Oak Wood Samples Research Articles

The effect of heat flux on the fire and chemical properties of oak wood (Quercus petraea)

Selected fire properties of oak wood (mass loss, burning rate, and charring rate) and its chemical composition (extraction substances, lignin, cellulose, hemicellulose) were assessed. Oak wood samples with dimensions of 50 × 40 × 50 mm (l × w × t) were thermally loaded by a heat flux of 15, 20, 25, and 30 kW·m-2, using a ceramic infrared heater with a power of 1000 W. At the given thermal loading, the mass loss ranged from 26% to 47%, whereas the burning rate ranged from 0.0365 to 0.0584%·s-1. The maximum thickness of charred layer was 20 mm, and the charring rate reached values from 0.65 to 0.87 mm·min-1, in a time interval of 1800 s. With increasing thermal loading, the content of extraction substances increased by 30% and the content of lignin increased slightly as well. In contrast, the content of hemicelluloses decreased by 10.3%. This indicates that hemicelluloses are the least thermally resistant wood component. The obtained results can be used as basic data for future testing using medium-sized tests. Subsequently, they can be compared with the input parameters for calculating the fire resistance of wooden constructions elements, which will be the subject of further research.

Interlaboratory Evaluation of Bretziella fagacearum Molecular Detection Assays to Guide the eDNA Monitoring of Oak Wilt Disease

ABSTRACTOak wilt disease, caused by the fungus Bretziella fagacearum, can kill mature red oaks within months of infection, severely affecting biodiversity, landscapes, and industries. The disease, originally only present in the United States, was officially reported for the first time in Canada in June 2023. The aim of this study was to suggest a standardized assay and sample processing method to optimize oak wilt detection both in infection centers and ahead of the disease front. Two previously published molecular assays, a Nested PCR and a TaqMan qPCR, were compared to detect B. fagacearum in a variety of samples in a ring trial across five laboratories. Sample types investigated included eDNA from trapped insect vectors (sorted insects and bulk content from traps), infested and healthy oak wood chips, and B. fagacearum conidia dilutions. Results demonstrated that both Nested and TaqMan assays can be used for molecular confirmation of oak wilt, and results are reproducible across different labs. There is a general agreement between both detection assays when testing true‐positive and true‐negative samples. Both methods demonstrated overall good accuracy. The TaqMan assay was more sensitive and detected lower amounts of DNA target. Both tests were 100% specific to oak wood samples, which was the best sample type to use for detection. In general, samples with high Cts were more prompted to yield false negative Nested results. Detecting oak wilt from bulk insect samples was by far more rapid than sorted sap beetles, but resulted in lower detection signals, especially with the Nested assay. The time‐period when the insect traps were set up also had considerable influence on detection results. We hope this study helps to formulate guidelines in oak wilt detection and biosurveillance management.

A rapid LAMP assay for the diagnosis of oak wilt with the naked eye

BackgroundOak wilt disease, caused by Bretziella fagacearum is a significant threat to oak (Quercus spp.) tree health in the United States and Eastern Canada. The disease may cause dramatic damage to natural and urban ecosystems without management. Early and accurate diagnosis followed by timely treatment increases the level of disease control success.ResultsA rapid assay based on loop mediated isothermal amplification (LAMP) was first developed with fluorescence detection of B. fagacearum after 30-minute reaction time. Six different primers were designed to specifically bind and amplify the pathogen’s DNA. To simplify the use of this assay in the field, gold nanoparticles (AuNPs) were designed to bind to the DNA amplicon obtained from the LAMP reaction. Upon inducing precipitation, the AuNP-amplicons settle as a red pellet visible to the naked eye, indicative of pathogen presence. Both infected and healthy red oak samples were tested using this visualization method. The assay was found to have high diagnostic sensitivity and specificity for the B. fagacearum isolate studied. Moreover, the developed assay was able to detect the pathogen in crude DNA extracts of diseased oak wood samples, which further reduced the time required to process samples.ConclusionsIn summary, the LAMP assay coupled with oligonucleotide-conjugated gold nanoparticle visualization is a promising method for accurate and rapid molecular-based diagnosis of B. fagacearum in field settings. The new method can be adapted to other forest and plant diseases by simply designing new primers.

