Fresh Wood Samples Research Articles

DEVELOPMENT OF WOOD GRINDING 4. EVALUATION OF THE THEORETICAL GRINDING MODEL

"Spruce wood was ground under certain fixed conditions to achieve data for interpretation of the grinding mechanism. For this purpose, wood moisture content, wood feeding rate and grindstone peripheral speed were given five, three and two different levels, respectively. The data obtained by application of a laboratory grinder were accordingly most reliable, because the grinder was run under well controlled conditions, and the wood samples represented one and the same wood quality, but at five moisture content levels. The grinding zone temperature was measured at the outlet from the grinding zone, and accordingly it would indicate the average grinding zone temperature. The grinding model suggests that the energy specific fibre production ( w/Pt) evaluated at various power friction levels (Pc/Pt) would help understanding the wood grinding mechanism. The energy specific fibre production showed significant dispersion, when evaluated as a function of the power friction. However, detailed analysis of the data revealed that there could be two linears, one representing moisture saturated wood, and one representing fresh wood that also contains free water in the lumina. Surprisingly, this linear also included data representing air-dry wood. Increasing wood moisture ratio from 0.2 kg to 1.4 kg per kg o.d. wood decreased the average grinding zone temperature significantly from about 98° to 88 °C. Further, there was roughly a difference of 8–12° C in grinding zone temperature due to the wood moisture, when evaluated as a function of the force friction coefficient (Ft/Fc). The two highest moisture ratios resulted in a low-level linear, as the other moisture ratios produced a high-level linear. The wood moisture content seems to affect the grinding process in different ways due to the moisture content level. Since moisture is absorbed in the fibre wall material and evidently linked to various lignin and cellulose components by hydrogen bonds, it will affect the grinding in a certain mode. However, the air-dry wood sample seemed to act as the fresh wood samples, which cannot be explained properly unless also considering fibrillation and fibre properties."

DNA isolation success rates from dried and fresh wood samples of selected 20 tropical wood tree species for possible consideration in forensic forestry

The successful isolation of DNA (Deoxyribonucleic Acid) is essential for the investigation process of forestry molecular genetics. Samples used are usually retrieved either from soft or juvenile plant organs because of their excellent DNA source. However, in certain cases, aforesaid samples are hard to obtain, as for forensic purposes. Alternatively, woods possess potential as alternative source of DNA whose extraction method has been developed with varying degrees of success. However, to date, effectiveness on tropical wood grown in Indonesia has not been widely reported. Therefore, objective of this study was to compare the results of DNA isolation of various dried and fresh wood samples by using two isolation methods: Cetyl Trimethyl Ammonium Bromide (CTAB) and Qiagen DNeasy Plant Mini Kit (QDPMK). Extraction results were visualized in agarose gels and quantified using Nanophotometer NP80 Implen which were then amplified using two universal primers: ITS and rbcL for detecting DNA signals. Extraction results from dried wood indicated no visualization in the gel, while fresh wood samples showed thick smeared bands on both extraction methods. Quantity test results denoted higher concentration in CTAB-extracted samples compared to samples extracted using QDPMK, in both types of samples, even though both resulted in optical density ratios outside the range of purity (λ260/280: 1,8–2,0 and λ260/230: 2,0, respectively). Success rates of ITS and rbcL primary amplification in dried wood samples were quite low yet outputs from the two methods did not differ significantly. Meanwhile, outcome of ITS and rbcL amplification on fresh wood samples had a fairly high success.

Ecotoxicological Effect of Aged Wood Leachates to Aquatic Organisms

Wood is an important natural resource used for various human activities. Toxicity of wood leachate in aquatic organisms has been previously established, but whether storage over time has an impact on the quality of leachate has not been assessed. Hence, this research seeks to assess the toxicity of aged wood leachate in aquatic organisms. Five fresh wood samples were randomly selected from the Oboyow forest reserve in the eastern region of Ghana: Mahogany (Khaya ivorensis), Cedrela (Cedrela odorata), Emire (Terminalia ivorensis), Wawa (Triplochiton scleroxylon), and Ceiba (Ceiba pendandra) to assess their toxicity to aquatic organisms. Algal (Desmodesmus subspicatus) duckweed (Lemna minor) and daphnia (Daphnia magna) were carried out using exposures to concentrations of 20%, 30%, 45%, 67%, and 100% v/v of wood leachate with control media, because they represented various concentration rate levels of wood leachate toxicity in the test organisms. The toxicity of the various wood leachates might be due to high levels of biochemical oxygen demand (BOD), chemical oxygen demand (COD), and total organic carbon (TOC), i.e., metals and phenols. The % IC50 of the various wood leachate ranged from 21.51–66.77% with mahogany exhibiting the highest toxicity and wawa the lowest. It was also observed that toxicity of wood leachates decreased as the wood leachate aged. The % IC50 showed both confirmed and potential toxicity among the various wood leachates.

