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The influence of the moisture content on the electrical resistance of two types of cork stoppers. Forest Systems. 19(2): 184-188.



Abstract: Using linear regression techniques, different regression models of the type Log10(Log10(R)+1)=a.h+b were derived to describe the relationship between the log of the electrical resistance (measured using pin electrodes) and the moisture content of two types of cork stoppers (natural [N] and agglomerate [AG]). The results obtained show that, using the models proposed, the moisture content of AG cork stoppers can be estimated with an error of ±0.3%, while that of N stoppers can be estimated with an error of 0.5%. The moisture content of cork stoppers could therefore be measured at the industrial scale using electrical resistance-type moisture meters. Neither the geographical origin of the N corks nor the surface treatment to which the AG corks were subjected significantly affected the proposed models.

 

Variation in wood anatomical traits of Pinus sylvestris L. between Spanish regions of provenance. Trees. Structure and function. 24(6): 1017-1028.



Abstract: The Spanish populations of Pinus sylvestris L. occupy differentiated sites and must therefore include structural variations to cope with varied climate conditions. This study compares wood anatomical traits of P. sylvestris from ten Spanish regions of provenance with contrasting climates, taking into account the effects of region of provenance and tree nested within provenance on variation in wood biometry. In general, the effect of both sources of variation (provenance and tree) on wood biometry was highly significant. Most of the anatomical variations observed were intra-populational (at the tree level), although variation explained by provenance was high for some parameters (e.g., ray frequency and ray parenchyma cell frequency), suggesting high environmental influence. Trees in the driest region, growing in a Mediterranean phytoclimate, were characterized by large tracheid lumens, suggesting more efficient water conduction. They also had thick cell walls, which would reduce the risk of cavitation caused by high implosion stress during periods of drought, as well as a high ray tracheid frequency, implying greater water storage capacity in the sapwood. The population with greatest growth, located in an oroboreal phytoclimate, was characterized by large bordered pits and long tracheids, which would reduce resistivity in water transport. At higher altitudes, tracheid lumen diameter and resin canal diameter tended to be smaller, and intertracheid wall strength was greater. Results are discussed in relation to adaptation of the species to growth demands and frost.

 

Prediction of plywood bonding quality using an artificial neural network. Holzforschung. 65(2): 209-214.



Abstract: The bonding quality test is the most important of all the tests performed on plywood, as it determines the suitability of boards for use in the type of exposure they are intended for. Because this test involves aging pretreatment, results are not available in less than 24-97 h after manufacture, depending on the type of board, and therefore any error in the manufacturing process is not detected until 1-4 days later. To solve this time problem, an artificial neural network was used as a predictive method to determine the suitability of board bonding through other properties that can be determined in less testing time: thickness, moisture content, density, bending strength and modulus of elasticity. The network designed, a feed forward multilayer perceptron trained by supervised learning after normalization of the input data, allowed the bonding test result to be predicted with 93% accuracy. This mathematical tool allows plywood bonding quality to be predicted through other properties that can be determined in less time, enabling errors in the production line to be detected quickly and reliably.

 

Comparative study of the 35ºC sorption isotherms of cork stripped from the tree in 1968 and 2006. Bioresources. 6(2): 2135-2144.



Abstract: A study was made of the hygroscopicity of two samples of cork with the same characteristics, taken from trees of the same age but with a 38- year gap between debarking. This was achieved by plotting the 35oC sorption-desorption isotherms and fitting them using the GAB model. Infrared spectra were used to determine any chemical changes in the cell wall. Extended exposure to controlled relative humidity and temperature did not cause hygroscopic changes to the cork. The equilibrium moisture content values were not significantly different in the two samples, but the monolayer saturation moisture content values were significantly lower in the older cork. This may be due to partial saturation of the moisture sorptive sites in the cell wall over time.

 

Influence of region of provenance and climate factors on wood anatomical traits of Pinus nigra Arn. subsp. salzmannii. European Journal of Forest Research. 131(3): 633-645.



Abstract: Region of provenance is defined as an area with uniform ecological conditions where stands with similar phenotypic or genetic features are found. This study assesses the effect of differing climate conditions of eight Spanish regions of provenance of Pinus nigra Arn. subsp. salzmannii on earlywood anatomical traits measured in samples from basal discs from mature trees. Results showed that variation of wood biometry between provenances was high, and more pronounced than intrapopulation variation. When comparing P. nigra with other Mediterranean pines, high intertracheid wall strength values are associated with better adaptation of pines to arid conditions. However, the intraspecific variations of this parameter in P. nigra did not follow the same pattern, due to the influence of mechanical support requirements. Trees subject to greater aridity were characterised by short tracheids, apparently resulting from their poorer growth, and high frequency of rays and ray parenchyma cells, which would allow trees to store greater amounts of starch, which is the source of metabolites invested in minimising the limitations imposed by water stress. Severe winter cold spells were strongly associated with high axial resin canal frequency and large radial resin canals, creating a powerful, preformed defence system. Increased tracheid lumen involved an increase in the size of bordered pits, favouring sap flow between tracheids, in addition to an increase in the maximum diameter of cross-field pits, favouring the flow of water and metabolites between the axial and radial systems. The high influence of region of provenance on structural variation in P. nigra shows the importance of provenance in the selection of seed origin for reforestation.

 

Esteban, L.G.

Martín, J.A.

de Palacios, P.

García Fernández, F.


2012

35

de Palacios, P.

Esteban, L.G.

García Fernández, F.

García-Iruela, A.

González-Adrados, J.R.

Conde, M. 2011.


2011

Esteban, L.G.

García Fernández, F.

de Palacios, P.


2010

Martín, J.A.

Esteban, L.G.

de Palacios, P.

García Fernández, F.


2010

Fernández-Golfín, J.I.

Conde García, M.

González Hernández, F.

Conde García, M.

Fernández-Golfín, J.J.,

Baonza Merino, V.

Esteban, L.G.,

González Adrados, J.R.


2010

34

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