Characterisation of wood combustion and emission under varying moisture contents using multiple imaging techniques

Characterisation of wood combustion and emission under varying moisture contents using multiple imaging techniques

The climatic signal in tree rings of the common oak (<i>Quercus robur</i> L.) on the south-eastern border of its range in the Ural River basin, Russia

Aim. The objective of this study was to identify and analyze the climatic signal contained in the tree-rings of common oak on the southeastern border of its range in Russia (Ural River basin).Material and Methods. The materials for the study were tree-rings in samples of common oak wood from three sites in the southern part of the Dziau-tyube ridge. Measurements of ring-width were performed on the MBS binocular microscope and on the Lintab measuring complex with the TSAP-WinTM software package. The construction of tree-ring chronologies was carried out in the ARSTAN program. Dendroclimatic analysis was carried out in the R package treeclim.Results. The limiting climatic factors for the radial growth of the common oak on the southeastern border of its range are precipitation during the winter-spring season and the initial period of vegetation and to the greatest extent with the precipitation in March-May. It was shown that the strength of this climatic signal in oak tree rings was not constant over time. The dynamics of this signal are characterized by the presence of local periods of decline, the beginning of which is timed to the years of mass gypsy moth outbreaks.Conclusions. Since the beginning of the 1980s, there has been a significant decrease in the relationship of radial growth with the amount of precipitation for March-May. The reason for this change, in our opinion, could be a strong change in the condition of trees and stands caused by the consistent impact of strong oak defoliation caused by Gypsy moths and late spring frosts.

Effect of Expandable Graphite Flakes on the Flame Resistance of Oak Wood

One of the strategies to improve the fire resistance of wood is to use flame retardants. It would be best to find an ecological, nonhalogenated flame retardant to improve the fire protection properties. In this work, oak wood (Quercus robur L.) samples were treated with an aqueous solution of sodium silicate and expandable graphite flakes, which were applied to different parts of the samples: only on the top, on the sides and together on the top and sides of samples. The fire characteristics of samples were studied by a non-standard test method—a radiant heat source test which is used to determine the mass loss and ignition time of the tested samples (50 mm × 40 mm × 10 mm), and the measurement was carried out using a visual recording of a thermal camera. The results of the laboratory test method showed a significant positive effect of the application of the retardant treated only on the top and together on the top and the sides of the samples in terms of decreasing the mass loss and the course of temperature. When we treated only the sides of the sample, the results were closer to the untreated samples, so there was more than 80% weight loss and a significant temperature increase. The results demonstrated that the appropriate modification of the wood using sodium silicate and expandable graphite flakes has the potential to reduce the loss of mass by 79% and reduce the rise in temperature on the surface of the sample.

Identification and Distribution of New Impact Aldehydes in Toasted Oak Wood (Quercus petraea)

The purpose of this study was to identify aroma compounds associated with the toasting intensity of oak wood (Quercus petraea). Crude organic extracts from oak wood samples (toasted at different temperature-time couples) were analyzed by a sensory-guided approach using GC-O-TOFMS, followed by purification with semipreparative HPLC (reverse phase). This approach revealed two specific odorous zones (OZs) reminiscent of metal and puff pastry. The first OZ was identified as trans-4,5-epoxy-(E)-2-decenal (1) by coinjection of the commercial product, whereas identification of (2E,4E,6Z)-nonatrienal (2) associated with puff pastry OZ was validated by a multistep chemical synthesis approach (Wittig reaction) followed by semipreparative HPLC purification (chiral phase). Their detection thresholds in model wine solution were 60 ng/L (1) and 16 ng/L (2). Their distribution in toasted oak wood samples [GC-NCI-MS (NH3) analysis] ranged from some ng/g to 210 ng/g for (1) and 85 ng/g for (2). Finally, additional sensory experiments demonstrated the impact of newly identified aldehydes in toasted oak wood.

