Resumen Se determinaron propiedades físico-mecánicas de tableros contralaminados (CLT) de tres capas, elaborados con madera de Tectona grandis y Gmelina arborea, procedente de plantación forestal. Se usaron dos tipos de adhesivo, emulsión de polímero de isocianato (EPI) y acetato vinílico pre-catalizado modificado con 3% de nanoarcilla (PVA-na). Se aplicaron dos tratamientos para activar la superficie de adhesión: lijado e impregnación con acetona. Los resultados mostraron que, aplicando ambos adhesivos (EPI y PVA-na) y ambos tratamientos de activación superficial (lijado y acetona) el tablero CLT con T. grandis obtuvo mejor comportamiento mecánico (modulo elástico dinámico, esfuerzo cortante y compresión paralela) y de densidad que el tablero CLT con madera de G. arborea. En cuanto a la absorción de humedad y el contenido de humedad entre los tableros CLT no se obtuvo diferencia estadística significativa. Los tableros CLT construidos con ambas especies, cumplen con las propiedades mecánicas (esfuerzo cortante y compresión paralela) y de densidad que establece la norma internacional ANSI/APA PRG 320 CLT.

Abstract Physical-mechanical properties of three-layer counter-laminated boards (CLT) were determined, made with Tectona grandis and Gmelina arborea wood, from forest plantations. Two types of adhesive were used, isocyanate polymer emulsion (EPI) and pre-catalyzed vinyl acetate modified with 3% nanoclay (PVA-na). They applied two treatments to activate the adhesion surface: sanding and impregnation with acetone. The results showed that, by applying both adhesives (EPI and PVA-na) and both surface activation treatments (sanding and acetone), the CLT board with T. grandis obtained better mechanical performance (dynamic elastic modulus, shear stress, and parallel compression) and density than the CLT board with G. arborea wood. Regarding moisture absorption and moisture content between the CLT boards, no statistically significant difference was obtained. CLT boards built with both species comply with the mechanical properties (shear stress and parallel compression) and density established by the international standard ANSI / APA PRG 320 CLT.

RESUMO A madeira de Dipteryx panamensis é usada no reflorestamento na Costa Rica, tendo um programa de melhoramento genético iniciado recentemente no país. O objetivo do presente estudo foi estudar o efeito da altura do tronco das árvores na variação de casca, alburno, cerne, densidade verde (GD), densidade básica (SG) e teor de umidade na condição verde (MC-G) em uma coleção de procedências/progênies aos 8 anos de idade, plantados na vila de Florencia no município de San Carlos na região nordeste da Costa Rica. De cada uma das 17 famílias, a madeira foi investigada em três progênies e as propriedades foram avaliadas em 0, 25, 50, 75 e 100 % da altura comercial. Os resultados mostraram que o diâmetro das árvores e a espessura da casca não apresentaram valores com diferenças estatísticas nas diferentes alturas da árvore. Houve diferenças significativas em diâmetro e porcentagem de cerne e alburno entre procedências e famílias. A espessura e porcentagem de alburno, espessura e porcentagem de casca, diâmetro, porcentagem e porcentagem de excentricidade da medula não registraram diferenças significativas entre as famílias. Nas propriedades físicas da madeira, determinou-se que o SG e o MC-G apresentaram uma variação significativa entre procedências em todas as alturas das árvores. Enquanto o GD registrou diferenças ao 25 %. A variação nas propriedades físicas, especialmente a SG, entre famílias dentro de cada proveniência, mostra o potencial de seleção para melhoramento genético, com ênfase na seleção com base na parte mais basal do tronco das árvores.

ABSTRACT Dipteryx panamensis is used in reforestation in Costa Rica and a genetic improvement program has been recently started in the country. The objective of the present study was to study the effect of tree trunk height on the variation of bark, sapwood, heartwood, green density (GD), specific gravity (SG) and green moisture content in green condition (MC-G), in a collection of 8-year-old provenances/progenies planted in the town of Florencia in San Carlos in the northern region of Costa Rica The wood of each of 17 families were studied based on 3 of their progenies, evaluating the properties relative to 0, 25%, 50%, 75% and 100% of the commercial height. According to the results, tree diameter and bark thickness showed no statistical differences in their values across trunk. Significant differences were found in diameter and percentage of heartwood and sapwood between provenances and families. The thickness and percentage of sapwood, thickness and percentage of bark, diameter, pith percentage and percentage of pith eccentricity, showed no significant differences between families. SG and the MC-G presented significant variation between provenances, while GD registered differences at above 25 % commercial height. The variation of physical properties, especially SG, between families within each provenance, shows selection potential for genetic improvement, focusing particularly on the bottom section of the tree.

