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Biofinish is an innovative wood protection system inspired by biological processes. It enhances the hydrophobicity of wood through oil treatment, resulting in improved dimensional stability. Living cells of the fungus Aureobasidium pullulans effectively protect wood from deterioration caused by other decaying fungi. The melanin pigment produced by the fungus provides an appealing dark surface and additionally protects the wood substrate against UV radiation. The significant advantage of Biofinish is its remarkable self-healing ability, which distinguishes it from conventional wood protection methods. This research aimed to explore fungal species colonising surfaces exposed to natural weathering and assess the survival of A. pullulans on wood surfaces coated with Biofinish during its in-service period. This study was performed on a facade composed of European larch wood (Larix decidua) treated with linseed oil and coated with Biofinish at the InnoRenew CoE building in Izola, Slovenia, following a 9-month exposure period. The majority of the detected species belonged to the genera Aureobasidium. The results indicated the survival and effective antagonistic action of A. pullulans, the living and active ingredient of the coating, against other wood-decaying fungi. [ABSTRACT FROM AUTHOR]

Engineered wood products (EWPs) are being increasingly used as construction materials. EWPs are currently being made using synthetic adhesives or metal fasteners, which lead to poor recyclability and reusability. Therefore, this review paper focused on emerging adhesive- and metal-free assembling techniques including wood dowels, rotary-dowel welding, wooden nails, and dovetail joining as alternative ways of making prefabricated EWPs. This will contribute towards green construction and optimising the building process to minimise its negative impact on the environment and its inhabitants, while maximising the positive aspects of the finished structure. The respective advantages and shortcomings will be compared with those of equivalent EWPs. In general, the dowel-laminated timber (DLT) provides sufficient load-bearing capacity and even better ductility than EWPs of equivalent size, but its relatively low stiffness under a bending load limits its application as a structural element. Optimised manufacturing parameters such as dowel species, dowel spacing, dowel diameter, dowel insertion angle, dowel shape, etc. could be studied to improve the stiffness. The improved mechanical properties and tight fitting due to set-recovery of densified wood support its use as sustainable alternatives to hardwood dowels in DLT to overcome problems such as the loosening of connections over time and dimensional instability. The rotary welding technology could also enhance the strength and long-term performance of dowel-type joints, but its poor water resistance needs further investigation. The main obstacles to implementing DLT products in the market are missing technical information and design guidelines based on national codes. [ABSTRACT FROM AUTHOR]

The distinct properties and affordances of paper provide benefits that enabled paper to maintain an important role in the digital age. This is so much so, that some pen–paper interaction has been imitated in the digital world with touchscreens and stylus pens. Because digital medium also provides several advantages not available to physical paper, there is a clear benefit to merge the two mediums. Despite the plethora of concepts, prototypes and systems to digitise handwritten information on paper, these systems require specially prepared paper, complex setups and software, which can be used solely in combination with paper, and, most importantly, do not support the concurrent precise interaction with both mediums (paper and touchscreen) using one pen only. In this paper, we present the design, fabrication and evaluation of the Hybrid Stylus. The Hybrid Stylus is assembled with the infinity pencil tip (nib) made of graphite and a specially designed shielded tip holder that is attached to an active stylus. The stylus can be used for writing on a physical paper, while it still maintains all the features needed for tablet interaction. Moreover, the stylus also allows simultaneous digitisation of handwritten information on the paper when the paper is placed on the tablet screen. In order to evaluate the concept, we also add a user-friendly manual alignment of paper position on the underlying tablet computer The evaluation demonstrates that the system achieves almost perfect digitisation of strokes (98.6% of strokes were correctly registered with only 1.2% of ghost strokes) whilst maintaining excellent user experience of writing with a pencil on the paper. [ABSTRACT FROM AUTHOR]

