Wood Species Research Articles

A comparative study of lignin-containing microfibrillated cellulose fibers produced from softwood and hardwood pulps

The expanding field of lignin-containing nanocellulose offers a sustainable alternative to fossil-based substances in applications such as packaging, coatings, and composites. This has underscored the importance to explore the impact of raw materials due to the complexities of lignin structures and different raw fiber characteristics, which plays a significant role in determining the properties of the resultant lignin-rich cellulose materials. This study presents a detailed investigation and comparison on the production and structure-property relationships of lignin-containing microfibrillated cellulose (LMFC) fibers prepared from unbleached softwood and hardwood kraft pulps. The microfibrillation process was analyzed for both softwood and hardwood pulps, comparing the results across various stages of fibrillation. Distinguishing features of lignin structures in softwood and hardwood pulps were identified through Py-GC/MS analysis. Additionally, Digital Image Correlation was employed to investigate the varying failure patterns in LMFC films derived from different wood species. Softwood-derived LMFC films demonstrate less strain-concentrated regions and strain variation, attributed to the formation of more physical crosslinking joints by the elongated fibers. Consequently, softwood-origin LMFC films displayed superior load-sharing and enhanced tensile strength (287 MPa) compared to those derived from hardwood. Additionally, the denser lignin structures in unbleached softwood pulp further boosted the stiffness of resultant softwood-derived films. Upon recycling, LMFC films exhibited superior recovery of mechanical properties following drying, suggesting their significant potential for widespread commercial use.

Effects of Cutting Parameters and Grain Direction on Surface Quality of Three Wood Species Obtained by CNC Milling

Computer Numerical Control (CNC) machines are increasingly popular in the production of furniture and wood products, because they combine high processing quality with short production time. The effective use of CNC machines depends on the processing parameters, which also affects the quality of the processed surface. The aim of this study was to determine the effect of feed rate, cutting direction, and grain direction on the surface roughness of various types of wood. Three European wood species (oak, beech, fir) were cut with a spindle speed of 16,000 rpm and two different feed rates (5,000 and 10,000 mm/min) using end mill tools on the CNC machine. The milling was performed in two cutting directions (radial and tangential) and two grain orientations (0° and 90°). An analysis of variance (ANOVA) was performed to evaluate the impact of the cutting parameters. The surface roughness measurements were taken, and two surface roughness parameters (Ra and Rz) were measured to determine the surface quality of the wood. According to the results of this study, the lowest surface roughness values, milling with the same processing parameters, occurred for oak wood, while the highest values occurred for fir.

The Challenge of Strength Grading UK Hardwoods

Recent research in Europe is bringing a wider range of wood species to the construction market as structural timber and glue laminated products. This option would also open markets for currently underused UK species, foremost hardwoods, but testing efforts when developing strength grading assignments for any minor UK species are prohibitive, as the resource is small and scattered. Grading approaches that require less material for destructive testing could be employed to open routes to market for structural hardwood products. In addition, the European hardwood research has revealed some gaps and uncertainties in grading standards. In particular, data are lacking to support adjustment equations for size, moisture content, and testing arrangement for hardwoods. This paper outlines a new PhD project that will focus on these problems and aims to develop an easier route for strength grading hardwoods.

Comparative Research Regarding the Hydrophilic Extractives Content in Turkey Oak and Sessile Oak Wood and Their Related Staining Susceptibility by Reaction with Iron

The paper presents the experimental results concerning the amount of extractable substances and the color changes determined by the reaction of the tannins contained in wood with iron. Tests were performed comparatively with sapwood and heartwood samples of two Quercus species, namely Turkey oak (Quercus cerris L.) and sessile oak (Quercus petraea (Matt.) Liebl.). The findings show that Turkey oak sapwood has an unexpectedly high amount of extractable substances, higher than the heartwood of the same species. This result was obtained with three extraction methods (cold water, hot water, and NaOH 1% solution). The FTIR investigation of the extracts impregnated on quantitative filter paper seems to confirm these results. Visual assessment and color measurements after applying FeCl3 highlight that both oak species are prone to staining in contact with iron due to their tannin content. The values of the total color difference between the state and after the reaction with FeCl3, lower fer for Turkey oak compared to sessile oak, correlate with a lower extractive content of this wood species.

