Short notes: First Report of the Phytopathogenic Fungus Alternaria tenuissima in cedarwood (Cedrus atlantica M.) in Morocco

Our research focuses on identifying lignivorous fungus from decayed cedarwood. A sample was taken from Azrou forest’s cedar grove, which is a part of Morocco’s Ifrane National Park. On a water agar medium first, and subsequently a PDA medium, the isolated fungus was cultured and purified. After the fungus was purified, an optical microscope morphological analysis allowed us to identify the pathogen Alternaria tenuissima. These findings were confirmed by a molecular characterisation, which had a coverage rate of 94% and an identity of 94,88%. This is the first report of A. tenuissima in decomposing cedarwood that we are knowledge of.

Color Improvement of Pretreated Gmelina Wood by Impregnation of Natural Dyes

The purpose of this research was to improve the appearance of pretreated gmelina wood (Gmelina arborea) by coloring with a natural dye. The dyes used in this research were obtained from sappan (Caesalpinia sappan) and tegeran (Cudrania javanensis) wood waste with a size of 20-40 mesh. The anatomical characteristic that determined the permeability of the gmelina wood was investigated referring to International Anatomist Wood Association (IAWA), while the characteristic of the dye was analyzed using X-ray diffraction (XRD). The wood was colored by immersing in dye mixture (ratio dye and water of 1:5 wt/wt) at room temperature during 72 h. The results showed that the lumen diameter of vessel, fiber, and pit of gmelina observed were 159 μm, 23 μm, and 6 μm, respectively. The XRD analysis showed that the structure of sappan was more amorphous than tegeran, which led to penetrate deeper into the wood. The pretreated wood provided more dyes penetration compared to the untreated wood due to the removal extractives from the wood. The pretreatment on gmelina wood would facilitate the natural dye to be impregnated into the wood cell resulting in more attractive color of the wood.

Stepwise Extraction of Hemicelluloses with Water and Alkali from Larch Wood and their Sugar Compositions

The aim of the present study was to isolate hemicelluloses by stepwise extraction with water and alkali from larch (Larix principis-rupprechtii Mayr) sapwood and heartwood. One water-soluble arabinogalactan (AG) and three alkali-soluble hemicelluloses- arabinoglucuronoxylan (AGX), galactoglucomannan (GGM) and glucomannan (GM) were obtained. The yield of AG extracted with hot-water from larch heartwood was 7.57%, it was 17.96% in total of three alkali-extracted hemicelluloses. There was no significant difference in the yield of hemicelluloses from sapwood and heartwood. Monosaccharide compositions of the hemicelluloses were determined by high performance liquid chromatography after acid hydrolysis. The results showed that galactose and mannose were the main glycosyl units of hemicellulose, followed by xylose. Galactose mainly derived from AG, whereas mannose and xylose originated from alkali-extracted hemicelluloses.

Effects of Different Climate Types on Color Change of Wood Material used Outdoor

Field tests are important for evaluating how wood performs in real-world conditions and making informed choices for material selection. These tests help assess wood’s durability, strength, decay processes, and resistance against harmful organisms. Furthermore, it helps users make more informed decisions about the color of wood and understand the importance of color changes depending on the place and time of use. Because weather conditions are a significant factor that influences the color of wood. Wood that is exposed to prolonged sunlight, moisture, and rain may experience fading, darkening, or staining in its color. In this study, heartwood, sapwood, and CCB impregnated sapwood samples of Scotch pine, spruce, beech and alder were exposed to the soil contact (hazard class 4) according to EN 252 for 3 years in Trabzon, Muğla, Çanakkale, and Elazığ provinces of Turkey with completely different climatic conditions from each other. Color parameters and color change values were evaluated using L*, a*, b* and ΔE* of the samples collected from test sites. The most significant color change was observed at Scotch pine in Çanakkale province. Greater color changes were observed in the heartwood of coniferous species. Impregnated samples showed the least color change.

Analysis of Finger-Joints in Glass Fiber-Reinforced Polymer (GFRP) Composite Glued Laminated Timber Beams

The objective of this paper was to evaluate the effect of finger-joint reinforcement on the bending strength and stiffness of glulam beams made from high-density Eucalyptus spp. glued with resorcinol-formaldehyde adhesive. Six glulam beams were tested: three reinforced with glass fiber-reinforced polymer (GFRP) and three unreinforced for comparison. The GFRP was placed between the last two laminates and at the bottom edge of the glulam only in the finger-joint position. The stiffness and strength of glulam beams were evaluated using static bending tests, which showed that the use of GFRP reinforcement resulted in a gain of more than 100% in average ultimate bending moment and about 10% in average bending stiffness. To calculate the theoretical bending stiffness and normal stresses, a theoretical analysis of beam bending was performed using the transformed section method, which showed agreement with the experimental results.

Study on preparation and properties of Anti-Ultraviolet Aging Wood-Plastic Composites

The degradable wood-plastic composites (WPC) were prepared by compression molding in this study. Polylactic acid (PLA), poly (butylene adipate-co-terephthalate) (PBAT) and salix powder were used as the main raw materials and nano-titanium dioxide (nano-TiO2) was used as anti-ultraviolet filler. The results show that when the addition amount of nano-TIO2 was 2%, the static bending strength and elastic modulus of WPC reach 41.88 MPa and 3730 MPa, respectively, which can meet the commercial application of WPC in building formwork. At this time, the composite material has a better effect of absorbing and reflecting ultraviolet light. The static bending strength, elastic modulus, tensile strength and impact strength of WPC were reduced by 68.3%, 61.5%, 51.9% and 57.4%, respectively. The mass loss rate and water absorption were 6.1% and 22.6%, respectively, that shows its good degradation performance. This study provides a low-cost and simple method for the design of anti-UV aging, high-performance and degradable WPC, which has broad application prospects in packaging, construction and other fields.

