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Bamboo node is a specialized structure that has great effect on both bamboo growth, physical-mechanical properties, and its utilization. Compact structure and particularly high hardness make bamboo node very difficult for slice specimens preparation. In this study, in order to explore the differences in anatomical characteristics of bamboo nodes' vascular bundles among species, 3D structures of bamboo nodes in four bamboo species (Bambusa emeiensis, Phyllostachys edulis , Pleioblastus amarus , and Bambusa rigida) were reconstructed by the micro-CT technique. The characteristics of vascular bundles were comparatively analyzed based on the CT images. The results showed that the vascular bundle morphology of Pleioblastus amarus and Bambusa rigida changed significantly from node to internode. The areas of fiber cells in the middle part along the radial direction of bamboo culm wall has the largest area (0.204 mm2), followed by the inner part (0.151 mm2) and the outer part (0.072 mm2). The area of transport tissue in the inner part along the radial direction of bamboo culm wall has the largest area (0.046 mm2), followed by the middle part (0.028 mm2) and the outer part (0.002 mm2). The bending vascular bundles in bamboo node can be divided into thick and thin types. The average thickness of the thin bending vascular bundles among the four bamboo species was 125 μm, with the thinnest value of 109 μm. While, the average thickness of thick bending vascular bundles was 265 μm, with the thickest value of 335 μm. The number proportion of thick vascular bundles was 60.8%, 42.5%, 32.9%, and 10.7% for Bambusa rigida , Bambusa emeiensis, Pleioblastus amarus , and Bambusa rigida. This study set up a nondestructive and efficient method for 3D anatomical structure characterization of bamboo node and the variation analysis in bamboo nodes' vascular bundles. • 3D structures of nodes of four bamboo species were successfully reconstructed. • Characteristics of Nodes' vascular bundle were determined based on CT images. • Variation in vascular bundle's characteristics could be evaluated by micro-CT. [ABSTRACT FROM AUTHOR]

Cellulose nanofibers were successfully isolated from bamboo using microwave liquefaction combined with chemical treatment and ultrasonic nanofibrillation processes. The microwave liquefaction could eliminate almost all the lignin in bamboo, resulting in high cellulose content residues within 7 min, and the cellulose enriched residues could be readily purified by subsequent chemical treatments with lower chemical charging and quickly. The results of wet chemistry analyses, SEM images, and FTIR and X-ray spectra indicated the combination of microwave liquefaction and chemical treatment was significantly efficient in removing non-cellulosic compounds. Ultrasonication was used to separate the nanofibrils from the purified residues to extract nanofibers. The TEM images confirmed the presence of elementary fibrils, nano-sized fibril bundles, and aggregated fibril bundles. As evidenced by the TGA analysis, cellulose nanofibers isolated by this novel technique had high thermal stability indicating that the isolated nanofibers could possibly be applied as reinforcing elements in biomaterials. [ABSTRACT FROM AUTHOR]

Bamboo stems were subjected to a mechanical treatment process for the extraction of bamboo fiber bundles. The fiber bundles were used as reinforcement for the fabrication of high-performance composites with phenolic resins as matrix. The influence of fabricated density and bamboo species on physical-mechanical properties of bamboo fiber bundle reinforced composites (BFCs) was evaluated. The results revealed that BFCs with density of 1200 kg/m exhibited lower water absorption, better dimensional stability, and higher mechanical properties with comparison to those with lower density. The changes in microstructures of BFCs with respect to density gave evidence that the high performance of BFCs with high density was due to the almost complete collapse of bamboo lumens, which resulted in the formation of solid bamboo and thin resin films with water resistance ability. BFCs fabricated from five bamboo species all showed better properties compared to commercialized bamboo-based composites. However, significant differences in physical-mechanical properties of BFCs among bamboo species were also found. This may be attributed to the variations in anatomical structure and physical-mechanical properties among original bamboo species. From a practical production view, the effect of bamboo species on properties of BFCs should be properly taken into consideration. [ABSTRACT FROM AUTHOR]

