Revistas Universidad del Bío-Bío
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Influence of initial wood moisture on decay process by two brown- rot fungi
Get PDFThe biological decomposition of lignocellulosic materials caused by basidiomycetes plays an essential role in the carbon cycle. Brown rot fungi represent important agents in biodegradation of wood products and standing coniferous trees in natural ecosystems. The initial moisture content of the wood is an important factor in the degradation process. In this work, the effects of initial moisture content of Eucalyptus grandis sapwood on decay by two brown rot fungi Gloeophyllum trabeum and Laetiporus sulphureus were studied over a 10-month period. Fungal activity was evaluated, through wood weight loss, moisture content, anatomical changes (scan electronic and fluorescence microscopy) and Fourier-transform infrared spectroscopy. Weight loss increased through the 10-month test for both fungi, Laetiporus sulphureus producing higher mass losses. Colonization of the wood by both fungi started below the fiber saturation range. It was observed that the initial moisture content of the wood influenced the rate of deterioration: the wet samples showed higher weight loss compared to the dry samples. Changes in the chemical composition and structure of cell walls were detected. The initial moisture content of the substrate affected the development of the fungi, slowing their growth
Relationship between vessel parameters and cleavage associated with checking in eucalyptus grandis wood
Get PDFIn this work, the relationship between vessels parameters and the wood cleavage strength were studied to clarify the process of formation of this type of check, very common in Eucalyptus wood. The objective was to identify the relationship between the wood cleavage strength, the average area of the vessel, and the percentage area of vessels on the wood transverse surface. For this, two Eucalyptus grandis trees at 22 years old were felled and specimens for the cleavage test were produced to determine the wood cleavage strength. From these specimens, samples were taken to determine the average area of the vessel and the percentage area of vessels, aiming at adjusting mathematical models that explain the variation in the cleavage strength. The results showed that the higher the average area of the vessel and the percentage of area occupied by vessels in the wood, the lower its cleavage strength. The multiple linear regression model can estimate the cleavage strength as a function of the average area of the vessel, and the percentage area of the vessels
Comparative performance of pxts versus creosote in an awpa e7 field stake test
No full textA need exists to develop new organic, environmentally benign wood preservatives for industrial applications to replace the older creosote and pentachlorophenol systems. In this study the performance of creosote at three retentions was compared to a new wood preservative candidate formulated with Polymeric Xylenol Tetrasulfide (PXTS) in an E7 AWPA field study using two sets of southern pine and yellow poplar field stakes treated with three creosote retentions or five retentions of PXTS. The stakes were installed at two test sites and evaluated after 3,5 years, 6 years, and 14 years exposure. After six years of exposure at both sites, which is double the minimum recommended exposure period of three years’ field data for AWPA submission of a proposed new preservative system, the average decay ratings data for southern pine stakes after three years exposure was not sufficient to definitively determine which system provides superior protection against decay and termite attack (Creosote at the AWPA UC4B pole retentions versus pine stakes treated with much lower PXTS levels). However, after a longer exposure time of 14 years the data conclusively shows that pine stakes treated to the utility pole AWPA UC4B creosote retention performed poorer at both sites against decay and termite degradation than pine stakes treated with 26 Kg/m3 PXTS. Similar results were obtained with the yellow poplar stakes. We conclude that: 1) much longer E7 exposure times are necessary then the minimum recommended three years in the AWPA GDA Standard for submission of new systems to definitively determine the efficacy of a proposed oil borne system compared to the efficacy of a traditional organic preservative for commercial applications, and 2) long term field PXTS performance against decay and termite deterioration is equal or greater than that obtained with creosote at about four times the PXTS retention
Plywoods of northeast argentinian woods and soybean protein-based adhesives: Relationship between morphological aspects of veneers and shear strength values
