Revistas Universidad del Bío-Bío
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Evaluation of the properties of hybrid yellow poplar (Liriodendron sino-americanum): A comparison study with yellow poplar (Liriodendron tulipifera)
Get PDFAs one of fast-growth wood species, hybrid yellow poplar (YP-h, Liriodendron sino-americanum) has been extensively planted throughout of China, however, little is known about its properties and applicability in structural and nonstructural applications such as construction and furniture. The aim of this study was to evaluate the properties of YP-h and examine its differences with yellow poplar (YP, Liriodendron tulipifera). The average vessel diameter of YP-h (55 μm) was 19 % lower than YP (68 μm), but, the density of YP-h was 37 % higher than YP and the dimensional change in YP-h was higher than YP. Comparable tensile strength and flexural modulus were found in YP-h and YP, however, the flexural, shear, and impact strength of YP-h was 35 %, 40 %, and 55 % higher than those of YP, respectively. The drilling, mortising, and turning processability of YP-h were superior to those of YP. Compared to the gluing and coating performance of YP, YP-h had inferior gluing properties and equivalent coating performance. Therefore, hybrid yellow poplar can be an ideal candidate for yellow poplar to be utilized in construction and furniture
Evaluation of wetting, structural and thermal properties of electrospun nanofibers at different pineapple leaf fiber / polyethylene terephthalate ratios
Get PDFIn this study, pineapple leaf fiber and polyethylene terephthalate electrospun nanofibers were produced via electrospinning process. Six ratios of pineapple leaf fiber/polyethylene terephthalate, namely 1/10; 1/7,5; 1/5; 1/1 and 1,3/1 were prepared and their wetting, structural and thermal properties were characterised. Wetting properties of this sample were studied using contact angle measurement. X-Ray Diffraction, differential scanning calorimetry and thermogravimetric analysis were conducted to get better understanding on the structural and its thermal properties respectively. The results revealed that increasing the pineapple leaf fiber content simultaneously increased the ability of nanofibers to adsorb water as shown by lower contact angle degree with 81,6° and adsorption time of 15 seconds. An increase in pineapple leaf fiber ratio did not change the peak position in X-Ray Diffraction and no new peaks observed for any sample. However, the peak at 23° for samples with ratio 1/1 and ratio 1,3/1 exhibited higher intensity compared to that of pure polyethylene terephthalate. Thermal properties obtained from thermogravimetric analysis results suggested that thermal properties were not influenced by the pineapple leaf fiber ratio. Overall, pineapple leaf fiber/polyethylene terephthalate electrospun nanofibers produced at the ratio of 1/1 displayed the optimum performance
Characterizations of tree-decay fungi by molecular and morphological investigationsin aniranian alamdardeh forest
Get PDFForest trees are considered important in ameliorating climate change through removing carbon dioxide from the atmosphere, for stabilizing water catchments and for timber production. Wood decay fungi are among the most important biotic factors in ecosystems, infecting valuable landscaping trees causing an economic loss or the preeminent recyclers of the wood. In a survey of forest trees in the Alamdardeh forest, northern Iran, fungal fruit bodies were collected and isolations made. Based on a combination of macro-morphological characteristics and molecular analyses, using the sequence data of ITS-rDNA, isolates were identified to the species level. A total of 22 species in nine families and 15 genera were identified. Most isolates were the white-rot fungi. Additionally, the brown-rot fungus Laetiporus sulphureus and the soft-rot species Xylaria longipes were indentified
Use of Eucalyptus grandis clones treated with a water repellent to improve the dimensional stability of utility poles
Get PDFWood is a common construction material used in most environments. However, its sensibility to abiotic agents, in particular those that affect the dimensional stability, limits the materials durability and decreases its properties. In this work, the efficiency of a paraffin-emulsion-based product as a water repellent, combined with the selection of Eucalyptus grandis clones with a low cracking index, was tested for its use in utility poles in order to improve the woods dimensional stability. Four selected Eucalyptus grandis clones were treated with the product mixed with Chromated Copper Arsenate - the most commonly used wood protector - in a single stage by the Bethell method at two retention levels. The dimensional stability of the treated samples was studied through the determination of anti-shrink efficiency. Test samples were also exposed to accelerated weathering processes for 200 h, and later analyzed by SEM microscopy. Results showed a significant improvement in the dimensional stability of treated wood when compared to samples without the water repellent, with variable efficacy depending on the clone used. Despite the weathering process slightly affected the appearance of the wood surface, the product is suitable for exterior use