Stain Fungi Control in Pinus sp. Wood with Silica mesoporous Particles Loaded with Essential Oils

The use of essential oils (EO) carried onto mesoporous silica particles (MSPs) was tested to control pinewood stains. Three types of MSPs were synthesized and physicochemically characterized with N2 physisorption (type IV), X-ray diffraction [Miller indices (100), (110), (200)], scanning electron microscopy, zeta potential (negative values), dynamic light scattering (< 200 nm) and thermogravimetric analysis (5% to 10% weight loss). A response surface design was used to find the EO loading conditions to control stain, the latter was measured as colour change with the CIEDE2000 formula. The essential oil loading onto MSPC was physicochemically confirmed by a weight loss of 47% in the thermogravimetric analysis. The Citrus, Syzygium sp. and Tagetes sp. oils carried onto mesoporous particles MSPC (30:1 w/w) controlled the pinewood stain caused by Alternaria sp. and Geosmithia sp. This was demonstrated by the absence of pigmentation and scarce fungal growth.

Technology of Particleboard’s Preparation by Cold Pressing after Hot Mat Compression

The article describes a method of preparing particleboards (PB) from fresh and recycled chips by a new technology of cold pressing after hot compression of the mat according to PCT/SK2023/000007 (ÚPV SR, 13.06.2023) using polyvinyl acetate (PVAc) glue. For comparison, the experiment was also carried out using urea formaldehyde (UF) glue and their mutual combination. The new method shortens hot pressing, or causes reduction of pressing temperatures, while the prepared PB released from pressure no longer spring and cure over time. The curing kinetics of both PVAc and UF adhesives were described by monitoring the flexural strength and modulus of elasticity of PB as a function of time after release of pressure.
Modeling of the PB pressing process based on PVAc glue, which consists of overheating the pressed cross-section of the board to 90°C and its subsequent cooling to a temperature when the board is already stable, i.e. below a temperature of 70°C, was carried out using of a hot and cold press, while the pressing cycle lasted 140 s. Shortening the pressing cycle to 100 s was achieved by applying the glue to the chips already preheated to 92°C. Laboratory tests have confirmed that the mechanical properties of PB are in accordance with the requirements of EN 312/3 for chipboards for interior conditions, including furniture, for use in dry environments.

Noise Emission and Quality of Surface of Thermally Modified Silver Fir Wood Planed by Horizontal Milling Machine

This study was conducted to provide information regarding to noise emission and the surface quality of silver fir wood (Abies alba Mill.) planed at different feed rates after thermal modification. Four groups of sixteen samples were prepared. One group was used as control and the others were heated at 160°C, 190°C and 220°C, at atmospheric pressure for 3 h. After, all samples were processed along the grain by a planer machine, 3 m/min and 10 m/min feed rates were applied. Noise was measured using a sound level meter, while surface roughness measurements were performed by a stylus profilometer. Higher feed rates produced noticeably higher noise emission as for natural wood as for thermally modified one. The temperature was found to have a modest positive effect on the noise reduction. The increase of temperature and feed rate affected the increase in the surface roughness of the wood. Feed rate resulted as a more significant factor on the noise emission and on the surface roughness than temperature.

Optical Properties of Transparent Wood prepared from Balsa

In this study, transparent wood was prepared by deactivating chromophore groups in raw balsa wood, followed by solvent free dehydration and a subsequent vacuum-assisted polymer infiltration. Thermal degradation of transparent wood takes place in two main steps. Optical properties (colorimetry, transmittance) of transparent wood made from balsa wood and acrylic polymers were studied. Highest values of transmittance in the visible part of spectra were achieved by 0.7 mm thick samples at approx. 77%. The dependence of thickness on transmittance showed a linear decrease with increasing thickness of transparent wood. The created material also exhibits absorbing properties in visible and UV spectra.

Study on Acoustic Black Hole Effect of Acoustic Emission Signals in Pinus sylvestris var. mongolica litv

The difference in density and wave velocity causes distinct wave impedance between air and wood, resulting in complex acoustic emission (AE) signals due to reflection on the wood’s surface. This study explores the suppression of AE signal reflection by modifying the structure of thin wood panels, utilizing the theory of acoustic black holes (ABH). Initially, a one-dimensional ABH structure was created by forming a wedge structure on one side of the specimen. Pencil-lead break (PLB) tests simulated sudden AE sources on the specimen’s surface. AE signals were collected using three equidistant sensors on the upper surface, with a sampling frequency of 2 MHz. The AE signal was then segmented into frequency bands using the differential method and analyzed in both time and frequency domains. Comparisons were made to understand the impact of the one-dimensional ABH on AE signal propagation. Results demonstrated that the one-dimensional ABH effectively suppressed AE signal reflection on the wood’s surface, reducing the high-frequency components by 18.31%, 20.83%, and 12.09% for each sensor, respectively. Furthermore, the experimental cut-off frequency of 0.98 kHz surpassed the theoretically calculated value of 0.39 kHz due to the disparity between the ABH structure’s thickness and the theoretical prediction.

Ecotoxicological Tests of the Particleboards Containing Rubber Waste

The article is focused on the production and environmental evaluation of wood composites using waste rubber in the construction industry. Used aqueous extracts were prepared from the experimental wooden composites with various additions of the waste rubber from tires and waste seals. The pH value and organic pollution (by COD) were determined in the aqueous extracts. The effect on the environmental components (aquatic and terrestrial) was ecotoxicologically tested using the test organisms Sinapis alba, Lemna minor and Daphnia magna. Preliminary acute ecotoxicity tests were performed.