Searching for Optimal Measurement Parameters by Thermogravimetry for Determining the Degree of Modification of Thermally Modified Wood

When wood is thermally modified, several chemical reactions take place that change the chemical and physical properties of the wood. These changes correlate with the degree of modification, which is mostly a function of the temperature and duration of modification, and consequently with the mass loss during this process. There is a lack of standardised quality control to verify the degree of heat treatment of wood and thus its quality. One of the possible methods to check the degree of thermal modification of a particular type of wood is thermogravimetry (TG). It is based on the assumption that processes that did not take place during thermal modification continue when the TG experiment is carried out. In this method, calibration curves have to be established based on TG measurements of standard samples that have been thermally modified at different temperatures and whose mass loss during modification is known. The calibration curves show the mass loss during the TG measurement as a function of the mass loss during the previous thermal modification. The course of thermal decomposition during the TG measurements is influenced by many parameters, such as the mass of the sample, the heating rate, the atmosphere in which the measurement takes place, and the shape of the crucible in which the sample is placed. In this paper, the influence of these parameters on the calibration curves was investigated. We have focused on oak wood. The best parameters result in a calibration curve with the largest correlation coefficient R2 and the highest slope of the line k. On this basis, we can determine the mass loss during the thermal modification of unknown samples of the same wood species under the same measurement conditions.

Optical and mechanical properties of multilayered transparent wood

The versatility of utilizing transparent wood composite (TWC) as structural building component has been envisioned by producing thicker section. The challenges and limitation while preparing transparent wood using thick wood sections can be addressed by the concept of multilayered construction. TWCs were produced using 2 mm thick lignin modified wood veneer sections of three wood species viz., Populus deltoides (Poplar), Melia dubia (Melia) and Grevillea robusta (Silver oak) followed by infiltration of epoxy polymer. To increase the thickness of composite, an easy method of multilayer construction of 2 mm thick epoxy infiltrated wood samples to produce thicker TWC composite was adopted. Assembly of 2 mm thick epoxy infiltrated wood samples one above the other to produce two layer (4 mm thickness), three layer (6 mm thickness) and four layer (8 mm thickness) thicker TWC of Poplar, Melia and Silver oak wood was carried out. The optical transmittance of TWC samples was measured using UV–VIS–NIR spectrophotometer equipped with an integrating sphere. The optical transmittance of multilayered TWC was reduced on increasing number of layers. The three-point static bending test of multilayer TWC indicated an improvement in flexural strength and slight decrease in the modulus of elasticity on increasing number of layers.

Conserving localized endemic butterflies through demographic and ecological studies: Polyommatus humedasae

1.Polyommatus humedasae is an endemic species narrowly distributed in a few sites in the Aosta Valley (NW Italy). Similarly to other alpine butterflies, the survival of the species is closely linked to the conservation of semi-natural grasslands.2.Despite the species being known since 1976, this is the first comprehensive data collection and analysis on this species, firstly to understand its distribution. At Pont d'Ael, the species core site, we applied the mark-release-recapture (MRR) method to estimate population size and density. To understand the species ecology, we collected data on preimaginal stages (eggs and larvae), host plants, and vegetation composition.3.The new data on species distribution (with 5 new sites and 2 subpopulations already extinct) permitted to update the extinction risk through IUCN assessment to Critically Endangered (CR). The estimated size (881 individuals) and density (73 N/ha) of the studied population are higher than those of other endemic Polyommatus species. Data suggest the species is monophagous on Onobrychis arenaria and prefers to lay eggs where the host plant is abundant, in ecotonal areas with some shrub cover (average 8 %), high herbaceous cover (average 68 %) and on plants in better physiological conditions.4.For species such as P. humedasae, which are threaten by woody encroachment, climate change, fires and collection, we propose the application of a management plan that includes: 1) mechanical cut of wood species; 2) small herds on a rotational basis to reduce woody encroachment and maintain shrub patches; 3) dissemination events to highlight the population importance.

