Análisis de envejecimiento en paneles sándwich de madera/ Ageing tests study on wood-based sandwich panels

Los paneles sándwich de madera son un producto de creciente aplicación en la edificación de nuestro país. Este ascendente uso del material debe estar acompañado de las garantías necesarias avaladas por un estudio previo de sus prestaciones. Como es preceptivo y entre otros, se evalúa su durabilidad frente a las condiciones climatológicas, clave en los productos derivados de la madera, acorde a la normativa actual definida con tal fin, la Guía ETAG 016. Sin embargo, debido a la clase de uso del material, se ha detectado que dicha normativa tal y como está concebida no es capaz de valorar su envejecimiento adecuadamente. En este trabajo se proponen ensayos alternativos al establecido tras exhaustivos aná- lisis que recrean las condiciones reales de uso y más acordes a los productos de madera. Se concluye que la incorporación de una lámina impermeable, pero permeable al vapor de agua hacia el exterior, como las utilizadas en el montaje, aportan el mejor procedimiento de ensayo. Composite lightweight wood panels are being increasingly used in construction in Spain. Their growing use should be accompanied by necessary guarantees based on studies of their properties. As it is prescriptive and in addition to others tests, in the present work is examinated the durability of these panels when exposed to the climatic conditions, a characteristic of great importance for wood products, according to Guide ETAG 016, the current standard defining the ageing tests to be used. However, due to the use class of this material, there are indications that the testing outlined in this Guide is inappropriate for assessing the ageing of wood-based sandwich panels. Alternative tests are here proposed that recreate rather better the real conditions under which these products are used. Covering the samples in a waterproof sheeting permeable to the outward movement of water vapour, which is in fact used in the installation, provided the best procedure for testing these panels.

Study of the Influence of Reference System in Surface Finishing Parameters Evaluation.

In the present paper the influence of the reference system with regard to the characterization of the surface finishing is analyzed. The effect of the reference system’s choice on the most representative surface finishing parameters (e.g. roughness average Ra and root mean square values Rq) is studied. The study can also be applied to their equivalent parameters in waviness and primary profiles. Based on ISO and ASME standards, three different types of regression lines (central, mean and orthogonal) are theoretically and experimentally analyzed, identifying the validity and applicability fields of each one depending on profile’s geometry. El presente trabajo realiza un estudio de la influencia que supone la elección del sistema de referencia en la determinación los valores de los parámetros más relevantes empleados en la caracterización del acabado superficial tales como la rugosidad media aritmética Ra o la rugosidad media cuadrática Rq y sus equivalentes en los perfiles de ondulación y completo. Partiendo de la definición establecida por las normas ISO y ASME, se analizan tres tipos de líneas de regresión cuadrática (línea central, línea media y línea ortogonal), delimitando los campos de validez y de aplicación de cada una de ellas en función de la geometría del perfil. Para ello se plantean diversos tipos de perfiles y se desarrolla un estudio teórico y experimental de los mismos.

Spectral Biomimetic Technique for Wood Classification

Palatal clicks are most interesting for human echolocation. Moreover, these sounds are suitable for other acoustic applications due to their regular mathematical properties and reproducibility. Simple and nondestructive techniques, bioinspired by synthetized pulses whose form reproduces the best features of palatal clicks, can be developed. The use of synthetic palatal pulses also allows detailed studies of the real possibilities of acoustic human echolocation without the problems associated with subjective individual differences. These techniques are being applied to the study of wood. As an example, a comparison of the performance of both natural and synthetic human echolocation to identify three different species of wood is presented. The results show that human echolocation has a vast potential.

Holocene distribution of woody taxa at the westernmost limit of the Circumboreal/Mediterranean boundary: evidence from wood remains

Información paleoecológica relativa a la distribución de táxones arbóreos durante el holoceno, basado en restos fósiles leñosos.