Digital transformation of the timber supply chain is more relevant at present than ever before. Timber tracking is one example of digital transformation, and can be performed in various locations, from the forest to the mill, or even beyond, to the final timber product. The integration of new technologies in the forestry and timber industries should contribute to enhancing supply chain efficiency and safety. For this purpose, a new timber tracking and processing system was tested by integrating RFID (Radio Frequency IDentification) technology with digital survey tools and intelligent machines, into a smart timber supply chain. A case study on this process was carried out in a mountain forest in Austria. The tags were used to link information to single items (trees and logs) and transfer relevant data (species, diameter, length, volume, defects, density, stiffness, branchiness, etc.), throughout the whole supply chain. The performance of the technology was analyzed by means of process flow, bottleneck, and risk analyses. Fourteen spruce trees went through the supply chain process from the forest stand to the log yard, monitored by the new timber tracking and processing system. The results revealed that the new system is useful for transferring information through the timber supply chain, and the system costs remained at a normal market level. The weakest point in the supply chain was the processing of the trees by the intelligent prototype processor. A high error rate and low durability lead to higher idling time and harvesting cost, but the findings of this study can be used to further improve this system. All other processes worked well and were at a marketable level. [ABSTRACT FROM AUTHOR]

Near-infrared spectroscopy (NIRS) allows for the rapid estimation of a wide range of wood properties. Typically, NIRS studies on wood have utilized benchtop spectrometers, but efforts to utilize NIR hyperspectral imaging to examine wood and wood products have increased. Compared to benchtop NIR systems, hyperspectral imaging has several advantages (speed, visualization of spatial variability), but the data typically have a lower signal-to-noise ratio as well as fewer wavelengths saved; thus, hyperspectral imaging systems have a larger spectral sampling interval (SSI). Furthermore, the SSI and wavelength range varies considerably among different HSI cameras. NIR-HSI systems based on indium gallium arsenide (InGaAs) detectors have a wavelength range typically from 900 to 1700 nm, while short-wave infrared hyperspectral imaging (SWIR-HSI) systems based on mercury cadmium telluride (MCT) detectors have the 'full' NIR wavelength range from 1000 to 2500 nm. These factors may influence the performance of wood property calibrations. We compared one NIR-HSI (900–1700 nm) and three SWIR-HSI (1000–2500 nm) commercially available cameras with an NIRS benchtop spectrometer (1100–2500 nm). The performance of specific gravity (SG) and stiffness (MOE) calibration models was compared with one-hundred Douglas-fir (Pseudotsuga menziesii) samples. The limited wavelength range of an NIR-HSI camera provided the best models for MOE, whereas the NIR-HSI and two SWIR-HSI cameras provided similar SG results. SWIR-HSI models heavily favored wavelengths greater than 1900 nm. [ABSTRACT FROM AUTHOR]

Heterogeneity of kraft lignin is one of the main limitations for the development of high-performance applications. Therefore, refining lignin using organic solvents is a promising strategy to obtain homogenous fractions with controlled quality in terms of structure and properties. In this work, one-step refining processes for hardwood kraft lignin using nine organic solvents of different chemical nature and polarity were carried out with the aim of investigating and understanding the effect of the type of organic solvent on the quality of resulting fractions. Structural features of both soluble and insoluble lignin fractions were assessed by GPC, Py-GC-MS, and FTIR linked to PCA analysis. Moreover, functional properties such as physical appearance, hygroscopicity, antioxidant capacity, and thermal properties were evaluated. The results evidenced the relationship between the nature and polarity of the solvents and the properties of the obtained soluble and insoluble fractions. [ABSTRACT FROM AUTHOR]

Various factors affect the bonding quality of elements used for timber construction. This review includes literature studies and personal experiences related to relevant technological variables defining glue bond performance in glue-laminated timber elements during their service life. The gluing of hardwood species receives special focus as it is considered by the industry to be the most challenging process for implementation. In particular, the effects of wood species, type of adhesive, glued-wood surface quality, physical and/or chemical modification of the wood, technological solutions for gluing, and varying climatic conditions during the use phase (relative humidity, temperature, air circulation, etc.) are considered. In addition, overlapping of individual influencing factors often leads to problems with bonding, thus requiring strongly integrating measurement methods (e.g. NIR spectroscopy). The causes of variations in the results when glued wood is tested using different standardized methods are discussed. A list of open research questions is provided, and problem solutions are recommended based on systematized cutting-edge knowledge. The aim of the work is to systematize the state of knowledge of wood gluing to create a basis for controlled and stable manufacturing processes. The progress of the work will be reported in further publications. [ABSTRACT FROM AUTHOR]