Abstract: Densification is one method used to modify low-density woods to make them achieve the hardness required for flooring application. The purpose of this study was to investigate the effect of thermo-mechanical densification with pre-heating in wood of Alnus acuminata, Vochysia ferruginea and Vochysia guatemalensis from, seeking to stabilize and reduce spring-back of the densified wood and evaluate its performance in flooring applications. The results showed that the wood of the three species turned dark. This is because brightness diminished and yellowness and redness increased. Weight loss due to pre-heating was statistically higher in V. ferruginea and V. guatemalensis. The final density and spring-back were statistically similar in the three species. The percentage of densification of A. acuminata and V. guatemalensis were statistically higher than for V. ferruginea and the degree of compression was statistically higher in V. guatemalensis. As for flooring evaluation, the percentage of densification, temperature and time of pre-heating affected the behavior of densified wood flooring. The low percentage of densification and high weight loss in the pre-heating stage caused greater values of wear, wear index, residual deformation, residual indentation for the falling ball indentation test, and more damages in the surface indentation test in wood of V. ferruginea.

RESUMO A pesquisa e a implementação de plantios energéticos usando espécies lenhosas de rotação curta (SRWC) estão aumentando na América Latina, especialmente para a produção de biomassa e uso na bioenergia. Para esse fim, um dos principais fatores a considerar é a avaliação de espécies. O objetivo do presente estudo foi avaliar as características de crescimento da árvore, a produção e distribuição de biomassa e as propriedades químicas, físicas e energéticas da biomassa de um plantio energético de Dipteryx panamensis de três anos de idade em SRWC em três diferentes espaçamentos (1,0x2,0 m, 1,0x0,5 m e 1,0x1,0 m) e, assim estabelecer a melhor condição de espaçamento para esta espécie tropical. Os resultados mostraram que a produção de biomassa varia entre 1,1 e 42,36 t.ha-1 e que 33-44% dessa produção está concentrada nas folhas. Aos três anos, o SRWC apresentou 50% de mortalidade com um diâmetro de 4,8 cm a 30 cm de altura do solo e com alturas totais de árvores de 5,17 a 6,98 metros. A avaliação da biomassa mostrou um valor calorífico foi de 18,9 a 19,4 MJ/kg, 1,81% de cinzas e 86% de conteúdo volátil. A densidade verde da madeira e o teor de umidade aumentaram com o aumento do espaçamento. Os espaçamentos 1,0x1,0 m e 1,0x0,5 m apresentaram o melhor comportamento em relação à produção anual de biomassa.

ABSTRACT Research and implementation of energy crops using short-rotation woody species (SRWC) are increasing in Latin America, especially for biomass production and use in bioenergy. For this purpose, one of the main factors to consider is species assessment. Therefore, the objective of the present study was to evaluate the growth characteristics, the production and distribution of biomass, and the chemical, physical, and energetic properties of the biomass of three-year-old Dipteryx panamensis plantations in SRWC in three different spacings (1.0x2.0 m, 1.0x0.5 m and 1.0x1.0 m) and establish the best spacing condition for this tropical species. The results showed that the production of biomass varies between 1.1 and 42.36 t.ha-1, and that 33-44% of the production are concentrated in the leaves. At three years, the SRWC presented 50% mortality, with a diameter of 4.8 cm at 30 cm-height from the ground, with total tree heights ranging from 5.17 to 6.98 meters. The evaluation of the biomass showed a calorific value between 18.9 and 19.4 MJ/kg, less than 1.81% of ash content and 86% of volatile content. As for the effect of the spacing, the green density of the wood and the moisture content increased with increasing spacing, while spacings of 1.0x1.0 m and 1.0x0.5 m showed the best behaviour regarding annual biomass production.