The impact of stain removal and bleaching on the adhesion strength of water-based varnish layers in oak

The aim of this study is to determine the performance of water-based varnish adhesion on the process of stain removal, bleaching and impregnation applied to wood surfaces. In order to accomplish this objective, the selected sessile oak (Quercus petreae Mill.) wood samples were firstly contaminated with grease and PVAc glue, after they were cleaned. Then, the wood samples were bleached by using oxalic acid (C2H2O4) and hydrogen peroxide (H2O2). Secondly, preprocessed specimens impregnated with imersol aqua (IA) and wood protective chemicals (WP) and together both these chemicals (IA+WP). Finally, adhesion strength performance of the wood samples were tested after they covered by single component primary resin (SCPR), double component polyurethane modified with acrylic (DCAP) and double component elastic polyurethane (DCEP). The adhesion resistance of varnish layers is determined according to ASTM 4541 principles. As a result, the oil stain removal and the protective chemical applications decreased the adhesion strength on the wood surface of water-based varnish layers. Contrary, the glue stain removal and the C2H2O4 and H2O2 bleaching increased the adhesion strength. Also, it was determined that DCEP applications have the highest value in oak wood samples.

Benchmarking Spectroscopic Techniques Combined with Machine Learning to Study Oak Barrels for Wine Ageing.

Due to its physical, chemical, and structural properties, oakwood is widely used in the production of barrels for wine ageing. When in contact with the wine, oak continuously releases aromatic compounds such as lignin, tannin, and cellulose to the liquid. Due to the release process, oak loses its characteristic aromatic compounds in time; hence, the flavour that it gives to the enclosed wine decreases for repeated wine refills and a barrel replacement is required. Currently, the estimation of the maximum number of refills is empirical and its underestimation or overestimation can impose unnecessary costs and impair the quality of the wine. Therefore, there is a clear need to quantify the presence of the aforementioned aromatic compounds in an oak barrel prior to a refill. This work constitutes a study to examine noninvasive optical biosensing techniques for the characterization of an oak barrel used in wine ageing, towards the development of a model to unveil its lifespan without inducing structural damage. Spectroscopic diagnostic techniques, such as reflectance, fluorescence, and Raman scattering measurements are employed to assess the change in the chemical composition of the oakwood barrel (tannin and lignin presence) and its dependence on repeated refills. To our knowledge, this is the first time that we present a benchmarking study of oak barrel ageing characteristics through spectroscopic methods for the wine industry. The spectroscopic data are processed using standard chemometric techniques, such as Linear Discriminant Analysis and Partial Least Squares Discriminant Analysis. Results of a study of fresh, one-time-used, and two-times-used oak barrel samples demonstrate that reflectance spectroscopy can be a valuable tool for the characterization of oak barrels. Moreover, reflectance spectroscopy has demonstrated the most accurate classification performance. The highest accuracy has been obtained by a Partial Least Squares Discriminant Analysis model that has been able to classify all the oakwood samples from the barrels with >99% accuracy. These preliminary results pave a way for the application of cost-effective and non-invasive biosensing techniques based on reflectance spectroscopy for oak barrels assessment.

Influence of Ageing on Abrasion Volume Loss, Density, and Structural Components of Subfossil Oak

