ResumoO uso de madeira de espécies alternativas na construção civil é uma alternativa para reduzir a utilização concentrada em poucas espécies e evitar a falta de matéria prima no mercado. Diante do exposto, o objetivo deste estudo foi avaliar propriedades físicas, químicas, anatômicas e mecânicas da madeira de Mimosa schomburgkii visando identificar o seu potencial para o uso na construção civil. Foi utilizada a madeira de Mimosa schomburgkii, com idade de 33 anos. As características anatômicas avaliadas foram as dimensões dos elementos de vasos (diâmetro e frequência), dos raios (altura e largura) e das fibras (comprimento, largura total, espessura de parede e de lume). Foi determinada a constituição química com a quantificação do teor de extrativo, lignina e holocelulose. Para a caracterização físico-mecânica, foram avaliadas a densidade básica e aparente, contrações, o coeficiente de anisotropia, a resistência à flexão estática, à compressão paralela às fibras, à tração paralela às fibras, ao cisalhamento e a dureza Janka (paralela e perpendicular às fibras). A madeira possui fibras libriformes, com comprimento médio de 1180 μm, sendo classificadas como curtas. A densidade básica da madeira é em média 0,80 g.cm -3 (alta densidade), o coeficiente de anisotropia, em média 1,74. A madeira apresenta elevada resistência mecânica, sendo classificada como pertencente à classe C 60. Pelos resultados obtidos no estudo, a madeira de jurema (Mimosa schomburgkii) apresenta aspectos estéticos atrativos e elevada resistência mecânica, sendo, portanto, indicada para uso na construção civil. Palavras-chave: Propriedades da madeira; construção civil; elevada resistência mecânica; alta densidade básica. Abstract Anatomical characterization and physical-chemical and mechanical description of Mimosa schomburgkiiwood. The use of wood of alternative species in civil construction has been an option to reduce the concentrated use of few species and to avoid the lack of raw material in the market. The objective of this study was to evaluate the physical, chemical, anatomical and mechanical properties of Mimosa schomburgkii wood, in order to identify its potential use in civil construction. Mimosa schomburgkii wood, at the age of 33 years, was used. The anatomical characteristics evaluated were the dimensions of vessel elements (diameter and frequency), rays (height and width) and fibers (length, width, wall thickness and lumen thickness). The chemical constitution was determined with the quantification of extractive content, lignin and holocellulose. For the physical-mechanical characterization, it was evaluated the specific gravity and apparent density, contractions, anisotropy coefficient, static bending strength, compression strength parallel to grain, traction strength parallel to grain, shear strength and Janka hardness (parallel and perpendicular to grain). The wood has libriform fibers, average length of 1180 μm, and it is classified as short. The wood basic density is on average of 0.80 g.cm -3 (high density). The anisotropy...

This study aimed to evaluate the static bending strength (f M) and modulus of elasticity (MOE) to static bending values of Eucalyptus grandis samples produced in different dimensions. It intended to identify samples that present similar mechanical properties to those recommended by other technical standards and those obtained according to NBR 7190. The samples were made in agreement with the dimensions of the following standards: IPT, AFNOR B51-016, ASTM D143, CEN-EN 408, COPANT 555, and NBR 7190. The strength was significantly reduced with the increase of the sample dimensions. The MOE was significantly influenced by the samples size with the values showing a parabolic trend. The samples produced according to COPANT 555 (5 x 5 x 75 cm) presented resistance values similar to the values obtained following NBR 7190 specifications, whereas for the MOE, the samples proposed according to the IPT presented the closest values of Brazilian technical standards (NBR 7190).

Dieback is a physiological disorder that has caused losses on eucalyptus plantations. Thinking that water stress is one of the triggers for the physiological disorder and aiming at the early identification of tolerant genotypes, we evaluated plantlets of four commercial clones with divergent behavior in field conditions. The plantlets were grown in a greenhouse where the drought conditions were provided by the application of polyethylene glycol 6000 solutions at 100 and 300 g L−1. After water deficit treatments, the morphological, physiological, nutritional and metabolic analyses were performed. SuzT maintained the carbon fixation and the instantaneous water use efficiency, even under water deficit, while sustaining growth. This resulted in higher leaf area and total dry mass in SuzT. Despite higher photosynthetic rate, SuzS exhibited reduced dry biomass accumulation, implying less efficient carbon use. SuzT revealed a higher level of calcium that supports cell structure and homeostasis and indicates higher capacity to manage specific resources and survival under water deficit. SuzT suffered reduction in some free amino acids; however, there was no significant variation for total amino acid content. The principal component and cluster analyses indicated that SuzMT and SuzTP genotypes behave similarly to SuzT under water deficit, while SuzS clustered in isolation. Our results support that there are common trends in water deficit responses for contrasting eucalypt genotypes. The existence of other strategies coping with water deficit resistance is not discarded and should be further evaluated.