Applications of eco-friendly soy protein (SP) adhesives in the wood industry are restricted by their poor wet bonding strength and mold resistance. In this study, we noted that epoxy crosslinking agents not only have cross-linking properties, but also antifungal properties and can be used as cross-linkable antifungal agents to simultaneously improve the mold resistance and strength of SP adhesives. In order to develop sustainable and highly active epoxy cross-linkable antifungal agents, biomass-derived oxalic acid (OA) was converted into epoxy oxalic acid (EOA) with two electron-withdrawing ester groups, with 99.93% antifungal activity. The 1% ultra-low amount of EOA (when used as crosslinking agent) was uniformly dispersed in the uncured adhesive, prompting the anti-mold life of the adhesive to increase from 2 to 26 days. After curing, the tighter and more stable cross-linked network structure of the adhesive was constructed by the reaction of low reactive groups such as amide II bonds with ultra-low amounts of EOA, and the dry and wet shear strengths were increased by 49.0% and 139.7%, respectively, compared with pure adhesives. In addition, the anti-mold life of the cured adhesive increased from 4 to more than 30 days under the action of residual EOA. This work demonstrates the novel antifungal effect of epoxy crosslinkers, providing a controllable, green, and sustainable idea for the high-efficient improvement of mold resistance and strength of bio-based adhesives. • Epoxy crosslinkers generally have antifungal properties and can act as antifungal agents. • Epoxy oxalic acid (EOA) exhibited 99.93% antifungal activity, derived from inexpensive bio-based oxalic acid. • Soy protein functional groups cross-linked with EOA to construct a stable cross-linked network structure of the adhesive. • The bonding strength and mold resistance of the adhesive were efficiently enhanced by ultra-low levels of EOA. [ABSTRACT FROM AUTHOR]

Purpose: Anthropogenic activities have increased the nitrogen (N) inputs in terrestrial ecosystems, thereby altering both the carbon (C) and phosphorus (P) availability along with resource stoichiometry. Stoichiometric deviations between microbial biomass and resources availablity cause stoichiometric imbalances and nutrient limitations for microbial activity. However, whether N deposition will further aggravate the existing P limitation is unknown. Furthermore, how soil microbes respond to these conditions, along with the biogeochemical cycles they mediate, still remains unclear. Methods: To answer these questions, a 7-year N addition experiment (+0, +50, +150 kg N ha−1 yr−1; CK, LN, HN) has been conducted in a subtropical evergreen-broadleaved forest in the Rainy Area of West China, where received the highest background N deposition in the world and the highest precipitation in inland China. Soil-available nutrients, microbial biomass, C-, N-, and P-acquiring enzyme activities, microbial community composition and diversity were measured. Results: With increasing N addition, the soil DOC:AP and AN:AP ratios increased significantly, whereas microbial biomass C:P and N:P ratios decreased significantly, resulting in increased C:P and N:P imbalances between the soil microbes and resources, thereby aggravating the existing P limitation of microorganisms in this subtropical N-saturated forest. Microbial communities maintained stoichiometric homeostasis by increasing ACP enzyme activity (by 8.99% to 19.28% under N treatment) and threshold elements ratio (TER) at P-limited levels. The aggravated imbalance of C:P and N:P caused by N addition decreased the bacterial and fungal community alpha-diversity. Interestingly, changes in the beta-diversity of the bacterial rather than the fungal community responded more strongly to stoichiometric imbalance. Bacterial communities transitioned from coprophilous (Proteobacteria-dominated) to oligotrophic (Actinobacteriota-dominated) under N addition treatment. Conclusions: This study not only highlights the importance of stoichiometric imbalances in regulating the soil microbial community structure and enzymatic activity, but also may help in understanding how global N deposition-induced resource stoichiometry changes affect the terrestrial C and nutrient flows. [ABSTRACT FROM AUTHOR]