Subfossil oak wood has spent centuries or millennia in the aquatic medium (rivers, lakes, bogs, etc.) and, due to water anoxic conditions, its decomposition is very slow. As a result of its long residing in specific conditions, its chemical composition, appearance, as well as mechanical and tribological properties have changed. Because of its aesthetic and mechanical properties, subfossil wood is very attractive and often used to produce valuable objects. The main objective of this study was to test how abrasion wear resistance of subfossil oak is affected by ageing. The effects of ageing on wood density and on the structure of lignin and cellulose were tested, as well as the loss of volume during abrasion in correlation with these changes. A study was conducted on samples of recent (regular) pedunculate oak wood and on six subfossil pedunculate oak samples in the age range of 890 and nearly 6000 years. Abrasion wear resistance was expressed through the loss of volume recorded using the Taber abraser. The smallest abrasion volume loss was measured for the recent oak specimens. Linear regression analyses showed that there was a very strong negative linear relationship between the age of subfossil oak and its abrasion volume loss. There was also a strong, but positive and significant linear correlation between subfossil oak age and density. Ageing also affected the structural composition of wood. Results obtained by Fourier Transform Infrared spectroscopy indicated a reduction of the relative crystalline fraction of subfossil wood in recent oak. The degradation of lignin in subfossil oak samples progressed more slowly over time than cellulose degradation. There was a negative correlation between age and the ratio of cellulose and lignin degradation; however, that relationship was found statistically insignificant. Similar results were obtained for the relationship between abrasion wear resistance and changes in the structural composition of the studied samples of subfossil oak wood.

INFLUENCE OF DIFFERENT MACHINING ON THE ROUGHNESS OF OAK WOOD

The paper presents research on the differences the in total roughness and the impact of parameters during different kinds of machining processes of oak samples. Oak wood samples were planed referring to a radial surface structure of wood. The planing machine was Weinig Unimat 500 and the planing head had two blades. The planing was conducted at a feed speed of 10, 15, 20, 25, and 30 m·min-1. The cutting depth of the machining grip was 1.00 mm and the rake angle of the tool blade was bio γ = 15°, at 6000°/min. The diameter of the cutting blade was Φ = 125 mm. Sanding was performed on a Viet Opera V contact sanding machine in combination heads with pre-planing knives and a roller with sanding belt. Roughness was measured along the grain in the latewood area of the annual growth using the electro mechanical profiler Mitutoyo SJ-500. The samples which were machined at a feed speed of 10 m·min-1 had the lowest roughness. The highest value of the roughness had samples which were machined at a feed speed of 30 m·min-1. After comparing roughness obtained during sanding and planing it was determined that the surface roughness obtained on a sanding machine approximately corresponds to the roughness obtained by planing at a feed speed of 20 and 25 m·min-1.

Determination of moisture content and density of silver oak (Grevillea robusta) and Mango (Mangifera indica) wood using gamma radiation

Due to the availability and particular features, wood is one of the first materials used by mankind with a wide variety of applications. Changes in moisture content lead to changes of virtually all physical and mechanical properties (e.g. shrinkage or swelling, strength and stiffness properties) of wood. The present study deals with the determination of mass attenuation coefficient of silver oak (Grevillea robusta) and mango (Mangifera indica) wood samples as it varies across material thickness and at varying moisture levels using gamma ray transmission method. NaI(Tl) scintillation detector and a radioactive source 137Cs of energy 0.662 MeV and having strength of 1.0 microcurie were used. Wood samples were placed in an oven for fixed durations to vary moisture levels. The attenuation varies with decreasing moisture content i.e., the mass attenuation coefficient was minimum for completely wet state and maximum for oven dry state of the samples. Wood density is also a vital parameter giving knowledge about anatomical and physical properties of wood. Wood densities were also measured for these wood samples by using conventional, oven dry and nuclear method. Owing to the fact that the shielding capacity of wood samples can also be determined easily, wood of sliver oak and mango can be used as shielding material from radiation.

Microporous activated carbons from lignocellulosic biomass by KOH activation

Oak wood samples were converted into activated carbons via chemical activation with KOH. The effects of KOH concentration and temperature on the yields and characteristics of the activated carbons were investigated; the yield of the activated carbons decreased with increased temperature and impregnation ratio. The lowest yield of activated carbon was obtained at the highest temperature (800 °C), with the highest KOH concentration of 100 wt%. The BET surface area of the activated carbons was comparable to that of commercially-activated carbon. The highest BET surface area of the activated carbon was 1662 m2.g−1, obtained at 800 °C with 50 wt% KOH concentration. KOH activation resulted in microporosity development in activated carbons.

