Revistas Universidad del Bío-Bío
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Effect of the heat treatment on the physicochemical characteristics of rubberwood: Results of thermal analysis and FTIR spectroscopy
Full text linkHeat treatment is an environmentally friendly method used to improve properties of rubberwood. In this work, the changes in the chemical composition, thermal behavior and thermal degradation kinetics of heat-treated Hevea brasiliensis (rubber tree) were evaluated using thermogravimetry, differential scanning calorimetry, and Fourier transform infrared spectroscopy. The rubberwood samples were exposed to temperatures of 180 °C and 220 °C in air under atmospheric pressure for durations of 15 25 and 35 h. Thermal analysis revealed degradation of hemicelluloses, an increase in the relative proportions of cellulose and lignin in heat-treated rubberwood. The thermal decomposition of rubberwood heat-treated at 220 °C started at a higher temperature compared to untreated wood. A shift in the position of peaks on differential thermogravimetry and differential scanning calorimetry curves of heat-treated samples was observed, indicating changes in the structure of wood polymers. The temperature of heat treatment had a stronger effect on the chemical composition of rubberwood than duration. Significant changes in the chemical composition of rubberwood occurred after the treatment duration of 15 h at both 180 °C and 220 °C. The duration of 25 h and 35 h had no further substantial effect. The isoconversional method of Flynn-Wall-Ozawa was used to determine the kinetics of thermal degradation of untreated and heat-treated rubberwood. It is found that the average values of activation energy in the conversion degree range of 0,05 - 0,65 (the thermal degradation of polysaccharides) increased with increasing treatment temperature and duration. Fourier transform infrared spectra demonstrated alterations in wood polymers
APLICACIÓN DEL DESPLIEGUE DE LA FUNCIÓN DE LA CALIDAD PARA EL DISEÑO Y DESARROLLO DE UN SISTEMA DE ENVASE Y EMPAQUE PARA ARTESANÍAS
No full textLas artesanías mexicanas son admiradas y valoradas en todo el mundo siendo algunas de ellas patrimonio cultural de la humanidad. Uno de los problemas que tienen los artesanos mexicanos es el empaque y embalaje, ya que no han profesionalizado este proceso fundamental para la exportación, pues evitan que las mercancías se dañen.
El envase, empaque y embalaje de las artesanías presentan un reto debido a la delicadeza de las figuras, la fragilidad de los materiales y el bajo margen de ganancia, por lo que se deben optimizar a fin de no incrementar el precio.
Para el desarrollo del envase, empaque y embalaje se utilizó el QFD con el fin de proponer un sistema eficiente partiendo de las necesidades de los artesanos.
El diseño de envases y empaques para la artesanía “Catrina” de Capula, Michoacán; se plantea como una necesidad para mejorar la presentación, facilitar su manejo, transporte, almacenaje, manipulación y distribución.
Actualmente, la industria cultural es del interés de muchas personas, organismos y gobiernos, ya que existe preocupación de que se pierdan los conocimientos ancestrales; siendo México un país con basta riqueza cultural existe el interés del gobierno por su conservación, así como del impacto que genera en la región.Mexican handicrafts are admired and valued all around the world, some of them being as Cultural Heritage of Humanity. One of the problems that Mexican artisans have is the secondary and tertiary packaging, since they have not professionalized this fundamental process for export, because they prevent the goods from being damaged.
The handicrafts present a challenge in terms of primary, secondary or tertiary packaging, due to the figures fragility, the used materials and low profit margin, so they must be optimized in order not to increase the price.
Currently, the cultural industry or craft trade has become interesting to many people, organizations and governments, since there is a real concern that the ancestral knowledge will be lost. Being Mexico a country with a vast cultural wealth there is the government's interest in its conservation, as well as the impact it generates in the region.
The design of containers and packaging for the crafts of the Catrina in Capula, Michoacán is considered as a necessity to improve the presentation, facilitating its handling, transport, storage, manipulation and distribution.
