<?xml version="1.0" encoding="UTF-8"?><xml><records><record><source-app name="Biblio" version="7.x">Drupal-Biblio</source-app><ref-type>17</ref-type><contributors><authors><author><style face="normal" font="default" size="100%">Bento, M F</style></author><author><style face="normal" font="default" size="100%">Pereira, H</style></author><author><style face="normal" font="default" size="100%">Cunha, M Á</style></author><author><style face="normal" font="default" size="100%">Moutinho, A M C</style></author><author><style face="normal" font="default" size="100%">van den Berg, K J</style></author><author><style face="normal" font="default" size="100%">Boon, J J</style></author><author><style face="normal" font="default" size="100%">van den Brink, O</style></author><author><style face="normal" font="default" size="100%">Heeren, R M A</style></author></authors></contributors><titles><title><style face="normal" font="default" size="100%">Fragmentation of Suberin and Composition of Aliphatic Monomers Released by Methanolysis of Cork from Quercus suber L.,Analysed by GC-MS, SEC and MALDI-MS</style></title><secondary-title><style face="normal" font="default" size="100%">Holzforschung</style></secondary-title></titles><keywords><keyword><style  face="normal" font="default" size="100%">Cork</style></keyword><keyword><style  face="normal" font="default" size="100%">MALDI-MS</style></keyword><keyword><style  face="normal" font="default" size="100%">Methanolysis</style></keyword><keyword><style  face="normal" font="default" size="100%">Quercus suber L.</style></keyword><keyword><style  face="normal" font="default" size="100%">SEC</style></keyword><keyword><style  face="normal" font="default" size="100%">Suberin fragmentation</style></keyword></keywords><dates><year><style  face="normal" font="default" size="100%">2005</style></year></dates><volume><style face="normal" font="default" size="100%">55</style></volume><pages><style face="normal" font="default" size="100%">487-493</style></pages><language><style face="normal" font="default" size="100%">eng</style></language><abstract><style face="normal" font="default" size="100%">Suberin from extractive-free cork from Quercus suber L. was depolymerised by methanolysis using different sodium methanolate (NaOMe) concentrations. 1% and 3% NaOMe completely removed suberin from cork (54%–56% of extractive-free cork), but for lower concentrations there was incomplete solubilisation; with 0.05% NaOMe, only approximately 80% of total suberin was removed. The monomeric composition of the extracts differed significantly: for the 0.05% NaOMe, only alkanoic acids and diacids were found; the yield of v-hydroxy acids increased with reactant concentration, as well as alkanols and ferulic acid. Results from light scattering, SEC and MALDI-MS showed that soluble oligomeric fragments containing suberinic acids were present in the methanolysis mixture. The molecular weight of these oligomeric fragments decreased with higher sodium methanolate concentrations.</style></abstract></record><record><source-app name="Biblio" version="7.x">Drupal-Biblio</source-app><ref-type>17</ref-type><contributors><authors><author><style face="normal" font="default" size="100%">Ferreira, A</style></author><author><style face="normal" font="default" size="100%">Lopes, F</style></author><author><style face="normal" font="default" size="100%">Pereira, H</style></author></authors></contributors><titles><title><style face="normal" font="default" size="100%">Characterization of cork growth and quality in one region of production.</style></title><secondary-title><style face="normal" font="default" size="100%">ANNALS OF FOREST SCIENCE</style></secondary-title></titles><keywords><keyword><style  face="normal" font="default" size="100%">Cork</style></keyword><keyword><style  face="normal" font="default" size="100%">Growth</style></keyword><keyword><style  face="normal" font="default" size="100%">Porosity</style></keyword><keyword><style  face="normal" font="default" size="100%">Quality</style></keyword><keyword><style  face="normal" font="default" size="100%">variability</style></keyword></keywords><dates><year><style  face="normal" font="default" size="100%">2000</style></year></dates><publisher><style