Get PDFThree-ply plywoods were produced using pine and Eucalyptus northeast Argentinian woods. A no-added formaldehyde biobased-adhesive was used for assembly, based on chemically modified soy protein concentrate. In this work we focused on the relationship between bonding quality parameters of the plywoods and the morphology of the glued line. Wood characteristics such as contact angle, roughness, density and moisture content were measured prior to plywood assembly. Bonding quality parameters (percentage of wood failure and shear strength) of the plywood were measured according to Argentinean standard IRAM 9562 and the results were evaluated with respect to microscopic observations of the glue joint. Eucalyptus wood was suitable for plywood interior condition applications, while pine barely exceeded the standards imposed by the norm
Efecto de la infraestructura pública en el precio del suelo urbano. Caso de la ciudad de Cuenca-Ecuador
Get PDFIn this paper, the expected sale value of urban properties is analyzed compared to the capital incorporated to the land by infrastructure. For this task, the market prices of 1,393 properties in the city of Cuenca, Ecuador, were collected using different sources, including online ads, realtors, and for-sale signs. The analysis reveals that in 95% of the lots, the capital incorporated by infrastructure represents up to 22.4% of the asking price. However, the profit expected by the owners -expected price minus incorporated capital- is high, reaching an average of 6.35 times the investment cost. Based on the lot’s spatial distribution, it was identified that the historic city center and its surroundings were areas where the highest expected profits are seen. Accurately distinguishing the areas that capture these profits can contribute in decision making regarding the capital gains recovery policies generated by public investment.En el presente documento se analiza el precio esperado de venta de predios urbanos versus el capital incorporado al suelo por infraestructura. Para esa tarea, se emplean los precios de oferta de mercado de 1,393 predios en la ciudad de Cuenca- Ecuador, obtenidos de anuncios en la web, inmobiliarias y letreros en sitio. Los resultados muestran que para el 95% de los predios, el capital incorporado por infraestructura representa hasta un 22.4% del precio solicitado, sin embargo, la ganancia esperada por los propietarios (precio solicitado menos capital incorporado) es alta, alcanzando como media 6.35 veces el costo de inversión. En base a la distribución espacial de los predios, se identificó que la zona del centro histórico y sus alrededores, constituye el sector donde se evidencian las mayores ganancias esperadas. Distinguir adecuadamente las áreas que captan dichas ganancias puede contribuir en la toma de decisión respecto a las políticas de recuperación de plusvalías generadas por la inversión pública
Construção de comunidade a partir da ressignificação do equipamento de culto. Uma proposta para as bordas urbanas na América Latina
Get PDFEl borde urbano de las ciudades latinoamericanas es resultado del acelerado crecimiento que conlleva la formación de nuevos asentamientos que no suplen las necesidades básicas de sus habitantes, y donde el equipamiento, ha perdido significado como espacio constructor del tejido social y urbano. A partir de esta problemática, el texto aborda el desarrollo de un equipamiento de culto que incorpora el concepto de dispositivo como pieza de articulación social. La propuesta arranca del análisis y diagnóstico del sector y plantea dos escalas de intervención en el marco del “modelo generador de opciones” (Carvajalino-Bayona, 1985). La primera consiste en el mejoramiento del barrio en sus estructuras urbanas principales y la segunda, en el desarrollo del proyecto arquitectónico que integra las actividades de culto con las dinámicas del barrio desde una mirada multifuncional. En este sentido, las relaciones urbanas se fortalecen, pero a su vez, dan continuidad a la reflexión planteada desde el diseño, en la cual el proceso participativo es una oportunidad de construcción de diálogo y tejido social entre los actores involucrados que, en este caso, forman parte de comunidades en condiciones de vulnerabilidad.As bordas urbanas das cidades latino-americanas são fruto do crescimento acelerado que acarreta a formação de novos assentamentos que não atendem às necessidades básicas de seus habitantes e onde o equipamento perdeu seu significado como espaço de construção do tecido social e urbano. A partir desta problemática, o texto aborda o desenvolvimento de um equipamento de culto que incorpora o conceito de dispositivo como peça de articulação social. A proposta parte da análise e diagnóstico do setor e propõe duas escalas de intervenção no âmbito do “modelo gerador de opções” (Carvajalino-Bayona, 1985). A primeira consiste na melhoria do bairro em suas estruturas urbanas principais e a segunda implica o desenvolvimento do projeto arquitetônico que integra as atividades de culto com as dinâmicas do bairro numa perspectiva multifuncional. Neste sentido, as relações urbanas se fortalecem, mas, por sua vez, dão continuidade à