Search

In this paper an efficient procedure for obtaining a cohesive law for Mode I timber fracture (crack opening), based on the Double Cantilever Beam (DCB) tests is given. DCB tests were performed on ten European spruce specimens in order to determine the energy release rate vs crack length (R curves). Two crucial parameters - crack length during the experiment and the crack tip opening displacement were obtained using 2D Digital Image Correlation (DIC) technique. In order to determine accurate fracture resistance (R curve), procedure which includes calculating cumulative released energy was employed. The cohesive law for Mode I fracture of wood was obtained by differentiation of the strain energy release rate as a function of the crack tip opening displacement. This cohesive law is further implemented in the successful numerical modelling of failure modes in large-scale end-notched glulam beams which were experimentally tested in four-point bending configuration.

Bioadhesives derived from biomass are steadily gaining spotlight as substitutes for formaldehyde-based resins in the adhesive industry. However, there is a need to develop novel water-resistant bioadhesives with high adhesive and cohesive strengths because the currently available biomaterial-based adhesives have low mechanical strength. In this study, a complex coacervate was prepared easily by mixing silk fibroin and tannic acid to produce a bioadhesive with high adhesive and cohesive strengths as well as water resistance. The silk fibroin-tannic acid coacervate adhered well to various substrates, and its adhesive strength according to the type of substrate and water contact angle were evaluated comparatively. In particular, the adhesive strength of this adhesive on a wood substrate was systematically analyzed by varying different experimental parameters (relative humidity, surface roughness of the substrate, water stability, and pH). This cost-effective coacervate is applicable as an eco-friendly wood adhesive.

Polymer shape-memory aerogels (PSMAs) are prospects in various fields of application ranging from aerospace to biomedicine, as advanced thermal insulators, actuators, or sensors. However, the fabrication of PSMAs with good mechanical performance is challenging and is currently dominated by fossil-based polymers. In this work, strong, shape-memory bio-aerogels with high specific surface areas (up to 220 m2/g) and low radial thermal conductivity (0.042 W/mK) were prepared through a one-step treatment of native wood using an ionic liquid mixture of [MTBD]+[MMP]−/DMSO. The aerogel showed similar chemical composition similar to native wood. Nanoscale spatial rearrangement of wood biopolymers in the cell wall and lumen was achieved, resulting in flexible hydrogels, offering design freedom for subsequent aerogels with intricate geometries. Shape-memory function under stimuli of water was reported. The chemical composition and distribution, morphology, and mechanical performance of the aerogel were carefully studied using confocal Raman spectroscopy, AFM, SAXS/WAXS, NMR, digital image correlation, etc. With its simplicity, sustainability, and the broad range of applicability, the methodology developed for nanoscale reassembly of wood is an advancement for the design of biobased shape-memory aerogels.

Anaerobic digestion of organic waste results in production of biogas and a nutrient-rich digestate that has an established use as fertilizer in plant production. This study evaluated use of anaerobic digestate based on a high concentration of organic household waste as a fertilizer in sawdust-based production of oyster mushrooms (Pleurotus ostreatus). Inclusion of 0.5 L of anaerobic digestate (AD) per kg sawdust gave similar productivity in terms of biological efficiency (79.5 +/- 5.4 %), and protein concentration (24.7 +/- 2.4 % of dry weight (dw)) as standard mushroom substrate (78.1 +/- 5.3 %, and 21.9 +/- 3.0 % of dw, respectively). However, mushroom growth was impaired at the highest concentration of anaerobic digestate tested, 1 L digestate per kg dw sawdust. Comparison of the AD-fertilized substrate with a mushroom substrate with standard components (sawdust, wheat bran, calcium sulfate) and with similar C/N-ratio revealed some differences in elemental composition of the fruiting bodies, with an major increase in sodium concentration for the AD-fertilized substrate compared with the standard substrate (413.3 +/- 28.9 and 226.7 +/- 30.6 mg kg(-1) dw, respectively). This difference can be explained by high sodium concentration in the anaerobic digestate, most likely due to inclusion of food scraps from households and restaurants in the biodigester feedstock. Screening of both substrates for a total of 133 micro -pollutants revealed that total sum of micropollutants was significantly higher in the AD-fertilized substrate (258 +/- 12 ng/g dw substrate) than in the standard substrate (191 +/- 35 ng/g dw substrate). Nitrogen losses during preparation of the AD-fertilized substrate were negligible.

Wood burning contributes to indoor and ambient particulate matter (PM) pollution and has been associated with increased morbidity and mortality. Here, we present an integrated methodology that allows to generate, sample, and characterize wood smoke derived from different moisture contents and representative combustion conditions using pine wood as a model. Flaming, smoldering, and incomplete combustion were assessed for low-moisture pine, whereas both low-moisture pine and high-moisture pine were investigated under flaming conditions. Real-time monitoring of carbon monoxide, volatile organic compounds, and aerosol number concentration/size in wood smoke was performed. The PM was size-fractionated, sampled, and characterized for elemental/organic carbon, organic functional groups, and inorganic elements. Bioactivity of PM was assessed by measuring the sterile alpha motif (SAM) pointed domain containing ETS (E-twenty-six) transcription factor (SPDEF) gene promoter activity in human embryonic kidney 293 (HEK-293T) cells, a biomarker for mucin gene expression. Findings showed that moisture content and combustion condition significantly affected the organic and inorganic elemental composition of PM

Pojavom građevinarstva kao djelatnosti, ljudi počinju koristiti prirodne materijale poput kamena, drva, bambusa, opeke i slame za izgradnju svojih utočišta. Ovi materijali su prirodni, održivi i ne izazivaju štetne posljedice na okoliš. Međutim,dolaskom industrijske ere i povećanom potražnjom za građevinskim proizvodima, započela je masovna proizvodnja industrijskih materijala kako bi se ubrzala i optimizirala gradnja. Kao posljedica toga, građevinska industrija postala je jedan od najvećih zagađivača na svijetu. Cilj ovog rada je prikazati tradicionalne materijale i analizirati prednosti i nedostatke njihove upotrebe u građevinskoj industriji. Nadalje, u ovom radu istražuju se suvremene primjene tradicionalnih ekoloških materijala u arhitekturi, čime se pokazuje kako se suvremena arhitektura uspješno može kombinirati s tradicionalnim materijalima., Ever since construction began as an activity, people have turned to natural materials such as stone, wood, bamboo, brick, and straw to build their shelters. These materials are natural, sustainable, and do not cause harmful effects on the environment. However, with the onset of the industrial era and the increased demand for construction products, mass production of industrial materials began to accelerate and optimize construction. As a result, the construction industry has become one of the world's largest polluters. The aim of this paper is present traditional materials and to analyze the advantages and disadvantages of their use in construction industry. Furthermore, this paper explores contemporary use of traditional ecological materials in architecture, which shows how contemporary architecture can be successfully combined with traditional materials.

