the extent of coating penetration into wood was observed. The coating penetration var...
A P Singh, S S Gallagher, U Schmitt, B S Dawson, Yoon Soo Kim
Bacterial degradation of Pinus radiata compression wood
1996 - IRG/WP 96-10153
An inspection of twelve year old, CCA-treated Pinus radiata wood from an industrial cooling tower showed extensive surface decay of wood. Electron microscopic examination of decaying compression wood indicated that compression wood cells were attacked exclusively by bacteria, which were of erosion and tunnelling types. As compared to the normal wood, compression wood appeared to be more resistance...
A P Singh, R N Wakeling
Hyphal tunnelling of belian (Eusideroxylon zwageri) wood cell walls
1996 - IRG/WP 96-10152
Belian (Eusideroxylon zwageri) is highly regarded among the naturally durable Malaysian hardwoods. Visual inspections at the groundline of belian transmission poles from Sarawak, Malaysia, showed only surface decay of wood after 20 years in service. The cause of decay in belian was investigated by light and transmission electron microscopy. Light microscopy of transverse sections of surface tissue...
A P Singh, A H H Wong
Ultrastructure of Prumnopitys ferruginea wood from a buried forest in New Zealand
1991 - IRG/WP 1489
The buried wood of Prumnopitys ferruginea, a New Zealand native tree, was examined by scanning and transmission electron microscopy to investigate the extent to which the wood had deteriorated and the cause of its deterioration. Examinations showed that some deterioration of wood had occurred. Microscopy revealed a decay pattern similar to that produced by cavitation bacteria. Lenticular cavities ...
A P Singh, T Nilsson, G F Daniel
Minimum inhibitory concentration of methylene bisthiocyanate towards selected wood inhabiting fungi in liquid culture and on radiata pine
2001 - IRG/WP 01-30261
The objective of the current study was to determine the minimum inhibitory concentration (MIC) of methylene bisthiocyanate (MBT) towards wood inhabiting fungi common on unseasoned radiata pine (Pinus radiata D. Don). The fungi used were Ophiostoma floccosum, Leptographium procerum, Sphaeropsis sapinea and Trichoderma viride. Fungi were individually inoculated into nutrient media spiked with differ...
T Singh, B Kreber, C Chittenden, R N Wakeling, A Stewart
Cavitation bacteria
1984 - IRG/WP 1235
A form of bacterial wood degradation is described. The term "cavitation bacteria" has been coined in order to describe the discrete cavities that are formed within the wood cell walls. The bacteria observed within the cavities appeared to be polymorphic with rounded as well as filamentous forms recognised. TEM studies suggest that the bacteria produce diffusable wood-degrading enzymes. Cavitation ...
T Nilsson, A P Singh
Bacterial degradation of wood cell wall: A review of degradation patterns
1990 - IRG/WP 1460
Information from bacterial degradation studies of 60's and 70's was reviewed by Nilsson in 1982. The application of electron microscopy to this area in recent years has provided much useful information and has eliminated earlier scepticism among workers about the ability of bacteria to degrade lignified wood cell walls. Studies using transmission electron microscopy together with...
A P Singh, J A Butcher
In vitro antifungal activity of chilli against wood degrading fungi
2006 - IRG/WP 06-10572
The efficacy of chilli juice and/or chilli extract oleoresin as antisapstain agents was evaluated against two common sapstain fungi, Sphaeropsis sapinea and Leptographium procerum. Possible synergy between chilli juice and Lactobacillus casei as antisapstain agents was also assessed.
Both the chilli juice and the oleoresin showed moderate antifungal activity. No growth of the test fungi was obse...
T Singh, C Chittenden, D Vesentini
The effect of chitosan on the growth and physiology of two wood inhabiting fungi
2006 - IRG/WP 06-10590
The effect of chitosan on the wood inhabiting fungi Sphaeropsis sapinea and Trichoderma harzianum was evaluated at cellular level. Increasing concentrations of chitosan caused an increase in the amount of peroxide in cultures of S. sapinea, which was accompanied by a simultaneous decrease in superoxide. The same effect was not observed in T. harzianum. The growth of both fungi was inhibited when h...
D Vesentini, T Singh
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 w...
T Singh
Effect of chitosan on the morphology and ultrastructure of two wood inhabiting fungi
2007 - IRG/WP 07-10606
An investigation was undertaken to compare the antifungal effects caused by chitosan against two selected wood degrading fungi Sphaeropsis sapinea and Trichoderma harzianum on their growth, morphological and ultra-structural characteristics, using differential interference microscopy, epifluorescence microscopy and transmission electron microscopy.
The effect of chitosan on fungal morphology was ...
T Singh, A P Singh, G Daniel
Efficacy of chitosan in combination with GRAS (Generally Recognised As Safe) compounds as a potential wood preservative
2007 - IRG/WP 07-30414
In vitro studies were undertaken to evaluate the synergy between chitosan and selected GRAS (Generally Recognised As Safe) compounds against two sapstain fungi Sphaeropsis sapinea and Leptographium procerum. Bioassays performed on nutrient medium suggested that some of the GRAS compounds tested including sodium benzoate, potassium sorbate and ascorbic acid had a synergistic effect when combined w...
C Chittenden, K Thämelt, T Singh