The forest industry operates in a dynamic and global market where change and competition are the rule rather than the exception. The color of wood is one of the most attractive features for the modem wood industry. Ev...The forest industry operates in a dynamic and global market where change and competition are the rule rather than the exception. The color of wood is one of the most attractive features for the modem wood industry. Even when wood is chosen for its structural qualities, attractive and decorative colors are usually an important factor. In many applications, particularly in furniture, decorative products, decorative veneers and flooring, accurate matching of the color of different samples is required. Wood attributes and properties are important because they have a direct bearing on market opportunities and consumer acceptance for many types of manufactured wood products. The aim of this review is to identify causes of wood discoloration and advances in drying technology to overcome this problem. Wood discoloration is a complex phenomenon, mainly affected by heat, light, physiological and biochemical reactions, as well as from attack by microorganisms.展开更多
A desorption isotherm is a very important basis in the understanding of drying process. In this study, the desorption isotherms from the sapwood of Mexican pine （Pinus pseudostrobus Lindl.） were determined by the gr...A desorption isotherm is a very important basis in the understanding of drying process. In this study, the desorption isotherms from the sapwood of Mexican pine （Pinus pseudostrobus Lindl.） were determined by the gravimetric method （discontinuous control of sample weight） at 30℃ and 50℃. The salt method was used in the range of water activities from 0.11 to 0.89. The results show that the desorption ability of Mexican pine sapwood increased with temperature at a given relative humidity. The experimental data was further simulated with the models, i.e., BET, GAB, Oswin and Henderson models. The GAB, Oswin and Henderson models allow the representation of the entire desorption isotherms. The BET model showed a better fit for water activity lower than 0.35, with a mean relative deviation of 0.0286 at 30℃ and 0.0167 at 50℃. Simultaneously, the BET model gave a better representation of moisture content in the monolayer saturation region. Overall, the GAB model ensured the best simulation of the entire isotherm, while the Henderson model displayed the worst simulation.展开更多
Anatomical features of wood have a great variation among species as a result of genetic and environmental factors. The anatomical heartwood characteristics of Prosopis laevigata species from two areas with differences...Anatomical features of wood have a great variation among species as a result of genetic and environmental factors. The anatomical heartwood characteristics of Prosopis laevigata species from two areas with differences on temperature and rain precipitation on northeast Mexico were compared. Fibers length (μm), diameter of vessels (μm), and the area of the vessels (μm-2) were measured using light microscopy coupled with a digitized-image analysis system. The differences were statistically analyzed with analysis of variance. Statistical differences between fibers length (p 0.0001) and diameter of the vessels (p 0.001) from the two localities were found. The locality Linares, Nuevo León, Mexico, with higher precipitation and lower temperature, showed higher fiber length and higher diameter of the vessels than China, Nuevo León. Hard environmental conditions, where low precipitation values and high temperatures prevail, condition P. laevigata trees do reduce the risk of losing water.展开更多
文摘The forest industry operates in a dynamic and global market where change and competition are the rule rather than the exception. The color of wood is one of the most attractive features for the modem wood industry. Even when wood is chosen for its structural qualities, attractive and decorative colors are usually an important factor. In many applications, particularly in furniture, decorative products, decorative veneers and flooring, accurate matching of the color of different samples is required. Wood attributes and properties are important because they have a direct bearing on market opportunities and consumer acceptance for many types of manufactured wood products. The aim of this review is to identify causes of wood discoloration and advances in drying technology to overcome this problem. Wood discoloration is a complex phenomenon, mainly affected by heat, light, physiological and biochemical reactions, as well as from attack by microorganisms.
文摘A desorption isotherm is a very important basis in the understanding of drying process. In this study, the desorption isotherms from the sapwood of Mexican pine （Pinus pseudostrobus Lindl.） were determined by the gravimetric method （discontinuous control of sample weight） at 30℃ and 50℃. The salt method was used in the range of water activities from 0.11 to 0.89. The results show that the desorption ability of Mexican pine sapwood increased with temperature at a given relative humidity. The experimental data was further simulated with the models, i.e., BET, GAB, Oswin and Henderson models. The GAB, Oswin and Henderson models allow the representation of the entire desorption isotherms. The BET model showed a better fit for water activity lower than 0.35, with a mean relative deviation of 0.0286 at 30℃ and 0.0167 at 50℃. Simultaneously, the BET model gave a better representation of moisture content in the monolayer saturation region. Overall, the GAB model ensured the best simulation of the entire isotherm, while the Henderson model displayed the worst simulation.
文摘Anatomical features of wood have a great variation among species as a result of genetic and environmental factors. The anatomical heartwood characteristics of Prosopis laevigata species from two areas with differences on temperature and rain precipitation on northeast Mexico were compared. Fibers length (μm), diameter of vessels (μm), and the area of the vessels (μm-2) were measured using light microscopy coupled with a digitized-image analysis system. The differences were statistically analyzed with analysis of variance. Statistical differences between fibers length (p 0.0001) and diameter of the vessels (p 0.001) from the two localities were found. The locality Linares, Nuevo León, Mexico, with higher precipitation and lower temperature, showed higher fiber length and higher diameter of the vessels than China, Nuevo León. Hard environmental conditions, where low precipitation values and high temperatures prevail, condition P. laevigata trees do reduce the risk of losing water.
