Wood Samples (wood + sample)

Distribution by Scientific Domains

Selected Abstracts

Climate,growth relationships of tropical tree species in West Africa and their potential for climate reconstruction

Abstract Most tropical regions are facing historical difficulties of generating biologically reconstructed long-term climate records. Dendrochronology (tree-ring studies) is a powerful tool to develop high-resolution and exactly dated proxies for climate reconstruction. Owing to the seasonal variation in rainfall we expected the formation of annual tree rings in the wood of tropical West African tree species. In the central-western part of Benin (upper Ouémé catchment, UOC) and in northeastern Ivory Coast (Comoé National Park, CNP) we investigated the relationship between climate (precipitation, sea surface temperature (SST)) and tree rings and show their potential for climate reconstruction. Wood samples of almost 200 trees belonging to six species in the UOC and CNP served to develop climate-sensitive ring-width chronologies using standard dendrochronological techniques. The relationship between local precipitation, monthly SST anomalies in the Gulf of Guinea, El Niño- Southern Oscillation (ENSO) and ring-width indices was performed by simple regression analyses, two sample tests and cross-spectral analysis. A low-pass filter was used to highlight the decadal variability in rainfall of the UOC site. All tree species showed significant relationships with annual precipitation proving the existence of annual tree rings. ENSO signals could not be detected in the ring-width patterns. For legume tree species at the UOC site significant relationships could be found between SST anomalies in the Gulf of Guinea indicating correlations at periods of 5.1,4.1 and 2.3 years. Our findings accurately show the relationship between tree growth, local precipitation and SST anomalies in the Gulf of Guinea possibly associated with worldwide SST patterns. A master chronology enabled the reconstruction of the annual precipitation in the UOC to the year 1840. Time series analysis suggest increasing arid conditions during the last 160 years which may have large impacts on the hydrological cycles and consequently on the ecosystem dynamics and the development of socio-economic cultures and sectors in the Guinea-Congolian/Sudanian region. [source]

Sugar Recovery and Fermentability of Hemicellulose Hydrolysates from Steam-Exploded Softwoods Containing Bark

Abdel Boussaid
The hemicellulose sugar recovery and ethanol production obtained from SO2 -catalyzed steam explosion of a mixed white fir (70%) and ponderosa pine (30%) feedstock containing bark (9% dry weight/dry weight) was assessed. More than 90% of the available hemicellulose sugars could be recovered in the hydrolysate obtained after steam explosion at 195 °C, 2.38 min, and 3.91% SO2, with 59% of the original hemicellulose sugars detected in a monomeric form. Despite this high sugar recovery, this hydrolysate showed low ethanol yield (64% of theoretical yield) when fermented with a spent sulfite liquor-adapted strain of Saccharomyces cerevisiae. In contrast, most hydrolysates prepared at higher steam explosion severity showed comparable or higher ethanol yields. Furthermore, the hydrolysates prepared from bark-free feedstock showed better fermentability (87% of theoretical yield) despite containing higher concentration of known inhibitors. The ethanol yield from the hydrolysate prepared from a bark-containing wood sample could be improved to 81% by an extra stage acid hydrolysis (121 °C for 1 h in 3% sulfuric acid). This extra stage acid hydrolysis and steam explosion at higher severity conditions seem to improve the fermentability of the hydrolysates by transforming certain inhibitory compounds present in the hydrolysates prepared from the bark-containing feedstock and thus lowering their inhibitory effect on the yeast used for the ethanol fermentation. [source]

Associations between Pityogenes bidentatus and fungi in young managed Scots pine stands in Poland

R. Jankowiak
Summary The association between Pityogenes bidentatus and fungi was studied in young, managed Pinus sylvestris stands in Poland. Fungi were isolated from emerged adults and their galleries collected from four populations. In total, 2089 fungal isolates including 42 species, were obtained. Penicillium sp. 1 and Geosmithia sp. 1 were the most commonly isolated fungi from beetles (49% and 41% of beetles respectively). Geosmithia sp. 1 species was the dominant species in P. bidentatus galleries with a frequency of occurrence of 57.9%. Hormonema dematioides was the second most abundant fungus in gallery systems (17.1% of wood samples). Two of the isolated Geosmithia species were previously undescribed. Pityogenes bidentatus also vectored three ophiostomatoid species: Ophiostoma minus, O. piceae and Graphium sp. ,W'. These species were occasionally isolated from beetles and their galleries, suggesting a non-specific relationship. [source]

Impact of impregnation chemical on surface glossiness of synthetic, acrylic, polyurethane, and water-based varnishes

