Sistema Regional de Información
en línea para Revistas Científicas de América Latina,
el Caribe, España y Portugal

Phenolic resin or phenol formaldehyde (PF) resin containing different percentage of zinc oxide (ZnO) nanoparticles was prepared and used to treat rubberwood. Three types of treatment solutions were prepared, namely (1) low molecular weight phenol formaldehyde resin (LMwPF), (2) 1.5 wt % nano ZnO dissolved in water (ZnO/H2O), and (3) combination of both LMwPF and 1.5 wt % nano ZnO (LMwPF/ZnO). The rubberwood samples were submerged into the treatment solutions for 60, 90, and 120 min, before vacuum impregnation. The untreated rubberwood samples served as the controlled samples. The thermal stability behaviour and resistance against white-rot fungi (Pycnoporus sanguineus) of the treated rubberwood samples were evaluated. The results reveal that the treated rubberwood had slightly better thermal stability compared to the untreated samples. In terms of decay resistance, the rubberwood treated with LMwPF and LMwPF/ZnO possess very high resistance against white-rot fungi. On the other hand, the rubberwood treated with ZnO/H2O did not attain similar effectiveness as the other two treatments, except for the samples that were submerged in ZnO/H2O for 120 min. The results indicate that 1.5 wt % nano ZnO could be sufficient in imparting superior durability to rubberwood provided that longer submersion time is adopted.

This paper presents the effect of thermal modification of 14-15 year-old plantation grown Acacia auriculiformis wood in the 150-240ºC temperature range under vacuum condition. Important techno-mechanical parameters of thermally modified wood such as density, dimensional stability, colour, surface roughness, decay resistance against brown and white rot fungi and flexural properties were evaluated and compared with control. Depending on severity of heat treatment, colour of modified sapwood was turned from light to dark brownish. Moreover, the change in colour was found to be uniform throughout the thickness of wood blocks. Amount of shrinkage of Acacia auriculiformis wood was observed to be decreased with increasing treatment temperatures. Maximum dimensional stability of wood thermally modified at 240ºC was in the range of 60-65%. The surface roughness parameters (Ra and Rz) were reduced significantly after the treatment. The flexural strength (modulus of rupture-MOR) was observed to be reduced with increasing treatment temperatures. However, flexural stiffness (modulus of elasticity-MOE) was not found to be affected significantly up to 210ºC temperature. The lower amount of weight loss of thermally modified wood compared to untreated control showed improved decay resistance against white and brown rot fungi. With desirable improvements in various esthetic and technologically important quality parameters such as enhanced dimensional stability, biological durability against fungi and certain other properties, thermally modified wood from short-rotation Acacia auriculiformis may be considered as viable alternative to scarcely available timber resource for different value-added applications.

Se examinó la variación del contenido de humedad verde, y de la densidad básica de la madera, en fustes de árboles de Eucalyptus nitens con dimensiones aserrables, provenientes de una plantación de 18 años de edad, crecida en la región del Biobío, Chile. Se seleccionaron 9 árboles aleatoriamente. De cada árbol se obtuvo un conjunto de 8 rodelas, que representaron las siguientes alturas fijas: 0,8 m; 3,2 m; 7,0 m; 9,4 m; 15,0 m; 17,4 m; 23,2 m; y 25,6 m. De cada rodela se obtuvieron muestras al 10, 30, 50, 70 y 90% del radio, en la exposición cardinal Norte y Sur del fuste, para las determinaciones de contenido de humedad verde y densidad básica. La exposición cardinal en el fuste, resultó relevante para el contenido de humedad verde, pero no para la densidad básica. Se reportaron cambios significativos en contenido de humedad verde y densidad básica, con la posición radial y axial en el fuste. Se encontraron distintos patrones de variación radial, del contenido de humedad verde y de la densidad básica, a lo largo del fuste del árbol. Los cambios radiales (en contenido de humedad verde y densidad básica) fueron menores en la parte alta del fuste, y los cambios axiales, menores en el leño cercano a la corteza.