Antigenic Proteins Involved in Occupational Rhinitis 1 and Asthma Caused by Obeche Wood (Triplochiton Scleroxylon)

Background Obeche wood dust is a known cause of occupational asthma where an IgE-mediated mechanism has been demonstrated. Objective To characterize the allergenic profile of obeche wood dust and evaluate the reactivity of the proteins by in vitro, ex vivo and in vivo assays in carpenters with confirmed rhinitis and/or asthma Materials and methods An in-house obeche extract was obtained, and two IgE binding bands were purified (24 and 12 kDa) and sequenced by N-terminal identity. Specific IgE and IgG, basophil activation tests and skin prick tests (SPTs) were performed with whole extract and purified proteins. CCD binding was analyzed by ELISA inhibition studies. Results Sixty-two subjects participated: 12 with confirmed occupational asthma/rhinitis (ORA+), 40 asymptomatic exposed (ORA−), and 10 controls. Of the confirmed subjects, 83% had a positive SPT to obeche. There was a 100% recognition by ELISA in symptomatic subjects vs. 30% and 10% in asymptomatic exposed subjects and controls respectively (p<0.05). Two new proteins were purified, a 24 kDa protein identified as a putative thaumatin-like protein and a 12 kDa gamma-expansin. Both showed allergenic activity in vitro, with the putative thaumatin being the most active, with 92% recognition by ELISA and 100% by basophil activation test in ORA+ subjects. Cross-reactivity due to CCD was ruled out in 82% of cases. Conclusions Two proteins of obeche wood were identified and were recognized by a high percentage of symptomatic subjects and by a small proportion of asymptomatic exposed subjects. Further studies are required to evaluate cross reactivity with other plant allergens.

La silvicultura como primera operación de transformación de la madera Forestry as the first operation of wood transformation

Se analiza la influencia de las principales actuaciones selvicolas en la calidad de la madera. Turno, Espaciamiento, Poda, Abonado, Riego y Tratamiento contra plagas.

Spectral Biomimetic Technique for Wood Classification Inspired by Human Echolocation

Los Clics palatales son sonidos interesantes para la ecolocalización humana pero tambien pueden utilizarse para determinar propiedades de la madera como para poder identificar tres especies diferentes de madera. Los resultados muestran que la ecolocalización humana tiene un enorme potencial.

Mechanical properties of wood from Pinus sylvestris L. treated with Light Organic Solvent Preservative and with waterbone Copper Azole

El objetivo del estudio es determinar el efecto de tratamiento de la madera de Pinus sylvestris con sustancias protectoras en las propiedades mecánicas. Para ello se utilizan 40 muestras de madera libre de defectos de Pinus sylvestris L. tratándose con protectores orgánicos (Vacsol Azure WR 2601) 50 con protectores hidrosolubles (Tanalith E 3492) y 40 muestras de control sin tratamiento. Se evaluó la resistencia mecánica a la flexión estática, módulo de elasticidad y la fuerza de compresión paralela a la fibra fueron comparados con madera no tratada. El análisis de regresión entre la penetración y la fuerza de compresión paralela se realizó con las muestras tratadas con conservante a base de agua. Resultados principales: Los resultados indican que la madera tratada (con cualquiera de los productos) presenta un aumento estadísticamente significativo de la resistencia mecánica en todas las tres características mecánicas. Los resultados obtenidos difieren de estudios anteriores llevada a cabo por otros autores. No hubo correlación entre la resistencia a la compresión en paralelo y el grado de impregnación de la madera con base de agua de cobre azoles. La explicación más probable para estos resultados se refiere a cambios en la presión durante el tratamiento. El uso de muestras de control no tratadas en lugar de las muestras tratadas sólo con agua es más probable para producir resultados significativos en los estudios de resistencia mecánica . La investigación pone de relieve que la madera tratada presenta un aumento estadísticamente significativo en el Modulo de Elasticidad, módulo de rotura a la flexión estática y resistencia a la compresión paralela. No hubo correlación entre la resistencia a la compresión en paralelo y el grado de impregnación con conservante hidrosoluble.

Descriptive study of production factors affecting performance traits in growing-finishing pgis in Spain.

