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R. H. Wearne

Bio: R. H. Wearne is an academic researcher. The author has contributed to research in topics: Cellulose & Hemicellulose. The author has an hindex of 3, co-authored 3 publications receiving 190 citations.

Papers
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Journal Article
TL;DR: In this paper, the polysaccharides in a series of Eucalyptus globulus and E. nitens pulps were analyzed by high performance anion exchange chromatography with pulsed amperometric detection (HPAEC-PAD), following hydrolysis with sulfuric acid.
Abstract: The polysaccharides in a series of Eucalyptus globulus and E. nitens woods, and E. globulus pulps, were analysed by high performance anion exchange chromatography with pulsed amperometric detection (HPAEC-PAD), following hydrolysis with sulfuric acid. The technique was evaluated as a small-scale method for characterising mltiple samples of eucalyp woods. Acetyl groups and 4-0-methylgluronic acids (MeGUAs) associated with the hemicellulose, fraction were removed during acid hydrolysis and were determined separately. Acetyl and MeGUA results were combined with the hydrolysis results to enable calculation of cellulose and hemicelluloses contents for each sample. The cellulose content of the wood samples varied over the range 41-50% (E. globulus) and 36-44% (E. nitens), although the range of total polysaccharide contents was similar for both woods. Analysis of the pulp polysaccharides after enzymic hydrolysis showed that the pulps contained hexenuronic acids. The analyses for cellulose and hemicellulose content showed satisfactory precision, and gave values similar to those associated with gravimetric determination of cellulose and hemicelluloses. The hydrolysis-HPAECPAD method for carbohydrates is proposed as a better alternative to gravimetric techniques for exploring the relationship between the chemical composition of plantation eucalypt woods and their pulp yields and papermaking properties.

101 citations

Journal Article
TL;DR: In this paper, the relationship between the chemical composition of plantation eucalyptus woods and their pulp yields and papermaking properties was explored. But the results were limited to the E.globulus and E.nitens species.
Abstract: Correlations of the chemical composition of a series of 11 Eucalyptus globulus wood samples ranging in ages from 6 to 32 years, and 21 seven year old E.nitens wood samples have been made with the yields and the composition of their kraft pulps. Analyses for extractives, lignin, pentosan, acetyl, glucuronic acid, and carbohydrates were carried out. The carbohydrates were determined as pentosans, and as their constituent sugar monomers after acid hydrolysis of the unextracted woodmeals and analysis of the hydrolysates by high performance anion exchange chromatography with pulsed amperometric detection (HPAEC-PAD). The total carbohydrates (calculated by difference) and extractives contents of E.globulus wood samples were well correlated with pulp yield at Kappa no.15, and lignin was moderately well correlated total carbohydrates for both species (measured by HPAEC-PAD) were only moderately well correlated with pulp yield. For both species, the correlation of pulp yield with cellulose and glucose was good, but was slightly inferior with hemicellulose, xylose, and pentosan. Wood samples which gave high pulp yields had cellulose as a high proportion of their polysaccharide fraction, and this trend was also evident in the pulps derived from them. Both wood samples showed variation in their oxidation products ; for the E.globulus woods the syringaldehyde/vanillin ratios were moderately well correlated with pulp yield, but for the E.nitens woods, the correlation was poor. The hydrolysis-HPAEC-PAD method for carbohydrates is proposed as a suitable basis to explore the relationship between the chemical composition of plantation eucalypt woods and their pulp yields and papermaking properties.

71 citations


Cited by
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Journal ArticleDOI
01 Jan 2007-Genetics
TL;DR: This first multigene association genetic study in forest trees has shown the feasibility of candidate gene strategies for dissecting complex adaptive traits, provided that genes belonging to key pathways and appropriate statistical tools are used.
Abstract: Genetic association is a powerful method for dissecting complex adaptive traits due to (i) fine-scale mapping resulting from historical recombination, (ii) wide coverage of phenotypic and genotypic variation within a single experiment, and (iii) the simultaneous discovery of loci and alleles. In this article, genetic association among single nucleotide polymorphisms (58 SNPs) from 20 wood- and drought-related candidate genes and an array of wood property traits with evolutionary and commercial importance, namely, earlywood and latewood specific gravity, percentage of latewood, earlywood microfibril angle, and wood chemistry (lignin and cellulose content), was tested using mixed linear models (MLMs) that account for relatedness among individuals by using a pairwise kinship matrix. Population structure, a common systematic bias in association studies, was assessed using 22 nuclear microsatellites. Different phenotype:genotype associations were found, some of them confirming previous evidence from collocation of QTL and genes in linkage maps (for example, 4cl and percentage of latewood) and two that involve nonsynonymous polymorphisms (cad SNP M28 with earlywood specific gravity and 4cl SNP M7 with percentage of latewood). The strongest genetic association found in this study was between allelic variation in α-tubulin, a gene involved in the formation of cortical microtubules, and earlywood microfibril angle. Intragenic LD decays rapidly in conifers; thus SNPs showing genetic association are likely to be located in close proximity to the causative polymorphisms. This first multigene association genetic study in forest trees has shown the feasibility of candidate gene strategies for dissecting complex adaptive traits, provided that genes belonging to key pathways and appropriate statistical tools are used. This approach is of particular utility in species such as conifers, where genomewide strategies are limited by their large genomes.

