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After thermal modification at 210 °C using the Thermowood method, changes in Pinus radiata D. Don wood cell wall components and hygroscopicity were studied for subsequent comparison with recently felled wood of the same species in samples from the same region of provenance (Basque Country, Spain). To this end, samples were characterised by sorption isotherms at 15, 35 and 50 °C fitted to the Guggenheim–Anderson–de Boer (GAB) model, the chemical composition was obtained by high performance liquid chromatography (HPLC) and infrared spectroscopy (FTIR), and crystallinity and structural organisation of cellulose (crystal orientation) were determined using powder and 2D X-ray diffraction (XRD). Heat treatment caused the following changes in the wood: a decrease in the equilibrium moisture content (EMC); a smaller hysteresis area and therefore more hygroscopically stable wood; a decrease in the hemicellulose content; an increase in the relative percentage of cellulose, lignin and extractives; and a higher degree of crystallinity and crystal orientation of the cellulose. The reorganisation of cellulose could be explained by epitaxial growth of cellulose starting from the highly oriented crystalline regions during the recrystallisation process. All these chemical and structural changes induced by heating could explain the reduction in hygroscopic properties of wood, as well as its stability.

Changes were evaluated in cell wall components, hygroscopicity, and thermodynamic properties of Pinus sylvestris L. wood that had been in contact with salt (NaCl) for 300 years in a former saltworks storehouse in Gerri de la Sal (Lérida, Spain), comparing it with recently felled wood (new wood) of the same species. The wood in contact with salt (salt-covered wood) had higher equilibrium moisture content values except in the first interval of the adsorption isotherm, probably because of mechanical blocking of polar sites by salt crystals. The high fibre saturation point values of this wood are caused by the salt dissolved in water above water activity of about 0.75. More energy is invested in the desorption process, and the values are higher in the salt-covered wood.

A comparison was made of the hygroscopicity, cell wall chemical composition and crystallinity of recently peeled poplar (Populus spp.) wood and wood of the same species subjected to repeated cycles (20, 60 and 80) of vacuum/pressure (85 kPa/600 kPa) and soaking in an autoclave followed by oven drying. The 15 and 35 °C sorption isotherms were obtained using the saturated salt method and fitted with the Guggenheim–Anderson–de Boer model. Chemical composition was determined and the infrared spectra and X-ray powder and 2D diffractograms were obtained to identify differences in the wood with and without cycles. The cycles caused a statistically significant decrease in equilibrium moisture content (EMC) between the wood without cycles and the wood with cycles, a statistically significant lower contribution by the monolayer as the number of cycles increased (in the 15 °C isotherm in adsorption without cycles from 8.12% EMC to 6.16% with 80 cycles, in desorption from 10.23 to 8.13%; in the 35 °C isotherm from 7.45 to 5.57% in adsorption and from 8.86 to 6.54% in desorption), a decrease in the area of the hysteresis loop with significant differences between the wood without cycles and the wood with cycles, a statistically significant decrease in the percentage of cell wall components (in cellulose and extractives, in lignin content between the wood without cycles and wood with 60 and 80 cycles, and in hemicellulose between the wood without cycles and the wood with 80 cycles), a statistically significant increase in crystallinity between the wood without cycles (CRI% 52.1%) and the wood with cycles (CRI% 81.60–92.50%), and reorganisation of the cell wall ultrastructure, as seen in the increased size of the cellulose crystal of the fraction oriented parallel to the fibre.

The wood structure of conifers in general and the Pinus genus in particular makes species differentiation by traditional qualitative or quantitative methods complicated or even impossible at times. Pinus sylvestris L.;Pinus nigra Arn subsp. salzmannii (Dunal) Franco are a clear example of this because they cannot be differentiated by traditional methods. However, correctly identifying these species is very important in some cases as they are extensively used in a large variety of fields because of their wide distribution range in the forests of Europe and Asia. Using trees selected from the same forest to minimise the influence of site and performing a biometric study of 10 growth rings from the same climate period, a feedforward multilayer perceptron network trained by the resilient backpropagation algorithm was designed to determine whether the network could be used to differentiate these species with a high degree of probability. The artificial neural network achieved 90.4% accuracy in the training set, 81.6% in the validation set and 81.2% in the testing set. This result justifies the use of this tool for wood identification at anatomical level. © 2017, Springer-Verlag GmbH Germany.

The hygroscopicity and thermodynamic properties of Pinus canariensis wood buried in volcanic ash, dating from 1100 BC, were studied and compared with recently felled juvenile and mature wood of the same species. The sorption iso_x0002_therms were obtained by the saturated salt method at 35 and 50 _x0003_C. The isotherms were fitted using the Guggenheim–Anderson–de Boer model. The thermodynamic parameters were determined following the Clausius–Clapeyron integration method. To understand the behaviour of each type of wood, the chemical composition, infrared spectra and X-ray diffractograms were determined for each sample. The mature wood has a higher sugar content and lower extractive content than the juvenile and the buried wood. For both temperatures, the isotherm of the mature wood is above the isotherm of the juvenile wood and this, in turn, is above the isotherm of the buried wood, primarily influenced by the higher cellulose and hemicellulose contents and lower extractives content in the mature wood, resulting in a higher number of accessible –OH groups. Degradation of the buried wood due to high temperatures explains why its isotherms are below the isotherms of the recent wood. The energy involved in the desorption process is greater than in adsorption. Similarly, more energy is involved in the mature wood than in the juvenile wood, and the energy involved in the juvenile wood is greater than in the buried wood.