European oak logs (Quercus robur, Quercus petraea) from the 15th auction of valuable logs in Slovenj Gradec in 2021 were included in the study. Of the 1,318 auctioned logs, 78 were randomly selected and visually graded into quality classes (A, B, C) according to the National Grading Rules (2017). In parallel, we analysed the wood growth dendrochronologically and the acoustic properties of the logs using the longitudinal vibration resonance method. The logs with the best quality had a larger diameter and, on average, wider annual rings. We confirmed the correlation between the visually determined quality and the obtained price of the logs. Longitudinal vibration velocity (v) and relative acoustic conversion efficiency (RACE) were positively correlated with log quality and price. The frequency spectra of the low-quality logs differed from the theoretical spectra. This study confirms the feasibility of non-destructive acoustic methods for evaluating oak log quality. V raziskavo smo vključili hrastovo hlodovino (Quercus robur, Quercus petraea) s 15. dražbe vrednejših sortimentov okroglega lesa v Slovenj Gradcu v letu 2021. Naključno smo izbrali 78 od 1318 licitiranih hlodov in jih skladno z veljavnim Pravilnikom o merjenju (2017) vizualno razvrstili po kakovosti (A, B, C). Vzporedno smo dendrokronološko analizirali priraščanje lesa ter z metodo frekvenčnega odziva pri vzdolžnem vzbujanju še akustične lastnosti hlodovine. Najkvalitetnejša hlodovina je bila večjih premerov, z več in povprečno širšimi branikami. Potrdili smo povezavo med vizualno določeno kakovostjo in doseženo ceno hlodovine. Hitrost vzdolžnega nihanja (v) in relativna učinkovitost akustične pretvorbe (RACE) sta bili s kakovostjo in ceno hlodovine pozitivno povezani. Frekvenčni spektri pri hlodovini nižje kakovosti odstopajo od teoretičnih. Raziskava je potrdila možnost uporabe nedestruktivnih akustičnih metod za oceno kakovosti hrastove hlodovine.

The work is part of the R&D&I Project PID2020-112954RA-I00 funded by MCIN/AEI/10.13039/501100011033. Publisher Copyright: © 2023 The Authors Fracture characterisation under mode I loading of Eucalyptus globulus Labill. bonded joints with one-component polyurethane adhesive (1C-PUR) is addressed in this work. The objective is to estimate the cohesive law representative of the fracture behaviour of these joints. A direct and two inverse procedures were employed to determine the softening laws. The direct method is based on local measurement of crack tip displacements using digital image correlation in the course of Double Cantilever Beam (DCB) tests, while the inverse methods rely on load–displacement data and on load-crack tip opening displacement relations by finite element modelling. It was verified that consistent results can be obtained from the three methodologies leading to the conclusion that the classical inverse procedure is the most appealing one owing to its simplicity. publishersversion published

Se realizo el estudio patológico con propósito educativo de una vivienda ubicada en la ciudad de Pasto, departamento de Nariño. El objetivo principal es desarrollar un documento técnico donde se recopilo los conocimientos adquiridos en la clase de historia clínica y diagnóstico, en donde se realizó el diagnóstico y presentación de las patologías que el proyecto contiene en su estructura. A lo largo de este informe vamos a enumerar y explicar las lesiones que se pueden producir en la vivienda, es importante saber identificar estas lesiones lo antes posible y ser capaces de determinar el alcance del daño. Esto nos ayudará a establecer un diagnóstico lo más acertado posible de sus causas y proyectar la intervención más adecuada. In situ se realizó una inspección visual de la estructura para identificar los elementos principales y secundarios, así como las dimensiones reales y las piezas correspondientes a estudiar. Con esta inspección visual se busca detectar diversas patologías, las cuales van a hacer recopiladas en fichas técnicas y planos. A pathological study was carried out for educational purposes in a house located in the city of Pasto, department of Nariño. The main objective is to develop a technical document where the knowledge acquired in the clinical history and diagnosis class was compiled, where the diagnosis and presentation of the pathologies that the project contains in its structure was made. Throughout this report we are going to list and explain the injuries that can occur in the home, it is important to know how to identify these injuries as soon as possible and be able to determine the extent of the damage. This will help us establish the most accurate diagnosis possible of its causes and project the most appropriate intervention. In situ, a visual inspection of the structure was carried out to identify the main and secondary elements, as well as the real dimensions and the corresponding pieces to be studied. With this visual inspection, the aim is to detect various pathologies, which will be compiled in technical sheets and plans. Especialista en Patología de la construccion Especialización

This research deals with the processing of wood using a circular saw, which is associated with several risks and factors that affect the wood-splitting process. One of them is the wear of the teeth of the saw blade that change the magnitude of the cutting forces. The aim of this study is to compare real measured values and theoretical values when processing Norway spruce wood using two types of saw blades, i.e., sintered carbide (SC) and high-speed steel (HSS), with a diameter of 600 mm and 54 and 56 teeth, respectively. Experimental measurements were carried out on a special test device with the possibility of moving the tested wood into the cutting devices and a simple saw blade replacement system. The results of the contributions show significant differences, based on defined factors which represent the cutting and feed speed, which are supported by FEM analysis of cutting forces in the process of cutting wood—when changing the design of the saw blade. The results of the experiment show that the cutting conditions (cutting speed and feed speed) do not have a significant effect on the size of the cutting forces. The theoretical and real stress values for HSS discs ranged from 14 to 22 MPa. Significantly larger differences were recorded for discs with SC, where the real values of the maximum stresses were around 14 MPa and the theoretical ones around 25 MPa. When cutting spruce with a disc with SC slices, the maximum values of the theoretical cutting forces were in the range of 76 to 94 N and the maximum values of the measured cutting forces were in the range of 40 to 44 N.

The demand for construction timber is continuously increasing, due to its favourable characteristics. However, the adequate protection of wood is key to its successful use, as it is flammable and susceptible to biodegradation. Given that thermal modification enhances the durability of wood, and mineralisation with CaCO3 considerably improves its fire properties, it is worth considering the combined effects of the two methods. European beech (Fagus sylvatica) was selected to determine the effects of a) thermal modification, b) mineralisation through the in-situ formation of CaCO3, and c) a combination of the two procedures, on resistance to decay fungi, reaction to fire and the mechanical properties of the wood. Microscopic analysis and comparisons of the samples before and after exposure to fungi were also conducted. Mineralised wood generally had a slightly alkaline pH value and higher equilibrium moisture content, while thermal modification lowered the equilibrium moisture content. The present study demonstrated the combined effect of thermal modification and mineralisation: the best response to fire as well as resistance to fungi was achieved when the two treatments were combined. Results from the Brinell hardness and three-point bending tests indicate that both modification procedures can slightly impair the mechanical properties of the wood. Nasl. z nasl. zaslona. Opis vira z dne 6. 7. 2023. Bibliografija.

The importance of renewable and environmentally acceptable materials in the construction industry is increasing. Wood is one of the most important construction materials and its use in building applications has further expanded in recent decades, mainly due to the development of modern composites, firstly glue lam, OSB (Oriented Strand Board), LVL (Laminated Veneer Lumber) and a considerable breakthrough was later achieved with the development of cross-laminated timber. In order to enable even more extensive and reliable use of wood in outdoor applications, factors affecting a wood’s service life need to be understood. It is well known that fungal degradation of wood is predominantly affected by temperature and wood moisture content. In order to elucidate the influence of these two factors, long-term monitoring of temperature, relative humidity and moisture content at the newly-built Annex of the Department of Wood Science and Technology was carried out. The Annex is designed from CLT composites and glue-lam beams and was finished in December 2015. The results clearly show that microclimatic conditions in the monitored building in the first years of use are far below the limit required for fungal decay or mould growth.