reflexão levantada a partir do projeto, de acordo com a qual o processo participativo é uma oportunidade de construção de diálogo e tecido social entre os atores envolvidos que, neste caso, fazem parte de comunidades em condições de vulnerabilidade.The urban fringes of Latin American cities are the result of the accelerated growth that entails the formation of new settlements, that do not meet the basic needs of their inhabitants, and where the facilities have lost their meaning as a space to build the social and urban fabric. Starting from this problem, this text addresses the development of a place of worship that incorporates the concept of device as a piece of social articulation. The proposal starts from the analysis and diagnosis of the area and proposes two intervention scales under the “option generator model” (Carvajalino-Bayona, 1985) framework. The first consists of the improvement of the neighborhood in its main urban structures, while the second consists of the development of the architectural project that integrates worship activities with the dynamics of the neighborhood, from a multifunctional perspective. In this sense, urban relationships are strengthened, but at the same time, give continuity to the reflection raised from the design, where the participatory process is an opportunity to build dialogue and social fabric between the players involved, which in this case are part of communities in conditions of vulnerability
MODELO DE GESTIÓN ESTRATÉGICA ORGANIZACIONAL: CASO DE ESTUDIO FERIAS FRANCAS
Get PDFLa “feria franca” es una alternativa particular de comercialización de alimentos procedente de la provincia de Misiones, Argentina. Es una organización de agricultores que de forma conjunta ofrecen sus productos alimenticios directamente a los consumidores. A pesar de su trayectoria y ser imitada como estrategia de comercialización en varios puntos de la provincia y del país, estas experiencias enfrentan numerosos obstáculos que dificultan su consolidación y crecimiento sostenible en el tiempo, presentan dificultades relacionadas principalmente con: la falta de un mecanismo de gestión; que les permita tomar decisiones a mediano y largo plazo; una articulación débil entre productores; así como, escasa y desfasada cooperación con los actores locales. Es por ello y con el objeto de disminuir dichas dificultades, se diseñó un modelo de gestión estratégica organizacional y su procedimiento específicamente para las ferias francas, teniendo en cuenta componentes clave como la cooperación y la planificación estratégica. La metodología utilizada para lograr el objetivo propuesto se derivó en varios pasos: en primer lugar se realizó una revisión bibliográfica en las principales base de datos, se complementó con información obtenida in situ a través de entrevistas realizadas en diversas ferias francas y se utilizó información de investigaciones precedentes. Los principales resultados señalan que el modelo propuesto y su procedimiento ofrecen un instrumento metodológico que permitirá a la organización de productores mejorar su desempeño organizacional.Trade Fair is a particular alternative for the commercialization of food from the province of Misiones, Argentina. It is an organization of farmers who jointly offer their food products directly to consumers. Despite its trajectory and their replication in various parts of the province and the country, these organizations have manifested difficulties mainly related to: the lack of a management mechanism; that allows them to make decisions in the medium and long term; a weak articulation between producers; little, and outdated cooperation with local actors. Based on this, and based on a review of similar marketing systems, an organizational strategic management model and its procedure were designed specifically for the trade fairs, taking into account key components such as cooperation and strategic planning. The methodology used to achieve the proposed objective was derived in several steps: first, a bibliographic review was carried out in the main databases, it was complemented with information obtained in situ through interviews carried out in various free trade fairs and information from previous investigations. The main results indicate that the proposal of a model and its procedure offer a methodological instrument that will allow the producer organization to improve its organizational performance
Golpe de Estado en las ciudades de Chillán y San Carlos, 1973
Get PDFEste artículo tiene por objetivo estudiar el impacto del golpe de Estado efectuado en Chile el año 1973, en escala local, enfocando el estudio en la ciudad de Chillán. Para ello se buscará comprender las dinámicas locales previas al golpe de Estado en la capital de la región de Ñuble que permitan explicar el despliegue cívico-militar represivo en la zona, analizando cómo se llevó a cabo el gobierno de la Unidad Popular, cuál fue la correlación de fuerzas y los principales actores políticos.
