Sistema Regional de Información
en línea para Revistas Científicas de América Latina,
el Caribe, España y Portugal

As a form of upgraded biomass characterized by its high energy density, low production costs, and low process energy requirements, wood pellets are an environmentally friendly fuel allowing for carbon neutral heating with high energy efficiency. In this work, the suitability of a valorization of the woods from the two most representative shrub species from the Iberian Peninsula (namely Cistus ladanifer and Erica arborea) for heating has been assessed. Whereas Erica arborea met the requirements of ISO 17225-2:2014 for ENplus-B class (the calorific content for both wood and bark was high and not significantly different, and the ash content was permissible for specimens with branch diameter ≥2,8 cm), Cistus ladanifer was in the limit of the normative and only met the requirements in terms of acceptable ash percentage (1,9%) and heating value (19 kJ·g-1) for old specimens with branch diameters >3,4 cm. Consequently, while the harvest of E. arborea for its use as fuel does not need to be selective, that of C. ladanifer should be limited to the most robust specimens and foliage should be avoided.   PDF XML

This study considered the effect of nanomagnesium oxide on the mechanical and flammability features of composites made of wood flour and high-density polyethylene. A sample of wood flour was made from the mixture of hardwoods and high density polyethylene with the weight ratio of 50%. Maleic anhydride was added as a compatibilizer (2 phc), and nanomagnesium oxide was applied at 6 levels (0, 1, 2, 3, 4, 5 phc). These materials were mixed, and samples were prepared with determined sizes by injection molding machine. The samples were subjected to flexural tests to examine the mechanical features, and to study flammability strength, various tests were conducted with a cone calorimeter, including the amount of char residue, total smoke production, time to ignition, and heat release rate, according to ASTM E1354-92 (1992). The addition of up to 3 phc nanomagnesium oxide increased flexural strength and modulus, but further additions decreased these values. The addition of 5 phc nanomagnesium oxide increased the char residue and ignition time, and it decreased the heat release rate, total smoke production, and burning rate. Scanning electron microscopy and energy dispersive X-ray (EDX) analysis indicated the improper transmittance of nanomagnesium oxide and accumulations in the samples.   PDF XML

        G M T   Detectar idioma Afrikáans Albanés Alemán Árabe Armenio Azerí Bengalí Bielorruso Birmano Bosnio Búlgaro Canarés Catalán Cebuano Checo Chichewa Chino (Simp) Chino (Trad) Cincalés Coreano Criollo haitiano Croata Danés Eslovaco Esloveno Español Esperanto Estonio Euskera Finlandés Francés Galés Gallego Georgiano Griego Gujarati Hausa Hebreo Hindi Hmong Holandés Húngaro Igbo Indonesio Inglés Irlandés Islandés Italiano Japonés Javanés Jemer Kazajo Lao Latín Letón Lituano Macedonio Malayalam Malayo Malgache Maltés Maorí Maratí Mongol Nepalí Noruego Persa Polaco Portugués Punjabí Rumano Ruso Serbio Sesoto Somalí Suajili Sueco Sundanés Tagalo Tailandés Tamil Tayiko Telugu Turco Ucraniano Urdu Uzbeco Vietnamita Yidis Yoruba Zulú   Afrikáans Albanés Alemán Árabe Armenio Azerí Bengalí Bielorruso Birmano Bosnio Búlgaro Canarés Catalán Cebuano Checo Chichewa Chino (Simp) Chino (Trad) Cincalés Coreano Criollo haitiano Croata Danés Eslovaco Esloveno Español Esperanto Estonio Euskera Finlandés Francés Galés Gallego Georgiano Griego Gujarati Hausa Hebreo Hindi Hmong Holandés Húngaro Igbo Indonesio Inglés Irlandés Islandés Italiano Japonés Javanés Jemer Kazajo Lao Latín Letón Lituano Macedonio Malayalam Malayo Malgache Maltés Maorí Maratí Mongol Nepalí Noruego Persa Polaco Portugués Punjabí Rumano Ruso Serbio Sesoto Somalí Suajili Sueco Sundanés Tagalo Tailandés Tamil Tayiko Telugu Turco Ucraniano Urdu Uzbeco Vietnamita Yidis Yoruba Zulú                 La función de sonido está limitada a 200 caracteres     Opciones : Historia : Feedback : Donate Cerrar

Parameters characterizing wood and air were studied in order to analyze the performance of a wood solar dryer functioning under Moroccan climate. A mathematical model based on the climate data of Rabat city was used to investigate theoretically the wood drying process. Two wood speciesthuya (Tetraclinis articulate) and pine (Pinus pinaster)-were examined in the present study. The results obtained by computer simulations are in good agreement with the experimental values. Furthermore, our findings indicate that the use of a global mass transfer coefficient for low temperature convective and homogenous drying conditions allows the influence of the principal operating parameters (wood thickness, wood density, air temperature, air velocity and ventilation mode) on the drying time to be estimated with great accuracy. Analyses pertaining to the two studied wood species revealed that(1) pine dries more quickly than thuya, (2) the drying process is faster in the summer relative to other seasons, (3) increasing the air velocity by 100% results in a 20% reduction in the drying time, and (4) continued ventilation reduces the drying time by 43%.   PDF XML

The objective of this study was to investigate the effects of hot water extraction process on the dimensional stability of oriented strand composites. Aspen wood strands were extracted using various severity factor levels. Phenol formaldehyde and polymethylene diphenyl diisocyanate resins were used for production of the oriented strandboard panels. Six panel groups were produced from the extracted or unextracted aspen wood strands. The dimensional stability of the material was evaluated by measures of equilibrium moisture content and thickness swell and water absorption after soaking in water for 2 hours and 24 hours. Results obtained in this study showed that thickness swell and water absorption values significantly decreased with the hot water extraction process, with the thickness swell of phenol formaldehyde bonded panels decreasing 70% after 2 hours soaking. The panels with polymethylene diphenyl diisocyanate resin exhibited lower thickness swell and water absorption relative to the panels prepared with phenol formaldehyde resin. Equilibrium moisture content values of the panels bonded with both phenol formaldehyde and polymethylene diphenyl diisocyanate resin decreased with the extraction process. The findings of this work indicate that hot water extraction process could be effectively used to produce oriented strand composites having an enhanced dimensional stability property.