Influences of different drying climates on Eucalyptus camaldulensis wood properties
Get PDFOne of the most important disadvantages of the wood material, whose usage is becoming more and more widespread, is the dimensional instability that occur in its interaction with water. Therefore, studies to improve these drawbacks of wood, remains always up to date. For mentioned purpose in this study, some chemical, morphological, physical and mechanical properties of Eucalyptus camaldulensis woods, which were naturally dried in outdoor and indoor climate in Eastern Mediterranean (Kahramanmaraş province) atmosphere conditions of Turkey, were investigated. According to the results of the study, chemical properties of eucalyptus woods dried indoor were measured as merely 0,23 % higher than dried ones in outdoor. The results of morphological measurements indicated that the fiber dimensions of eucalypts wood dried in indoor were averagely 1,48 % lower than the ones dried out in outdoor. Also, as a result of statistical analysis, it was found that there were significant differences (ρ < 0,000) between the physical properties of eucalyptus wood samples in indoor and outdoor according to t-test. At the same time, as a result of t-test applied to determine effect of drying conditions on mechanical properties of eucalyptus wood, modulus of elasticity, compression, tensile, dynamic bending and shear strength did not cause any significant difference between indoor and outdoor, while bending and Janka hardness strengths showed significant differences at ρ < 0,000 level. Finally, when the data obtained as a whole is considered, it can be said that testing of eucalyptus wood which requires a very sensitive drying in different climates has important contributions on the subject. Regarding eucalypts, which has a high distribution area (20 million hectares) in the world, it is recommended to relevant institutions and organizations to expand and maintain such study in the future. Lastly, according to obtained data from this study, it can be said that the experiments of eucalyptus woods which requires a very delicate drying in different environments provide important contributions on the subject
Mass transfer properties of Acacia mangium plantation wood
Get PDFThis study investigated the mass transfer properties (permeability and mass diffusivity) in the longitudinal, radial and tangential directions of plantation-grown Acacia mangium in Vinh Phuc province, northeast, Vietnam. These properties will be used to complement a conventional drying model in the future. Measurements of gas and liquid permeability were performed using a Porometer (POROLUXTM1000). Mass diffusivity was determined in a constant humidity and temperature chamber using PVC-CHA vaporimeters. Results showed the gas permeability was significant higher than liquid with the descending order of longitudinal, radial, and tangential directions. The permeability anisotropy ratios from the longitudinal to transverse directions of Acacia mangium were much lower than other published species. However, the obvious anisotropy ratios from radial to tangential for both permeability and diffusivity, is one of concerns as they can exacerbate defects during drying. Besides, the high permeability and diffusivity of Acacia mangium compared to some other species reported compounds its relatively fast drying rate
Simultaneous treatment with oil heat and densification on physical properties of Populus × canadensis wood
Get PDFSamples of wood from Populus × canadensis (9,5 % moisture) were treated with olive oil at 195 °C simultaneously with 15 % or 30 % compression densification, and the results were compared with samples subjected to oil heat treatment without densification, and control samples. The density of the treated samples increased by 18 %, 43 % and 1,5 % respectively, and barely changed over the six subsequent months stored inside the laboratory room (at approximately 65 % RH, 20 °C). This was due to the fact that the slight weight increment caused by the additional moisture content was offset by the increase in volume from the springback effect. When subjected to atmospheres with different relative humidities, the treated samples stabilised at the same time as the control samples, although the treated samples had a significantly lower moisture absorption than the control samples. It was also observed that the hygroscopic shrinkage in oil heat densification treatment samples was approximately half those of the control samples. The initial densification was partially lost as a result of springback: approximately 3 % in the first springback at a relative humidity of 65 % RH, and an additional 4 % in the second springback to a relative humidity of 85 % RH. Once this latter relative humidity had been attained, no new losses in densification were observed. The ageing of the oil used in the treatment caused a slight loss of densification in the densest samples
Diffuse urban sprawl in intermediate cities. Simulation of the expansión process in the city of Temuco, Chile