338 citations

Journal ArticleDOI
TL;DR: It is to be noted that the relative amount of dissolved acidic sugar units was larger from the heartwood than from the sapwood for all species, and the main dissolved polysaccharides were xylans only for a few samples, while easily soluble galactans, arabinogalactan, or mannans dominated in most species.
Abstract: The amount and composition of sugar units comprising polysaccharides in sapwood and heartwood, or stemwood, of 11 industrially important pulpwood species were analysed. The polysaccharide content was between 60 and 80% (w/w) for all species, with cellulose as the predominant polysaccharide type and glucuronoxylans as the main non-cellulosic polysaccharides. The second most abundant non-cellulosic polysaccharides were either pectins, i.e. polygalacturonic acids, or glucomannans. The amount of acidic sugar units were 15–23% of the total amount of non-cellulosic sugar units in all samples, with the Acacia species in the high end. The amount and composition of water-soluble carbohydrates from ground wood samples were also analysed, since these are important in mechanical and chemimechanical pulping, and as a possible source of bioactive polymers. Sapwood released more carbohydrates than heartwood for most species. It is to be noted that the relative amount of dissolved acidic sugar units was larger from the heartwood than from the sapwood for all species. Probably due to the mild treatment conditions, the main dissolved polysaccharides were xylans only for a few samples, while easily soluble galactans, arabinogalactans, or mannans dominated in most species. Pectins dominated in heartwood of Populus grandidentata. Generally, pectins and acidic xylans were the main acidic polysaccharides.

259 citations

Journal ArticleDOI
TL;DR: In this paper, a set of Eucalyptus globulus woods from different origins and growth conditions, giving a wide range of pulp yields (from 40 to 60%) upon kraft cooking, was analyzed using Py-GC/MS.

175 citations

Journal ArticleDOI
TL;DR: In this paper, the potential markets and products for plantation eucalypts leading to a defi- nition of which wood properties should be assessed for a range of products are discussed.
Abstract: Traditional methods of assessing wood properties are both destructive and expensive, limiting the numbers of samples that can be processed. Over the past decade, non-destructive sampling techniques and new assessment methods have been developed leading to a large in- crease in the numbers of trees and traits that can be evaluated. This technology has enabled the assessment of progeny trials to determine the pat- terns of variation, degree of genetic control and economic importance of many wood traits, leading to the inclusion of wood properties in many eucalypt-breeding programs. Issues addressed in this paper include the potential markets and products for plantation eucalypts leading to a defi- nition of which wood properties should be assessed for a range of products. Current recommendations for non-destructive sampling for basic density, fibre length and predicted pulp yield in Eucalyptus globulus and E. nitens are provided. Other non-destructive assessment techniques are illustrated including cellulose content, acoustic testing methods for wood stiffness and SilviScan X-ray densitometry and diffraction analysis for density and microfibril angle. The degree of genetic control for wood properties is compared to tree growth traits and a series of issues and chal- lenges for the future presented. eucalypt / breeding / wood quality / genetic parameters / non-destructive sampling

151 citations

Journal ArticleDOI
TL;DR: The feasibility and efficiency of predicting cellulose content using near infrared reflectance (NIR) analysis was examined for Eucalyptus globulus Labill, and calibrations indicated that NIR analysis could be used as a reliable predictor.
Abstract: Determining kraft pulp yield in the traditional way is slow and expensive, limiting the numbers of samples that may be processed. An alternative is to use a secondary standard, such as cellulose content of the wood, which is strongly correlated with kraft pulp yield. The feasibility and efficiency of predicting cellulose content using near infrared reflectance (NIR) analysis was examined for Eucalyptus globulus Labill. Calibrations for NIR prediction of cellulose content indicated that NIR analysis could be used as a reliable predictor. Standard errors of calibration were 1% or lower, and there was excellent agreement between laboratory and predicted cellulose values. Cellulose content was under moderate genetic control (h2 ranging from 0.32 to 0.57), and genetic correlations with tree diameter and basic density were variable (ranging from –0.11 to –0.51 and –0.33 to 0.67, respectively). The advantages, disadvantages, and potential applications of NIR analysis for predicting cellulose content are examined.

144 citations