Durable Woods and Antifungal Activity of Their Essential Oils: Case of <em>Tetraclinis articulata</em> (Vahl) Masters and <em>Cedrus atlantica</em> Manetti

Cedrus atlantica Manetti and Tetraclinis articulata (Vahl) Masters are a resinous species originated from North Africa and well known for their durable and noble timbers. This work was conducted to assess the relationship between natural durability of their woods, assessed in previous works by European standards NF EN 350 and CEN/TS 15083-1, and the bioactivity of essential oils extracted from these woods by hydrodistillation and analyzed by GC-FID and GC-MS. Bioassay of sawdust essential oils, conducted by direct contact technique on agar medium on four wood-decaying fungi strains, revealed strong antifungal inhibition especially by T. articulata root burl oil due to its richness in phenols. Natural durability classes of T. articulata and C. atlantica woods were then positively correlated with antifungal activity levels of their oils

Searching for material symmetries in the burr wood of thuja by a direct contact ultrasonic method on spherical samples

International audienceThis work is part of a program that aims at studying the burr wood of thuja (Tetraclinis articulata). The goal of this work is to identify material symmetries of burr wood to improve its machining. To have a sufficient number of data and to limit the variability between samples, an ultrasonic experimental device, in direct contact on spherical samples, has been developed and improved. Until now, the geometry used in direct contact ultrasonic methods was either cubic or polyhedral allowing to obtain, on the same sample, 3 (cube) to 13 (polyhedron) measurements or usable data. By choosing a reasonable angular gap, the spherical geometry allows the ultrasonic velocity to be measured in 133 different directions on the same specimen. We present here the adaptation and development of the ultrasonic experimental device and results obtained on (i) aluminum chosen as a reference material, (ii) beech wood and (iii) burr wood of thuja

Natural durability of Cedrus atlantica wood related to the bioactivity of its essential oil against wood decaying fungi

The Atlas cedar, Cedrus atlantica is a resinous species of Pinaceae originated from North Africa and well known for its noble timber. This work was conducted to assess the natural durability of its wood, to study the chemical composition of essential oil extracted from its sawdust wood and to test the bioactivity of this essential oil against four wood decaying fungi: Gloeophyllum trabeum, Oligoporus placenta, Coniophora puteana and Trametes versicolor. The assessment of natural durability of wood was conducted according to the methods described in the European standards, CEN/TS 15083-1 and NF EN 350-1. Mass losses of wood specimens, after 16 weeks of exposure to fungi attack, in laboratory test, showed that Cedrus atlantica wood is very durable to durable against wood decay fungi attack. The extraction of essential oil from sawdust by hydro-distillation yielded about 3,35% and the chemical analysis of this essential oil by GC-MS showed that E-γ-Atlantone (19,73%); E-α- Atlantone (16,86%), 5-Isocedranol (11,68%); 9-iso-Thujopsanone (4,45%); Cedranone (4,13%) and Z α- Atlantone (4,02%) were the main major identified components. The antifungal activity tested by the direct contact technique on agar medium showed a strong inhibition of wood decaying fungi, especially Gloeophyllum trabeum inhibited at 1/1000 v/v concentration

Searching for material symmetries in the burr wood of thuja by a direct contact ultrasonic method on spherical samples

This work is part of a program that aims at studying the burr wood of thuja (Tetraclinis articulata). The goal of this work is to identify material symmetries of burr wood to improve its machining. To have a sufficient number of data and to limit the variability between samples, an ultrasonic experimental device, in direct contact on spherical samples, has been developed and improved. Until now, the geometry used in direct contact ultrasonic methods was either cubic or polyhedral allowing to obtain, on the same sample, 3 (cube) to 13 (polyhedron) measurements or usable data. By choosing a reasonable angular gap, the spherical geometry allows the ultrasonic velocity to be measured in 133 different directions on the same specimen. We present here the adaptation and development of the ultrasonic experimental device and results obtained on (i) aluminum chosen as a reference material, (ii) beech wood and (iii) burr wood of thuja

Study of acoustic wave propagation through the cross section of green wood

Dans ce travail une approche expérimentale est utilisée pour la modélisation de la propagation des ondes acoustiques dans le bois vert (Douglas). Le bois est supposé un matériau orthotrope et la vitesse de propagation des ondes acoustiques dans la section transverse est déduite des équations de mouvement pour une déformation plane. L'expérimentation est réalisée en deux étapes sous des conditions d'encastrement, le temps de propagation est mesuré sur des rondelles échantillon et sur des petits barreaux extrait des rondelles. Les propriétés mécaniques et physiques sont déterminées en vibration libre. Les résultats montrent une différence significative entre les vitesses de propagation obtenues sur les rondelles échantillons et celles des ondes guidées dans les barreaux. L'anisotropie du bois vert dans le plan transverse est discutée et la simulation de la forme des ondes est présentée. Un bon accord est observé entre les résultats expérimentaux et simulés. (Résumé d'auteur

Effect of bark stripping on the electrical impedance of quercus suber leaves

This study examined the effect of bark stripping on the electrical impedance parameters of cork oak young leaves between 40Hz and 100 kHz. This was a new application of the electrical impedances spectroscopy (EIS) in plant science. Various stripping coefficients (CD) were applied on the trees. Bark stripping is expected to affect water metabolism of leaves and therefore changes in the EIS parameters are expected as well. Single-DCE (ZARC) model was used as equivalent circuit for leaves. Several electrophysiological parameters of this model were compared with moisture content (MC) of the leaves. Intracellular resistance (Ri), extracellular resistance (Re) and relaxation time (τ) of the leaves increased during 14 days aft er stripping while the distributed coefficient (Ψ) and MC decreased. Signifi cant correlation between EIS parameters, MC and trees treatments were found