Density functional theory (DFT) and molecular dynamics (MD) simulations were employed to investigate the interaction of cellulose and lignin with acetic anhydride for explaining the wood modification process. Cellulose was modelled with a cellobiose unit and dibenzodioxocin was used to represent the lignin model. Results obtained from both methods revealed that acetic anhydride interacted substantially more with the cellobiose model than the lignin model. The interaction energy of cellobiose–acetic anhydride was higher (about 20 kJ mol−1) than that of lignin-acetic anhydride. DFT results on hydrogen bonding indicated that the hydroxyl group from cellobiose and the aromatic hydroxyl group from lignin models have similar energy values, which explain the equal strength of hydrogen bond interaction. The same trend was also obtained for the substitution of acetyl group in the hydroxyl group. MD results have also predicted that acetic anhydride forms a stronger interaction with cellobiose than with the lignin model, and these findings were in agreement with the DFT results. [ABSTRACT FROM AUTHOR]

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Portable spectroscopic instruments are an interesting alternative for in-field and on-line measurements. However, the practical implementation of visible-near infrared (VIS-NIR) portable sensors in the forest sector is challenging due to operation in harsh environmental conditions and natural variability of wood itself. The objective of this work was to use spectroscopic methods as an alternative to visual grading of wood quality. Three portable spectrometers covering visible and near infrared range were used for the detection of selected naturally occurring wood defects, such as knots, decay, resin pockets and reaction wood. Measurements were performed on wooden discs collected during the harvesting process, without any conditioning or sample preparation. Two prototype instruments were developed by integrating commercially available micro-electro-mechanical systems with for-purpose selected lenses and light source. The prototype modules of spectrometers were driven by an Arduino controller. Data were transferred to the PC by USB serial port. Performance of all tested instruments was confronted by two discriminant methods. The best performing was the microNIR instrument, even though the performance of custom prototypes was also satisfactory. This work was an essential part of practical implementation of VIS-NIR spectroscopy for automatic grading of logs directly in the forest. Prototype low-cost spectrometers described here formed the basis for development of a prototype hyperspectral imaging solution tested during harvesting of trees within the frame of a practical demonstration in mountain forests. [ABSTRACT FROM AUTHOR]

The overall goal of this work was to develop a prototype expert system assisting quality control and traceability of particleboard panels on the production floor. Four different types of particleboards manufactured at the laboratory scale and in industrial plants were evaluated. The material differed in terms of panel type, composition, and adhesive system. NIR spectroscopy was employed as a pioneer tool for the development of a two-level expert system suitable for classification and traceability of investigated samples. A portable, commercially available NIR spectrometer was used for nondestructive measurements of particleboard panels. Twenty-five batches of particleboards, each containing at least three independent replicas, was used for the original system development and assessment of its performance. Four alternative chemometric methods (PLS-DA, kNN, SIMCA, and SVM) were used for spectroscopic data classification. The models were developed for panel recognition at two levels differing in terms of their generality. In the first stage, four among twenty-four tested combinations resulted in 100% correct classification. Discrimination precision with PLS-DA and SVMC was high (>99%), even without any spectra preprocessing. SNV preprocessed spectra and SVMC algorithm were used at the second stage for panel batch classification. Panels manufactured by two producers were 100% correctly classified, industrial panels produced by different manufacturing plants were classified with 98.9% success, and the experimental panels manufactured in the laboratory were classified with 63.7% success. Implementation of NIR spectroscopy for wood-based product traceability and quality control may have a great impact due to the high versatility of the production and wide range of particleboards utilization. [ABSTRACT FROM AUTHOR]

The influence of the thermal modification process on wood machinability was investigated with four minor species of low economic importance. A set of representative experimental samples was machined to the form of disks with sharp and dull tools. The resulting surface quality was visually evaluated by a team of experts according to the American standard procedure ASTM D-1666-87. The objective quantification of the surface quality was also done by means of a three dimensions (3D) surface scanner for the whole range of grain orientations. Visual assessment and 3D surface analysis showed a good agreement in terms of conclusions. The best quality of the wood surface was obtained when machining thermally modified samples. The positive effect of the material modification was apparent when cutting deodar cedar, black pine and black poplar in unfavorable conditions (i.e., against the grain). The difference was much smaller for an easy-machinability specie such as Italian alder. The use of dull tools resulted in the worst surface quality. Thermal modification has shown a very positive effect when machining with dull tools, leading to a relevant increment of the final surface smoothness. [ABSTRACT FROM AUTHOR]