The effectiveness of the use of cellulose fibers as particulates/composite reinforcers involves the assessment of the crystallinity of such fibers. The aim of the present work is to provide information on the degree of crystallinity of the cellulose microfibers obtained from the stems of Cistus ladanifer and Erica arborea shrubs through two different methods, namely an alkaline treatment and a microwave-assisted deep eutectic solvent (DES) method. The crystallinity indexes (CrI) obtained from X-ray powder diffraction patterns indicated that higher CrI were attained for cellulose obtained from the DES treatment. Complementary information on the degree of crystallinity was also retrieved from attenuated total reflection- Fourier transform infrared spectroscopy (ATR-FTIR) vibrational spectra, scanning electron microscopy (SEM) micrographs, and accessibility data for the DES-treated celluloses from the two species. The crystallinity results for the fibers derived from these two Mediterranean shrubs were within the range of the results for those derived from wood pulp, opening the door to their valorization for cellulose-derived packing applications or for their use as reinforcers in composite materials in combination with other biopolymers.

El algarrobo blanco (Prosopis alba) se caracteriza por sus excelentes propiedades física-mecánicas en su madera, lo cual la hace muy apreciable en la industria del mueble. El color es un rasgo importante en ciertos usos  de la madera, e incide en su calidad. El objetivo de este trabajo fue evaluar la variación colorimétrica de la madera entre sitios, sección y región de la madera y correlacionar parámetros colorimétricos con rasgos dentrométricos del árbol. Las muestras se extrajeron de tres rodales naturales (Los Arias, Santiago del Estero; Isla Cuba, Formosa y Villa Ángela, Chaco) y una plantación (San Isidro, Santiago del Estero), de la Región Chaqueña Argentina. Los parámetros colorimétricos (L*, a*, b*) se obtuvieron con un espectrofotómetro KONICA MINOLTA CM-5 con iluminante D65. El análisis confirmó que existen diferencias significativas en parámetros colorimétricos entre sitios, secciones y regiones de las muestras de madera analizadas. El tamaño de los árboles se encuentra directamente relacionado con los parámetros colorimetricos. The algarrobo blanco (Prosopis alba) is characterized by its excellent physical-mechanical properties in its wood. The colour is an important feature in certain use of wood, and affects its quality. The objective of this work was to evaluate the colorimetric variation between sites, section and region of the wood samples and correlate colorimetric parameters with dentrometric features of the tree. The samples were obtained from three natural stands (Los Arias, Santiago del Estero, Isla Cuba, Formosa and Villa Ángela, Chaco) and a plantation (San Isidro, Santiago del Estero), in the Chaqueña region of Argentina. The colorimetric parameters (L *, a *, b *) were obtained with a KONICA MINOLTA CM-5 spectrophotometer with illuminant D65. The colorimetric analysis confirmed that there are significant differences in colorimetric parameters between sites, section and region in the wood samples analyzed. The size of the trees is directly related to the colorimetric parameters.

Pyrolysis is a promising technology for thermal conversion of lignocellulosic biomass into a higher added value fuel. The aim of this study was to analyze the potential of four agroforestry biomass to produce energy as a raw material or as a bio-coal. In this study, slow pyrolysis was conducted in three final temperatures to evaluate the bio-coal production of four agroforestry biomasses widely available in Brazil. The biomass used was sugarcane bagasse (Saccharum sp.), bamboo (Dendrocalamus giganteus), straw bean (Phaseolus vulgaris) and eucalypts wood chips (Eucalyptus sp.). In the first part was presented the raw biomasses proprieties, such as lignin, carbon, hydrogen and ash content. In the second part was showed the bio-coal proprieties, such as, gravimetric and fixed carbon yield, fixed carbon and ash content. These bio-coal results were showed as a function of final temperature of pyrolysis. The best energy indicators for bio-coal production, such as fixed carbon yield, high heating value, was found in the bamboo and eucalypts. The bagasse and straw bean biomasses possess high concentrations of ash and low lignin content when compared with the other biomasses assessed and are less suitable to produce bio-coal.