Para ello se estudiará este proceso desde la perspectiva de la nueva historia política chilena, tomando como fuentes entrevistas realizadas por el autor a militantes que sobrevivieron a la dictadura, problematizando la perspectiva de la memoria histórica, situándola como objeto y sujeto de estudio de la historia contemporánea chilena.This article aims to study the impact of the coup d'état carried out in Chile in 1973, on a local scale, focusing the study on the city of Chillán. To do this, it will seek to understand the local dynamics prior to the coup d'etat in the capital of the Ñuble region that explain the repressive civilian-military deployment in the area, analyzing how the government of Popular Unity was carried out, which was the correlation of forces and the main political actors.
For this, this process will be studied from the perspective of the new Chilean political history, taking as sources interviews carried out by the author with militants who survived the dictatorship, problematizing the perspective of historical memory, placing it as an object and subject of study of history Chilean contemporary
Physical, chemical and mechanical characterization of Acrocarpus fraxinifolius cultivated in Sao Paulo
Get PDFIndian cedar (Acrocarpus fraxinifolius) is a wood species that occurs naturally in India, Myanmar (Burma) and Bangladesh, and has a high commercial value, with characteristics like mahogany and native cedars. The planting of Indian cedar has been undertaken in Brazil, but there is little information available regarding the characterization of the species. Therefore, considering its timber potential and its possibility of development in the country, the present work aimed to evaluate the physical, chemical, and mechanical properties of 9-year-old Indian cedar wood, planted in the southern region of Brazil. A low specific mass (502 kg/m³), low average dimensional stability (anisotropy coefficient of 2,09 %) was observed, in addition to the low content of extractives (1,94 %). From the mechanical characterization, an average value for the elastic modulus of 8963 MPa was obtained, and for the compressive strength parallel to the grain the average and characteristic values were 32,14 MPa and 21,46 MPa, respectively. This indicates that this wood belongs to resistance class C20 (dicotyledons). The results obtained classify the wood for use in light, external, or internal civil construction
Evaluación de impactos ambientales de viviendas en madera: el caso de “La casa Uruguaya”
Get PDFVarias medidas se están llevando a cabo en Uruguay para reducir las emisiones de CO2 a la atmósfera, entre las que destaca la modificación de la matriz energética. En estos últimos años más del 90 % de la energía eléctrica que se produjo provino de fuentes renovables, tales como la eólica, la hidroenergía o la biomasa. A pesar de estos progresos, el sector de la edificación, la construcción y el transporte continúan siendo en gran parte responsables de los impactos ambientales que producen las actividades humanas en el país. Por otra parte, diversos estudios muestran el avance en el desarrollo de metodologías de cálculo y la definición de estrategias que permitan reducirlas. En ese sentido la metodología del Análisis del Ciclo de Vida (ACV) es considerada una de las más trasparentes y reconocidas por la comunidad científica internacional. Este estudio tiene por objetivo el desarrollo de una propuesta metodológica basada en el ACV, para calcular los impactos ambientales que producen los edificios residenciales en madera durante su ciclo de vida. La verificación experimental se desarrolla a través del caso de “La Casa Uruguaya”, una vivienda social unifamiliar construida en madera. La metodología propuesta permite, a partir de la fase avanzada del diseño de la vivienda, obtener resultados de los impactos ambientales que se producen durante su ciclo de vida completo. Los resultados demuestran la relevancia de las etapas de uso (uso de energía, mantenimiento, reparación, rehabilitación y sustitución) y de producto (extracción de materias primas, fabricación y transporte) sobre el resto de las fases del ciclo de vida consideradas