Resumen El conocimiento de las propiedades de la biomasa proveniente de clones de Gmelina arborea Roxb en cultivos energéticos en sistemas de corta rotación (SRC en inglés) en Costa Rica es limitado. Los primeros intentos están basados en el uso de clones para la producción de madera, pero plantados en SRC. Así, el presente estudio tuvo como objetivo evaluar las propiedades físicas (peso específico, densidad y contenido de humedad), energéticas (poder calorífico, contenido de cenizas y materiales volátiles) y contenido de carbón de dos clones de G. arborea utilizados para la producción de madera, pero plantados en SRC bajo tres espaciamientos (1,0x1,0 m, 0,75x0,75 m y 1,0x0,5 m), entre 6 y 24 meses de edad. Los resultados muestran que el peso específico básico fue de entre 0,30 a 0,38, la densidad verde de 0,9 a 1,0 g/cm3, el contenido de humedad entre 40 y 70%, el poder calorífico de 18.000 a 20.000 kJ/kg, la cantidad de cenizas fue menor a 4,8% y el contenido de volátiles de entre un 70 a 86%, mientras que el contenido de carbono disminuyo con la edad. Se observaron diferencias entre los dos clones en edades tempranas, pero estás tienden a desaparecer con el aumento de la edad, en especial a la edad de 24 meses, que es cuando se pretende que la plantación sea cosechada, siendo esto una ventaja ya que se tiene una biomasa uniforme si los dos clones son utilizados.

Abstract The knowledge of biomass properties from Gmelina arborea clones Roxb in energy crops in short rotation crops systems (SRC) in Costa Rica is limited. The first attempts are based on the use of clones for the production of wood, but planted in SRC. Thus, the present study aimed to evaluate the physical properties (specific gravity, density and moisture content), energy (net calorific value, ash content and volatile materials) and carbon content of two clones of G. arborea used for wood production, but planted in SRC under three spacings (1.0x1.0 m, 0.75x0.75 m and 1.0x0.5 m), between 6 and 24 months of age. Results show that the basic specific gravity was between 0.30 to 0.38, the green density of 0.9 to 1.0 g/cm3, the moisture content between 40 and 70 %, the net caloric value of 18,000 a 20,000 kJ/kg, ash content was less than 4.8 % and the volatile content between 70 and 86%, while the carbon content decreased with age. Differences were observed between the two clones at early ages, but they tend to disappear with increasing age, especially at the age of 24 months, which is when the plantation is intended to be harvested, this being an advantage since we have a uniform biomass if the two clones are used.

ABSTRACT In countries like Costa Rica, there is an interest in developing wooden trusses in a versatile and light way. However, there is a key aspect in the behavior of truss connections in this product. Therefore, the present study determines the structural behavior of the truss connections and the displacement, the resistance, the stiffness values and the failure mode of truss connections made with Gmelina arborea and Tectona grandis timber for angles of 0° and 90°; and three types of truss connectors (metal plates, screws and nails), subject to tension and compression loads. The results showed that metal plates show the highest load values with respect to the nails and screws in both species. Likewise, in the design and critical displacement stress, metal plates surpass the nails and screws in both species; and in the two angles. From these stress values, we proposed a model for the prediction of the stiffness for the truss connections of the intermediate angles (30°, 45° and 60°) and the test showed that the prediction was low, the bias was 3%.

Resumen En construcción de viviendas, las estructuras más eficientes para soportar las cargas provenientes de techumbres corresponden a las cerchas. Cuando se trata de fabricarlas con madera, un punto importante de estas son las uniones. Actualmente se ha introducido la utilización de placas metálicas dentadas para estas uniones, sin embargo, el mercado aún conoce poco de ellas y su posibilidad de utilización en casas. Por lo que, este estudio reporta un primer sondeo cualitativo por medio de una encuesta estratificada por público objetivo, del uso de cerchas de madera con placas metálicas dentadas fabricadas con madera de plantación en Costa Rica. Fue encontrado que el 100 % de los encuestados considera a la madera como un material viable para la construcción, por almacenar dióxido de carbono y ser un recurso renovable. Además, el 90 % de los encuestados, considera que la madera de las plantaciones nacionales es de buena calidad. Sin embargo, sólo un 28 % prefiere la utilización de las cerchas como elemento estructural en techumbres y el 40 % coincide en que el uso de la placa es una buena opción tecnológica. Según este primer sondeo de mercado de la cercha de madera con placa metálica, el 80 % de encuestados estaría dispuesto a adquirirla; dándole un rango de precio entre ¢45 000 a ¢50 000 por cercha.