The structure of the bamboo node obviously differs from that of the internode and largely affects the mechanical properties of bamboo. However, the node structure of moso bamboo, an important economic and ecologic bamboo species, was still unclear. Thus, in this study, the 3D structural changes of the vascular bundle (VB) in the moso bamboo node were visualized and quantified. The compressive properties and failure mechanisms of the bamboo node were discussed based on the structural changes. The results showed that the horizontal VB in bamboo node was classified into three types: branching, cross-linking, and thickening. The cross-sectional area of the vertical VB in bamboo node increased, and the vertical VBs shifted to the outer side after passing through the node. Due to the "wire hoop" effect of the horizontal VBs, the longitudinal compressive strength of the node was greater than that of the internode. The deflection of VBs caused slippage between VBs and resulted in the decrease of the node's transversal compressive strength. This research provided key information for a deeper understanding of the structure and mechanical properties of bamboo for potential applications. [ABSTRACT FROM AUTHOR]

The thermal decomposition characteristics of microwave liquefied rape straw residues with respect to liquefaction condition and pyrolysis conversion were investigated using a thermogravimetric (TG) analyzer at the heating rates of 5, 20, 50 °C min−1. The hemicellulose decomposition peak was absent at the derivative thermogravimetric analysis (DTG) curve of liquefied residues, because it had been decomposed during the liquefaction. Furthermore, among the liquefied residues, the one from the reaction condition of 180 °C/15 min had the highest thermal stability under a high temperature (>700 °C). The DTG profiles revealed that raising the temperature heating rate could result in an increase in the maximum decomposition temperature. The apparent activation energy (Eα) values of the liquefied residues were lower than that of non-liquefied raw rape straw, whereas the recondensation reaction occurred at 180 °C/15 min remarkably increased the Eα. A noticeable increase in the Eα was observed for the liquefied residue from the 180 °C/10 min samples as the pyrolysis conversion increased from 0.15 to 0.55, suggesting a complex decomposition process with the increasing pyrolysis temperature. The liquefaction process could decrease the thermal decomposition temperature of biomass, which means higher reactivity and lower operational costs during pyrolysis. [ABSTRACT FROM AUTHOR]

In this work, both the bio-polyol and cellulose nanocrystals (CNCs) used to produce high bio-content polyurethane (PU) foams were prepared from microwave liquefaction of rape straw. As high as 40% petro-based polyol was replaced by bio-polyol and the bio-foams containing 40% bio-polyol (PU40) were further reinforced by incorporating 1 to 6% CNCs. GC–MS, 1 H NMR and FTIR observations demonstrated that the bio-polyol is a hydroxyl-rich source consisting of C5, C6 sugars and aromatics. The maximum physico-mechanical performance of bio-foam without CNCs was observed from the bio-foam containing 20% bio-polyol. When further increasing bio-polyol content from 20 to 40%, these properties dramatically decreased. This result was possibly due to the complex polyurethane crosslinking reactions with C5, C6 sugars and aromatics. As compared with reference (PU40), the Young's modulus and compressive stress in the optimal 4% CNCs reinforced bio-foam increased by 590% and 150%, respectively. It was noteworthy that these values were highly superior to those of the petro-based foam. Solid state 13 C NMR and FTIR analysis of CNC reinforced bio-foam evidenced that the hydroxyl-rich structure in CNCs participated in the cross-linking reactions, resulting in an increase of the polyurethane crosslinking density, which contributes to the increased physico-mechanical performance of bio-foam. [ABSTRACT FROM AUTHOR]

The rheological behavior, molecular weight distribution (MWD), reactivity, and chemical structures of UF resin during the pre-curing process were elucidated by rheometry, gel permeation chromatograph (GPC), differential scanning calorimetry (DSC), and 13 C NMR, respectively. The unsynchronized increasing processes between viscosity and rigidity during the pre-curing process were closely related to the changes of activation energy, MWD, and chemical structures. The results indicated that, due to the pre-curing behavior showed significant influence on the activation energy, both the occurrence of pre-curing behavior and its degree could be accurately judged, and the change trend of MWD and the chemical structures of the pre-curing resin could be also predicted by the non-isothermal DSC method. Once the value of E a was higher than that of E 0 , the degree of cross-linking was increased and the network structure was formed indicating that the pre-curing behavior of UF resin had taken place. [ABSTRACT FROM AUTHOR]