In this work, the potential for usage recycled polystyrene and wood flour wastes as materials for development wood plastic composites was evaluated. The effects of wood flour loading and coupling agent addition on the mechanical, dynamic mechanical and morphological properties of polystyrene wood flour composites were examined. The results showed that the mechanical properties decreased with the wood flour loading. However, an improvement in composite compatibility was observed when the coupling agent was used resulting in the increase of mechanical and dynamic mechanical properties. A morphological study demonstrates the positive effect in the interfacial adhesion between filler and matrix caused by the coupling agent addition. Based on the findings of this work, both waste materials can be used for development composites with higher performance.   PDF XML

The effects of differing ratios of bamboo/plastic polymers on resistance to fungal attack was assessed using two different decay test methods. Weight losses for non-treated southern pine and Carpinus betulus sapwood blocks indicated that the test conditions were suitable for aggressive decay by Gloeophyllum trabeum and Trametes versicolor. Mass losses on the bamboo/composites tended to be very low, regardless of the method employed. In general, moisture levels in the composites were extremely low although they were close to the point where fungal attack could occur when only the bamboo components were considered. The standard decay tests indicated that bamboo can be considered a suitable substitute for wood flour in wood-plastic composites.   PDF XML

The toxic effects of selected Malaysian timbers (Madhuca utilis, Anisoptera laevis and Endospermum malaccense) heartwood extracts were studied with the aim to determine and understanding the function of wood extracts as a natural protection against termite. The results show that no-choice experiments revealed toxic properties of all investigated extracts by the contact against Coptotermes gestroi and Coptotermes curvignathus. However, high termite mortality was only achieved with Madhuca utilis extracts and methanol solvents.   PDF XML

Los microrganismos benéficos fueron aislados del tracto digestivo del lechón, Enterococcus hirae ATCC 9790, Lactobacillus brevis ATCC 367, Lactobacillus johnsonii NCC 533, Pediococcus pentosaceus ATCC 25745), luego de identificarlos se utilizó la mezcla en proporciones iguales como inoculo para la preparación del ensilado biológico de residuos del procesamiento del procesamiento de langostino, fue incorporado a las dietas bases pos destete, a los lechones en cantidades de T0 0% de EB, T1 10% de EB, T2 15% de EB y T3 20% de EB en las dietas para lechones con 18% de proteína, los cuales obtuvieron una ganancia de peso de T1 10.94 kg, T0 9.75 kg, T2 9.43 kg y T3 8.57 kg los cuales no tiene significancia estadística entre sí, el consumo de alimento muy variado donde tuvieron dos grupos semejantes estadísticamente, de alto consumos y semejantes entre sí T0 21.63 kg, T1 18.53 y menor consumo , T2 14.43 kg y T3 12.88 % para lo cual se determinó una conversión alimenticia ICA mejor del tratamiento T2 1.39, semejante estadísticamente a los tratamientos T1 1.68 y T3 1.70 y todos ellos diferentes estadísticamente a T0 2.38, para hallar la digestión proteína de las dietas se realizó la caracterización química del ensilado, alimento y excretas mejorando la digestibilidad en los tratamientos T2 73.42%, T1 71.09%, en comparación al testigo, T0 69.77% y T3 67. 82%

El dren Correntoso y el dren El Piojo constituyen cauces antiguos del río Tumbes; estos podrían aprovecharse como cauces de alivio durante períodos de crecida para reducir los efectos de las inundaciones en la parte baja del valle. Se construyó un Modelo Hidrodinámico Bidimensional, empleando mallas flexibles, con el software MIKE 21 Flow Model FM desarrollado por DHI, representando el valle del Rio Tumbes con un área de 143,10 km2, considerado desde la estación El Tigre (Caserío Higuerón) hasta la desembocadura del río en el Océano Pacífico. Las simulaciones permitieron determinar el caudal mínimo que genera desbordes en el tramo de estudio, siendo su valor aproximadamente igual a 723 m3/s. El cauce de alivio se diseñó considerando las dimensiones actuales del tramo que cruza por el puente El Piojo. Comparando la inundación del valle entre la situación actual y la situación con el cauce de alivio, los resultados nos indican que para caudales menores a 1000 m3/s que se registren en la estación El Tigre, las áreas inundables en la margen izquierda del río, aguas abajo del inicio del cauce de alivio se reducirían hasta en 100%, y para caudales entre 1000 a 1400 m3/s se reducen hasta en 75%. La habilitación de un cauce de alivio permite mitigar considerablemente el efecto de las inundaciones aguas abajo del sector San Jacinto y por tanto reducir las pérdidas económicas de las actividades productivas y los daños en las infraestructuras que año a año se generan por el desborde del Río Tumbes.