To use wood as a structural element in vehicles, it is necessary to measure its physical properties locally in order to deduce its mechanical behaviour. Density is one of the characteristics that influences the most the mechanical properties, and it is on its measurement that this study will focus, using a technology that is still little studied for this application: terahertz radiation. Measurements using a Terahertz radar on samples will allow to obtain maps of the optical index and absorption coefficient, these values being linked to the density of the samples. The present study will consider wood species with various global densities and exhibiting local density pattern (growth rings) to assess the prediction of the density.

At present, the popularity of timber as a structural material is booming. However, the current knowledge on disproportionate collapse prevention and extreme loading of timber buildings is scarce. To prevent disproportionate and progressive collapse, catenary action is an important mechanism, where the axial capacity of bending members is activated. Because of the brittle behavior of timber in the relevant failure modes, it can only achieve catenary action via strengthening. In this paper, analytical expressions are derived for the elastic, plastic, and catenary capacity of laterally loaded wood and timber beams with a tension-side strip reinforcement. A load-path dependent M-N interaction diagram with damage accumulation explains the ultimate catenary capacity and the transition between the bending- and catenary-dominated load-carrying mode. The analytical expressions are validated and discussed based on tests on beech clearwood specimens reinforced with carbon fibers in a polyurethane matrix. Furthermore, a case study on glued laminated timber beams is presented to demonstrate the potential of reinforcing timber beams subjected to extreme loading., Construction and Building Materials, 385, ISSN:0950-0618

The fire reaction of various types of flammable lightweight materials is investigated using a cone calorimeter. The influences of parameters such as sample density, sample mass, effective heat of combustion and heat flux on the mass loss after exposition are discussed. Interpretations of the hemp fibers’ tests results lead us to propose a phenomenological model able to calculate the peak of heat release rate (pHRR) of such thermally thin materials, with or without flame retardant. A database gathering the whole results of tests performed on a large set of materials including fibers, bio-resources panels, bio-based concretes and fabrics is used to validate the proposed model. Interestingly, the model is found to be relevant also for denser wood specimens. The model is based on the distinction of the contributions of the exposed top layer and the deeper layer to the combustion. Indeed, in such materials, the heat conduction is limited (either by the intrinsic properties of the material or by the formation of an insulating char) and therefore the pHRR only depends on a limited volume of materials directly absorbing the heat flux from the radiant cone. Accuracy and limitations of the model are discussed.

Timber, as a building material, is subject to structural changes in the used interior, which result from the influence of various local environmental conditions and their changes during the service life. Samples of naturally aged historic silver fir (Abies alba Mill.) wood were taken from the roof of St. Barbara Church (Ravnik above Hotedršica, Slovenia). The slices of historic wood were dendrochronologically dated and analyzed by CIELab color determination, light microscopic analysis and IR spectroscopy. Our results showed that the interior of the 18th-century fir structural timber had lower color lightness (L*) and intensity (b*), particularly in the latewood. The partial increase in lignin and decrease in hemicelluloses relative to cellulose content, associated with an increased degree of crystallinity of cellulose, was confirmed by epifluorescence and polarized light microscopy combined with FTIR spectroscopy.

Timber, as a building material, is subject to structural changes in the used interior, which result from the influence of various local environmental conditions and their changes during the service life. Samples of naturally aged historic silver fir (Abies alba Mill.) wood were taken from the roof of St. Barbara Church (Ravnik above Hotedršica, Slovenia). The slices of historic wood were dendrochronologically dated and analyzed by CIELab color determination, light microscopic analysis and IR spectroscopy. Our results showed that the interior of the 18th-century fir structural timber had lower color lightness (L*) and intensity (b*), particularly in the latewood. The partial increase in lignin and decrease in hemicelluloses relative to cellulose content, associated with an increased degree of crystallinity of cellulose, was confirmed by epifluorescence and polarized light microscopy combined with FTIR spectroscopy.

Lignocellulosic materials in an alkaline cement environment can be subjected to degradation that always starts from the surface. Atomic force microscopy has been used to establish the changes of surface properties of wood-cell walls. We measured the topographies and adhesion force curves of wood-cell wall surfaces before and after treatments in cement alkaline solutions ranging from 0.5 to 1,104 h at 20°C and 50°C and compared them with untreated controls. We studied the degradation of the cell wall surfaces chemically (dissolution of extractives and degradation of the hemicelluloses-lignin matrix), structurally (changes in surface modulus and deformation), and topographically (looking at the change in cell wall surface). The adhesion forces and jump-off force ratios shifted along two sigmoidal curves and showed a transition phase based on the treatment times. In this article, we analyzed and explained how the cutting and surface heterogeneity affects the atomic force microscopy measurements, and how the temperature rise due to the cement hydration heat could accelerate the surface degradation.

International audience; The fire reaction of various types of flammable lightweight materials is investigated using a cone calorimeter. The influences of parameters such as sample density, sample mass, effective heat of combustion and heat flux on the mass loss after exposition are discussed. Interpretations of the hemp fibers’ tests results lead us to propose a phenomenological model able to calculate the peak of heat release rate (pHRR) of such thermally thin materials, with or without flame retardant. A database gathering the whole results of tests performed on a large set of materials including fibers, bio-resources panels, bio-based concretes and fabrics is used to validate the proposed model. Interestingly, the model is found to be relevant also for denser wood specimens. The model is based on the distinction of the contributions of the exposed top layer and the deeper layer to the combustion. Indeed, in such materials, the heat conduction is limited (either by the intrinsic properties of the material or by the formation of an insulating char) and therefore the pHRR only depends on a limited volume of materials directly absorbing the heat flux from the radiant cone. Accuracy and limitations of the model are discussed.

Kiparica je 1954. posjetila Dalmatinsku zagoru, zavičaj svojeg supruga slikara Frane Šimunovića i potvrđuje se kao lucidan promatrač zbilje, sposobna na jedinstven, uvjerljiv i sugestivan način motritelju prenijeti autentičnu i realističnu sliku toga jedinstvenog podneblja. Opisivala je „vlašku” svakodnevicu i njihove „koncentrirane muke”, nakon čega smo postali svjesni sublimacije tog kraja, njegove egzotike, civilizacije i kulture. Počinje proces sve dubljeg slijeganja i identifikacije njezina kiparskog i ljudskog morala, stvaralačkog kapaciteta s tvrdoćom, oskudnošću i imanentnom, monumentalnom arhaičnošću „vlaškog” podneblja. Taj prvi posjet bio je prijelomni trenutak koji će odrediti smjer širenja i produbljivanja autoričina kiparskog izričaja. Ona interpretira taj svijet iskreno, intuitivno i slobodno, istodobno mijenjajući svoj izraz., In 1954, Ksenija Kantoci visited Dalmatinska Zagora, the homeland of her husband, painter Frano Šimunović, and showed herself as a lucid observer of reality, capable of conveying an authentic and realistic image of that unique region in a unique, convincing, and suggestive way. She described the everyday life of the “Vlachs” and their “concentrated suffering,” making us aware of the sublime character of that region, its exoticism, civilization, and culture. This initiated the process of profound subsidence and identification of her sculptural and human morality, her creative capacity with the hardness, scarcity, and immanent, monumental archaism of the “Vlach” area. That first visit was a turning point that determined the direction in which the artist’s sculptural expression expanded and deepened. She interpreted that world honestly, intuitively and freely, simultaneously changing her expression.