Get PDFUrbanization advances vertiginously and its impacts are visible beyond metropolitan spaces. In this context, urban sprawl simulation methodologies become relevant to understand and add to future urban growth scenarios. In this work, the case of the city of Temuco in the La Araucanía Region is analyzed, using the following tools: Markov chains; Cellular Automaton; Multicriteria-Multi-objective Assessment; and the determination of land usage/cover using Geographic Information Systems (GIS). Based on the above, the urban scenario was determined for 2049 from the spatial patterns of the area under study, since 1985. The model shows a trend to a peripheral and diffuse sprawl towards the north of the city and a strong development towards the western sector in the Labranza neighborhood. That is to say, the first sector is projected as a possible node of expansion, and the second, as one of consolidation. It is concluded that both zones require pertinent updated urban planning instruments, which the city has not had until now.La urbanización avanza de manera vertiginosa y sus impactos son visibles más allá de los espacios metropolitanos. En ese contexto, las metodologías de simulación del crecimiento urbano adquieren relevancia para comprender (y aportar a) futuros escenarios de crecimiento urbano. En concreto, aquí se analiza el caso de la ciudad de Temuco en la Región de La Araucanía empleando las siguientes herramientas: Cadenas de Markov, Autómata Celular, Evaluación Multicriterio-Multiobjetivo, como también de la determinación de usos/coberturas de suelo mediante Sistemas de Información Geográfica (SIG). Así, el trabajo determina el escenario urbano al año 2049 a partir de los patrones espaciales del área de estudio desde el año 1985. El modelo muestra la tendencia al crecimiento periférico y difuso hacia el norte de la ciudad y un fuerte desarrollo hacia el sector oeste en el barrio de Labranza, es decir, el primer sector se proyecta como un foco de posible expansión y el segundo, como uno de consolidación. Se concluye que ambas zonas requieren de instrumentos pertinentes y actualizados de planificación urbana, con los que la ciudad no ha contado hasta ahora
Por un derecho a la alimentación constitucional para las ciudades chilenas: saludable, sostenible y de proximidad
Get PDFIn May 2021, Chile democratically elected the people who will be part of the Constituent Assembly, whose mission is to write a new constitution. Over recent months, several issues have emerged as proposals from the candidates to be debated and introduced into the future Chilean Constitution. Among these, is the right to food, which is a human right found in article 12 of the Additional Protocol to the American Convention on Human Rights in matters of economic, social, and cultural rights, the “San Salvador Protocol”, that indicates that not only does everyone have a right to suitable nutrition, but that the States “commit to perfecting the food production, supply and distribution methods, so that they commit to promote a greater international cooperation in support of the national policies on the matter”. Chile signed up to the agreement, although it has still not been ratified in Congress. Its ratification or inclusion in the future constitution would make this right into an obligation of the State, one that is demandable, and thus, can be tried in court.En mayo de 2021, Chile eligió democráticamente a las personas que formarán parte de la Asamblea Constituyente y que redactarán unanueva constitución. Durante los últimos meses diversos temas emergieron como propuestas de los/as candidatos/as para ser debatidose introducidos en la futura Carta Magna de Chile. Entre ellos, se encuentra el derecho a la alimentación, el cual es un derecho humanorecogido en el artículo 12 del Protocolo adicional a la Convención Americana sobre Derechos Humanos en materia de derechos económicos,sociales y culturales “Protocolo de San Salvador”, en el que se indica que no sólo toda persona tiene derecho a nutrición adecuada, sino quelos Estados “se comprometen a perfeccionar los métodos de producción, aprovisionamiento y distribución de alimentos, para lo cual secomprometen a promover una mayor cooperación internacional en apoyo de las políticas nacionales sobre la materia”. Chile adhirió alpacto, sin embargo, este aún no ha sido ratificado en el Congreso. La ratificación o la inclusión en la futura constitución convertiría estederecho en un deber del Estado exigible y, por tanto, judicializable
Vivienda Los Mañíos
Get PDFInmersa en los bosques de la Décima Región de Chile, sector de Chamiza, perteneciente a la Comuna de Puerto Montt. Su sistema constructivo es realizado con fardos de paja de trigo, combinado con estructura de madera como soporte. El diseño pasivo de esta vivienda considera una eficiente envolvente térmica utilizando al fardo de paja de trigo en sus muros exteriores, y orientando la mayor superficie de vanos hacia el norte maximizando las ganancias solares e iluminación natural. Además este proyecto incorpora recintos propios del habitar de la zona sur de Chile, como ser el espacio de chiflonera y el flojero; asiento en torno a la cocina a leña. La vivienda resalta las materialidades y técnicas constructivas en madera propias de la zona sur de Chile