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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


Copper Nanoparticles in Southern Pine Wood Treated with a Micronised Preservative: Nanodistribution of Copper in the Pit Membrane and Border of an Earlywood Bordered Pit
2011 - IRG/WP 11-30566
Copper nanoparticles can penetrate the cell walls of unlignified parenchyma cells in southern pine wood treated with a micronised wood preservative, but they are excluded from lignified tracheid walls. This paper extends these observations to include the cell wall layers of the bordered pit. Focused ion beam and ion milling were used to make an ultra-thin section of the cell wall layers of an earlywood bordered pit excised from southern pine wood that had been treated with a micronised wood preservative. 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 detect and examine the penetration of the torus and pit border by copper. Copper was more abundant in the torus than in the pit border, but the depth of penetration of copper in both cell wall layers was approximately the same, ~100nm. High resolution transmission electron microscopy was unable to detect crystalline material in either the torus or pit border. Therefore we conclude that copper nanoparticles are unable to penetrate the torus and border of the bordered pit in accord with our previous observation that nanoparticles are excluded from the cell walls of lignified tracheids.
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


Fire performance of the wood treated with retardant
2012 - IRG/WP 12-40591
To prepare the eco-friendly fire retardant wood, Japanese red pine (Pinus Densiflora), hemlock (Tsuga Heterophylla), and radiate pine (Pinus Radiata) were treated with inorganic chemicals, such as sodium silicate, ammonium phosphate, and ammonium boric acid. Different combination and concentration of those chemicals were injected by pressure treatment methods. The electron-beam treatment was used to increase the chemical penetration into the wood. The fire performance of the fire retardant was investigated. The penetration of chemicals into the wood was enhanced after irradiation of 200 kGy of electron beam. Ignition time of the treated wood was the most effectively retarded by sodium silicate, ammonium phosphate, and ammonium boric acid. The most effective chemical combination was found at 50% sodium silicate and 3% ammonium boric acid; which showed 3-grade flammability defined in the KS F ISO 5660-1 standards.
Jong In Kim, Mi-ran kang, Sang bum Park, Dong won Son


Effect of electron beam irradiation on the fire retardant penetration into wood
2013 - IRG/WP 13-40642
Electron beam processing which can fast and easy change the nature of the material has received considerable attention recently. Studies using electron beam has been conducted in various fields and it has been applied in many industrial sectors. Electron beam has higher energy than other electromagnetic waves. It has excellent object permeability. It affects degradation of intermolecular cross-linking between molecules or atoms bond formation, polymerization. High permeability of the electron beam has applied to improve penetration of fire retardant into wood. Changes in the characteristics of the wood, retention of the retardant on different electron beam dose, leaching resistance of treated wood were examined. Scanning electron microscopy EDS analysis has been conducted to investigate the chemical elements and to calculate the distribution of each component.
Dong won Son, Jong Sin Lee, Mee Ran Kang, Sang Bum Park


Evaluation of chemical densification of three hardwood species through in-situ electron beam polymerization
2020 - IRG/WP 20-40893
Hardwoods are the most suitable species for wood flooring for their appearance as well as their hardness. Yet, improving hardness can provide substantial benefit for the wood flooring market. Chemical densification of wood and in-situ polymerization through electron beam technology was chosen to increase hardness of three hardwoods (Yellow birch (YB) (Betula alleghaniensis Britt.), Sugar maple (SM) (Acer saccharum Marshall) and Red Oak (RO) (Quercus rubra L.)). Monomer formulations were chosen for their viscosity. Impregnation was carried out through a simple vacuum process and was followed by 100 kGy electron beam irradiation to allow in-situ polymerization. Successful polymerization was proved by infrared spectroscopy and thermogravimetric analysis. Chemical retention and hardness of densified and reference samples were measured. Chemical retention (CR) varied between the three species being the lowest for porous red oak and the highest for diffuse porous yellow birch. CR also decreased with increasing viscosity of the impregnant for SM and YB. However, viscosity did not affect chemical retention of RO samples. Hardness of wood increased substantially for all treatments and all species and was comparable to that of Jatoba. Densified YB samples showed greater improvement of hardness compared to RO and SM due to higher chemical retention. Results also showed that with low chemical retention, hardness was improved but densified wood hardness is mostly influenced by wood properties. While the three species showed significant hardness improvement, yellow birch seems more suitable for densification.
J Triquet, P Blanchet, V Landry


Surface chemical wood densification through in situ electron beam polymerization: description and dose study
2022 - IRG/WP 22-40933
Traditional wood chemical densification processes can be used to improve wood mechanical properties by increasing density of the material throughout its thickness. While mechanical surface densification has heavily been investigated, surface treatments involving impregnation of monomers remain unexplored. This study describes a new material, surface densified through lateral impregnation of acrylate monomers and their in-situ polymerization using high-energy electron beams. Yellow birch (Betula alleghaniensis, Britt.) was surface densified and its morphology was studied using X-Ray density profiles and microtomography. Brinell hardness of densified samples increased while irradiated controls showed lower hardness compared to untreated controls. Effect of electron beam dose was studied at 25, 50 and 100 kGy. Using acetone extraction and GC-MS, residual monomers were found at low dose while degradation of wood was observed ah higher dose using FT-IR. This study demonstrates how carefully choosing the electron beam dose impacts the material in different ways.
J Triquet, P Blanchet, V Landry


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


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


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 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


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


Distribution of copper/chrome/boron preservative in light red meranti (Shorea leprosula) before and after exposure test for 72 months
1995 - IRG/WP 95-20073
Copper/chrome/boron (CCB) preservative at 6% w/w was impregnated into light red meranti (Shorea leprosula) by full cell process. The quantitative analysis for copper, chrome and boron contents in treated wood samples was carried out by Inductive Couple Plasma (ICP). Electron Probe Microanalyser (EPMA) was used to monitor the distribution of copper, chrome and boron in the various treated wood tissues before and after exposure for 72 months.
S Salamah, S Ani


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.
I Usta


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