Klasifikacija vrsta drva prema slikama uz pomoć dvodimenzionalne konvolucijske neuronske mreže

The woodworking industry’s recognition and classification of timber is essential for trade, production and timber science. Traditional methods of identifying wood types are complex, time-consuming, costly and require expertise in wood science. Traditional techniques have been replaced by convolutional neural networks (CNNs), a deep learning tool to better identify wood species. In contrast to earlier studies that used pretrained models, a novel architecture designed explicitly for the WOOD-AUTH dataset was proposed in this study to develop a new 2D CNN model. The data collection encompasses high-level visual representations of 12 distinct types of timber. It is aimed to create a simpler and faster model as an alternative to time-consuming and heavy wood classification models. Compared to previous studies, this research worked with a newly structured 2D CNN network based on 12 wood species. High accuracy and fast computation time were achieved using fewer numbers (three layers) of the convolutional neural network. The proposed model achieved 94 % accuracy, 87 % precision, 81 % recall, 80 % F1 score and 112 minutes 27 seconds computation time. The 2D CNN model performed better than the transfer learning models regarding training epochs. The primary benefit of the model is its ability to achieve high accuracy with lower computation time, even at high epochs compared to other models. The introduced 2D CNN model produced satisfactory outcomes for wood species classification.

Macroscopic and Microscopic Anatomical Characteristics of Six Korean Oak Species

The macroscopic and microscopic anatomical characteristics of wood impact its utilization. This study investigated and compared the anatomical characteristics of six Korean oak wood species: Quercus variabilis, Quercus serrata, Quercus mongolica, Quercus dentata, Quercus aliena, and Quercus acutissima. Microscopic anatomical characteristics were evaluated according to the International Association of Wood Anatomists’ list for hardwood identification. Q. variabilis had a corky bark texture, with a color similar to that of Q. serrata. Flat ridges and shallow-fissured barks were observed in Q. serrata and Q. mongolica. The heartwood color was darker than that of sapwood in all species, with color variations. Q. variabilis had heartwood–sapwood colors similar to those of Q. acutissima, while Q. mongolica and Q. aliena presented similar heartwood–sapwood colors. Concerning microscopic features, Q. variabilis and Q. acutissima exhibited similar latewood vessel arrangements, featuring diagonal and/or radial patterns. In contrast, dendritic-to-diagonal patterns of vessels with angular outlines were observed in Q. serrata, Q. mongolica, Q. dentata, and Q. aliena. Additionally, Q. variabilis and Q. acutissima had vasicentric, confluent, and unilateral paratracheal axial parenchyma in the latewood. In summary, bark morphology, bark color, wood color, and latewood vessel characteristics can be used as identification keys for Korean oak species.

Usporedba reakcijskoga i normalnog drva nekih komercijalnih vrsta drva

This study aims to analyze the reaction wood samples for some industrial tree species naturally grown in Kastamonu province in Turkey and compare them with the relevant standards. Some anatomical, chemical, fiber morphological, optical properties, and color changes before and after drying were analyzed for the reaction wood (RW) samples. While the holocellulose content of fir and pine compression wood (CW) was found to be lesser (~3-4 %), the lignin content was higher than those of the opposite wood (OW) (~34 % for pine and 12 % for fir). On the contrary, the amount of holocellulose was found to be higher (~1-4 %), and the lignin was lower (at about 6-15 %) in the tension wood (TW) samples. It was observed that average lengths are more extended in TW(~50-54 %) and shorter in CW (~13-17 %) than those of OW. Significant differences were observed between the anatomical structures of the coniferous and deciduous species studied. Although, the greatest color differences in wet and oven-dried samples of coniferous trees were measured in CW (~15-17 %), it has been found as about 0.7-3 % in TW for deciduous species. Some differences were observed in the anatomical, optical, fiber morphological, and chemical properties of the RW for the studied wood species. Due to its higher lignin content and better physical properties, CW can be used for producing small households and hand tools, ornaments, toys, etc. It will also be appropriate for use in milling and turning work. It is recommended that, because of the lower lignin content and higher polysaccharide ratio, TW should be primarily used for the cellulose, pulp, and paper industries, where high mechanical resistance values are required. Consequently, RW formation causes some physical, chemical, mechanical, anatomical, and optical differences compared to OW in deciduous and coniferous species.