The objective of this study was to build up a data set including productive performance and production factors data of growing-finishing (GF) pigs in Spain in order to perform a representative and reliable description of the traits of Spanish growing-finishing pig industry. Data from 764 batches from 452 farms belonging to nine companies (1,157,212 pigs) were collected between 2008 and 2010 through a survey including five parts: general, facilities, feeding, health status and performance. Most studied farms had only GF pigs on their facilities (94.7%), produced ‘industrial’ pigs (86.7%), had entire male and female (59.5%) and Pietrain-sired pigs (70.0%), housed between 13-20 pigs per pen (87.2%), had  50% of slatted floor (70%), single-space dry feeder (54.0%), nipple drinker (88.7%) and automatic ventilation systems (71.2%). A 75.0% of the farms used three feeding phases using mainly pelleted diets (91.0%), 61.3% performed three or more antibiotic treatments and 36.5% obtained water from the public supply. Continuous variables studied had the following average values: number of pigs placed per batch, 1,515 pigs; initial and final body weight, 19.0 and 108 kg; length of GF period, 136 days; culling rate, 1.4%; barn occupation, 99.7%; feed intake per pig and fattening cycle, 244 kg; daily gain, 0.657 kg; feed conversion ratio, 2.77 kg kg-1 and mortality rate, 4.3%. Data reflecting the practical situation of the Spanish growing and finishing pig production and it may contribute to develop new strategies in order to improve the productive and economic efficiency of GF pig units.

Variation throughout the tree stem in the physical-mechanical properties of the wood of Abies alba Mill. from the Spanish Pyrenees

This study analyses the variation of main physical-mechanical properties of wood along the longitudinal and radial directions of the tree for Abies alba Mill. growing in the Spanish Pyrenees. Small clear specimens were used to study the properties of volumetric shrinkage (VS), density (?), hardness (H), bending strength (MOR), modulus of elasticity (MOE), maximum compressive strength parallel to the grain (MCS) and impact strength (K). Several models of properties variation in the longitudinal and radial directions were analyzed. Main trends of variation of properties throughout the tree stem were identified although none of them could be fitted to predictive statistical models. Along the longitudinal direction, the properties studied followed a downward trend from the base to the crown, which was not significant in all cases, indicating that no differences in quality existed. Throughout the radial direction the trend is upward for the first 40-50 growth rings, after which it slopes downwards, more gently at first until rings 70-75 and then more steeply. This behaviour is related to variation in wood structure from the pith to the bark, depending on whether the wood is juvenile, sapwood or heartwood, and to wood maturity and microfibril angle. Authors encourage carrying further studies on other populations of A. alba in the Spanish Pyrenees to check if the trends found in this study apply to other provenances.

Comparative study about the use of two and three-dimensional methods in surface finishing characterization

The increasing number of works related to the surface texture characterization based on 3D information, makes convenient rethinking traditional methods based on two-dimensional measurements from profiles. This work compares results between measurements obtained using two and three-dimensional methods. It uses three kinds of data sources: reference surfaces, randomly generated surfaces and measured. Preliminary results are presented. These results must be completed trying to cover a wider number of possibilities according to the manufacturing process and the measurement instrumentation since results can vary quite significantly between them.

Management factors affecting mortality, feed intake, and feed conversion ratio of grow-finishing pigs

The aim of this study was to determine the effect of animal management and farm facilities on total feed intake (TFI), feed conversion ratio (FCR) and mortality rate (MORT) of grower-finishing pigs. In total, 310 batches from 244 grower-finishing farms, consisting of 454 855 Pietrain sired pigs in six Spanish pig companies were used. Data collection consisted of a survey on management practices (season of placement, split-sex by pens, number of pig origins, water source in the farm, initial or final BW) and facilities (floor, feeder, ventilation or number of animals placed) during 2008 and 2009. Results indicated that batches of pigs placed between January and March had higher TFI (P=0.006), FCR (P=0.005) and MORT (P=0.03) than those placed between July and September. Moreover, batches of pigs placed between April and June had lower MORT (P=0.003) than those placed between January and March. Batches which had split-sex pens had lower TFI (P=0.001) and better FCR (P<0.001) than those with mixed-sex in pens; pigs fed with a single-space feeder with incorporated drinker also had the lowest TFI (P<0.001) and best FCR (P<0.001) in comparison to single and multi-space feeders without a drinker. Pigs placed in pens with <50% slatted floors presented an improvement in FCR (P<0.05) than pens with 50% or more slatted floors. Batches filled with pigs from multiple origins had higher MORT (P<0.001) than those from a single origin. Pigs housed in barns that performed manual ventilation control presented higher MORT (P<0.001) in comparison to automatic ventilation. The regression analysis also indicated that pigs which entered to grower-finisher facilities with higher initial BW had lower MORT (P<0.05) and finally pigs which were sent to slaughterhouse with a higher final BW presented higher TFI (P<0.001). The variables selected for each dependent variable explained 61.9%, 24.8% and 20.4% of the total variability for TFI, FCR and MORT, respectively. This study indicates that farms can increase growth performance and reduce mortality by improving farm facilities and/or modifying management practices.