Abstract In housing construction, the most efficient structures to support the loads coming from roofs correspond to the trusses. When it comes to manufacturing them with wood, an important point of these are the joints. Currently the use of metal plates has been introduced for these unions, however, the market still knows little about them and its possibility of use in wooden houses. Therefore, this study reports a first qualitative survey by means of a survey stratified of the use of wooden trusses with metal plates fabricated with plantation wood in Costa Rica. It was found that 100 % of respondents consider wood as a viable material for construction, for storing carbon dioxide and for being a renewable resource. In addition, most consider that the wood from trees growing in plantations in Costa Rica is of good quality. However, only 28 % prefer the use of trusses as a structural element in roofs and 40 % agree that the use of the metal plate is a good technological option. According to this first market survey of the wooden truss with metal plate, 80 % of respondents would be willing to acquire it; giving it a price rango between ¢ 45 000 to ¢ 50 000 per truss.

Resumen En un proceso de gasificación la geometría de la biomasa es un factor necesario que considerar. El tamaño, forma y densidad de las partículas del biocombustible influyen en el transporte de las especies del sistema de reacción, velocidades de secado y descomposición térmica; los cuales son factores relacionados al desempeño general del proceso. Este trabajo evaluó las diferencias significativas que existen en el rendimiento y eficiencia del sistema de generación de energía eléctrica y térmica por la incidencia de dos geometrías en la biomasa de alimentación (pellets y astillas de madera), en el desempeño de un gasificador tipo “downdraft”. El perfil de temperatura de la zona de pirólisis fue en promedio (147 ± 15) °C mayor al utilizar astillas como alimentación en comparación con el uso de pellets. La caída de presión dentro del reactor fue menor en promedio, así como su variabilidad en el sistema, al utilizar astillas como alimentación; esto a pesar de que el poder calorífico del gas de síntesis obtenido fue levemente mayor para pellets (8,00 MJ/Nm3) que con respecto al obtenido con astillas (6,18 MJ/Nm3). Se obtuvo una Eficiencia de Gas Frío, así como la Eficiencia Térmica Global mayor al utilizar astillas de madera. La capacidad de aprovechamiento de la energía del syngas para producir potencia eléctrica, medido como la Eficiencia del Motor/Generador, estuvo dentro de los valores típicos para este sistema de conversión, y fue de (21,41 ± 3,23) % para astillas y (18,94 ± 3,68) % para pellets. Se obtuvo 564,50 kWh/t de rendimiento de proceso en términos eléctricos al emplear astillas, el cual fue mayor que al utilizar pellets (487,35 kWh/t), esto a una potencia de 6,2 kW. Con respecto al rendimiento de producción de gas de síntesis, con pellets fue menor con respecto a las astillas de madera (i.e. en promedio se produjo 1,75 kg de gas de síntesis por kilogramo de astillas, lo que significa un 25 % más que con pellets de madera). En conclusión, a pesar de que el manejo de astillas de maderas requiere ciertos cuidados para evitar el atascamiento dentro del sistema de conversión “downdraft” para producir gas combustible, en general las ventajas en proceso y eficiencias son mayores al utilizar madera en forma de astillas en comparación con pellets.

Abstract The size, geometry, density and mechanical properties of the biofuel particles are important factors in the performance of any biomass gasification process. They influence the mass transfer rates of the reacting species just as the drying and the thermal decomposition rates in the rest of the system. This work evaluates the significant differences between two different feedstocks, wood pellets and woodchips, on the performance and efficiency of a pilot scale “downdraft” gasifier unit with a combined heat and power system. When using woodchips as feedstock, on average, the temperature profile of the pyrolysis zone was 147 ± 15 °C higher, while the pressure drop inside the reactor and its variability were lower. The Cold Gas Efficiency and Global Thermal Efficiency of the system were higher as well with the woodchips as feedstock, despite the fact that the calorific value of the synthesis gas produced from the wood pellets was 8.00 MJ/Nm3 and the one obtained from the woodchips was slightly lower at 6.18 MJ/Nm3. At a power generation of 6.2 kW, the syngas and electrical energy yields, were also higher on average for the woodchips at 1.75 kg/kg and 564.50 kWh/t, compared to the wood pellets as feedstock at 1.40 kg/kg and 487.35 kWh/t respectively. The relationship between the electrical energy yield and the calorific value of the syngas flow was stablished by means of the Motor/Generator Efficiency, and it was within typical range for this type conversion systems, at 21.41 ± 3.23 % for the woodchips and 18.94 ± 3.68 % for wood pellets. In conclusion, even though the transport of the woodchips within system is more prone to clogging, the higher efficiency and better overall process performance obtained when using woodchips, makes it the preferred feedstock for the system compared to the wood pellets.

