Revistas Universidad del Bío-Bío
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El Imperio Alemán y la Guerra del Pacífico (1879-1883): Análisis del actuar de su legación en Chile
Get PDFThis paper analyzes the German diplomatic actions carried out by officials from their legation in Santiago de Chile under the context of the War of the Pacific (1879-1883). This conflict generated many differences and fears in America, a situation that was replicated in Europe through the Great Powers, standing out in this investigation the German Empire. To carry out this work, primary sources linked to the institution of German diplomacy in the Chilean capital were used, together with various bibliographic sources that allowed us to characterize nineteenth-century thinking. This will allow to understand and historiographically reconstruct the role assumed from Berlin during the most important war on this Pacific coast in the 19th century.El presente artículo analiza el actuar diplomático alemán realizado por funcionarios desde su legación en Santiago de Chile bajo el contexto de la Guerra del Pacífico (1879-1883). Este conflicto generó muchas diferencias y temores en América, situación que fue replicada en Europa a través de las Grandes Potencias, destacando en esta investigación el Imperio Alemán. Para llevar a cabo este trabajo se utilizaron fundamentalmente fuentes primarias ligadas a la institución de la diplomacia germana en la capital chilena junto a diversas fuentes bibliográficas que nos permitieron caracterizar el pensamiento decimonónico. Esto permitirá comprender y reconstruir historiográficamente el rol asumido desde Berlín durante la guerra más importante en esta costa del Pacífico en el siglo XI
Effectiveness of european oak wood staining with iron (ii) sulphate during natural weathering
Get PDFArtificial graying of wood can be solution for contemporary trends of using uncoated wood for the arrangement of external architecture. The presented work was aimed at investigation of colour changes of European oak (Quercus sp.) wood surface treated with iron (II) sulphate. Three different procedures differing in time (2 h and 24 h) and temperature (20 °C and 70 °C) were used, as well as three different concentrations of aqueous iron (II) sulphate solutions (10 %, 20 %, 30 %). Beside the colour itself, it was evaluated the stained oak wood discolouration due to natural weathering. Thanks to iron (II) sulphate, wood colour changed to dark grey. In general, the colour changes on tangential section of wood were higher than those on radial section what was result of wood structure, in particular parenchyma cells arrangement in wooden rays. Contrary to expectations, the concentration of the iron (II) sulphate solution was not of significant importance for wood staining. Usage of concentrations higher than 10 % for the modification of the colour of wood gives the same effects. However, with increasing solution used to wood staining, the colour stability of the wood decreases during external exposure. The parameters of the procedure were not significantly affected. This allows the application of the simplest and least time-consuming modification method to be considered
Ecología política de las tensiones y conflictos socioambientales en la región de Ñuble
Get PDFEl estudio caracteriza la expresión territorial de actividades productivas en la región de Ñuble, de acuerdo a las diversas categorías determinadas por el SEIA para la evaluación de las mismas. Se considera el enfoque de la ecología política en el análisis, diagnóstico y comprensión de la relación que el modelo de desarrollo chileno tiene en los diferentes territorios, evidenciando que su carácter extractivista confronta dinámicas socioambientales, produciendo tensiones socioambientales necesarias de explicitar. Para ello se identificación 319 actividades productivas, y se caracterizan los principales conflictos socioambientales en la región, sobre la base de una visión de conjunto que permite inferir la escasa relación territorial que tienen estas actividades en la definición de progreso, crecimiento y desarrollo locales.The study characterizes the territorial expression of productive activities in the Ñuble region, according to the various categories determined by the SEIA for their evaluation. The political ecology approach is considered in the analysis, diagnosis and understanding of the relationship that the Chilean development model has in the different territories, showing that its extractivist character confronts socio-territorial dynamics, producing socio-environmental tensions that are necessary to make explicit. For this, 319 productive activities are identified, and the main socio-environmental conflicts in the region are characterized, based on an overall vision that allows inferring the scarce territorial relationship that these activities have in the definition of progress, growth and local development
Estimation of density, moisture content and strength properties of Tectona grandis wood using near infrared spectroscopy
Get PDFNear infrared spectroscopy is non-invasive and may be applied as a rapid and cost effective technique for assessment of quality parameters of timber. Near infrared spectra of Tectona grandis (teak) wood samples of were collected before measuring physical (density, equilibrium moisture content) and strength (flexural and compressive) properties using conventional methods. Partial least squares regression was used to develop calibration models between measured wood properties and near infrared data. The best near infrared spectra pre-processing methods differed by property. Linear calibration models with high R², low error and high ratio of performance to deviation values were observed from partial least squares analysis for different wood properties. These linear models may be applied for rapid and precise estimation of the properties examined in testing and evaluation procedures for commercially valuable teak wood
Natural weathering performance of thermally treated poplar and black pine wood