The reasons behind the occurrence of a second/end peak heat release rate (PHRR) during wood combustion under radiative heating were determined. Effects of the type of rear material, wood thickness, char progression, and its microstructure, as well as moisture content/transport in spruce wood, were studied. Rear materials used were insulating Kaowool, conducting steel, and the same wood but physically separated from test specimen by aluminium foil. The intensity of the second/end PHRR with Kaowool was almost 50% more than that of the sample with steel. Thus, the second/end peak is governed by the boundary condition defined by the rear material, which determines the heat losses at the rear side of the specimen and consequently the temperature of the specimen. Higher specimen temperature enhances the pyrolysis rate, thereby causing the second/end PHRR. The appearance times and values of the second/end PHRR for 30, 20, and 10 mm wood were 1740 s/78 kWm−2, 685 s/134 kWm−2, and 450 s/160 kWm−2, respectively. Char progressed to the rear of the samples even with a thin (8 mm) conductive steel substrate. Cracks in char grew almost three times wider during the second/end PHRR compared to the sample with no second/end peak. Char cracking had no significance on the time of occurrence of the second/end PHRR but affected the overall heat release. High moisture content reduced the charring rate and delayed the time of occurrence of the second/end PHRR as more water was needed to undergo a phase change, requiring a higher amount of energy. Validerad;2023;Nivå 2;2023-06-29 (sofila)

As a renewable biological macromolecule with aromatic structure, lignin can serve as matrix substance to maintain cell wall integrity and is regarded as the natural biomass recalcitrance. Substantial differences in the cell wall lignin topochemistry between opposite (Ow) and compression wood (Cw) trachieds in Pinus bungeana Zucc. were visualized during [Emim][OAc] pretreatment at room temperature. The ionic liqiuds treatment induced a more obvious wall swelling for highly lignified Cw tracheids than that of Ow, while dynamic Raman spectra analysis indicated the higher lignin and carbohydrates removal for Ow tracheids. Raman imaging further revealed that both lignin and carbohydrates were dissolved simultaneously within the middle lamella and secondary wall of Ow and pretreatment has little effects on Cw tracheids wall. Moreover, it was demonstrated that lignin composition was the key factor to affect the composition dissolution. In particular, lignin G-units were selectively removed from cell corner middle lamella (52.3 %) and secondary wall (62.0 %) of Ow tracheids. When cotton fiber, as a reference was treated under the same conditions, lattice conversion moving from cellulose I to II occurred. The findings confirmed the important role of lignin compostion in the dissolution behavior of carbohydrate dominant tracheids wall.

Sustainable biomass resources are favored by researchers on account of their biodegradability and biocompatibility, which is a replacement for non-renewable fossil fuels. The development of low-carbon, green, and high-value bio-based adhesives are the inevitable trend of the industry development. However, the main factors limiting their application are poor water resistance and low bonding performance. Herein, the crosslinking network was constructed based on the reaction between the epoxy groups of trimethylolpropane glycidyl ether (TMPEG) and the amino groups of the synthesized aminated cellulose (AC) to form an interlocking bond. Through the synergy of covalent bond, electrostatic interaction, and hydrogen bond, the bonding strength and water resistance of the proposed adhesive can be effectively improved. Fourier transform infrared spectroscopy (FT-IR), X-ray photoelectron spectroscopy (XPS), and solid-state nuclear magnetic resonance spectroscopy (

Major source of carbon-containing air born particular matter that significantly pollutes environment and provokes development of neuropathology is forest fires and wood combustion. Here, water-suspended smoke particulate matter preparations (SPs) were synthesized from birch, pine, poplar wood, and also birch bark and pine needles. Taking into account importance of the gut-brain communication system, SP properties were compared regarding their capability to modulate functioning of nerve terminals and gut cells/preparations. In cortex nerve terminals, poplar wood SP was more effective in decreasing uptake and increasing the extracellular levels of excitatory and inhibitory neurotransmitters L-[

Biomass-based adhesives are considered to be the preferred alternative to formaldehyde-type wood adhesives due to their wide range of sources, low cost, and sustainability. Herein, an environmentally friendly Schiff base cross-linked compact three-dimensional network structure bio-adhesive (DAC-PEI-U) derived from polyethyleneimine (PEI), urea, and cellulose was successfully prepared, verifying by detailed FTIR, NMR, and XPS analysis. Schiff base bridging between aldehyde groups in dialdehyde cellulose (DAC) and amino groups in polyurea (PEIU) not only constructed crosslinking networks but also endowed adhesives with good adhesion property. The dry bond strength of DAC-PEI-U adhesive reached 2.71 MPa, and the wet shear strength was 1.51 MPa (hot water) and 1.34 MPa (boiling water), respectively. It not only improves the water resistance and bonding process, but also displays simple synthesis and low cost. The improved performance of DAC-PEI-U adhesive is attributed to the generation of hyperbranched cross-linking structure in the adhesive system, which results in increased cross-linking density and promotes the formation of dense cross-sections in the curing adhesive. This work paves a solid way for developing cellulose-based wood adhesives with wet bonding properties, thus holding great potential as an alternative to formaldehyde-type adhesives in wood-based panel and indoor panel bonding industries.

Resumo Pela complexidade anatômica e variabilidade intrínseca das propriedades encontradas dentro de uma mesma espécie, a madeira tem sido tratada, pelos diversos documentos normativos, como material isotrópico, com valores de resistência e de rigidez determinados por meio de formulações advindas da resistência dos materiais. A falta de informações experimentais, aliada ao desconhecimento da utilização de critérios de resistência para materiais anisotrópicos, aumenta as incertezas na análise de falha das estruturas quanto às estimativas das propriedades de resistência e rigidez em função da orientação das fibras. Com o objetivo de solucionar este problema, modelos empíricos têm sido desenvolvidos e incorporados em diversos documentos normativos nacionais e internacionais. Tais modelos são ajustados em função de um expoente (n) que fornece o melhor ajuste, entretanto, mesmo em se tratando do mesmo modelo, ainda há divergências com relação ao uso desse expoente. Nesse contexto, esta pesquisa objetivou propor um modelo para a estimativa do valor característico de resistência à tração inclinada (ftθ,k) e compará-lo com modelos empíricos provenientes da literatura correlata (com os ajustes ótimos do expoente n), para evidenciar o melhor ajuste. Os resultados obtidos revelaram que o modelo desenvolvido na pesquisa foi o mais preciso. Abstract Due to the anatomical complexity and intrinsic variability of properties found in the same species, wood is treated as an isotropic material by various normative codes, where the strength and stiffness values are determined by the strength of materials. The lack of experimental information combined with the lack of knowledge on using strength criteria for anisotropic materials increases the uncertainties in the analysis of structures failures with regards to estimating strength and stiffness properties depending on fiber orientation. To address this issue, empirical models have been developed and incorporated in several Brazilian and international normative documents. Those models are adjusted according to an exponent (n) that provides the best fit, however, even in the case of the same model, there are still differences regarding the use of this exponent. Hence, the aim of this study is to propose a model to estimate the characteristic off-axis tensile strength value (f tθ,k ), as well as to compare it with empirical models from the literature (with the optimal adjustments of exponent n), making it possible to highlight the best fit. The results showed that the model developed in the research study was the most accurate.