face="normal" font="default" size="100%">EDITIONS SCIENTIFIQUES MEDICALES ELSEVIER</style></publisher><pub-location><style face="normal" font="default" size="100%">23 RUE LINOIS, 75724 PARIS CEDEX 15, FRANCE</style></pub-location><volume><style face="normal" font="default" size="100%">57</style></volume><pages><style face="normal" font="default" size="100%">187-193</style></pages><language><style face="normal" font="default" size="100%">eng</style></language><abstract><style face="normal" font="default" size="100%">Cork growth and quality were characterised in 5 cork oak stands within the production area of the Sado basin (Alcacer do Sal, Portugal) based on a field sampling on 40 trees/stand. Cork thickness was on average 33.8 mm, with 75% of the samples in the commercial classes above 27 mm suitable for production of stoppers. Porosity measured by image analysis was 4.6% on average. Between toe and between stand variability of cork quality was large. The annual average cork growth for a production cycle with 8 complete growth years was 4.1 mm, being highest during the years following cork extraction and decreasing during the cycle. For this region, a production cycle of 9 years is adequate for raw-material industrial requirements. The results show the importance of between tree variability in growth and especially in quality.</style></abstract></record><record><source-app name="Biblio" version="7.x">Drupal-Biblio</source-app><ref-type>17</ref-type><contributors><authors><author><style face="normal" font="default" size="100%">Marques, A V</style></author><author><style face="normal" font="default" size="100%">Pereira, H</style></author><author><style face="normal" font="default" size="100%">Meier, D</style></author><author><style face="normal" font="default" size="100%">Faix, O</style></author></authors></contributors><titles><title><style face="normal" font="default" size="100%">Structural characterization of cork lignin by thioacidolysis and permanganate oxidation</style></title><secondary-title><style face="normal" font="default" size="100%">HOLZFORSCHUNG</style></secondary-title></titles><keywords><keyword><style  face="normal" font="default" size="100%">Cork</style></keyword><keyword><style  face="normal" font="default" size="100%">cork lignin</style></keyword><keyword><style  face="normal" font="default" size="100%">ferulic acid</style></keyword><keyword><style  face="normal" font="default" size="100%">milled wood lignin (MWL)</style></keyword><keyword><style  face="normal" font="default" size="100%">permanganate oxidation</style></keyword><keyword><style  face="normal" font="default" size="100%">Quercus suber</style></keyword><keyword><style  face="normal" font="default" size="100%">suberin</style></keyword><keyword><style  face="normal" font="default" size="100%">thioacidolysis</style></keyword></keywords><dates><year><style  face="normal" font="default" size="100%">1999</style></year></dates><publisher><style face="normal" font="default" size="100%">WALTER DE GRUYTER &amp; CO</style></publisher><pub-location><style face="normal" font="default" size="100%">GENTHINER STRASSE 13, D-10785 BERLIN, GERMANY</style></pub-location><volume><style face="normal" font="default" size="100%">53</style></volume><pages><style face="normal" font="default" size="100%">167-174</style></pages><language><style face="normal" font="default" size="100%">eng</style></language><abstract><style face="normal" font="default" size="100%">Quercus suber L. milled cork lignins obtained from extractive-free cork (MCL) and from saponified cork (MCLsap) were characterized by thioacidolysis and KMnO4 oxidation. These techniques and the previously used analytical pyrolysis revealed that cork contains a guaiacyl lignin (G lignin) with 94-96% guaiacyl-, ca. 3% syringyl-, and 2-3% of 4-hydroxyphenyl propane units. The total yields of degradation products in thioacidolysis and KMnO4 oxidation experiments were lower in comparison to those of a spruce milled wood lignin (MWLspruce) suggesting a higher cross-linking in the G-lignin of cork. The higher frequency of ``condensed{''} structures (having C-C or C-O-C linkages to aromatic rings) in cork lignin was also manifested in the relative abundance of various aromatic acids obtained by KMnO4 oxidation. The cork lignin (MCLsap) contains only low amounts (ca. 2%) of covalently bonded suberinic acids. Numerous free aliphatic suberinic acids were detected and identified in the ether soluble part of MCLsap. Ferulic acid was not liberated by thioacidolysis, pointing at an in situ acylation. We suggest that the major part of the aromatic domain in cork is a G-lignin but that it includes also another structural moiety with higher H-unit content and linked by thioacidolysis resistant bonds.