Hakan Keskin
Abstract This study was performed to determine the effects of impregnation chemical on surface glossiness of some varnishes. For this purpose, the test samples prepared from Oriental beech, European oak, Scotch pine, Oriental spruce, and Uludag fir woods according to ASTM D 358 were impregnated with Imersol-Aqua according to ASTM D 1413 and producer's definition by short-term (S), medium-term (M), and long-term (L) of dipping methods and coated by synthetic (Sv), acrylic (Ac), water-based (Wb), and polyurethane (Pu) varnishes according to ASTM D 3023. After the varnishing process, the surface glossiness parallel to fibers was determined according to TS 4318. Consequently, among the nonimpregnated wood samples, surface glossiness parallel to fibers was found to be the highest in Oriental spruce and the lowest in European oak. As for the period of dipping, the highest surface glossiness was obtained in medium-term dipping and the lowest in long-term dipping. As for the varnish types, the surface glossiness was found to be the highest in polyurathane varnish and the lowest in water-based varnish. Considering the interaction of wood type, period of impregnation, and type of varnish, surface glossiness was the highest in Uludag fir, long-term dipping, and polyurathane varnish (103.9 gloss) and the lowest in Oriental beech, long-term dipping, and water-based varnish (67.78 gloss). In consequence, in the massive constructions and furniture elements the surface glossiness parallel to fibers after the impregnation with Imersol-Aqua is of great concern, long-term impregnation of Uludag fir materials could be recommended. © 2008 Wiley Periodicals, Inc. J Appl Polym Sci, 2008 [source]

Delignification of Pinus taeda wood chips treated with Ceriporiopsis subvermispora for preparing high-yield kraft pulps,

Régis Mendonça
Abstract Pinus taeda wood chips were treated with the white-rot fungus Ceriporiopsis subvermispora in 20-dm3 bioreactors for periods varying from 15 to 90 days. Decayed samples, non-inoculated controls and extractive-free wood samples were submitted to kraft pulping using 25% of sulfidity and different active alkali concentrations in the cooking liquor. Cooking reactions were carried out isothermally at 170,°C. Residual lignin contents of pulps prepared from biotreated wood chips were lower than those observed in pulps from the undecayed control. Delignification kinetic studies showed that the initial delignification phase was accelerated and shortened by the fungal pretreatment. At a cooking time fixed before the end of the bulk delignification phase, the fungal pretreatment provided pulps with significantly lower kappa numbers or pulps with a fixed kappa number were obtained by reducing the amount of active alkali added to the liquor. Pulps of kappa 80 were obtained both from the undecayed control cooked with 20.8% of active alkali and from the 15-day-biotreated sample cooked with only 15% of active alkali. The biopulping benefits were neither proportional to the extent of the biodelignification nor to the biological removal of some specific wood component. DFRC-determination (derivatization followed by reductive cleavage) of the amount of aryl,ether linkages in residual lignins of biotreated samples indicated an extensive depolymerization during the initial stages of biodegradation, which suggested that bio-depolymerized lignin was easily released during the first stages of cooking, resulting in a faster and shorter initial delignification phase. © 2002 Society of Chemical Industry [source]


ARCHAEOMETRY, Issue 4 2010
A series of 112 waterlogged archaeological wood samples of different provenances, wood species, burial times and states of preservation were analysed with the aim of assessing the validity (in terms of limits and reliability) of procedures conventionally used in the pulp and paper industry, to evaluate the state of preservation of decayed wood. In particular, the extent of any damage wrought on decayed wood tissue by the repetitive cycles that characterize these procedures was evaluated as a function of the degradation of the samples. The results indicated that standard methodologies give reliable measurements regardless of the extent of wood decay. However, it is essential to compare these data with those of non-decayed wood that has been measured using the same procedures to take account of the errors that are inherent in these methodologies and that affect measurements. [source]

Identification, distribution and current taxonomy of Botryosphaeriaceae species associated with grapevine decline in New South Wales and South Australia

Abstract Background and Aims:, Botryosphaeriaceae species are recognised as important pathogens of grapevines both in Australia and overseas. The identity, prevalence and distribution of Botryosphaeriaceae species in vineyards throughout the major winegrowing regions of New South Wales (NSW) and South Australia (SA) was determined to provide a foundation for improved disease prevention and management. Methods and Results:, Field surveys from 91 vineyards across NSW and SA resulted in the collection of 2239 diseased wood samples and subsequent isolation of 1258 Botryosphaeriaceae isolates. Morphological identification along with phylogenetic analysis of ribosomal DNA internal transcribed spacer regions (ITS1-5.8S-ITS2) and partial sequences of the translation elongation factor 1-, gene (EF1-,) showed that eight Botryosphaeriaceae species from four phylogenetic lineages occur on grapevines in eastern Australia, including Diplodia seriata, Diplodia mutila, Lasiodiplodia theobromae, Neofusicoccum parvum, Neofusicoccum australe, Botryosphaeria dothidea, Dothiorella viticola and Dothiorella iberica. Conclusions:, The prevalence of individual species varied according to geography and climate. Species of Diplodia and Dothiorella, characterised by thick-walled, pigmented conidia were the most prevalent and were distributed widely throughout both NSW and SA. Species with hyaline conidia, such as Neofusicoccum and Fusicoccum, were isolated less frequently and displayed more limited geographic ranges, whilst only a single isolate of Lasiodiplodia was recovered, this being from the northern most region of NSW. Significance of the Study:, The identification of eight taxa within the Botryosphaeriaceae, and their distributions throughout south-eastern Australia was established and discussed in context with climate, reported optimum growth temperatures, and more recent taxonomic and nomenclatural revisions. We established a sound base for control strategies based on the prevailing species in Australian viticultural regions. [source]