In this study, it was investigated the possibilities of the use of fungal extract as wood protection solution against wood-degrading fungi. For that purpose, the decay resistance of Scotch pine wood samples, impregnated with Agaricus campestris fungal extract, was observed against the brown rot fungus Coniophora puteana. Impregnation procedure was applied at four different concentration levels and with two different extraction methods (hot water and methanol). The concentration levels were arranged as 1%, 3%, 5%, 7% for hot water and as 1.25%, 3.75%, 6.25%, 8.75% for methanol. The wood protective efficacy of extract solutions was determined by means of fungi decay test. The mass losses of the samples treated with both fungal extracts ranged from 3.53 to 20.91. The lowest mass losses in hot water (4.57%) and methanol extractions (3.53%) were seen in the samples treated at the highest concentration levels (7% and 8.75%). The wood samples impregnated at 7% and 8.75% concentration levels met the requirements of durability class 1 and were classified as very durable. Antifungal activity of methanol extract was stronger than that of the hot water extract. The variations which concentration levels were less than 7% did not have adequate protection to meet the requirements of the European norms.

Esta investigación nace en una Facultad de Ciencias de la Educación como enteresponsable de la formación de docentes. Su objetivo es analizar las diferentes modalidades de aprendizaje del alumnado del Máster del Profesorado de la Universidad Católica de Valencia y las diferencias entre las distintas especialidades. Para ello utilizamos el Cuestionario VARK, que clasifica a los alumnos como: visuales, auditivos, lectoescritores y cinestésicos. Este cuestionario ha sido aplicado a 262 alumnos, siendo la mayoría multimodales (71,4%). Los estilos más frecuentes son el AK (auditivo-cinestésico), el ARK (auditivo-lectoescritor-cinestésico) y el VARK (visual-auditivo-lectoescritor-cinestésico), encontrándose el mayor porcentaje de puntuación en la modalidad auditiva (32,2%). Se han encontrado diferencias estadísticamente significativasen función del sexo, no encontrándose en función de la especialidad cursada. La escasez de diferencias encontradas la atribuimos a la vivencia de una ense˜nanza tradicional (lección magistral y aprendizaje pasivo-memorístico). Estos resultados han sido comparados con investigaciones similares,  encontrando algunas discrepancias significativas

El autoconcepto es un aspecto interno de las personas que influye tanto en situaciones cotidianas de la vida como en cuestiones académicas. A lo largo del presente artículo se ha revisado la definición y los modelos principales del autoconcepto, para posteriormente detenerse en la novedosa propuesta de autoconcepto artístico de Vispoel, la cual encuadra en el modelo general de autoconcepto establecido por Shavelson, Huebner y Stanton (1976), que es susceptible de ser valorado por medio de un cuestionario dise˜nado a su medida denominado Inventario de Autopercepciones Artísticas. Vispoel (1993, 1995) opina que el autoconcepto artístico está compuesto por las autopercepciones que cada individuo tiene de sí mismo en las actividades artísticas, considerando que estas se encontrarían dentro de las Artes Visuales, la Música, la Danza y el Arte Dramático. Ha observado también que el autoconcepto artístico tiene un claro carácter multidimensional, pero en cambio el aspecto jerárquico sería moderado.Actualmente se siguen realizando investigaciones sobre el autoconcepto artístico.

Las personas mayores usuarias de las tecnologías de la información y la comunicación (TIC) en los centros sociales de personas mayores de Asturias son el objeto de estudio en la presente investigación. Un análisis previo nos permite afirmar que la población mayor tan solo hace uso de las TIC en un porcentaje poco representativo respecto al peso poblacional que los mayores tienen en la sociedad asturiana. Así, se hace necesario conocer de estos mayores, usuarios de las TIC, sus rasgos diferenciadores (de tipo personal y sociodemográfico), con el propósito de orientar unas pautas de actuación claras que permitan extender su uso a otras personas mayores. De ahí que el dise˜no mixto de la investigación vaya orientado a conocer en profundidad el perfil de las personas mayores usuarias de las TIC en los centros sociales de personas mayores de Asturias.