Abstract: Physical and mechanical properties were evaluated on cross-laminated panels (plywood) fabricated with three plantation species (Cordia alliodora, Gmelina arborea and Vochysia ferruginea) from tropical climates in Costa Rica. The panels were glued with urea-formaldehyde resin modified with nanoclay at four concentrations (0,75; 1,00; 1,50 and 2,00 %) and unmodified resin. It was determined that addition of nanoclay to urea-formaldehyde adhesive positively decreased moisture absorption and swelling of the plywood panel with statistical significance. However, nano-modification did not have a significant effect on the density and specific weight of plywood. Nano-modification of urea-formaldehyde resin with nanoclay at 0,75 % improved the Module of rupture and Modulus of elasticity in flexure parallel to surface in the three species, also increasing mechanical resistance to strains in parallel tension, shear and compression. By means of electronic microscopy, it was evidenced that the nano-modified adhesive became diffused at the inside of the cellular structure of wood in a better way, allowing for the generation of a transition zone that increased the mechanical properties at the macro level. According to the properties evaluated, it was determined that 0,75 % is the optimal percentage to use of nanoclay on urea-formaldehyde resin.

Abstract Torrefaction and pelletizing were studied in the generation of energy from lignocellulosic residues to increase the energy properties of the biomass. The aim of this study was torrefied sawdust from Gmelina arborea and Dipteryx panamensis at 200 °C in three time period: 0, 15 and 20 minutes. Then with the biomass, pellets of 6 mm diameter were manufactured and their physical properties, calorific value, density and compression force were evaluated. Both species had similar physical characteristics according to the average diameter (0.50 mm), length (21.50 mm), and water absorption rate (6.00 %). The calorific value increased from 9,749 kJ•kg-1 in un-terrified biomass to 18,126 kJ•kg-1 with torrefied biomass. The pellets from D. panamesis had greater density and compression force compared to G. arborea biomass. Based on the results, pellet compression force decreases as the torrefaction time increases. There is positive correlation between bulk density of pellets and compression force. The D. panamensis species has better torrefaction behavior and pelletizing than the wood of G. arborea.

Resumen La torrefacción y peletización se han estudiado en la generación de calor a partir de residuos lignocelulósicos, para incrementar las propiedades energéticas del material. El objetivo del presente trabajo fue torrefaccionar aserrín de Gmelina arborea y Dipteryx panamensis a 200 °C en tres tiempos: 0, 15 y 20 minutos. Con las biomasas obtenidas se fabricaron pellets de 6 mm de diámetro y se evaluaron sus propiedades físicas, el poder calórico, la densidad y la propiedad mecánica de resistencia a la compresión. Ambas especies presentaron características físicas similares con respecto al diámetro (0.50 mm), longitud (21.50 mm) y porcentaje de absorción de agua (6.00 %). El poder calórico aumentó de 9,749 kJ•kg-1 en la biomasa sin torrefaccionar a 18,126 kJ•kg-1 en la biomasa torrefaccionada. Los pellets de D. panamesis presentaron mayor densidad y resistencia a la compresión que los de G. arborea. Con base en los resultados, la resistencia a la compresión del pellet disminuye cuando el tiempo de torrefacción aumenta. Existe correlación positiva entre la densidad de los pellets y la resistencia a la compresión. La especie D. panamensis presenta mejor comportamiento a la torrefacción y peletización que la madera de G. arborea.

Resumen En los procesos de transformación y aserrío de la madera se generan residuos que pueden usarse como fuentes de materia prima para la producción de pellets. El objetivo de este trabajo fue evaluar la eficiencia, la calidad por imágenes de rayos X y las propiedades energéticas, físicas y mecánicas de pellets fabricados con residuos obtenidos del procesamiento de trozas de Cupressus lusitanica y Tectona grandis. Los resultados indicaron un porcentaje de eficiencia bajo para ambas especies forestales, con 25% para C. lusitanica y 20% para T. grandis. En la evaluación de calidad, los pellets de C. lusitanica se caracterizaron por poseer zonas de mayor claridad y pocas fisuras de corto tamaño en su superficie, mientras que en los de T. grandis se presenta un mayor número de zonas de mayor claridad, además de mostrar fisuras de mayor profundidad y largo. En relación con las propiedades evaluadas, se encontró que los pellets de T. grandis tienen una menor densidad aparente, menor PC, menor resistencia a la compresión y menor uniformidad en la densidad de su superficie y un porcentaje de cenizas, CH y durabilidad mecánica mayor, al compararlos con los de C. lusitanica.