The current study investigates for the first time the physico-chemical performances of lignins from cactus waste seeds (CWS) and spent coffee (SC) in comparison to previously isolated lignins from sugar byproducts (bagasse (SCB) and beet pulp (SBP)). In this work, lignin-phenol formaldehyde (LPF) resins were formulated using various lignin loadings (5-30 wt%), characterized and applied in the manufacturing of plywood panels. Several characterization techniques were applied to identify the chemical and morphological properties, thermal stability, and phenolic content of the extracted lignins, as well as the bonding strength and wood failure of the formulated resins. Results showed that the CWS and SC could be considered as an important source for lignin recovery with a considerable yield of 15.46 % and 27.08 % and an important hydroxyl phenolic content of 1.26 mmol/g and 1.36 mmol/g for CWS and SC, respectively. Interestingly, 20 wt% of extracted lignins in PF adhesives were the optimal formulation showing an improved modulus of elasticity (MOE) of about 3505, 3536 and 3515 N/mm

The apportionment of the contribution of wood smoke emitted particles to the total concentration of particulate matter in a region has been greatly aided by the development of new analytical methods. These analytical methods quantitatively determine organic marker compounds unique to wood combustion such as levoglucosan and dehydroabietic acid. These markers have generally been determined in 24-hour averaged samples. We have developed an instrument based on the collection of particles on an inert filter, desorption of the organic material in an inert atmosphere with subsequent GC separation and MS detection of the desorbed compounds. The GC-MS Organic Aerosol Monitor (OAM) instrument has been used in three field studies. An unexpected finding from these studies was the quantification of the contribution of secondary organic aerosols from gases present in wood smoke in addition to primary wood smoke emitted particles. The identification of this secondary material was made possible by the collection of hourly averaged data that allowed for the time patterns of black carbon, organic material, and wood smoke marker compounds to be included and compared in a Positive Matrix Factorization (PMF) analysis. Most of the organic markers associated with wood smoke (levoglucosan, stearic acid and dehydroabietic acid) are associated with primary wood smoke emissions, but a fraction of the levoglucosan and stearic acid are also associated with secondary organic material formed from gaseous precursors in wood smoke. Additionally, this secondary material was shown to be present in each in of the three urban area where wood smoke burning occurs. There is a need for additional studies to better understand the contribution of secondary particulate formation from both urban and wildfires.iImplications/i: This paper presents results from three field studies which show that in addition to the formation of primary particulate matter from the combustion of wood smoke and secondary particulate matter is also formed from the gaseous compounds emitted with the wood smoke. This material is identified in the studies of wood combustion reported here by the identification and quantification of specific organic marker compounds related to wood combustion and is shown to and represents a contributor nearly as large as the primary emitted material and better quantifying the impact of wood combustion on airborne fine particulate matter.

The cellulose nanocrystals (CNCs) were produced from spruce wood using less hazardous and toxic reagents with understanding of influence of process parameters on CNCs properties. This study employed acetosolv pulping followed by alkaline-peroxide bleaching, eliminating highly reactive chemicals such as Na-chlorites and Na-sulfite for cellulose pulp extraction from spruce wood. Cellulose pulp yield of 41.5 ± 0.7 wt% of dry wood was obtained from pulping followed by bleaching treatment. Cellulose pulp was hydrolyzed with 59.0-65.0 wt% sulfuric acid followed by ultrasonic treatment to produce CNCs. CNCs yield of 8.0 ± 3.2 wt% of dry wood was obtained at 65 wt% acid concentration and yield of 25.1 ± 0.7 wt% at 62 wt% acid concentration. The optimization of acid hydrolysis and ultrasonic treatment resulted in CNCs with high aspect ratios (length/width) up to 48.1. It was demonstrated that higher acid concentration requires lower intensity of ultrasonic treatment for CNCs dispersion, and that higher intensity could enhance aspect ratio without impacting the crystallinity index. However, ultrasonic treatment for longer than 5 min led to destruction of the whisker morphology of CNCs. The extracted CNCs possess high crystallinity index of 80.8 ± 1.7 %, low residual hemicellulose (2.0 %) and lignin (0.7 %), and high-char content of 26.7 wt% from thermal degradation.

Wood and wood-based materials are used by being processed in various machines in furniture, joinery and construction industries. Various cutting forces arise based on mechanics of machining. It is stated that the cutting power and power consumption factors depend on the cutting forces. The cutting forces are especially used as the main output in the analysis of the cutting process and physico-mechanical cutting models are very important in understanding the cutting factors. Vibration, noise, temperature and machining defects as well as cutting power, surface and chip quality are usually not considered. Determination of optimal machining conditions with efficient and economical works are based on material, tool geometry and mechanics of machining in terms of obtaining smooth surfaces with the lowest power consumption in machining. In this research, the factors affecting the mechanics of machining in the processing of wood and wood-based materials are discussed. Cutting forces, cutting power and their measurement methods with tool and machining geometry were investigated.g geometry were investigated., Odun ve odun kökenli malzemeler mobilya, doğrama ve yapı endüstrilerinde çeşitli makinelerde işlenerek kullanılmaktadır. İşleme mekaniklerine dayalı çeşitli kesme kuvvetleri ortaya çıkmaktadır. Kesme gücü ve güç tüketimi faktörlerinin kesme kuvvetlerine bağlı olduğu belirtilmektedir. Kesiş sürecinin analizinde özellikle kesme kuvvetleri ana çıktı olarak kullanılmakta olup, kesişte etkili faktörlerin daha iyi anlaşılmasında fiziko-mekanik kesiş modelleri oldukça önemlidir. Odun ve odun kökenli malzemelerin fiziksel ve teknolojik özellikleri, makinede işleme koşulları ve kesici aletlerin mekanik durumu işleme mekaniklerini etkileyen faktörler olarak belirtilmektedir. Titreşim, ses, sıcaklık ve işleme kusurları yanında kesme gücü ile yüzey ve yonga kalitesi genellikle göz önünde bulundurulmamaktadır. İşlemede en düşük güç tüketimi ile düzgün yüzeyler elde edilebilmesi bakımından verimli ve ekonomik çalışmalar ile uygun işleme koşullarının belirlenmesi, malzeme ve kesici geometrisi ile işleme mekaniklerine dayandırılmaktadır. Bu araştırmada, odun ve odun kökenli malzemelerin işlenmesinde işleme mekaniklerini etkileyen faktörler tartışılmıştır. Kesme kuvvetleri, kesme gücü ve bunların ölçüm yöntemleri ile kesici ve işleme geometrisi incelenmiştir.