</style></abstract></record><record><source-app name="Biblio" version="7.x">Drupal-Biblio</source-app><ref-type>17</ref-type><contributors><authors><author><style face="normal" font="default" size="100%">Bento, M F</style></author><author><style face="normal" font="default" size="100%">Pereira, H</style></author></authors></contributors><titles><title><style face="normal" font="default" size="100%">Thermally assisted transmethylation gas chromatography–mass spectrometry of suberin components in cork from Quercus suber L.</style></title><secondary-title><style face="normal" font="default" size="100%">Phytochemical Analysis</style></secondary-title></titles><keywords><keyword><style  face="normal" font="default" size="100%">Cork</style></keyword><keyword><style  face="normal" font="default" size="100%">pyrolysis mass spectrometry</style></keyword><keyword><style  face="normal" font="default" size="100%">Quercus suber</style></keyword><keyword><style  face="normal" font="default" size="100%">suberin</style></keyword><keyword><style  face="normal" font="default" size="100%">thermally assisted methylation</style></keyword></keywords><dates><year><style  face="normal" font="default" size="100%">1998</style></year></dates><volume><style face="normal" font="default" size="100%">9</style></volume><pages><style face="normal" font="default" size="100%">75-87</style></pages><language><style face="normal" font="default" size="100%">eng</style></language><abstract><style face="normal" font="default" size="100%">Thermally assisted transmethylation gas chromatography - mass spectrometry with tetramethylammonium hydroxide has been applied for the qualitative and quantitative analysis of the suberin fraction of wax-free cork. With this method, hydrolysis of esters together with methylation of carboxylic and hydroxylic groups was observed. Mostly long chain aliphatic components, such as alkanols, alkanoic acids, v-hydroxyacids, v,v-alkanoic diacids, and several 9,10-epoxy and 9,10-dihydroxy forms have been found in keeping with results of other workers in the ﬁeld. Two other components that may give a more complete view of the architecture of suberin were also found, namely the phenolic compound ferulic acid, and glycerol which is probably esteriﬁed to carboxylic groups of the aliphatic building units of suberin</style></abstract></record><record><source-app name="Biblio" version="7.x">Drupal-Biblio</source-app><ref-type>17</ref-type><contributors><authors><author><style face="normal" font="default" size="100%">Rosa, M E</style></author><author><style face="normal" font="default" size="100%">Pereira, H</style></author></authors></contributors><titles><title><style face="normal" font="default" size="100%">THE EFFECT OF LONG-TERM TREATMENT AT 100-DEGREES-C-150-DEGREES-C ON STRUCTURE, CHEMICAL-COMPOSITION AND COMPRESSION BEHAVIOR OF CORK</style></title><secondary-title><style face="normal" font="default" size="100%">HOLZFORSCHUNG</style></secondary-title></titles><keywords><keyword><style  face="normal" font="default" size="100%">c</style></keyword><keyword><style  face="normal" font="default" size="100%">Cellular materials</style></keyword><keyword><style  face="normal" font="default" size="100%">Cork</style></keyword><keyword><style  face="normal" font="default" size="100%">mechanical properties</style></keyword></keywords><dates><year><style  face="normal" font="default" size="100%">1994</style></year></dates><publisher><style face="normal" font="default" size="100%">WALTER DE GRUYTER &amp; CO</style></publisher><pub-location><style face="normal" font="default" size="100%">GENTHINER STRASSE 13, D-10785 BERLIN, GERMANY</style></pub-location><volume><style