Bio-Durability and Engineering Characteristics of Heat-Treated Poplar Wood

The aim of this study was to evaluate the effect of brown rot fungus Coniophora puteana activity on physical and mechanical properties as well as biological resistance of heat-treated poplar wood. Two poplar wood species (Populus deltoids and Populus nigra) were heat-treated by thermo-wood (Thermo-D) method. Control and heat-treated specimens were exposed to brown rot fungus C. puteana for 16 weeks. Physical and mechanical characteristics of specimens including density, compression strength parallel to the grain and impact strength were evaluated before and after exposure to fungus. Mass loss of specimens caused by fungal activity (MLF) was also calculated. In addition, the effect of thermal modification on laccase production by C. puteana was assayed. The highest mass loss due to fungal deterioration was observed in control specimens, coinciding with the highest substrate-enzyme interactions and constant decrease in detectable laccase levels. According to the results, thermal modification can be used effectively to protect poplar wood against brown rot fungus attack.

Institutional analysis of the conservation management for Litsea leytensis Merr. in Laguna and Quezon, Philippines

This paper aims to analyze the institutions involved in the conservation management of Litsea leytensis Merr., with the trade name Medang, a wood species preferred by carvers in the Philippines, particularly in Paete, Laguna. The art of wood carving is thriving as a culture and as a wood-based industry for Filipinos, intertwined with natural resource management, where the seeds and wildlings are collected as planting materials for the nationwide greening program, while the wood as raw material is carefully selected from a list of Philippine native species. Litsea leytensis Merr. represents the many endemic trees in the country that need serious attention for conservation because of their continuing decline in habitat and population. The study highlights in situ and ex situ conservation of L. leytensis by institutions in Laguna and Quezon. The results suggest that the rules-in-form guided the institutions in conservation management, and their interactions in the action arena were in downward, upward, and horizontal patterns. The outcomes of their interventions for L. leytensis were relevant, coherent, effective, and efficient, while project impact and sustainability were implied by the participation and community ownership of conservation activities, government policies, and funding.

Microwave wood chip treatment use in chemical pulp manufacturing (technical-economic assessment)

The low permeability of many wood species causes problems in the chemical pulp industry. These include very long cooking times, high chemical consumption, large material losses, high energy consumption, and environmental pollution. New microwave (MW) wood modification technology can provide an increase in wood permeability for liquids and gases that solves many of these problems. MW wood pre-treatment can increase pulp mill throughput, reduce chemical and power consumption, increase pulp quality and yield, and improve environmental performance. Economic modelling of this new technology use in different chemical pulp mill conditions allowed to assess the effect of capital costs, electricity costs, labour costs and other cost components to specific total costs of MW chip processing. MW chip treatment costs for pulp mills with output 50,000 to 500,000 ait dry ton (ADT) per year at electricity cost range US$0.04 to US$0.24/kWh vary in the range from US$17.7 to US$60.8 per air dry ton of pulp. Electricity costs form the most significant part – 51- 69% of the total specific costs of MW chip processing at electricity costs US$0.08 to US$0.12/kWh. New technology applications in different Russian conditions can provide benefits up to 7 – 22 Mil US$ per year for pulp mills with output of more than 200,000 ADT/year. The ecological effect and high economic advantages of this MW technology provide a good opportunity for commercialisation.

Eco-Friendly Method for Wood Aerogel Preparation with Efficient Catalytic Reduction of 4-Nitrophenol.