Timber structures can undergo alteration during their service life, which can be caused by mechanical, environmental or biological agents (bacteria, fungi and insects), because of the biological nature of the material. On site characterization of timber members is a very challenging task, especially assuming that both, the structure itself and material used for construction have to be evaluated. Current assessment procedures are limited to visual inspection, occasionally supported by a few instrumental analyses (such as wood moisture content measurement and drilling resistance tests). However, a clear tendency for the application of various non-destructive techniques is observed nowadays. The paper presents an overview on the current applications of infrared spectroscopy for the characterization of various alteration phenomena in wooden artefacts. A literature review is complemented by a series of results, reported from experimental campaigns carried out by the authors. The aim of the paper is to demonstrate the applicability of the proposed method for the analysis of different degradation processes occurring in timber members, with a special attention on wood aging, weathering, biotic decay by fungi and waterlogging. Examples of spectra evaluation as well as limitation of proposed methods are presented. Case studies including classification of decay type, analysis of the weathering dynamic and characterization of waterlogged wooden samples are briefly illustrated. Practical application of spectroscopy within timber structure assessment is considered as a very important supplement to the typical information collected during ordinary tests. Copyright © 2015 John Wiley & Sons, Ltd. [ABSTRACT FROM AUTHOR]

The use of wood-based connectors as a possible substitute of metal fasteners, for specific applications, in modestly loaded and moderately dense timber components, in new timber assemblies as well as for restoration works, is discussed. The densification technique has been used to obtain a wood-based material with higher mechanical performance with respect to the natural wood. A dedicated research has been carried out to monitor the compression behaviour of the wooden nails. The progress of pushing force during insertion of the wooden nails into wood samples was analysed and served for insertion process control. 600 compression tests were carried out to evaluate the mechanical behaviour of densified wooden nails, obtained from four different hardwood species and with different densification ratios. Beech, densified at 0° ring angle, 60% densification ratio, was selected for the further experimental campaign on the joints. Ten push-out tests have been performed on timber-to-timber joints. Results in terms of rigidity, resistance and post-elastic behaviour are discussed. The observed variability (slip modulus CoV = 26.7%, maximum load CoV = 23.7%) is mainly dependent on the occurrence of geometric flaws during nail insertion. Ductility exhibited by a group of joints was given by nail embedding into the wood before failure as well as by the bending resistance of the nail. The choice of an optimized technology for wood densification and for nail insertion is considered as a key factor for the optimal employment of the novel connectors. [ABSTRACT FROM AUTHOR]

On site characterization of wood members is a very challenging task, after consideration of all the variables affecting the material used for the construction and the complexity of the structure itself. Current procedures are limited to few characterizations; in general based on visual inspection supported by the localized drilling resistance analysis and moisture content estimation. The goal of this work was to highlight the potential of the infrared spectroscopy as a tool capable of providing complementary information for the expert inspector assessing the timber structures. The paper presents several examples of successful application of mid and near infrared spectroscopy as used for prediction of physical and mechanical properties of wood. Requirements for implementation of mid and/or near infrared spectroscopy in routine assessment protocols are also provided. [ABSTRACT FROM AUTHOR]

The proper timber structure assessment is of great importance to assure safe service of buildings as well as to preserve cultural heritage objects for future generations. However, due to peculiar anatomic structure of wood, anisotropy and heterogeneity, its characterization is a problematic task. Several methods are used nowadays for improving existing structure assessment routines, including also continuous monitoring of the structure performance. Current trend for using multiple sensors simultaneously is more favorable than a single sensor approach due to superior representation of the real-world cases. Moreover, the availability of novel statistical tools to handle many variables concurrently is another motivation for rapid changes within the field of measurement technology. It is important, therefore, to assure proper pre-processing of the signals from sensors, appropriate data fusion and optimal data analysis. The integrated use of non-destructive testing methodologies and data handling techniques to assess, monitor and predict properties of wood within structures and buildings is briefly described in this work. Examples for successful applications of the different data analysis techniques on the assessment and monitoring of civil engineering constitutions are reported. Multi-sensor approach may be a very attractive alternative to the conventional assessment and can provide supplementary data to be considered when inspector decision is made. It is assumed that, after additional developments, such methodologies can serve as assisting tools for non-destructive assessment of the wooden structures, service life prediction of structural elements and to support selection of optimal conservation process. [ABSTRACT FROM AUTHOR]