To promote the development of the green and low-carbon wood industry and explore the current status and trend of China's used-furniture recycling, this paper summarizes the research status of used-furniture recycling and interprets governmental strategies, such as the development of used-furniture recycling system, the way of handling used-furniture by manufacturers, and the attitudes of customers towards used-furniture, through extensive literature reviews and market research. From such three respects as government, furniture manufacturers, and consumers, the problems of national used-furniture recycling are analyzed, for example, imperfect system, high cost, and weak awareness. Therefore, to solve the above issues, it is necessary to construct national used-furniture recycling system and methods. The government should pay attention to the construction of recycling network, the supervision and support of entrepreneurial responsibilities, and the formulation of recycling standards. For furniture manufacturers, the improvement of the durability and recyclability of furniture and the development of new models and new technologies for furniture recycling and transportation are their primary assignment. And for consumers, the improvements of their concepts of consuming and the environmental protection are in focus. In sum, it aims to provide both suggestions for the amelioration of the measures and methods, and support for the understanding of the change, of used-furniture recycling in China.

Using the organic artefacts from the fourth-century BC grave at Bulhakovo in southern Ukraine, this article discusses the economics of the perishable material culture of the Scythians of the Pontic Steppe region. Thanks to the survival of organic materials (wood, leather, textiles), the burial provides important information about the complex networks of production and exchange that existed in European Scythia. Scientific analyses produced new data regarding materials and techniques used for the production of wooden, leather and textile objects, providing an opportunity for a more nuanced discussion of their production and consumption.

An environmentally friendly chlorine-free technology for producing wood sulfite soluble pulp using only one oxidizing bleaching agent – hydrogen peroxide has been developed: unconventional catalyzed peroxide delignification and hydrogen peroxide bleaching. The conditions of cooking, delignification, extraction and bleaching of spruce sulfite pulp obtained as a result of studies, as well as successful combinations of conditions of all stages made it possible to obtain two types of soluble pulp by one technology: soluble pulp for nitration (for gunpowder) was obtained under a short scheme including a delignification step and hot alkaline extraction; by continuing this scheme with hydrogen peroxide bleaching in two steps, viscose pulp was obtained. The use of this technology will make it possible to implement a double import substitution – in raw materials (wood instead of cotton) and in finished products (pulp for chemical processing - for nitration and viscose pulp, which are currently imported)., Разработана экологичная бесхлорная технология получения древесной сульфитной растворимой целлюлозы с использованием только одного окислительного отбеливающего реагента – пероксида водорода: нетрадиционная катализируемая пероксидная делигнификация и отбелка пероксидом водорода. Полученные в результате исследований условия варки, делигнификации, облагораживания и отбелки еловой сульфитной целлюлозы, а также удачные сочетания условий всех ступеней, позволили получить по одной технологии два вида растворимой целлюлозы: по короткой схеме, включающей ступень делигнификации и горячего щелочного облагораживания, получена растворимая целлюлоза для нитрования (для пороха); продолжением этой схемы отбелкой пероксидом водорода в две ступени получена вискозная целлюлоза. Использование такой технологии позволит реализовать двойное импортозамещение – по сырью (древесина вместо хлопка) и по готовой продукции (целлюлоза для химической переработки – для нитрования и вискозная, которые в настоящее время импортные).

The main goal of the investigation was to measure and estimate the thermal stability of pinosylvin, pinosylvin monomethyl ether, robinetin, and dihydrorobinetin, i.e., characteristic compounds of wood of Scots pine and black locust, respectively. The pure compounds were analyzed with chromatography before and after they were steam-sterilized and oven-dried. Detailed thermogravimetric analysis was followed to check the thermal decomposition of the stilbenes and flavonoids of wood. The tested phenolic compounds were susceptible to thermal degradation. After the steam-sterilization and oven drying, the amount of investigated phenolic extractives decreased by more than a half. The thermogravimetric analysis showed that stilbenes decompose differently than flavonoids, which can be attributed to the different chemical structures. Twenty minutes of steam sterilization followed by 24 h of oven drying decreased the amount of phenolic compounds in the vials; however, after the applied thermal treatments, the stilbenes and robinetins stayed available in such quantities that they can still provide sufficient bioactivity. Nasl. z nasl. zaslona. Opis vira z dne 28. 9. 2022. Bibliografija: str. 9-12. Abstract.

Developing highly efficient advanced battery deionization (BDI) electrode materials at a low cost is vital for seawater desalination. Herein, a high-efficiency wood-based BDI electrode has been fabricated for seawater desalination, benefiting from the self-supporting three-dimensional (3D) nanoporous structure and rich redox-active sites. The finely tuned rich electrochemical redox active C═O groups on the surface of the wood electrode derived from the facile thermochemical conversion of lignin play a crucial role in the Faradaic cation removal dynamics of BDI. Coupling the 3D wood electrode and a polyaniline-modified wood electrode as the cathode and anode, an all-wood-electrode-based deionization battery has been successfully assembled with a state-of-the-art ion removal capacity of up to 164 mg g

A Bronze Age palstave found at Emmen. In 2019, a Bronze Age palstave was found in a field west of Emmen by a father-and-son team of metal detectorists. In agreement with the landowner, the find was reported to PAN. During the process of conservation, the opportunity presented itself to study the alloy using pXRF analysis. This suggested that the copper ores used in the bronze alloy ultimately derived from Swiss or Slovakian mines, but that the metal was cast locally into a form well-known in the sandy regions of the Low Countries. A review of the find in its topographical and cultural context indicated that it – like various other items in the Bronze Age – had been deposited in (the margin of) wetland parts of the landscape, not far from a contemporaneous settlement.

The high density and poor thermal insulation of traditional wood-plastic composites limited the application in the field of building materials. In this paper, wood fiber (WF) and PLA were used as raw materials and azodicarbonamide was used as the foaming agent. Lightweight WF/PLA composites were prepared by the hot-pressing foaming method, aiming to obtain renewable, low-density material with high strength-to-weight ratio and thermal insulation performance. The results showed that after adding 20 % WF into PLA, the cell morphology was excellent and the cell size was uniform. The magnification reached the minimum value of 0.36 g/cm

Programmed cell death (PCD) is essential for wood development in trees. However, the determination of crucial factors involved in xylem PCD of wood development is still lacking. Here, two Populus trichocarpa typical aspartic protease (AP) genes, AP17 and AP45, modulate xylem maturation, especially fibre PCD, during wood formation. AP17 and AP45 were dominantly expressed in the fibres of secondary xylem, as suggested by GUS expression in APpro::GUS transgenic plants. Cas9/gRNA-induced AP17 or AP45 mutants delayed secondary xylem fibre PCD, and ap17ap45 double mutants showed more serious defects. Conversely, AP17 overexpression caused premature PCD in secondary xylem fibres, indicating a positive modulation in wood fibre PCD. Loss of AP17 and AP45 did not alter wood fibre wall thickness, whereas the ap17ap45 mutants showed a low lignin content in wood. However, AP17 overexpression led to a significant decrease in wood fibre wall thickness and lignin content, revealing the involvement in secondary cell wall synthesis during wood formation. In addition, the ap17ap45 mutant and AP17 overexpression plants resulted in a significant increase in saccharification yield in wood. Overall, AP17 and AP45 are crucial modulators in xylem maturation during wood development, providing potential candidate genes for engineering lignocellulosic wood for biofuel utilization.