The advancement of science and technology and the growth of industry have led to an escalating discharge of domestic sewage and industrial wastewater containing dyes. This surge in volume not only incurs higher costs but also exacerbates environmental burdens. However, the benefits of green and reusable catalytic reduction materials within dye processes are still uncertain. Herein, this study utilized the eco-friendly deep eutectic solvent method (DESM) and the chlorite-alkali method (CAM) to prepare a cellulose-composed wood aerogel derived from natural wood for 4-nitrophenol (4-NP) reduction. The life cycle assessment of wood aerogel preparative process showed that the wood aerogel prepared by the one-step DESM method had fewer environmental impacts. The CAM method was used innovatively to make uniform the chemical functional groups of different wood species and various wood maturities. Subsequently, palladium nanoparticles (Pd NPs) were anchored in the skeleton structure of the wood aerogel with the native chemical groups used as a reducing agent to replace external reducing agents, which reduced secondary pollution and prevented the agglomeration of nanoparticles. Results showed that the catalytic reduction efficiency of 4-NP can reach 99.8%, which shows promises for applications in wastewater treatment containing dyes. Moreover, investigation of the advantages of preparation methods of wood aerogel has important implications for helping researchers and producers choose suitable preparation strategies according to demand.

Wood-species identification based on terahertz spectral data augmentation and pseudo-label guided deep clustering

ABSTRACT In order to address the problem that existing methods combining spectral data and machine learning for wood species identification rely on labeled samples, this study introduces unsupervised learning into the field of wood identification. It proposes a novel wood-identification model called DCVAE (deep conditional variational autoencoder)-PLCAE (pseudo-label convolutional autoencoders). Terahertz time-domain spectra of wood samples at breast height of five broadleaf and five coniferous species were obtained (40 samples of each species of wood, 400 in total). A conditional variational autoencoder was applied to augment the terahertz spectroscopy dataset. Subsequently, a pseudo-label-guided deep clustering model was developed to extract more discriminative deep features. The model was compared with three traditional clustering algorithms and four deep clustering methods. Clustering experiments and visualization results show that the comprehensive clustering performance of DCVAE-PLCAE is better than the other comparative algorithms and that the extracted low-dimensional features has a more straightforward structure. The algorithm in this study can solve the problems of fewer labeled samples and the difficulty of extracting discriminative features by traditional clustering algorithms.

Species and deterioration of woods used in a traditional Turkish house

This study identified the wood species and evaluated the weathering and biological degradation of historical timber from a traditional Turkish house in Konuralp, Türkiye. The wood material was obtained from the floorboards, window frames, cabinets, cripple studs, ceiling boards, and joists. The species were identified as Pinus spp. for the cabinet, window frame, and cripple stud, Abies spp. for the floorboards, Populus spp. for the ceiling boards, and Quercus spp. for the joist. The macroscopic observation revealed multiple types of degradation caused by weathering, fungi, and insect attacks. The cripple studs made of pine and the floorboards made of fir had become completely unusable due to insect damage. Relatively less biological damage was observed on the cabinet made of pine wood and the ceiling boards made of poplar wood.

A new species of Keteleeria (Pinaceae) from the Lower Cretaceous of Inner Mongolia, Northeast China, and its palaeogeographic and palaeoclimatic implications

Keteleeria Carrière (Pinaceae) is a small genus of evergreen conifer trees, with three to five extant species and six variants distributed across China, Laos, and Vietnam. A new species of conifer fossil wood, Keteleeria huolinhensis sp. nov., is described from the Lower Cretaceous Huolinhe Formation in Inner Mongolia, China. This species is characterized by a heterogeneous pith, endarch primary xylem, the presence of axial resin canals, abietinean radial tracheid pitting, mostly taxodioid and occasionally cupressoid cross-field pitting, nodular horizontal and end walls of ray parenchyma cells, and uniseriate rays of 1–15 (mainly 1–8) cell height. This newly discovered fossil wood represents the earliest record of Keteleeria wood, and sheds light on its evolutionary history and palaeogeographical distribution ranges in the geological past. Cladistic analysis based on 12 morphological characteristics supports the assignment of Protopiceoxylon as the ancestral group of Keteleerioxylon and Keteleeria, reflecting the evolution of radial tracheid pitting from the mixed to abietinean type. Quantitative analysis of the growth rings indicated that K. huolinhensis sp. nov. is an evergreen tree with a Leaf Retention Time (LRT) of 1–3 years. The growth ring patterns in the present fossil wood specimen suggest that the Huolinhe Basin experienced a temperate climate with regular seasonal fluctuations, and relatively sufficient water supply during the Early Cretaceous. Traumatic resin canals, wound scars, presumed fungal remains, and insect tracks in the stem contribute to a further understanding of the complex ecological relationships in the Early Cretaceous Huolinhe flora.