The manuscript presents the application of NDT imaging techniques as complementary tools to be used during visual inspection. NDT imaging can be used to map inhomogeneity and to identify the areas at the highest risk for damage in timber structures. The paper highlights the potential of imaging techniques accepted and practiced for the assessment of timber structures. Multi-sensor approaches are presented and recommended for multi-scale, multi-resolution correlated information, which allow the non-destructive, reliable and fast assessment of damage and risk level in the existing timber structures. [ABSTRACT FROM AUTHOR]

Oleoresin samples collected directly from living-trees by three different tapping methods, and from four geographical origins were analyzed using two gas chromatography (GC) methods. The GC was coupled to a flame ionization detector (GC-FID) for quantification, and to a mass spectrometer (GC-MS) for identifying the chemical composition. Twenty-eight chemical components were detected and quantified. The proportions of each chemical component varied exceedingly between different samples, and other associated factors. The specific sample traits, including Pinus species, tapping method and geographical origin differentiated the sample batches. Notwithstanding, the main chemical components present in all the characterized samples are α-pinene and β-pinene. Statistical analysis demonstrated that the majority of molecules are of significant importance to sample traits. Moreover, the statistical analysis allows for the identification of the biomarkers associated with the sample traits. Additionally, Linear Discriminant Analysis models have shown very good performance in classifying samples based on the sample traits. Furthermore, the biomarkers allowing the establishment of differences between geographical origins are sativene, camphene, limonene, isopimaric acid and pimarinal, whereas the differentiation between tapping methods is established by sativene, pimaric acid, β-phellandrene, isopimaric acid, retinol and camphene, and lastly biomarkers allowing the differentiation between Pinus species are palustric acid, limonene, β-pinene and sativene. • Oleoresin samples collected from three Pinus species, three oleoresin tapping methods, and four geographical locations were analyzed using gas chromatography methods. • Statistical analyzes were used to create classification models according to the specific sample traits (Pinus species, tapping method and geographical origin). • Furthermore, characteristic biomarkers of the sample traits are highlighted. [ABSTRACT FROM AUTHOR]

The goal of this work was to understand and model the combined effect of time, geographical location, and exposure on the physical–chemical mechanisms of wood weathering in structures. Series of wooden samples were exposed to natural weathering in seven locations varying in climatic conditions, including Italy and north Germany. The set of samples was exposed for 4 years, collecting representative samples each year. Four exposure directions (north, south, east, and west) were investigated. Measurements of samples included: photogrammetry, near and mid infrared spectroscopy, color, gloss, roughness, and elemental composition (x-ray fluorescence spectroscopy). Results showed that the surface degradation mechanisms caused by weathering were affected by the site of exposure. The wood samples weathered in the Italian sites, in Udine and Macerata, were most degraded. The most significant changes were observed in samples exposed to the south direction. The original algorithm for calculation of “the weathering indicator”, by merging the multi-sensor data and linking these to the surface performance indicators was developed. Finally, the subjective visual assessment by the expert person was compared with parameters obtained by measuring the weathered surfaces with various sensors. A good correspondence between weathering indicator Windand subjective quality index was established. [ABSTRACT FROM PUBLISHER]

Chemical and physical characteristics of wood from six European populations of Picea abies were investigated taking into consideration their genetic differentiation determined by four microsatellites markers. The growth conditions of investigated spruce trees differed significantly. As a consequence, several adaptations were observed in samples from varying environments. The adaptation mechanisms include a variation to the annual rings morphology as well as the physical properties of the wood. It was proved that some properties, such as wood density or latewood ratio, are strictly correlated to the environmental variables. Results show that trees from geographically distinct populations present some diversity in the genotypes. It was also noticed that some trees did not share their genetic profile with other plants from the same location due to high intrapopulation variability. Samples from Finland possessed the lowest level of internal differentiation, while samples from northern Poland presented the lowest allele richness and were most divergent from the others. It was not possible to correlate any wood properties (chemical or physical) to genetic features of the population due to high intrapopulation diversity. [ABSTRACT FROM AUTHOR]