Since natural cellulose is mostly cellulose I and has a fibrous form, most cellulose-based adsorbents are fibrous/rod-shaped and exhibit the cellulose I crystal structure. This study reports a cellulose II-based spherical nanoparticle microcluster adsorbent (SNMA), synthesized from biomass by a bottom-up approach, for removing toxic hexavalent chromium (Cr(VI)). The basic structure of SNMA was investigated. Notably, the prepared adsorbent was a microcluster composed of spherical nanoparticles, while exhibiting cellulose II crystal structure, resulting in higher thermal stability and significantly enhanced adsorption performance. The adsorption process and mechanism of SNMA on Cr(VI) were studied in detail. The SNMA achieved a high adsorption capacity (225.94 mg/g) and receptor site density. The SNMA is expected to be used as a bio-based spherical nanoparticle microcluster adsorbent platform for the adsorption of different toxic substances by changing the surface functional groups of its components, spherical nanoparticles. [Display omitted] • The prepared adsorbent from biomass has a spherical nanoparticle microcluster morphology. • The obtained adsorbent exhibits cellulose II crystal structure. • The obtained adsorbent has good adsorption performance for Cr(VI). • It offered a strategy in preparing bio-based spherical nanoparticle microcluster adsorbent platform. [ABSTRACT FROM AUTHOR]

Chemical components with anti-oxidant, anti-inflammatory, and anti-cancer properties extracted from Alnus bark and leaves have been extensively studied. However, less attention has been paid to extractives from Alnus pods, which are mostly treated as waste. Here, extractives of Alnus cremastogyne pods from 12 provenances in Sichuan Province were studied for high value-added utilization of Alnus waste. The extractives were analyzed by Gas Chromatography-Mass Spectrometer (GC-MS), Ultraviolet-visible spectroscopy (UV-Vis spectra), and 1,1-diphenyl-2-picrylhydrazyl (DPPH) scavenging activity. A total of 58, 49, and 51 chemical components were found when the organic solvents of ethanol, petroleum ether, and ethyl acetate were used to collect extractives, respectively. These chemical components including Phytol, CIS-5,8,11,14,17-eicosapentaenoic acid, Germacrene D, Lupeol, and β-sitosterol, etc., have wide applications in the fields of pharmacy and cosmetics. Moreover, it was also found that extractives in ethanol and ethyl acetate had impressive UV resistance, especially for UV-C and UV-B blocking. The results showed that the maximum block ratio towards UV-C and UV-B could reach 99%. In addition, the ethanol extract showed good anti-oxidant activity with a maximum free radical scavenging rate of 96.19%. This comprehensive and systematic study on extractives from Alnus cremastogyne pods promotes the development of high-value utilization of Alnus components. [ABSTRACT FROM AUTHOR]

Alkaline lignin and sodium lignosulfonate were chemically modified by using maleic acid for potential application on the production of ultra-flexible gelatin films. The comparison results in morphology and chemical structures of the two types of lignin before and after modification revealed that carboxyl and C C groups were successfully grafted onto the lignin, resulting in the changes in physical-chemical properties. Compared to modified sodium lignosulfonate, modified alkaline lignin (MAL) was much more appropriate in the preparation of gelatin (GEL)/lignin films by endowing the films with transparency and excellent UV light shielding ability. Elongation at break of GEL/MAL films were more than two times that of the pure gelatin film, which greatly addressed the brittleness issues of the pure gelatin films during use, indicating that the modified alkaline lignin could be used as renewable additive with replacement of glycerol. The results in this study also gave evidence that the sources and structure of lignin affect its compatibility with gelatin solution. The higher weight loss rate and lower pyrolysis degradation temperature indicated that the gelatin/lignin films were much more easily thermal degradable at the end of service life. This research provided a potential and efficient approach on the production of renewable and biological films from gelatin and lignin. [Display omitted] [ABSTRACT FROM AUTHOR]