Wettability of Sanded and Aged Fast-growing Poplar Wood Surfaces: I. Surface Free Energy

The sanding process influences the surface morphology and chemical components of wood, which are two important factors that influence the surface free energy and wettability of wood. The objective of this study was to investigate the roughness of sanded poplar wood and the effects of sanding and aging on the surface free energy using different methods. The roughness parameter (Ra) decreased as the grit number increased, but no change was evident when the grit number increased from 120 to 240. The contact angle of water on the fresh wood samples decreased as the grit number increased. Fresh wood samples were more easily wetted by water than was the aged wood sample, and the contact angles increased as the surface roughness decreased. The surface free energy of sanded, aged wood obtained by the Zisman method may be unsuitable. For the fresh wood samples, the change of surface free energy and its components were not significantly changed when the grit number was higher than 120; for the aged wood samples, the dispersion component appeared to increase slightly as the grit number decreased. The effect of roughness on the acid/base component, acid component, and base component calculated by the vOCG method was unremarkable. The surface free energy of the wood samples (obtained using the liquid parameters provided by Volpe and Siboni (1997)) can effectively balance the relationship between the acid and base components.

Fossil wood from the Miocene and Oligocene epoch: chemistry and morphology.

Fossil wood is the naturally preserved remain of the secondary xylem of plants that lived before the Holocene epoch. Typically, fossil wood is preserved as coalified or petrified and rarely as mummified tissue. The process of fossilization is very complex and it is still unknown why in the same fossil record, wood can be found in different fossilisation forms. In 2007, a fossil forest was found in the Bükkábrány open-pit coal mine in Hungary. The non-petrified forest is estimated to be 7 million years old (Miocene epoch) and its trees were found standing in an upright position. This fossil assemblage is exceptionally rare because wood has been preserved as soft waterlogged tissue. This study aimed to investigate this remarkable way of fossil wood preservation, by examining its chemistry with (13)C CPMAS NMR and its morphology with light and electron microscopy. For comparison reasons, a petrified wood trunk from the Oligocene epoch (30 Myr) found in 2001 at Porrentruy region in Switzerland and two fresh wood samples of the modern equivalents of the Miocene sample were also examined. The results obtained showed that the outstanding preservation state of the Miocene fossil is not owed to petrification or coalification. Mummification is a potential mechanism that could explain Bükkábrány trunks' condition, however this fossilisation process is not well studied and therefore this hypothesis needs to be further investigated.

Airborne endotoxin in woodworking (joinery) shops

Symptoms such as shortness of breath and cough have been noted in woodworking facilities even where wood dust itself is well-controlled. Suspicion has fallen on other possible contaminants in the workplace atmosphere, including bacterial endotoxin. A few studies have indicated potentially high endotoxin exposure with exposure to fresh wood in sawmills and in the production of fiberboard and chipboard, but fewer studies have been carried out on exposure to endotoxin in dry wood work, for example in joineries. A study of the endotoxin content of airborne wood dust samples from US woodworking facilities is presented, from the re-analysis of samples which previously had been taken to establish mass collection relationships between the IOM sampler, the closed-face 37 mm plastic cassette (CFC) sampler and the Button sampler. Endotoxin was strongly correlated with total dust, but the endotoxin content of a few fresh wood samples was found to be up to ten times higher per unit of wood dust than for dried-wood samples, and this difference was significant. No long-term time-weighted average sample exceeded the recommended limit value of 50 EU m(-3) (EU, endotoxin units)used in the Netherlands, although a number of the IOM samples came close (seven samples or 44% exceeded 20 EU m(-3)) and one short-term (48 minute) sample registered a high value of 73 EU m(-3). The geometric mean concentration from the IOM samples (11 EU m(-3)) is within the range of geometric means found from Australian joineries (3.7-60, combined: 24 EU m(-3)). In contrast, the corresponding values from the CFC (3.6 EU m(-3)), and the Button sampler (2.1 EU m(-3)) were much lower and no samples exceeded 20 EU m(-3). Endotoxin is likely only to be a significant problem in working with dried woods when associated with very high dust levels, where the wood dust itself is likely to be a cause for concern. The results from the few samples in this study where fresh wood was being worked were similar to results from other studies involving fresh woods. The agreement between these studies is encouraging given the difficulties of endotoxin analysis and the wide variation often expected between different laboratories.

Peroxidase Activity, Isoenzymes and Histological Localisation in Sapwood and Heartwood of Scots Pine (Pinus sylvestris L.)