Wood is one of the oldest building materials and, thanks to its favorable mechanical and technological properties, one of the most versatile. Due to its biological nature, wooden artefacts can undergo some alteration during their service life that can be caused by mechanical, environmental or biological agents. Waterlogged and buried wood elements, present in wetlands and aquatic environments, are subject to modifications at the chemical and anatomical level, which also affect physical and related mechanical properties of the material. The possibility to predict long-term performance and the rate of modification of mechanical/physical properties of the wood material in specific environmental conditions is crucial for proper design and optimal maintenance of submerged load-bearing timber structures. Therefore, prediction models to estimate selected material properties were developed within this study. For this purpose Fourier Transform near-infrared (FT-NIR) spectroscopy and multivariate analysis based on partial least-squares (PLS) were used. The models proved to be effective to predict selected dynamic and physical parameters of waterlogged samples. However, in order to include the effect of water saturation in the material on site further research is indispensable. The possible detrimental effect on wood mechanical properties of waterlogging in differing environmental conditions is also discussed in this paper. Dynamic tests were performed on samples of two species, Quercus robur L. and Pinus sylvestris L., after 8 years of deposition in two differing sites. Additionally, the results obtained from fresh and archaeological samples were compared. No significant effects have been observed due to the depositional environment after short-term waterlogging. A more remarkable difference in the rate of the modification of dynamic and physical (density) properties can be attributed to differing natural features of the tested wooden species. It may be concluded that, in order to ensure a longer service-life of waterlogged timber structures, original wooden material should be properly selected, with regard to species, growth conditions, and log characteristics. [ABSTRACT FROM AUTHOR]

Further intensive research is in progress to discover new wood modification solutions to ensure improvement of wood properties and functionality, allowing elongated service life and reducing the risk of unexpected product failure. Wood has been recognized as an attractive alternative to several other traditional construction solutions, and it is often called the "building material of the 21st century". The wide range of covered modification processes and the scope of applications proved that wood modification is not only the sole concern of a few wood scientists but it became a truly inter-disciplinary research area. [Extracted from the article]

The service life performance of timber products exposed to natural weathering is a critical factor limiting the broad use of wood as an external building element. The goal of this study was to investigate the in-service characterization of an innovative biofinish coating system. It is a novel surface finishing solution based on the bioinspired concept of living fungal cells designed for effective wood protection. The performance of Scots pine (Pinus sylvestris L.) wood coated with biofinish was compared with uncoated references. Samples were exposed to natural weathering for 12 months under the climatic conditions of northern Italy. The visual appearance, colour, gloss, wettability, and 3D surface topography of the wood surface were examined. Results revealed that the total colour changes (∆E) of biofinish-coated wood were negligible. Untreated Scots pine wood revealed the changes in colour after just three months of exposure. The gloss changes of both surface types were small. The contact angle measured on biofinish-coated wood was higher compared to that of uncoated Scots pine. Surface roughness increased in uncoated wood due to the erosion effect caused by the weathering progress. Conversely, the surface roughness of biofinish-coated samples decreased along the exposure time. This phenomenon was explained by two self-healing mechanisms: migration of non-polymerized oil to the cracked surface, where it polymerizes and creates a closed layer, and local regrowth to cover damaged spots by living fungal cells present in the coating. The obtained results revealed the superior aesthetic performance of the biofinish surface treatment against natural weathering. By considering the fully bio-based nature of the investigated coating, it was concluded that this solution can be an attractive alternative for state-of-the-art wood protection technologies. [ABSTRACT FROM AUTHOR]

Wood, as a biological material, is sensitive to environmental conditions and microorganisms; therefore, wood products require protective measures to extend their service life in outdoor applications. Several modification processes are available for the improvement of wood properties, including commercially available solutions. Among the chemical treatments, acetylation by acetic anhydride is one of the most effective methods to induce chemical changes in the constitutive polymers at the cellular wall level. Acetylation reduces wood shrinkage-swelling, increases its durability against biotic agents, improves UV resistance and reduces surface erosion. However, even if the expected service life for external cladding of acetylated wood is estimated to be 60 years, the aesthetics change rapidly during the first years of exposure. Hybrid, or fusion, modification includes processes where the positive effect of a single treatment can be multiplied by merging with additional follow-up modifications. This report presents results of the performance tests of wood samples that, besides the modification by means of acetylation, were additionally protected with seven commercially available coatings. Natural weathering was conducted in Northern Italy for 15 months. Samples were characterized with numerous instruments by measuring samples collected from the stand every three months. Superior performance was observed on samples that merged both treatments. It is due to the combined effect of the wood acetylation and surface coating. Limited shrinkage/swelling of the bulk substrate due to chemical treatment substantially reduced stresses of the coating film. Hybrid process, compared to sole acetylation of wood, assured superior visual performance of the wood surface by preserving its original appearance. [ABSTRACT FROM AUTHOR]