Whether sources or sinks control wood growth remains debated with a paucity of evidence from mature trees in natural settings. Here, we altered carbon supply rate in stems of mature red maples (Acer rubrum) within the growing season by restricting phloem transport using stem chilling; thereby increasing carbon supply above and decreasing carbon supply below the restrictions, respectively. Chilling successfully altered nonstructural carbon (NSC) concentrations in the phloem without detectable repercussions on bulk NSC in stems and roots. Ring width responded strongly to local variations in carbon supply with up to seven-fold differences along the stem of chilled trees; however, concurrent changes in the structural carbon were inconclusive at high carbon supply due to large local variability of wood growth. Above chilling-induced bottlenecks, we also observed higher leaf NSC concentrations, reduced photosynthetic capacity, and earlier leaf coloration and fall. Our results indicate that the cambial sink is affected by carbon supply, but within-tree feedbacks can downregulate source activity, when carbon supply exceeds demand. Such feedbacks have only been hypothesized in mature trees. Consequently, these findings constitute an important advance in understanding source-sink dynamics, suggesting that mature red maples operate close to both source- and sink-limitation in the early growing season.

We are currently screening human volunteers to determine their sputum polymorphonuclear neutrophil (PMN) response 6- and 24-hours following initiation of exposure to wood smoke particles (WSP). Inflammatory responders (≥10% increase in %PMN) are identified for their subsequent participation in mitigation studies against WSP-induced airways inflammation. In this report we compared responder status (lt;igt;Nlt;/igt; = 52) at both 6 and 24 hr time points to refine/expand its classification, assessed the impact of the GSTM1 genotype, asthma status and sex on responder status, and explored whether sputum soluble phase markers of inflammation correlate with PMN responsiveness to WSP.Six-hour responders tended to be 24-hour responders and vice versa, but 24-hour responders also had significantly increased IL-1beta, IL-6, IL-8 at 24 hours post WSP exposure. The GSTM1 null genotype significantly (lt;igt;plt;/igt; amp;lt; 0.05) enhanced the %PMN response by 24% in the 24-hour responders and not at all in the 6 hours responders. Asthma status enhanced the 24 hour %PMN response in the 6- and 24-hour responders. In the entire cohort (not stratified by responder status), we found a significant, but very small decrease in FVC and systolic blood pressure immediately following WSP exposure and sputum %PMNs were significantly increased and associated with sputum inflammatory markers (IL-1beta, IL-6, IL-8, and PMN/mg) at 24 but not 6 hours post exposure. Blood endpoints in the entire cohort showed a significant increase in %PMN and PMN/mg at 6 but not 24 hours. Sex had no effect on %PMN response.The 24-hour time point was more informative than the 6-hour time point in optimally and expansively defining airway inflammatory responsiveness to WSP exposure. GSTM1 and asthma status are significant effect modifiers of this response. These study design and subject parameters should be considered before enrolling volunteers for proof-of-concept WSP mitigation studies.

The study comprises three laboratory tests in which typical Finnish highly insulated (HI) walls were exposed to concentrated leakages of indoor air under steady outdoor temperatures of 1–5°C. Airflows with a relative humidity of 50% and at rates of 1–3 L/min were directed close to the wooden frames inside the walls. The thermal resistance ratios between the exterior sheathing(s) and the whole wall (Γ) were 20%–22% and 1%–10% for the HI and baseline (BL) walls. The HI walls that presented Γ values of at least 20% were observed to be resistant to air exfiltration, and their durability was not affected by the addition of a gypsum sheathing outside the wooden frame or a more permeable vapor retarder. This is related to the negative linear correlation that exists between the moisture accumulation rate in wood-based material and the dew point depression (DPD) value. The developed approach, called the DPD method, shows that a significant degree of moisture accumulation does not occur even for DPD values of as low as −2°C if the exterior sheathing is vapor permeable. The airflow does not penetrate into the rigid mineral wool sheathing, which helps to avoid interstitial condensation. Regardless of thermal transmittance, the HI and BL walls with maximum Γ values of 1% were exposed to a high relative humidity and even interstitial condensation because the DPD values were often below −2°C. For these walls, the mold index analysis and visual observations confirmed the local risk for mold growth on the opposite side of the leakage point. In practice, long-term mold growth may be limited if the seasonal periods during which the outdoor temperature is 1–5°C last for a maximum of about 1 month every year.

Lignin is one of the main factors causing lignocellulosic biomass recalcitrance to enzymatic hydrolysis. Glasshouse-grown poplars severely downregulated for CINNAMYL ALCOHOL DEHYDROGENASE 1 (CAD1), the enzyme catalysing the last step in the monolignol-specific branch of lignin biosynthesis, have increased saccharification yields and normal growth. Here, we assess the performance of these hpCAD poplars in the field under short rotation coppice culture for two consecutive rotations of 1 yr and 3 yr. While 1-yr-old hpCAD wood had 10% less lignin, 3-yr-old hpCAD wood had wild-type lignin levels. Because of their altered cell wall composition, including elevated levels of cinnamaldehydes, both 1-yr-old and 3-yr-old hpCAD wood showed enhanced saccharification yields upon harsh alkaline pretreatments (up to +85% and +77%, respectively). In contrast with previous field trials with poplars less severely downregulated for CINNAMYL ALCOHOL DEHYDROGENASE (CAD), the hpCAD poplars displayed leaning phenotypes, early bud set, early flowering and yield penalties. Moreover, hpCAD wood had enlarged vessels, decreased wood density and reduced relative and free water contents. Our data show that the phenotypes of CAD-deficient poplars are strongly dependent on the environment and underpin the importance of field trials in translating basic research towards applications.

Neapolitan pizza, a renowned Italian food recognized as one of the traditional specialties guaranteed (TSG) by European Commission Regulation no. 97/2010, should be exclusively baked in wood-fired ovens for approximately 90 s. Despite its extensive use in restaurants and rotisserie shops all around the world, such equipment has been very poorly studied thus far. The aims of this study were to characterize the operation of a pilot-scale wood-fired pizza oven from its start-up phase to its baking operation and assess its thermal efficiency. To manage brick firing, the oven was lighted at a firewood feed rate (Q

Water-enabled electricity generation (WEG) technologies are considered to be an attractive and renewable approach to meet energy crisis and environmental pollution globally. However, the existing WEG technologies still face tremendous challenges including high material cost, harmful components, and specific environmental requirements. Herein, a high-performance wood-based moisture-enabled electric generator (WMEG) is fabricated. Natural wood is cut perpendicular to the tree growth direction and engineered by simple chemical modification. The obtained bilayer wood membrane has robust mechanical framework with aligned ion nanochannels, abundant dissociated functional groups, and spontaneous water adsorption in the air. At the relative humidity of 85%, one WMEG can generate a voltage of 0.57 V. The device can also effectively sense biological water information as a self-powered sensor. The biophile design contributes a practical moist-electric generation strategy that offers clean energy, especially for undeveloped and disaster-relief regions where electricity is limited by high cost or crippled power facilities.