The hygroscopicity and thermodynamic properties of juvenile and mature wood of Abies alba Mill. were studied through the 15, 35 and 50 °C sorption isotherms. The Guggenheim, Anderson and de Boer-Dent model was used to fit the isotherms. The thermodynamic parameters were obtained from the sorption isotherms by applying the integration method of the Clausius–Clapeyron equation. The chemical composition of both types of wood (extractives, lignin and carbohydrate polymer-cellulose and hemicellulose-content) was determined, and infrared spectroscopy and X-ray diffractograms were used to identify any chemical modifications and changes in the crystal structure of the cell wall. The mature wood has more cellulose and hemicellulose content and less extractives content than the juvenile wood. The shorter crystallite length in the mature wood creates a higher amount of amorphous zones and, as a consequence, a higher number of access areas to the –OH groups. The combination of these phenomena explains the different hygroscopic behaviour between the juvenile and the mature wood, as the latter has higher moisture content in the three isotherms. As regards the thermodynamic properties, the amount of energy involved in the sorption process is greater in the mature wood than in the juvenile wood. © 2015, Springer Science+Business Media New York.

The wood anatomy of the three species of Juniperus occurring in Macaronesia is compared for the first time using representative samples of each species collected in its natural region of provenance J. cedrus Webb & Berthel and J. phoenicea L. var. canariensis Guyot, in the Canary Islands, and J. brevifolia (Seub.) Antoine, in the Azores. The three species are anatomically similar, although some qualitative differences were observed distribution of axial parenchyma very scarce in J. phoenicea compared with the other two species, presence of crassulae only in J. phoenicea, presence of torus extensions and notches on pit borders in the radial walls of J. brevifolia, and ray parenchyma end walls slightly nodular in J. cedrus as opposed to very nodular in J. phoenicea and J. brevifolia. In addition, the biometry of tracheid pit diameter in the radial walls, ray height in number of cells, and largest and smallest diameters of cross-field pits shows differences for a significance level of 95%. © Copyright 2014 by Koninklijke Brill NV, Leiden, The Netherlands.

Because of its characteristics, cork currently has no substitute in the bottle stopper industry for high quality wines and champagnes. Few studies have been conducted on water-cork interactions, and especially on the thermodynamic behaviour of cork. The hygroscopic and thermodynamic properties of two cork samples of the same quality, harvested in 1968 and 2006, were studied to determine any differences in behaviour over time. The 35°C and 50°C isotherms were plotted following the saturated salts method and fitted using the GAB model. The isotherms were compared by means of hysteresis coefficients. The infrared spectra were recorded to analyse chemical changes in the cell wall, and the thermodynamic parameters were determined using the integration method based on the Clausius- Clapeyron equation. No significant differences were observed between the equilibrium moisture content obtained in the two samples, although the monolayer saturation moisture content was significantly lower in the older cork. In both types of cork, as also occurs with wood, the points of inflexion where multilayer sorption begins to predominate over monolayer sorption occurred at very similar values, at around 31- 35% relative humidity (RH). In terms of thermodynamic properties, the net isosteric heat curves were similar to those obtained for wood, and the bond energy in the recently harvested cork was lower than in the older cork.

An analysis was made of the wood anatomy of seven species, one subspecies and two varieties of the genus Abies from the Mediterranean area (A. alba, A. borisii-regis, A. cephalonica, A. cilicica, A. nordmanniana, A. nordmanniana subsp. equi-trojani, A. numidica, A. pinsapo, A. pinsapo var. marocana and A. pinsapo var. tazaotana) in order to find phyletically relevant features to help clarify and complement the evolutionary patterns based on molecular studies. The wood structure within the genus was qualitatively similar, except for specific features characteristic of certain provenances. However, the wood biometry allowed the different taxa to be grouped in accordance with their anatomical similarity. A. alba, A. pinsapo, A. pinsapo var. marocana and A. pinsapo var. tazaotana possess biometric features which distinguish them from the other Mediterranean firs. Furthermore, A. numidica showed biometric features which distinguish it from the eastern firs (A. borisii-regis, A. cephalonica, A. cilicica, A. nordmanniana and A. nordmanniana subsp. equi-trojani) and place it closer to certain Iberian populations of A. pinsapo. The maximum ray height in number of cells, frequency of rays with more than 30 cells and tracheid length can be regarded as specific patterns of the Mediterranean fir phylum.