Gasification with supercritical water is an efficient process that can be used for the valorization of biomass. Lignin is the second most abundant biopolymer in biomass and its conversion is fundamental for future energy and value-added chemicals. In this paper, the supercritical water gasification process of lignin by employing reactive force field molecular dynamics simulations (ReaxFF MD) was investigated. Guaiacyl glycerol-β-guaiacyl ether (GGE) was considered as a lignin model to evaluate the reaction mechanism and identify the components at different temperatures from 1000 K to 5000 K. The obtained results revealed that the reactions and breaking of the lignin model started at 2000 K. At the primary stage of the reaction at 2000 K the β-O-4 bond tends to break into several compounds, forming mainly guaiacol and 1,3-benzodioxole. In particular, 1,3-benzodioxole undergoes dissociation and forms cyclopentene-based ketones. Afterward, dealkylation reaction occurred through hydroxyl radicals of water to form methanol, formaldehyde and methane. Above 2500 K, H2, CO and CO2 are predominantly formed in which water molecules contributed hydrogen and oxygen for their formation. Understanding the detailed reactive mechanism of lignin's gasification is important for efficient energy conversion of biomass. [ABSTRACT FROM AUTHOR]

Arctic driftwood has reached the coast of Iceland for centuries. This material was used by the inhabitants of the island as a building material for houses, boats, churches and pasture fences. Nowadays, the driftwood is used in the furniture industry, for the finishing of internal and external walls of buildings and also by artists. The properties of driftwood differ to that of original resource due the long-term effects of exposure to Arctic Sea water and ice. This process can be considered as a natural modification, even if its effect on various wood properties and the potential use of driftwood are not yet fully understand. This research is focused on the comparison of cutting forces measured for Siberian larch (Larix sibirica L.) from Siberia provenance and driftwood found on the coast of Iceland. The cutting forces were determined directly from the cutting power signal that was recorded during the frame sawing process. A new procedure for compensation of the late/early wood ratio variation within annual rings is proposed to homogenize mechanical properties of wood. It allows a direct comparison of machinability for both types of larch wood investigated (driftwood and natural). Noticeable differences of normalized cutting force values were noticed for both wood types, which were statistically significant for two set values of feed per tooth. These results provide a new understanding of the effect of the drifting process in the Arctic Sea (natural modification) on mechanical and physical properties of wood. Such a natural modification may influence transformation processes of driftwood as well as performance of the coating systems applied on its surface. [ABSTRACT FROM AUTHOR]

Advanced imaging techniques can noninvasively characterise, monitor, and evaluate how conservation treatments affect cultural heritage objects. In this specific field, hyperspectral imaging allows nondestructive characterisation of materials by identifying and characterising colouring agents, binders, and protective coatings as components of an object's original construction or later historic additions. Furthermore, hyperspectral imaging can be used to monitor deterioration or changes caused by environmental conditions. This paper examines the potential of hyperspectral imaging (HSI) for the evaluation of heritage objects. Four cameras operating in different spectral ranges were used to nondestructively scan a beehive panel painting that originated from the Slovene Ethnographic Museum collection. The specific objective of this research was to identify pigments and binders present in the samples and to spatially map the presence of these across the surface of the art piece. Merging the results with databases created in parallel using other reference methods allows for the identification of materials originally used by the artist on the panel. Later interventions to the original paintings can also be traced as part of past conservation campaigns. [ABSTRACT FROM AUTHOR]