For the developing the packaging, the QFD was used in order to propose an efficient packaging system based on the needs of the artisans
Relationship between acoustic wave velocity and mechanical properties in Acacia mangium wood
Full text linkThere is a strong interest in developing and using acoustic technology to evaluate the mechanical properties of wood in situations where a static bending test is not feasible to undertake. In this study, the mechanical properties of Acacia mangium (black wattle) wood were predicted by using stress wave and ultrasonic wave methods. The values of dynamic modulus of elasticity based on stress wave and ultrasonic wave were 9,29 % and 4,75 % higher than those obtained from static modulus of elasticity, respectively. There was no statistically significant correlation between acoustic velocity and mechanical properties measured by destructive tests. The strong experimental correlation coefficients were found between stress wave and modulus of elasticity (r = 0,94; P < 0,001), and ultrasonic wave and modulus of elasticity (r = 0,83; P < 0,001). This result indicates that stress wave and ultrasonic wave techniques are suitable for predicting the static modulus of elasticity of Acacia mangium (black wattle) wood if the density of the measured elements is known. There was no dependence of wood density and acoustic propagation velocity measured in this study, whereas statistically significant correlations were found between the fiber length with stress wave velocity (r = 0,44; P < 0,05) and ultrasonic velocity (r = 0,48; P < 0,05)
La naturaleza en los espacios para el adulto mayor: un enfoque biofílico, en el mundo
Full text linkO objetivo do estudo é descobrir como a biofilia pode condicionar o projeto de espaços arquitetônicos para idosos. A pesquisa é descritiva, qualitativa e não-experimental. Uma revisão documental de antecedentes teóricos e arquitetônicos foi utilizada para definir o objeto de estudo, o comportamento da variável e identificar critérios arquitetônicos. Cinco casos de realidade empírica foram analisados para validar os critérios e obter diretrizes de projeto. Da mesma forma, um dos resultados obtidos nos cinco casos foi a diretriz de criar terraços e espaços externos naturais e transitáveis que permitam a integração com a área aberta e a conexão com o ambiente natural, diretriz aplicada em 100% dos casos estudados. Conclui-se que a biofilia condiciona o projeto de espaços para idosos ao gerar uma relação fluida entre o interior e o exterior por meio de espaços abertos e semiabertos que incluem a natureza e promovem a interação social dos idosos.El propósito del estudio es conocer cómo la biofilia puede condicionar el diseño de espacios arquitectónicos del adulto mayor. La investigación es descriptiva, cualitativa y no experimental, se utilizó la revisión documental de antecedentes teóricos y arquitectónicos para precisar el tema de estudio, el comportamiento de la variable e identificar criterios arquitectónicos. Se analizaron cinco casos de la realidad empírica para validar los criterios y obtener lineamientos de diseño. Asimismo, uno de los resultados obtenidos en los cinco casos fue el lineamiento de generar terrazas y espacios exteriores naturales transitables que crean integración con el área libre y éstos conecten con el entorno natural, un lineamiento aplicado en un 100 por ciento de los casos estudiados. Se concluye que, la biofilia condiciona el diseño de espacios del adulto mayor al generar una relación fluida entre interior/exterior mediante espacios abiertos y semiabiertos, que incluyan la naturaleza y promuevan la interacción social de los ancianos.The study aims to find out how biophilia can condition the design of architectural spaces for older people. The research is descriptive, qualitative, and non-experimental, using a documentary review of the theoretical and architectural background to specify the subject of study, the behavior of the variable, and to identify architectural criteria. Five cases of empirical reality were analyzed to validate the criteria and obtain design guidelines. Similarly, one of the results obtained in the five cases became the guideline to generate terraces and natural, walkable outdoor spaces that create integration with open areas and connect with the natural environment, a guideline applied in 100% of the cases studied. It is concluded that biophilia conditions the design of spaces for older people by generating a fluid indoor/outdoor relationship through open and semi-open spaces, which includes nature and promotes social interaction among older people
Análisis térmico de muros de quincha alivianada para diferentes temperaturas de diseño en Argentina
Full text linkSe analiza el comportamiento térmico de los muros de quincha liviana en distintas zonas bioclimáticas de Argentina, que surgen como una alternativa sustentable frente a otros materiales de construcción. Se determinaron experimentalmente las conductividades térmicas del relleno de quincha (0.07 W/mK) y del revoque (0.34 W/mK), obteniendo una transmitancia térmica global de 0.79 W/m²K para muros de 15.6 cm de espesor. A partir de mediciones in situ en una vivienda, se demostró la capacidad de los muros de quincha liviana para mantener estabilidad térmica interior, con amplitudes térmicas significativamente menores respecto del exterior. El análisis comparativo con ladrillos macizos y ladrillos huecos concluyó que los muros de quincha requieren menores espesores para alcanzar niveles de aislamiento óptimos, adaptándose a diversas zonas bioclimáticas. Esta técnica constructiva permite la replicabilidad en el contexto argentino, destacándose