face="normal" font="default" size="100%">48</style></volume><pages><style face="normal" font="default" size="100%">226-232</style></pages><language><style face="normal" font="default" size="100%">eng</style></language><abstract><style face="normal" font="default" size="100%">The effects of heating of cork in air at 100-degrees-C and 150-degrees-C&lt;br/&gt;for up to 42 days have been studied. Dimensional and mass changes&lt;br/&gt;induced by heat treatment were measured and the chemical composition was&lt;br/&gt;analysed. The thermal degradation of cork is small for short periods of&lt;br/&gt;treatment but increases with time and temperature. Cork looses after 42&lt;br/&gt;days of treatment 6.8 % of its mass at 100-degrees-C and 19.9 % at&lt;br/&gt;150-degrees-C. Cork extractives and polysaccharides were found to be the&lt;br/&gt;most temperature labile components. The cellular structure, observed by&lt;br/&gt;scanning electron microscopy, did not change with treatment in these&lt;br/&gt;conditions. Compression curves of untreated and heat treated cork&lt;br/&gt;samples were obtained, which show an increase of compression strength&lt;br/&gt;upon heating for short exposure periods and a decrease for longer ones.&lt;br/&gt;The changes observed in the compression behaviour of cork treated at&lt;br/&gt;100-degrees-C and 150-degrees-C were related to the chemical composition&lt;br/&gt;changes induced by heat treatment.</style></abstract></record><record><source-app name="Biblio" version="7.x">Drupal-Biblio</source-app><ref-type>17</ref-type><contributors><authors><author><style face="normal" font="default" size="100%">Pereira, H</style></author><author><style face="normal" font="default" size="100%">Graça, J</style></author><author><style face="normal" font="default" size="100%">Baptista, C</style></author></authors></contributors><titles><title><style face="normal" font="default" size="100%">THE EFFECT OF GROWTH-RATE ON THE STRUCTURE AND COMPRESSIVE PROPERTIES OF CORK</style></title><secondary-title><style face="normal" font="default" size="100%">IAWA BULLETIN</style></secondary-title></titles><keywords><keyword><style  face="normal" font="default" size="100%">COMPRESSION PROPERTIES</style></keyword><keyword><style  face="normal" font="default" size="100%">Cork</style></keyword><keyword><style  face="normal" font="default" size="100%">GROWTH RATE</style></keyword><keyword><style  face="normal" font="default" size="100%">QUERCUS-SUBER L</style></keyword><keyword><style  face="normal" font="default" size="100%">YOUNG's MODULI</style></keyword></keywords><dates><year><style  face="normal" font="default" size="100%">1992</style></year></dates><publisher><style face="normal" font="default" size="100%">INT ASSOC WOOD ANATOMISTS</style></publisher><pub-location><style face="normal" font="default" size="100%">RIJKSHERBARIUM, PO BOX 9514, 2300 LEIDEN, NETHERLANDS</style></pub-location><volume><style face="normal" font="default" size="100%">13</style></volume><pages><style face="normal" font="default" size="100%">389-396</style></pages><language><style face="normal" font="default" size="100%">eng</style></language><abstract><style face="normal" font="default" size="100%">Cork samples with an age of 9 years and with different growth rates, corresponding to calibre classes `small', `medium' and `large', were observed by scanning electron microscopy and tested mechanically in compression. Differences in calibre correspond to different widths of annual growth rings; widths differ because both the number of cells produced per year and cell dimensions differ. For instance, small and large calibre cork had, respectively, 50 and 151 cells in one row of an annual growth ring, with an average prism height of 32.6 and 39.8 mum. The stress-strain curves obtained in compression parallel to the three main directions showed that cork with the higher growth rate (large calibre) has lower strength in compression for all strains and lower Young's moduli.