The function of altering weathering factors and degradation mechanisms are essential for understanding the weathering process of materials. The goal of this work was to develop a method for the acceleration of natural weathering and to investigate the molecular, microstructure and macrostructure degradation of wood caused by the process. Tests were performed in the whole month of July, which, according to previous research, is considered as the most severe for weathering of wood micro-sections. Sample appearance was evaluated by colour measurement. Scanning electron microscopy was used for evaluation of the structural integrity and changes in the microstructure of wood morphological components. Changes on the molecular level were assessed by means of FT-IR spectroscopy. Observation of the effects of weathering allowed a better understanding of the degradation process. Typical structural damage, such as cracks on bordered pits and cross-field pits, and, as a consequence, their erosion, revealed the sequence of the degradation process. It was confirmed that earlywood was more susceptible to damage than latewood. Even if the weathering test was conducted for a relatively short time (28 days) the ultra-thin wood samples changed noticeably. The progress of alteration was similar as usually noticed for wood surfaces, but occurred at shorter exposure times. The estimated acceleration factor was ×3, compare to the natural weathering kinetics of wood. The research methodology presented can be used for the determination of the weather dose-response models essential to estimate the future service life performance of timber elements. [ABSTRACT FROM AUTHOR]

The modern wood converting processes consists of several stages and material drying belongs to the most influencing future performances of products. The procedure of drying wood is usually realized between subsequent sawing operations, affecting significantly cutting conditions and general properties of material. An alternative methodology for determination of mechanical properties (fracture toughness and shear yield stress) based on cutting process analysis is presented here. Two wood species (pine and beech) representing soft and hard woods were investigated with respect to four diverse drying methods used in industry. Fracture toughness and shear yield stress were determined directly from the cutting power signal that was recorded while frame sawing. An original procedure for compensation of the wood density variation is proposed to generalize mechanical properties of wood and allow direct comparison between species and drying methods. Noticeable differences of fracture toughness and shear yield stress values were found among all drying techniques and for both species, but only for beech wood the differences were statistically significant. These observations provide a new highlight on the understanding of the effect of thermo-hydro modification of wood on mechanical performance of structures. It can be also highly useful to optimize woodworking machines by properly adjusting cutting power requirements. [ABSTRACT FROM AUTHOR]

The goal of this work was to develop Fourier-transform-near-infrared-spectroscopy-based methodology for monitoring kinetics and estimating the biodegradation rate of coniferous pulp paper. Two experiments with paper-degrading fungi were tested: one with Chaetomium globosum alone and the other with a mixture of Aspergillus niger , Trichoderma viride , and Penicillium funiculosum . Paper sheets made of fibers with the addition of 0, 2, 3, or 5% of cationic starch and resinous adhesive were used as test samples. In order to quantify the resistance of the paper to biodegradation, tests of breaking length and evaluation of the degree of fungal infestation were performed during infestation. It was found that addition of cationic starch and resin adhesives improved mechanical properties of paper; however, it also increased susceptibility to fungal colonization. Degradation of paper colonized by C. globosum was more advanced and exhibited more rapid kinetics. Spectral analysis revealed that spectra were most varying in bands 4283, 4400, 4742, and 4808 cm −1 , which correspond to –CH, and –OH functional groups of cellulose and hemicelluloses. Differences in spectra were in good agreement with the reference methods; therefore this technique has potential for monitoring the paper biodegradation process and predicting changes in the paper's mechanical properties. [ABSTRACT FROM AUTHOR]

Refining of industrial lignin to produce homogeneous fractions is essential for high-value applications. However, the understanding of key interactions between a variety of solvents with lignin polymer is still uncertain. In this work, single-step fractionation of industrial hardwood kraft lignin (HKL) using organic solvents of different polarities – ethanol, acetone, diethyl ether and hexane – was investigated by combining an experimental and theoretical approach. Experimental results revealed that higher polarity solvents (ethanol and acetone) exhibited higher solubility yield compared to moderate and low polarity solvents. The chemical differences between lignin fractions were proven by pyrolysis gas chromatography mass spectrometry and near infrared spectroscopy. Density functional theory (DFT) results indicated that ethanol presented higher interaction energy followed by acetone, diethyl ether and hexane, which was consistent with experimental findings. Hydrogen bond and non-covalent interaction results from DFT demonstrated that the predominant interaction was found for high polarity of ethanol over other solvents and γ-OH in the lignin model is the key site. Unlabelled Image • Single-step fractionation was carried out for hardwood kraft lignin using 4 solvents. • Higher polarity solvents exhibited higher solubility yield. • Fractionation with diethyl ether leaded to homogeneous low molecular weight fraction. • Quantum chemical calculations showed that ethanol exhibited higher interaction energy. • γ-OH in the lignin model is the key site for strong hydrogen bonding. [ABSTRACT FROM AUTHOR]