Experimental research on the molecular-topological structure of oak (Quercus robur L.) and birch wood (Betula pendula Roth) and its shape-memory effect

Features and characteristics of wood as a natural smart material allow us to use it to create new smart biocomposite materials, intelligent systems and environments. The shape-memory effect of oak (Quercus robur L.) and birch (Betula pendula Roth) veneers was investigated. Thermomechanical spectrometry was used to study these two species, which makes it possible to establish the relationship between the deformation transformations and the nature of intermolecular interactions and the interchain organization of wood polymers. The quantitative and molecular relaxation characteristics of the topological structure were obtained for the characterization of the shape-memory effect for the permanent, temporary and after recovery shapes of birch and oak wood samples. The results showed a relationship between the quantities of shape-memory effect and changes in the molecular-topological structure. A reversible transformation of a topological structure was experimentally confirmed for birch and oak woods, with the formation of a temporary deformation and the recovery of the original permanent shapes.

Fast quantification of whisky lactone in oak wood by ion mobility spectrometer

An Ion Mobility Spectrometry (IMS) apparatus has been used to detect the β-methyl-γ-octalactone (Whisky Lactone - WL) standard in the air and as well WL vapours originating from the oak wood samples. The IMS was equipped with Atmospheric Pressure Chemical Ionisation (APCI) ion source based on a Corona Discharge (CD) and was operated in the positive polarity. The IMS spectrum of WL exhibits two peaks, a monomer with reduced ion mobility value K0=1.39 cm2V-1s-1 and dimer K0=1.09 cm2V-1s-1. Using Ion Mobility orthogonal acceleration Time of Flight mass spectrometer (IMS-oaTOF MS) these peaks were identified as protonated monomer M.H+.(H2O)0,1 and dimer M2.H+ ions respectively. The limit of detection study resulted in LOD for WL of 50ppbv. Detection of WL from oak wood samples of different "Quality Level" (QL) categories (categories 1 to 10), indicated strong correlation between the QL category number and the response of the IMS.

Are the wooden remains of the Lusatian culture settlement at Biskupin safe? Decomposition of archaeological oak wood samples during a 10-year experiment

A study was made of the decomposition of oak wood samples deposited in different environments on the Lusatian culture site in Biskupin, Poland. Waterlogged archaeological wood samples were examined after 10 years of deposition in peat, sand or mineral soil or in a water-filled trench. Wood decay was evaluated on the basis of wood mass loss, sample volume loss, physical properties (maximum water content, basic density, porosity) with and without mineral compounds, chemical composition (holocellulose, cellulose, pentosans, lignin, substances soluble in 1% NaOH, 95% ethanol and hot and cold water, and ash content) and microscopic observations. The oak wood was found to be least degraded in the strongly reducing waterlogged peat in which the preserved remains of wooden constructions of the Biskupin settlement are deposited. Nevertheless, even in this near-anaerobic environment, wood decomposition was significant. The loss of wood mass was about 8–10%, whilst the decrease in the cellulose content ranged from 14 to 16%. To preserve the remains of the Biskupin settlement for future generations, it is proposed to consider excavating some of the wood for conservation and exhibition under controlled museum conditions.

Effects of moisture content on mechanical properties of micro-size oak wood

Effects of moisture content (MC) were investigated for the mechanical properties of oak wood (Quercus petraea Liebl.) using micro-size test specimens. The micro-size specimens for bending, tensile, and compression tests were prepared and divided into five groups. Each group was conditioned at a different relative humidity and temperature to achieve MC values of 8%, 12%, 16%, 20%, and above-fiber-saturation-point MCs. After conditioning, the bending strength, modulus of elasticity (MOE) in bending, tensile strength, and compression strength values were determined. The results showed that MC had statistically significant effects on all the measured mechanical properties in the micro-size oak wood samples. The greatest decrease was observed for the compression strength, while the lowest decrease was observed for the tensile strength, when MC increased. The changing rates induced by 1% MC were calculated as 3% for bending strength, 2.5% for the MOE, 2.0% for the tensile strength, and 3.1% for the compression strength.