Lignin-containing bamboo cellulose, fractionated from a pilot-scale microwave liquefaction of bamboo was dissolved in tetrabutylammonium acetate/dimethyl sulfoxide (TBAA/DMSO) for the fabrication of highly flexible, transparent and UV-blocking films. Tea polyphenol (TP) or citric acid (CA) was added during the dissolving process in order to modify the film's properties. The results showed that the addition of TP obviously improved the elongation at break (triple that of the control) and UV-blocking ability of the films. Both the addition of TP and CA could increase the water contact angle of the films. The films incorporated with TP and CA were much more thermal stable than previously reported similar films. The proposed film fabrication mechanism revealed that stable hydrogen bonds formed between the lignin-cellulose matrix and TP/CA, resulting in the enhancement on the properties of the films. This present study showed that lignin-containing cellulose with the incorporation of TP/CA had great potential in the preparation of films in place of plastic. [Display omitted] • Lignin-containing cellulose was directly obtained from microwave liquefaction. • The films were highly transparent, flexible, weakly hydrophilic and UV-blocking. • The elongation at break of TP-2%-RCF was about triple that of RCF. • Stable and strong hydrogen bonds formed between cellulose/lignin and modifier. [ABSTRACT FROM AUTHOR]

In this work, tea powder was used as a filler to produce low-formaldehyde-emission tea-based melamine-modified urea–formaldehyde resin (TMUF). The thermal stabilities of TMUF and the resin without tea powder (MUF0) were characterized using thermogravimetry. The optimal amount of tea powder m(tea)/m(tea + urea) was equal to 0.15. The formaldehyde emission of the three-layer plywood produced by TMUF was reduced by 75.43%, and the wet bonding strength of the plate was increased by 26.67% as compared with the plywood prepared by MUF0. Compared with MUF0, the thermal degradation peak temperature of TMUF resin was shifted to higher temperature, while the carbon residue was increased. The thermal degradation activation energies of TMUF and MUF0 were similar, while TMUF had a lower pre-exponential A. The Flynn–Wall–Ozawa model-free method is used to estimate various activation energy values at different conversion rates and to predict possible reaction mechanisms. Judging the reaction mechanism according to the slope of the straight line fitted by different models, the best model was based on random nucleation. [ABSTRACT FROM AUTHOR]

Herein, a novel magnetic adsorbent (BC/AA/MN@Fe 3 O 4) was successfully prepared from waste bamboo fiber tissue and montmorillonite, and subsequently applied for the highly selective removal of malachite green (MG, removal efficiency = 97.3 %) from the mixed dye solution of MG with methyl orange (MO, removal efficiency = 4.5 %). The magnetic adsorbent has a high porosity with abundant mesopores. In the single dye MG solution, the adsorbent could effectively remove MG over a wide pH range from 4 to 10, and the maximum adsorption capacity (q max) was 2282.3 mg/g. Moreover, the magnetic adsorbent could remove MG from various solutions including mixed dye solution, high salinity solution, and real river water dye solution. The thermodynamic results proved that the adsorption process of MG was spontaneous and endothermic. The adsorption of MG was due to the comprehensive effects of electrostatic attraction, hydrogen bonding interactions and ions exchange, between the adsorbent and MG. Furthermore, the BC/AA/MN@Fe 3 O 4 exhibited an excellent reusability with adsorption efficiency above 53.4 % after five consecutive cycles. Therefore, the prepared magnetic nanocellulose-based adsorbent was expected to be a promising material for highly selective adsorption and separation of MG from mixed dye solution. • A novel magnetic adsorbent (BC/AA/MN@Fe 3 O 4) was successfully prepared. • It showed prominent uptake capability toward MG over a wide pH range from 4 to 10. • The calculated maximum adsorption capacity of BC/AA/MN@Fe 3 O 4 for MG was 2282.3 mg/g. • It can be effectively reused to selectively adsorb and separate MG from wastewater. [ABSTRACT FROM AUTHOR]