Effects of nutrition on digestión efficicency and gaseous emissions from slurry in growing-finishing pigs. I. Influence of the inclusión of two levels of orange pulp and carb meal in isofibrous diets

An experiment was conducted to investigate the effects of increasing the level of two sources of fibrous by-products, orange pulp (OP) and carob meal (CM), in iso-NDF growing-finishing pig diets on nutrient balance, slurry composition and potential ammonia (NH3) and methane (CH4) emissions. Thirty pigs (85.4 ± 12.3 kg) were fed five iso-nutritive diets: a commercial control wheat/barley (C) and four experimental diets including two sources of fibrous by-products (OP and CM) and two dietary levels (75 and 150 g/kg) in a 2 × 2 factorial arrangement. After a 14-day adaptation period, faeces and urine were collected separately for 7 days to measure nutrient digestibility and the excretory patterns of N from pigs (6 replicates per diet) housed individually in metabolic pens. For each animal, the derived NH3 and CH4 emissions were measured in samples of slurry over an 11- and 100-day storage periods, respectively. Source and level of the fibrous by-products affected digestion efficiency in a different way as the coefficients of total tract apparent digestibility (CTTAD) for dry matter (DM), organic matter (OM), fibre fractions and gross energy increased with OP but decreased with CM (P < 0.05). Crude protein CTTAD decreased with the inclusion of both sources of fibre, being lower at the highest dietary level. Faecal concentration of fibre fractions increased (P < 0.05) with the level of inclusion of CM but decreased with that of OP (P < 0.01). High dietary level for both sources of fibre increased (P < 0.02) CP faecal content but urine N content decreased (from 205 to 168 g/kg DM, P < 0.05) in all the fibre-supplemented compared to C diet. Additionally, the proportions of undigested dietary, water soluble, and bacterial and endogenous debris of faecal N excretion were not affected by treatments. The initial slurry characteristics did not differ among different fibre sources and dietary levels, except pH, which decreased at the highest by-product inclusion levels. Ammonia emission per kg of slurry was lower in all the fibre-supplemented diets than in C diet (from 2.44 to 1.81 g, P < 0.05). Additionally, slurries from the highest dietary level of by-products tended (P < 0.06) to emit less NH3 per kg of initial total Kjeldahl N and showed a lower B0, independently of the fibre source. Thus, the fibre sources and their dietary levels affected pig nutrient digestion and composition of urine and faeces, showing potential to decrease NH3 and CH4 emissions at high levels of inclusion, independently of type of fibre.

Effects of nutrition on digestión efficicency and gaseous emissions from slurry in growing-finishing pigs. II. Effect of protein source in practical diets.

Uso de diferentes fuentes de proteína en la alimentación de cerdos en fase de cebo y su relación con las emisiones de gases amoniaco y metano.

NDT to identify biological damage in wood

Nondestructive techniques are widely used to assess existing timber structures. The models proposed for these methods are usually performed in the laboratory using small clear wood specimens. But in real situations many anomalies, defects and biological damage are found in wood. In these cases the existing models only indicate that the values are outside normality without providing any other information. To solve this problem, a study of non-destructive probing methods for wood was performed, testing the behaviour of four different techniques (penetration resistance, pullout resistance, drill resistance and chip drill extraction) on wood samples with different biological damage, simulating an in-situ test. The wood samples were obtained from existing Spanish timber structures with biotic damage caused by borer insects, termites, brown rot and white rot. The study concludes that all of the methods offer more or less detailed information about the degree of deterioration of wood, but that the first two methods (penetration and pullout resistance) cannot distinguish between pathologies. On the other hand, drill resistance and chip drill extraction make it possible to differentiate pathologies and even to identify species or damage location. Finally, the techniques used were compared to characterize their advantages and disadvantages.