Leaf mass per area (LMA), which is an important functional trait in leaf economic spectrum and plant growth analysis, is measured from leaf discs or whole leaves. Differences between the measurement methods may lead to large differences in the estimates of LMA values.We examined to what extent estimates of LMA based on whole leaves match those based on discs using 334 woody species from a wide range of biomes (tropics, subtropics, savanna, and temperate), whether the relationship varied by leaf morphology (tissue density, leaf area, leaf thickness), punch size (0.6- and 1.0-cm diameter), and whether the extent of intraspecifc variation for each species matches.Disc-based estimates of species mean LMA matched the whole-leaf estimates well, and whole-leaf LMA tended to be 9.69% higher than leaf-disc LMA. The ratio of whole-leaf LMA to leaf-disc LMA was higher for species with higher leaf tissue density and larger leaves, and variance in the ratio was greater for species with lower leaf tissue density and thinner leaves. Estimates based on small leaf discs also inflated the ratio. The extent of the intraspecific variation only weakly matched between whole-leaf and disc-based estimates (ROur results suggest that simple conversion between whole-leaf and leaf-disc LMA is difficult for species obtained with a small leaf punch, but it should be possible for species obtained with a large+ leaf punch. Accurately representing leaf traits will likely require careful selection between leaf-disc and whole-leaf traits depending on the objectives. Quantifying intraspecific variation using leaf discs should be also considered with caution.

Exploring the reusability of wood-based panels is imperative in the wood industry for sustainable development and carbon balance. Non-reusable adhesives make wood-based panel recycling difficult. In this study, inspired by the adhesion and de-adhesion behavior of snail slime, we built dynamic covalent/hydrogen hybrid networks into adhesive system for achieving both high bonding performance and reusability. Specifically, the softwood lignin was purified and pretreated by ultrasonication to form a catechol structure (UAL) and then combined with soybean protein to develop a 100 % bio-based wood adhesive. The catechol structure of UAL formed dynamic covalent bonds (CN) with the amino groups of the protein to improve the water resistance and formed multiple hydrogen bonds as a sacrificial network to improve the toughness of the adhesive. Thus, the wet shear strength of plywood bonded by the resultant adhesive improved by 101.4 % to 1.37 MPa. The adhesive also exhibited flame retardancy (LOI = 37.7 %), mildew resistance (60 h), and antibacterial performance (inhibition zone = 8 mm). Notably, owing to the rearrangement of dynamic covalent/hydrogen hybrid networks and the thermoplastic property of UAL, the resultant adhesive was reusable (3 cycles) and degradable (2 months), which provides a potential method for the reuse of wood-based panels.

Abundant studies have revealed that single-walled carbon nanotubes (SWCNTs) regulate plant growth. However, whether or how SWCNTs influence plant wood formation remains largely unknown. In this report, we found that SWCNTs had positive effects on poplar growth, as reflected by significantly increased plant height, leaf size, and fresh and dry weight. Transmission electron microscopy (TEM) images showed that the SWCNTs were absorbed in the exposed poplar root cells. A relatively higher content of cellulose and lignin was observed in the SWCNTs-treated poplar stems than in those of the control plants. It also showed darker phloroglucinol staining in the stems of exposed plants than that in control plants. Further analysis showed that the activities of key enzymes related to cellulose synthesis (cellulose synthase, CesA) and lignin biosynthesis (phenylalanine ammonia-lyase, PAL; cinnamate 4-hydroxylase, C4H; 4-coumarate:CoA ligase, 4CL; cinnamyl alcohol dehydrogenase, CAD) increased significantly after SWCNTs treatment. Consistent with the change trend of enzyme activity, the relative expression levels of a few lignin- and cellulose-related genes were activated by SWCNTs. Taken together, we proposed that SWCNTs have positive effects on poplar wood formation by modifying the expression of enzymes involved in the cellulose and lignin synthesis pathways. Our data suggest the modifications of wood formation through SWCNTs application could be a useful strategy for improvement of wood bioengineering.

Irregular hemorrhagic traumas always threaten the health of patients due to uncontrollable bleeding and wound infections. The traditional hemostatic materials show dissatisfactory hemostatic efficiency and antibacterial activity in solving these potential bleeding dangers. Herein, we proposed a kind of composites based on flexible wood membrane (FWM) loaded with chitosan/alginate derivative for accelerating rapid hemostasis and preventing infection. FWM was removed part of hemicellulose and lignin by using NaOH/Na

Social insects’ constructions are diverse and functionally flexible. We aimed to understand how termites modify their behavior and building material to change the function of a shelter tube. Construction behaviors of three termite species, Coptotermes formosanus Shiraki (Blattodea: Rhinotermitidae), Odontotermes formosanus (Shiraki) (Blattodea: Termitidae), and Nasutitermes takasagoensis (Nawa) (Blattodea: Termitidae), were recorded and analyzed. We measured the thickness and organic matter content of shelter tubes, and further tested their water loss and water drop resistance. All three termite species used a cement-brick construction procedure. The shelter tubes of C. formosanus and N. takasagoensis incorporating of woody material and feces present a strong resistance to water drops. Shelter tubes of the fungus-growing termite, O. formosanus, constructed using only soil and fluid secretion had a weak resistance to water drops. The trade-off between using feces to increase hydrophobicity of shelter tubes and using feces to grow fungus likely occurs in fungus-growing termites. Among intraspecific colonies, increasing the thickness of shelter tube improved resistance to water loss and water drops. This study demonstrated termites employed limited construction material and building behaviors to achieve functional plasticity of foraging shelter.

Homeowners burn wood of a wide range of species and moisture content (MC) in residential cordwood and pellet stoves. An effective emission certification test protocol must account for and accurately measure the impact of those variables in order to ensure a reasonable correlation between laboratory results and in-use emissions and to promote the design and manufacture of cleaner burning appliances. This study explored the effect of wood species and MC on emissions and efficiency in four cordwood and four pellet stoves. PM emissions were consistently lower with pellets manufactured from softwood than for hardwood species and were highly correlated with ash content. Higher MC oak fuel substantially increased PM emissions in a non-catalytic cordwood stove; however, a hybrid cordwood stove was able to meet federal emissions limits even with the higher MC fuel. The results of this study, in combination with previous research, suggest that certification tests that use softwood fuel likely report lower emissions than tests that use hardwood. Requiring hardwood and higher MC cordwood fuel in certification tests would enable the assessment of an appliance's ability to operate well even when fuel conditions are not optimized.