Ink in secular and religious documents from the Pelliot collection (BnF, Paris): A study of ingredients and uses of ink in1st millennium Tocharian, Sanskrit and Chinese manuscripts from the Kucha and Dunhuang regions

This paper presents the study of ink from first millennium manuscripts discovered in the Kucha and Dunhuang regions (West China) from the “Pelliot collection” stored at the Bibliothèque nationale de France (Paris, France). The sixteen analyzed manuscripts written in black ink were selected partly because of their diverse characteristics (script, type, etc.) and partly because of the high possibility for their accurate dating between 4th to the 8th century. This period is defined by an important economic growth as well as cultural and artistic activities, facilitated by the fact that Kucha and Dunhuang played a key role in the passage of the Silk Road network connecting China, India and western Central Asia.FTIR and Raman spectroscopies were first employed as they are non-destructive and non-invasive methods. They indicated that the ink present on the manuscripts was composed of soot and protein binder, however they did not provide direct insight on the precise origin of the soot (e.g pine soot or lampblack) and the protein binder used in the fabrication of inks. The analysis of the inked manuscripts by pyrolysis-comprehensive two-dimensional gas chromatography/mass spectrometry (Py-GCxGC-MS) – for which only a small amount of sample (microgram quantities) is required - and the exploration of the obtained multivariate datasets combining Hierarchical Clustering and PCA provide invaluable information on Asian inks, their manufacture and use in different historical periods. Our research suggests that the majority of the inks were made with pine soot. Furthermore, our results reveal different chemical signatures that may be indicators of difference in the production of pine soot (use of various species of pine wood, combustion parameters, etc.). Moreover, diverse proteinaceous binders and additives, known to have been used in ancient Chinese ink manufacture to ensure ink’s consistency and for their antimicrobial and aromatic properties, were identified.

Supercritical CO2 drying of New Zealand red beech to below the fibre saturation point reduces collapse distortion

Supercritical CO2 offers an alternative method of removing wood moisture and reducing cellular collapse compared to traditional drying techniques. The technique has been previously demonstrated for Pinus radiata and Eucalyptus nitens dewatering and was modified in this study for New Zealand red beech (Nothofagus fusca) heartwood, which is notoriously difficult to dry without causing excessive distortion. The technique was also successfully extended to drying below the fibre saturation point. A specific dewatering and drying schedule was developed for N. fusca because of negligible dewatering using a schedule previously designed for wood with an open hydrofluidic network of interconnected vessels. An anatomical assessment confirmed lumen pathways were occluded with tyloses and polyphenol resins. A fluid dynamics assessment concluded that permeability measurements are recommended together with tortuosity and porosity information for improved wood species dewatering characterisation. Using the dewatering and drying schedule, collapse was successfully reduced by 92% for both normalised internal wood area and void collapse when compared to oven-dried samples. The beech specimens took 18 days to reach 17.3% moisture content (MC) but displayed some checking from early dewatering depressurisation, compared to air-dried control specimens which showed no collapse or checking but took 6 months to reach 12% MC. Supercritical CO2 dewatering and drying could be combined with extractives separation, preservative treatment, and mechanical forming of wood in one plant to make a potentially economically viable process with improved energy, environmental and carbon footprints. A techno-economic analysis is suggested to fully compare supercritical drying of wood against conventional drying operations.

Thermal properties and water content of two tropical wood species as a function of the air relative humidity.

Thermal properties and water content of two tropical wood species as a function of the air relative humidity.