Abstract The process of transformation and sawmilling of sawlog generates residuals that can be used as sources of raw material for the production of pellets. The aim of this study was to evaluate the efficiency, pellet quality for x-ray photographic and the energetic, physical and mechanical properties of pellets fabricated from residuals obtained from processing sawlogs of Cupressus lusitanica and Tectona grandis. The results showed a percentage of low efficiency for both species, 25% for C. lusitanica and 20% for T. grandis. In the quality evaluation, pellets were found that pellet fabricated with C. lusitanica pellets is characterized by having high density areas (about 1300 kg m-3) and few cracks of short size on the surface. But the pellets of T. grandis residues present an irregular density (high and low density in the pellet) and present deeper and longer cracks. Regarding the properties evaluated, it was found that the pellets of T. grandis were characterized by having a lower apparent density, lower net calorific power, lower resistance to compression and lower uniformity in the density of its surface and a greater percentage of ash, moisture content and mechanical durability, if they are compared with pellets of C. lusitanica.

RESUMO A madeira de Tectona grandis é importante no mercado devido às suas excelentes características de trabalhabilidade, durabilidade e estética. Por isso é importante melhorar as condições de reprodução e do desenvolvimento das plantações comerciais utilizando clones com o objetivo de produzir árvores produtoras de madeira de boa qualidade. No presente estudo foram estudadas as propriedades gerais, físicas e a coloração da madeira de 20 clones de teca (20 anos de idade) da região de Guanacaste, Costa Rica. Os resultados indicaram que clones no 15º ano atingem um diâmetro do tronco variando de 19,82 a 30,13 cm e a porcentagem de cerne de 49,76 a 60,02 %, ambas em valores similares aos reportados na literatura. Em relação às propriedades físicas da madeira, verificou-se que a massa especifica varia de 0,45 a 0,60 g.cm-3, o teor de umidade na condição verde de 70 a 110,6%. Em relação à cor da madeira, os valores de L* variaram de 48 a 59, a* de 7 a 9,5 e b* de 20,5 a 26,3. Determinou-se que a coloração da madeira (ΔE*) em relação à da madeira comercial é comumente categorizada como perceptível para todos os clones. Entretanto, três dos clones estudados apresentaram madeira mais escura e tonalidade avermelhada que indica ser a coloração mais apreciada do usuário final.

ABSTRACT Tectona grandis is an important wood in the commercial market due to its excellent workability, durability and aesthetic characteristics. Therefore, it is important to improve the conditions of reproduction and development in commercial plantations using clone reproduction, in order to produce trees with better wood quality. In this study we analyzed the general properties, physical properties and color of 20 adult teak clones (fifteen-year-old) from the area of Guanacaste, Costa Rica. It was found that at 15 years, the clones have a diameter which varies from 19.82 cm to 30.13 cm, the percentage of heartwood ranges from 49.76 to 60.02%, and that these values are similar to those found in the literature. In regards to the physical properties, it was found that the specific gravity ranges from 0.45 to 0.60 g.cm-3, the green moisture content varies from 70% to 110.6%. In the color properties, it was found that L* values ranged from 48 to 59, a* 7 to 9.5 and b * from 20.5 to 26.3. Likewise it was determined that the color change (ΔE*) compared to commercial wood color, is commonly categorized as perceptible in all clones. However, three of the clones studied have a darker color and reddish wood which indicates a color more desirable to the end user.

Persian Ironwood (Parrotia persica (DC) CA Meyer) is native species from Iran and covers 10,54% of the commercial volume. Its wood structure and its chemical composition are affected by growth conditions. The aim of the study was to assess the variation of mineral content (Ni, Fe, Cu, Zn, Pb, Cd), wood density and chemical properties (cellulose, lignin, ash and extractive) of ironwood in relation to altitude above sea level (100, 500 and 700 meter) and pith distance within stem (near to pith and bark and middle point). In addition was investigate the relationship between mineral content with oven-dried density and chemical properties. Results showed that Cd, Cu, Fe, Ni and Zn content (except Pb concentration) increased by increasing of altitude and decreased along radial position within stem from the pith to the bark. Lignin, ash and extractive content increased by increasing altitudes from 100 to 700 meter while cellulose decreased. Radial position had not significant impact on the chemical properties. There are significant relationships between mineral content-chemical properties and between mineral content-wood density (except Cu - density). Forward stepwise regression showed that ash and lignin content had important role on the variation of all of mineral content except on Cd.