Get PDFWood of poplar (Populus sp.) and black pine (Pinus nigra) species was subjected to thermal treatment under variant conditions of temperature, 180 ºC and 200 ºC, and duration of 3 h, 5 h, 7 h, and its resistance to natural weathering was investigated through the determination of crucial properties, such as the colour and surface roughness, while the appearance of the boards was assessed both visually and through a microscope, prior to and after their exposure outdoors. Prior to the outdoors exposure, it was observed that, as the intensity of heat treatment increases, wood tends to darken, with the parallel decrease of L* index, referring to tangential, radial and cross-sectional surface of both species specimens. The surface roughness of both wood species was found decreased only in the boards of the mildest treatment, while as the treatment intensity increases, the roughness degree demonstrated a strong increase compared to unmodified wood. After the 100-day exposure of poplar and pine boards to external conditions, they acquired a wilder look and new checks and cracks emerged in the boards surface, while fungi infestation signs appeared, most apparent in control and boards treated at milder treatments, with modified poplar boards to demonstrate more dense defects patterns on their surfaces, compared to modified black pine boards. A similar degree of discoloration recorded on unmodified boards was observed also on the thermally modified boards, which was except for the visual assessment, confirmed by the recorded progress of L*, a* and b* colour indexes of poplar and pine surfaces and is probably attributed to leaching of the water soluble extractives. The roughness of all of the exposed boards surfaces was found higher than the respective values recorded prior to the exposure and among the treated boards only those of the milder treatments presented lower roughness values than the unmodified ones. Thermal treatment enhanced the biological durability and dimensional stability of both species, but it did not adequately protect wood from the weathering effect when it was exposed outdoors. Nevertheless, wood modified at short-term heat treatments exhibited enhanced properties compared to unmodified wood and taking into account that the milder treatments did not cause mechanical strength loss, these materials could be utilized in applications where structures are not continually and directly exposed to aging factors, such as under shelter applications, or after the application of a thermal and surface modification with protective preservatives combination
Weathering characteristics of impregnated and coated calabrian pine wood
Get PDFThis study was designed to investigate the weathering characteristics of Calabrian pine (Pinus brutia) wood. The wood specimens were impregnated with some copper-based chemicals and then varnish coated. As copper-based chemicals, Celcure C4, Korasit KS, and Tanalith E 8000 were used for impregnation. Polyurethane varnish (PV) and water-based varnish (WBV) were used as coating materials. Firstly, Calabrian pine wood was impregnated with 2,5 % and 5 % aqueous solutions of chemicals then coated with polyurethane varnish and WBV. Impregnated and coated Calabrian pine wood specimens were subjected to 6 months of natural weathering in Mugla, Turkey. After weathering; surface hardness, surface roughness, and adhesion strength changes of Calabrian pine wood specimens were determined. Impregnation caused to increase in surface hardness values of Calabrian pine. Surface hardness increases of water-based varnish coated Calabrian pine specimens were higher than polyurethane varnish coated Calabrian pine specimens. Impregnation resulted in higher surface roughness values of Calabrian pine specimens. Polyurethane varnish coated Calabrian pine specimens gave higher surface roughness than water-based varnish coated Calabrian pine specimens. The adhesion strength values of all treatment groups were decreased after weathering. In general, adhesion strength decreases of water-based varnish coated Calabrian pine specimens were higher than that of polyurethane varnish coated Calabrian pine specimens. The concentration levels of chemicals did not have a significant effect on surface roughness and adhesion strength of Calabrian pine wood after weathering.
 
Preparation and performance of tannin–glyoxal–urea resin-bonded grinding wheel loaded with sio2 reinforcing particles
Get PDFIn this study, an easily prepared bio-based abrasive grinding wheel based on tannin–glyoxal–urea (TGU)thermosetting matrix is presented.The synthesised resin was prepared via co-polycondensation reaction of glyoxal and ureawith condensed tannin, which is a forest-derived product. Fourier transform infrared spectroscopy and electrospray ionisation mass spectrometry results confirmed that urea and glyoxal react well under acidic conditions and that –(OH)CH–NH–group is primarily involved in TGU cross-linking. Differential scanning calorimetry, thermomechanical analysis and thermogravimetric analysis investigations showed that the preparation of TGU resin is easier compared to commercial phenol–formaldehyde (PF) resin; moreover, TGU resin has a more robust chemical network structure, which contributes efficiently to heat resistance and improved mechanical properties. This observation is supported by Brinell hardness, compression resistance and grinding testing; these showed that the new grinding wheel acquired higher hardness, superior resistance against compression and stronger abrasion resistance compared with a PF-based grinding wheel prepared in the laboratory. Moreover, few holes and no cracks were found in the new grinding wheel
Determination of the strength performance of table frames
Get PDFThe objective of this study was to investigate relation of diameter of pilot hole and screw, and machining accuracy on withdrawal strengths of the screws and durability of the dining tables. For this purpose, fasteners and material types on the failure loads of dining table corner joints have been analyzed experimentally and statistically. Double ended thread bolts with different drilling regimes have been used as fastener types. Parallel investigation of rigidity and durability of tables, according to the current EN norms, and withdrawal capacities in accordance with the procedures described in ISO 9087 was performed. According to the results, it is concluded that the diameter of the drilled hole significantly influences the value of the withdrawal strengths of the screws. By analyzing the effect of drilling diameter on rigidity of tables, a statistically significant difference was determined. As the drilling diameter increases, the rigidity of the examined dining tables decreases
Vigas de pino resinoso del noreste de argentina bajo cargas de larga duración: Deformaciones, recuperación y criterios de diseño
Get PDFEn este artículo se presentan y discuten los resultados de un proyecto orientado a investigar las deformaciones bajo carga de larga duración, y la recuperación luego de la descarga, en vigas de pino resinoso de rápido crecimiento (Pinus taeda y Pinus elliottii) cultivado en el noreste de Argentina. La investigación empírica se llevó a cabo en un local sin climatización con el propósito de incorporar fluctuaciones de la temperatura y la humedad relativa ambiente durante el período de carga, utilizando una muestra integrada por 14 vigas de muy variada calidad. Las deformaciones se registraron bajo carga constante durante 392 días y luego libres de carga durante un período de recuperación de 28 días. No obstante las variaciones climáticas producidas, se encontró una destacada similitud entre el valor de la deformación inicial instantánea de cada viga y el de su recuperación instantánea luego de la descarga. Los resultados también probaron que, independientemente de la calidad de la madera, el desarrollo de las deformaciones diferidas se mantiene estable y las reglas de diseño resultan eficaces para calcular su valor si el nivel de tensión en la viga es inferior al 35 % de su resistencia instantánea.