por su eficiencia térmica, sostenibilidad y confort interior, con oportunidades futuras para explorar su resistencia al fuego.Analisou-se o desempenho térmico de paredes de pau a pique leve (em espanhol quincha alivianada) em diferentes zonas bioclimáticas da Argentina, que surgem como uma alternativa sustentável a outros materiais de construção. As condutividades térmicas do enchimento de pau a pique (0,07 W/mK) e do reboco (0,34 W/mK) foram determinadas experimentalmente, obtendo-se uma transmitância térmica geral de 0,79 W/m²K para paredes de 15,6 cm de espessura. Com base em medições in situ em uma casa, foi demonstrada a capacidade das paredes de pau a pique leve para manter a estabilidade térmica interna, com amplitudes térmicas significativamente menores em comparação com o exterior. A análise comparativa com tijolos maciços e tijolos ocos concluiu que as paredes de pau a pique exigem menos espessura para atingir níveis ideais de isolamento, adaptando-se a diversas zonas bioclimáticas. Esta técnica de construção permite a replicabilidade no contexto argentino, destacando-se por sua eficiência térmica, sustentabilidade e conforto interior, com oportunidades futuras para explorar sua resistência ao fogo.The thermal performance of lightweight wattle and daub walls is analyzed in different bioclimatic zones of Argentina, presenting them as a sustainable alternative to other construction materials. The thermal conductivities of the wattle and daub (0.07 W/mK) and plaster (0.34 W/mK) infill were experimentally determined, yielding an overall thermal transmittance of 0.79 W/m²K for walls with a thickness of 15.6 cm. In situ measurements conducted in a dwelling demonstrated the ability of lightweight wattle and daub walls to maintain interior thermal stability with significantly lower thermal amplitude than outside. A comparative analysis with solid and hollow bricks concluded that wattle and daub walls require less thickness to achieve optimal insulation levels, making them suitable for different bioclimatic zones. This construction technique is replicable within the Argentinian context, with its thermal efficiency, sustainability, and indoor comfort standing out, with future opportunities to explore its fire resistance
Contribution of extractives to the bark color of Caesalpinia sappan
Full text linkThe purpose of this study was to investigate the contribution of Caesalpinia sappan (sappan wood) bark extractives by analyzing color change of the bark after extraction and the color of the extracts with several color measurement methods. Successive extraction was performed with n-hexane, ethyl acetate, methanol, and hot water. Color change of the bark was measured using CIELab color system and the extracts were analyzed with Ultraviolet-Visible Spectrophotometer, total phenolic content (TPC), and Gas Chromatography Mass Spectrometry (GC-MS). The results showed that the highest change on the bark color after methanol extraction with the Δa* and Δb* values of -2,53 ± 0,60 and -3,64 ± 1,20 respectively. Also, methanol extract showed the highest total phenolic content (860,24 ± 30,19 mg GAE/g). In addition, the Ultraviolet-Visible is analysis showed a peak at 478 nm in the hot-water soluble extract and two peaks in the methanol soluble extract at 396 nm and 478 nm. Hydroquinone was detected as one of the major compounds by Gas Chromatography Mass Spectrometry in the methanol soluble extract. It was suggested that the color of Caesalpinia sappan (sappan wood) bark as well as the deep red coloration of its extract might be contributed by multiple phenolic compounds contained in the methanol extract with hydroquinone as its precursor. Therefore, it is also a potential source for coloring matter
Utilization of nanotalc modified adhesives in plywood panels
Full text linkAs an alternative for the partial replacement of synthetic adhesives are the modifications that occur still during their synthesis, to improve and adhere new properties. Among the possible materials used in nanoscale, talc is a mineral material of natural origin and a promising raw material due to its low cost, lightness, natural hydrophobicity. Due to the scarcity of studies with the insertion of nanotalc in adhesives, this study aimed to produce plywood panels bonded with phenol-formaldehyde adhesive nanomodified with talc to evaluate its physical-mechanical resistance when compared to conventional synthetic adhesives. To carry out this study, three Pinus oocarpa trees with 28 years of age were used. Different concentrations of talc were used in the formulation with the phenol-formaldehyde adhesive, being the treatments 0; 0,05; 1; 1,5 and 2 % of talc (mass/mass) in relation to the adhesive, with three panels per treatment, totaling 15 panels. The pressing time was 8 minutes with temperature of 160 ºC and pressure of 1 MPa. The physical-chemical characteristics of the lignocellulosic material and of the plywood panels were determined. The quality of the adhesive produced was demonstrated by its resistance to water absorption with the insertion of up to 2 % talc to the adhesive, reducing it considerably. From 1 % talc inserted, the plywood panels had their mechanical characteristics superior to those glued with pure phenol-formaldehyde adhesive. However, as the study is innovative in nature, further research should focus on the application and quality evaluation of other talc nanomodified adhesives on different types of wood panels
Pitrufquén, Chile: la ciudad como estrategia de ocupación territorial