The effect of three levels thinning intensity in Gmelina arborea plantation on tree diameter, heartwood (diameter and percentage), wood density and drying defects (twist, crook, bow and check) was studied. Wood used for this study was obtained from eight-year-old plantations with thinning intensity of 60, 70 and 80% of initial density. Nine trees were selected from each trial. Results showed that tree diameter and wood density were similar in thinning intensity of 70 and 80%, but tree diameter from the plantation with 60% of thinning intensity was lower than plantation of 70 and 80%. Wood density of trees from 60% thinning intensity plantation was higher than 70 and 80%. Heartwood diameter and its percentage were the highest in 80% of thinning intensity. But not difference was found between 60 and 70% in heartwood (diameter and percentage). Finally, drying defects were not affected significantly by thinning intensity.

No processamento dos grãos de café (Coffea arabica) ocorre o problema de geração de grandes quantidades de resíduos não utilizados pela indústria, tornando-se uma fonte de poluição ambiental. Portanto, é necessária a busca de soluções para atender a este problema de geração de resíduos. O objetivo do trabalho foi determinar a possibilidade de utilização da polpa dos grãos de café processados para a fabricação de briquetes e pellets. A pesquisa compreendeu a secagem da polpa dos grãos de café (pelo meio do ar, solar e ar aquecido); a manufatura de briquetes e de pellets; a avaliação das suas propriedades como fonte de energia e propriedades físicas e mecânicas e a determinação da sua qualidade pela metodologia de densitometria de raios X. Os resultados mostraram que a umidade inicial da polpa de café foi de 90% e o tempo de secagem foi de 699, 308 e 55 horas no ar, secagem solar e por ar quente, respectivamente. O poder calórico foi de 12 501 kJ kg-1 e de 11 591 kJ kg-1 de pellets e de briquetes, respectivamente; o teor de cinzas foi de 8,68% e de 6,74% para os briquetes e os pellets, respectivamente. Em relação às propriedades físicas, a densidade dos briquetes foi de 1.110 kg m-3 e dos pellets de 1.300 kg m-3 a densidade aparente dos briquetes foi 1.000 kg m-3 e de 600 kg m-3 dos pellets e a absorção de água de 7,90% dos briquetes e 8,10% e dos pellets. Finalmente, o esforço de compressão horizontal máxima foi de 4,52 kg cm-2 para os briquetes e de 26,86 kg cm-2 para os pellets, a carga máxima horizontal foi 93,24 kg e de 33,50 kg para os briquetes e os pellets e de 75,54% para o teste de durabilidade dos pellets. A avaliação da qualidade dos pellets por densitometria de raios X mostrou que a sua homogeneidade, observando-se algumas fissuras ou fendas em sua superfície.

Coffee bean (Coffea arabica) processing generates high amount of residues that are sources of environmental pollution. Therefore, an appropriate solution is needed. The objective of this study was to determine the potential of coffee pulp to produce briquettes and pellets. The study included pulp drying (using air, solar and hot air methods); the production of briquettes and pellets; the evaluation of their energy, physical and mechanical properties; and the evaluation of pellet quality using X-ray densitometry. The results showed that the pulp presented an initial moisture content of 90%, resulting in drying times of 699, 308 and 55 hours for air, solar and hot air drying, respectively, and the calorific values of the pellets and briquettes were 12,501 kJ kg-1 and 11,591 kJ kg-1, respectively. The ash content was 8.68% for the briquettes and 6.74% for the pellets. The density of the briquettes was 1,110 kg m-3, compared with 1,300 kg m-3 for the pellets. The apparent densities were 1,000 kg m-3 and 600 kg m-3 for the briquettes and pellets, respectively, and the water absorptions by the briquettes were 7.90% and 8.10% by the pellets. The maximum horizontal compression effort was 26.86 kg cm-2, measured in the pellets, compared with 4.52 kg cm-2 in the briquettes. The maximum horizontal load was 93.24 kg, measured in the briquettes, compared with 33.50 kg in the pellets. The value of the pellet durability test was 75.54%. X-ray densitometry showed that the pellet was uniform and a few cracks were observed on the pellet surface.