Peroxidase activity and isoenzymes of fresh wood samples of the third shoot of 12-year old trees and from the sapwood, transition zone and heartwood of c. 60-year old stems of Scots pine (Pinus sylvestris L.) were investigated. Wood samples were ground at–30°C, extracted, and the extracts concentrated c. 20-fold for peroxidase activity assays (guaiacol method) and for IEF-PAGE. At least 11 major isoenzymes could be found in the gels. Even the heartwood contained some peroxidase isoenzymes. Isoenzyme patterns of the juvenile wood did not change with the season. However, juvenile wood showed the highest peroxidase activity at the end of the growing season. Peroxidase activity decreased from the outer sapwood towards the heartwood. Thin sections of different wood zones stained for peroxidase revealed activity in ray parenchyma and resin canal epithelial cells. Intensive staining was localised in the bordered pits of vertical and ray tracheids, and in the end walls of ray parenchyma cells.

Mechanical Properties of Black Locust (Robinia pseudoacaciaL.) Wood. Size- and Age-dependent Variations in Sap- and Heartwood

Abstract Variations in the density and stiffness (Young's elastic modulus) of fresh wood samples drawn from different parts of the three main trunks of a 32-year-old black locust tree, Robinia pseudoacacia (measuring 19.8 m at its highest point), were studied to determine whether tree ontogeny can achieve a constant safety factor against mechanical failure. Based on the properties of isolated wood samples, the fresh density of sapwood decreased along radial transects from bark to pith, while that of progressively older heartwood samples increased, on average, towards the centre of each of the three trunks. Along the same radial transects, the Young's elastic modulus of sap- and heartwood increased. In terms of longitudinal changes in wood properties, mean wood moduli (averages of sap- and heartwood samples) increased, on average, towards the base of each of the three trunks of the tree. However, the mean fresh densities of wood samples increased towards the top and the bottom of each trunk and were lowest roughly near trunk mid-length. The mean density-specific stiffness (the quotient of Young's modulus and fresh density) of wood was thus lower toward the top and the bottom of the trunks and highest near trunk mid-length. Mean values of fresh wood density-specific stiffness were used to estimate the critical buckling heights for sections of the trunks differing in diameter and age. These estimates indicated that ontogenetic variation in the physical properties and relative amounts of sap- and heartwood in trunks could maintain a constant factor of safety (approximately equal to 2) as a sapling grows in height and girth into a mature tree. This expectation was supported by data from 16 black locust trees differing in height and diameter at breast height (DBH).

Invasion of wood by basidiomycetous fungi II. Obliterated differences between pathosism and saprophytism on pre‐degraded wood substrates in monoxenic culture

AbstractMycelial production and linear extension growth of 41 wood‐destroying basidiomycetous fungi (WBF) whose pathogenicity and kratovirulence levels permitted their subdivision into 7 fungal categories was determined on nonsterile and autoclaved wood dust materials from fresh, discoloured (nondecay), and decay wood samples. The resident microflora of nonsterile wood meals compels the intruding WBF mycelium to mobilize its entire competitive ability when going to colonize a contaminated substrate. This demand excludes the pathogenic WBF from utilizing the non‐sterile substrates but allows for extensive development of the fresh‐wood and successive saprophytes that afford the required kratovirulence level. On sterilized wood dust, any differences in the growth patterns of pathogenic and saprophytic WBF vanish immediately. Sterile fresh wood samples from host and nonhost trees the latter being never infected in the field allow for widely uniform mycelial production by fungal species with wide or extremely narrow host range. Some fungi display, in addition, a strong substrate preference to certain natural host tree species or their close relatives. No correlation was found between the total exoenzymatic activity reported for the fungus concerned and its mycelial production. Top values of mycelial formation were observed in fungi with lowest enzymatic activity as well as in producers of normal enzyme quantities while some brown‐rot fungi showed extremely restricted mycelial output although they are known for enzymatic activities to be highest.Among the 41 fungal species listed, 25 prefer certain particular nondecay and decay wood samples to fresh wood meal although the general rule is a higher mycelial production on fresh wood. The addiction to pre‐degraded wood can be traced, surprisingly, throughout all fungal categories with the tendency to abate in saprophytic ones. The brown‐rot fungi are more frequently stimulated by the discoloured nondecay wood while white‐rot fungi tend to prefer decay wood samples. The partially diminutive mycelial production in certain brown‐rot fungi means no defect in vitality or wood‐decay capacity. The weekly linear extension growth figure LE7 of the fungal mycelia can reach top values throughout the 7 fungal categories. No relationship was detected between rapid mycelial growth and both kratovirulence level or pathogenic potency. Fungi most reliably transplanted to raw substrates have medium‐sized LE7 figures. It is concluded that the striking differences between pathogenic and saprophytic members of WBF they display in their competitive ability immediately vanish in the absence of substrate microorganisms. The in vitro tests neither reveal differences in a striking host substrate specificity, the preference to fresh or decay wood, mycelial dry matter production, general enzymatic particularities, and weekly mycelial growth rate.