Full text linkThis paper analyzes the development of Pitrufquén (located in the Araucanía Region, Chile, and founded in 1897) from a historical, territorial, urban, and architectural point of view. It is proposed that the city’s development is framed in a new moment, where the Chilean State abandons military criteria and assumes economic-territorial factors where the railroad’s presence is a determining factor. The choice of the site, its particular layout, and the development of its architecture are evidence of this change. From the historical point of view, it is analyzed how, in Pitrufquén, the Mapuche society had cattle raising as the main economic activity, as it had pastures to feed the cattle, the land was suitable for crops, and there was a vital ford to cross the Toltén River. This strategic location was maintained and accentuated by the city’s founding and the railroad’s arrival in 1898, turning the town into a railhead for progress towards the south of the country. In the case of the urban layout, its peculiarity was addressed since, together with Lonquimay, these are the only sections in the La Araucanía region organized based on an ellipse, which, in the case of Pitrufquén, also coexists with a checkerboard layout. The study analyzed its squares, diagonal avenues, and the perimeter ring road. At an architectural level, the article explores the three layers or aspects of the city: The first one studies the wooden architecture with works from the late 19th and early 20th centuries; the second refers to public architecture, represented by buildings such as the municipality, public services, the post office, and others; and a third layer addresses the modern architecture, such as housing and stores from the period between 1940 and 1960.El presente trabajo analiza el desarrollo de la ciudad de Pitrufquén (ubicada en la Región de La Araucanía, Chile, fundada en 1897) desde el punto de vista histórico, territorial, urbano y arquitectónico. Se plantea que el devenir de la ciudad se enmarca en un nuevo momento en que el Estado chileno abandona criterios militares y asume factores económico-territoriales donde la presencia del ferrocarril es determinante. La selección del lugar, su particular trazado, así como el desarrollo de su arquitectura, son evidencias de este cambio. Desde el punto de vista histórico, se analiza cómo en el sitio de Pitrufquén, la sociedad mapuche desarrolló la ganadería como actividad económica principal, al contar con praderas para alimentar el ganado, la tierra era apropiada para los cultivos agrícolas y se encontraba allí un importante vado para cruzar el río Toltén. La situación de punto estratégico, se mantuvo y acentuó con la fundación de la ciudad y la llegada de la vía férrea hacia el año 1898, convirtiéndose el poblado en punta de riel, en el avance hacia el sur del país. En el caso de la traza urbana, se abordó su peculiaridad ya que, junto a Lonquimay, constituyen en la región de La Araucanía las únicas tramas ordenadas en base a una elipse que, además en el caso de Pitrufquén, convive con una traza de damero. En el estudio se analizaron sus plazas, avenidas diagonales y la vía de circunvalación perimetral. En el plano arquitectónico, el artículo analiza las tres capas o aspectos de la ciudad: el primero, estudia una de arquitectura en madera con obras de fines del siglo XIX y comienzos del XX; el segundo se refiere a la arquitectura pública, representada por edificios como, la municipalidad, los servicios públicos, el correo y otros, y el tercero capa corresponde a la arquitectura moderna, como vivienda y comercio del período comprendido entre los años 1940 y1960
ESTRATEGIAS UTILIZADAS POR PROFESORES EN ESCUELAS ESPECIALES PARA NIÑOS CON TEA Y SUS CONDUCTAS DISRUPTIVAS
Full text linkEl Trastorno del Espectro Autista (TEA) son deficiencias persistentes en la comunicación y en la interacción social, además, desarrollan intereses restringidos y patrones repetitivos de conducta. El objetivo de este artículo es determinar los apoyos conductuales que entregan los docentes a niños y niñas con Trastornos del espectro autista pertenecientes a Escuelas Especiales. Se utilizó un enfoque cuantitativo de tipo no experimental-descriptivo. Dentro de los resultados se demuestran que los apoyos más utilizados por los docentes son moldeamiento de la conducta, anticipación y entregar instrucciones simples, así mismo, las estrategias más eficientes son anticipación, refuerzo positivo, tiempo fuera y crear acuerdos con los estudiantes. Finalmente, se discute la necesidad de implementar estas estrategias en aulas de escuelas especiales que cuentan con estudiantes con TEA y que presentan conductas problemáticas, debido a que disminuye la ansiedad, las conductas disruptivas y logran un control del entorno, lo que lleva a un mejor aprendizaje en estos estudiantes.Autism Spectrum Disorder (ASD) are persistent deficiencies in communication and social interaction, in addition, they develop restricted interests and repetitive patterns of behavior. The aim of this article is to determine the behavioral supports provided by teachers to children with autism spectrum disorders in special schools. A non-experimental-descriptive quantitative approach was used. The results show that the supports most used by teachers are behavioral molding, anticipation and delivery of simple instructions; likewise, the most efficient strategies are anticipation, positive reinforcement, time out and creating agreements with students. Finally, the need to implement these strategies in classrooms of special schools that have students with ASD and who present problematic behaviors is discussed, because it decreases anxiety, disruptive behaviors and achieves control of the environment, which leads to better learning in these students