</style></abstract></record><record><source-app name="Biblio" version="7.x">Drupal-Biblio</source-app><ref-type>17</ref-type><contributors><authors><author><style face="normal" font="default" size="100%">Pereira, H</style></author></authors></contributors><titles><title><style face="normal" font="default" size="100%">The thermochemical degradation of cork</style></title><secondary-title><style face="normal" font="default" size="100%">Wood Science and Technology</style></secondary-title></titles><keywords><keyword><style  face="normal" font="default" size="100%">Cellular structure</style></keyword><keyword><style  face="normal" font="default" size="100%">Cork</style></keyword><keyword><style  face="normal" font="default" size="100%">mass loss (voyant)</style></keyword><keyword><style  face="normal" font="default" size="100%">thermochemical degradation</style></keyword></keywords><dates><year><style  face="normal" font="default" size="100%">1992</style></year></dates><volume><style face="normal" font="default" size="100%">26</style></volume><pages><style face="normal" font="default" size="100%">259-269</style></pages><language><style face="normal" font="default" size="100%">eng</style></language><abstract><style face="normal" font="default" size="100%">. The thermochemical degradation of cork from Quercus suber L. was studied in the temperature range 150 ~ ~ in relation to mass loss, chemical composition and the influ- ence on the cellular structure. The degradation of cork is strongly dependent on temperature and mass losses become significant at 200~ (15% of initial dry weight) and increase rapidly for higher temperatures (27% at 250 ~ 49% at 300 ~ 62% at 350 ~ until ashing at 450 ~ The polysaccharides are the most heat sensitive components: at 200 ~ hemicelluloses disappear and cellulose is degraded to a considerable extent. Suberin is more resistant and degradation starts at approx. 250~ 300~ samples only contain 7% suberin. The cellular structure of cork is also significantly influenced by temperature. Upon heating, cells expand and the cell walls stretch, attaining at 250~ a maximum cell volume increase corresponding to a factor of approximately 2. Above 300 ~ the structure of cell walls is considerably changed and show profound physical damage; in the later stages of pyrolysis, a cellular structure is no longer observed.</style></abstract></record><record><source-app name="Biblio" version="7.x">Drupal-Biblio</source-app><ref-type>17</ref-type><contributors><authors><author><style face="normal" font="default" size="100%">Pereira, H</style></author></authors></contributors><titles><title><style face="normal" font="default" size="100%">Chemical composition and variability of cork from Quercus suber L.</style></title><secondary-title><style face="normal" font="default" size="100%">Wood Science and Technology</style></secondary-title></titles><keywords><keyword><style  face="normal" font="default" size="100%">chemical composition</style></keyword><keyword><style  face="normal" font="default" size="100%">Cork</style></keyword><keyword><style  face="normal" font="default" size="100%">reproduction cork (voyant)</style></keyword><keyword><style  face="normal" font="default" size="100%">virgin cork</style></keyword></keywords><dates><year><style  face="normal" font="default" size="100%">1988</style></year></dates><volume><style face="normal" font="default" size="100%">22</style></volume><pages><style face="normal" font="default" size="100%">211-218</style></pages><language><style face="normal" font="default" size="100%">eng</style></language><abstract><style face="normal" font="default" size="100%">The chemical composition of cork from Quercus suber L. was determined for virgin cork and for reproduction cork. Average chemical composition of virgin cork is: ash 0.7%, total extractives 15.3%, suberin 38.6%, lignin 21.7% and polysaccharides 18.2%. The carbo- hydrate composition shows that glucose represents 50.6% of all monosaccharides, xylose 35.0%~ arabinose 7.0% and galactose and mannose, respectively, 3.6% and 3.4%. Reproduction cork has a composition similar to virgin cork. For the cases studied, reproduction cork had however less extractives and a higher amount of suberin. Significant differences were found for the chemical composition of virgin cork in relation to location of extractives and polysaccharide content. The between-tree variability was large and a variation within the tree was also recorded.</style></abstract></record></records></xml>