On the use of vibrational spectroscopy and scanning electron microscopy to study phenolic extractability of cooperage byproducts in wine

Wood is an important source of phenolic compounds, which can be transferred to wine during aging process, improving its properties, from an organoleptic point of view. Therefore, understanding and optimizing the extractability of phenolic compounds from wood are crucial in the oenological field. The structural composition of oak wood samples has been evaluated using Raman and attenuated total reflectance Fourier transform infrared (ATR–FTIR) spectroscopies, and their main spectral features have been linked to phenolic compound extractabilities, as measured by classic chemical analyses. To support the analysis, microscopic images of the samples were also recorded using scanning electron microscopy (SEM). The applied methodology is shown to be useful to relate the wood cell wall structure to phenolic extractability levels of wood samples. It could assist in selecting oak wood suited for improving wine quality with regard to its color or/and stability through the addiction of external copigments to wine.

Micromechanical properties of longitudinally compressed wood

Longitudinal compression induces changes in wood tissue resulting in better bendability. The main purpose of the present study is to identify the changes occurring at the microscopic level. Air-dried oak wood samples (Quercus petraea (Matt.) Liebl.) exposed to a thermo-hydro-mechanical treatment—combined with different longitudinal compression and relaxation treatments—were subjected to micromechanical (nanoindentation) and ultrastructural (scanning electron microscopy, atomic force microscopy) analyses at the wood cell wall level. The comparison of the various methods of treatments shows that the secondary cell wall S2 hardness decreased by 6% as a result of the compression and by 12%, when combined with a long relaxation period. Cell wall indentation modulus decreased by 25% and 51%, respectively. Relative elastic deformation work increased at the expense of plastic deformation work, while the relative proportion of viscoelastic work remained unchanged. Atomic force microscopic images revealed distinct disorientation of the normally straight microfibrils as a result of longitudinal compression, which was attributed to cause the weakening of the cell wall. The results indicate that changes at the ultra-structural level of the wood cell wall contributed to the changes in the macromechanical properties (for example modulus of elasticity and bendability) already reported previously, of the treated wood samples.

Trehalose, mannitol and arabitol as indicators of fungal metabolism in Late Cretaceous and Miocene deposits

Abstract Trehalose, mannitol and arabitol are the main saccharides of extant fungal metabolism, but their occurrence and distribution in geological materials have rarely been considered. Here, we identify these sugars in Miocene lignites and for the first time in Late Cretaceous mudstones and coals. The co-occurrence of trehalose, mannitol and arabitol in the sedimentary rocks investigated suggests their fungal origin, because these three saccharides are major compounds present in most modern fungi, including the very common mycorrhizal and wood-rotting groups. Therefore, we conclude that these sugars should be treated as new fungal biomarkers (biomolecules) present in geological rocks. Trehalose and mannitol are major compounds in total extracts of the samples and a sum of their concentration reaches 4.6 μg/g of sample. The arabitol concentrations do not exceed 0.5 μg/g, but in contrast to trehalose, the concentration correlates well with mannitol (R2 = 0.94), suggesting that they have the same, translocatory role in fungi. Based on the trehalose vs. mannitol and arabitol distributions in Cretaceous samples and their comparison with data for modern fungi, we preliminarily conclude that the coal seams from the Rakowice Male (SW Poland) section were formed during warmer climatic periods than the overlying sediments. Furthermore, no DNA could be isolated from the samples of lignites and overlying sediments, whereas it was abundant in the control samples of maple, birch and oak wood degraded by fungi. This indicates an absence of recent fungi responsible for decay in lignites and implies that the saccharide origin is connected with ancient fungi. Other sugar alcohols and acids like D-pinitol, quinic acid and shikimic acid, were found for the first time in sedimentary rocks, and their source is inferred to be from higher plants, most likely conifers. The preservation of mono- and disaccharides of fungal origins in pre-Palaeogene strata implies that compounds previously thought as unstable can survive for tens to hundreds of millions of years without structural changes in immature rocks unaffected by secondary processes.