Prediction of microfibril angle for Eucalyptus microcorys wood by fiber length and basic density

Aim of the study was to estimate the influence of the fiber length and basic density on microfibril angle of Eucalyptus microcorys wood. The study area was in an experimental planting at the Universidade Federal de Lavras, Minas Gerais State, Brazil. Three 37 year-old Eucalyptus microcorys trees were used, from whose stems six centimeter-thick discs were removed, cut at a high of three meters. The disks were sanded and planed to highlight the growth rings. Specimens were taken every 1.5 cm across the radius from pith to bark for determining microfibril angle, fiber length and wood basic density. The microfibril angles were determined by use of polarized light microscopy, while the fiber morphology and basic density were determined by usual methods. The averages found for microfibril angle (12.6°), fiber length (968 µm) and basic density (480 kg.m-3) are, in general, within the range of values reported for these characteristics of wood. The microfibril angle showed accentuated reduction of the average values in the pith-bark direction. The fiber length and basic density showed the opposite behavior. We observed that the density and fiber length may be used as an microfibril angle predictor, accounting for 96% and 79% of its variation, respectively

Teores de fenóis totais e taninos nas cascas de angico-vermelho (Anadenanthera peregrina)

Este trabalho teve como objetivo quantificar fenóis totais e taninos nas cascas de angico-vermelho (Anadenanthera peregrina) em diferentes classes de diâmetro, além de comparar duas metodologias de quantificação de fenóis. Foram coletadas cascas de 35 árvores, distribuídas em sete classes diamétricas. As cascas foram secas ao ar livre, trituradas e peneiradas, sendo utilizado o material retido na peneira de 60 mesh. Para a extração dos fenóis, utilizou-se metanol:água (50%). O doseamento de fenóis totais foi realizado pelos métodos de Folin-Denis e Folin-Ciocalteau modificados, e para taninos, pelo método difusão radial. Não foi encontrada diferença estatística entre as metodologias de quantificação de fenóis. Verificou-se aumento nos teores de fenóis e taninos com o aumento do diâmetro das árvores

Tannins gravimetric yield condensed in Anadenanthera peregrina bark in different diameter classes

This work aimed to determine the gravimetric yield of condensed tannins in the Anadenanthera peregrina bark in different diameter classes. Fifty-nine trees samples were collected of Anadenanthera peregrina, at 1.30m of the ground (diameter at breast height - DBH), distributed in seven diameter classes. The barks were dried and crushed in mill of hammer. Composite sample was made to prepare the extract. The extraction was done using water in the ratio 15:1 (v/w), added 3% sodium sulfite (w/w) in water-bath at 70°C for 4 hours. The material was filtered using fine cloth strainer and concentrated on a heating plate at approximately 150 g. It was determined the extract mass and removed 10 g for obtaining solids content and 20g for the Stiasny's index. The average values of total solids content, Stiasny's index, condensed tannin content and the compound content non-tannin were 11.34%; 75.79%; 12.76% and 4.07%, respectively. The content of solids, Stiasny's index, compound content non-tannin show significant differences between diameter classes. For the condensed tannins production, the diameter class parameter there was no influence

Prediction of microfibril angle for "Eucalyptus microcorys" wood by fiber length and basic density

Aim of the study was to estimate the influence of the fiber length and basic density on microfibril angle of Eucalyptus microcorys wood. The study area was in an experimental planting at the Universidade Federal de Lavras, Minas Gerais State, Brazil. Three 37 year-old Eucalyptus microcorys trees were used, from whose stems six centimeter-thick discs were removed, cut at a high of three meters. The disks were sanded and planed to highlight the growth rings. Specimens were taken every 1.5 cm across the radius from pith to bark for determining microfibril angle, fiber length and wood basic density. The microfibril angles were determined by use of polarized light microscopy, while the fiber morphology and basic density were determined by usual methods. The averages found for microfibril angle (12.6°), fiber length (968 µm) and basic density (480 kg.m-3) are, in general, within the range of values reported for these characteristics of wood. The microfibril angle showed accentuated reduction of the average values in the pith-bark direction. The fiber length and basic density showed the opposite behavior. We observed that the density and fiber length may be used as an microfibril angle predictor, accounting for 96% and 79% of its variation, respectively

Simulação e avaliação econômica para o primeiro desbaste de Khaya ivorensis A. Chev.

This research aimed to evaluate the economic viability of different scenarios for the first thinning in Khaya ivorensis monocultures and present an estimate of age and thinning intensity that provide a higher invested capital return. There were carried out 576 simulations considering different implementation and maintenance costs, ages for first thinning, thinning intensities, and recipes for standing wood sale. The Net Present Value (NPV) and Internal Rate of Return (IRR) were calculated. The minimum price for standing wood, which all simulations were economically feasible, was 1 638 R$m-3 for 10$ m-3 to 20%, from 546 R$m-3 for 30$ m-3 for 40%. The simulations that maximized the NPV values were those with thinning prediction at five years of age. The percentage planning of thinned volume can be carried out by adopting economic criteria such as NPV and IRR. To obtain a return from the capital invested from the first thinning at five years of age, the percentage estimate from the thinned volume can be obtained according to the standing wood sale price for different minimum rates of attractiveness.O objetivo da presente pesquisa foi avaliar a viabilidade econômica de diferentes cenários para a realização do primeiro desbaste em monocultivos de Khaya ivorensis e apresentar uma estimativa de idade e intensidade de desbaste que proporcionem maior retorno de capital investido. Foram realizadas 576 simulações considerando diferentes custos de implantação e manutenção, idades para primeiro desbaste, intensidades de desbaste e receitas para a venda de madeira em pé. Calcularam-se o Valor Presente Líquido (VPL) e Taxa Interna de Retorno (TIR). O preço mínimo da madeira em pé para o qual todas as simulações foram viáveis economicamente foi de 1 638 R$m-3 para uma intensidade de desbaste de 10$ m-3 para 20%, de 546 R$m-3 para 30$ m-3 para 40%. As simulações que maximizaram os valores de VPL foram aquelas com previsão de desbaste aos 5 anos de idade. O planejamento do percentual de volume desbastado pode ser realizado adotando critérios econômicos como o VPL e a TIR. Para que haja retorno do capital investido logo no primeiro desbaste aos 5 anos idade, a estimativa percentual do volume desbastado pode ser obtida em função do preço de venda da madeira em pé para diferentes taxas mínimas de atratividade