Herein, a novel magnetic adsorbent (BC/AA/MN@Fe 3 O 4) was successfully prepared from waste bamboo fiber tissue and montmorillonite, and subsequently applied for the highly selective removal of malachite green (MG, removal efficiency = 97.3 %) from the mixed dye solution of MG with methyl orange (MO, removal efficiency = 4.5 %). The magnetic adsorbent has a high porosity with abundant mesopores. In the single dye MG solution, the adsorbent could effectively remove MG over a wide pH range from 4 to 10, and the maximum adsorption capacity (q max) was 2282.3 mg/g. Moreover, the magnetic adsorbent could remove MG from various solutions including mixed dye solution, high salinity solution, and real river water dye solution. The thermodynamic results proved that the adsorption process of MG was spontaneous and endothermic. The adsorption of MG was due to the comprehensive effects of electrostatic attraction, hydrogen bonding interactions and ions exchange, between the adsorbent and MG. Furthermore, the BC/AA/MN@Fe 3 O 4 exhibited an excellent reusability with adsorption efficiency above 53.4 % after five consecutive cycles. Therefore, the prepared magnetic nanocellulose-based adsorbent was expected to be a promising material for highly selective adsorption and separation of MG from mixed dye solution. • A novel magnetic adsorbent (BC/AA/MN@Fe 3 O 4) was successfully prepared. • It showed prominent uptake capability toward MG over a wide pH range from 4 to 10. • The calculated maximum adsorption capacity of BC/AA/MN@Fe 3 O 4 for MG was 2282.3 mg/g. • It can be effectively reused to selectively adsorb and separate MG from wastewater. [ABSTRACT FROM AUTHOR]

Common walnut Juglans regia L. suffered devastating damage from the white‐striped longhorn beetle Batocera horsfieldi (Hope) in southwest China, which resulted in a dramatic decrease of local walnut production. However, the control of this wood‐boring pest with traditional methods is difficult as a result of its cryptic feeding habit.We proposed that developing host‐plant resistance is a more effective way of controlling this insect with long‐term benefits. One way of improving host‐plant resistance is to identify plant traits related to host‐plant preference of targeted insects.In the present study, we investigated the differences in feeding and oviposition preferences of B. horsfieldi on four J. regia cultivars in the field and tested whether such preferences are associated with structural and chemical traits in plant branches.The results obtained showed that the host‐plant resistance of J. regia cultivars to B. horsfieldi was related to increased wood density, higher amounts of cellulose and lignin, and higher contents of tannins, total flavonoids and total phenolics, whereas the susceptible cultivars were characterized by thicker bark, higher contents of water, sugar and soluble protein.The identified traits involved in host‐plant preference can subsequently contribute to the selection and breeding of resistant J. regia cultivars to B. horsfieldi. [ABSTRACT FROM AUTHOR]

In this study, the prepolymers (TYF) were prepared by formaldehyde and l -tyrosine, different amounts of TYF were added to prepare TYF modified urea-formaldehyde adhesives (LUF), and the gel time of resin, formaldehyde emission and wet shear strength of the plywood were tested. This result indicated that the optimal addition amount was 3 wt%, and the formaldehyde emission of plywood decreased by 23% to 0.57 mg/L, and the wet shear strength increased by 47% to 1.47 MPa. The thermal degradation and curing characteristics of urea-formaldehyde (UF) and LUF resins were characterized by thermogravimetric (TG) and differential scanning calorimetry (DSC), and the kinetic parameters were analyzed. The results showed that TYF could reduce the formaldehyde emission and improve the wet shear strength significantly. Moreover, the thermal degradation activation energy (E α) of UF resin was increased, and the thermal stability was enhanced. Although the initial and peak curing temperatures of LUF were higher, but the LUF cured more easily than the UF once the curing temperature was reached. [Display omitted] [ABSTRACT FROM AUTHOR]

Abstract In this study, diethyl ether extractives were isolated from Phoebe zhennan wood and then added into PLA matrix for the preparation of UV protective films (UV-PF). The results revealed that the diethyl ether extractives had good compatibility with PLA. The prepared UV-PF with the addition of 24 wt% extractives showed complete absorption of UV-C (200–280 nm) and UV-B (280–315 nm) and more than 90% absorption of UV-A (315–400 nm), indicating the addition of extractives into PLA contributed to the super UV resistant ability of the PLA based films. The UV-PF still exhibited excellent UV absorbability after strong UV light irradiation. The differential Scanning Calorimetry (DSC) analysis of the films showed that the UV-PF had relatively low thermal degradation temperature compared to the neat PLA films (PF), while the UV-PF showed stronger tensile strength with comparison to that of the PF. The results on the chemical composition analysis of the diethyl ether extractives revealed that the UV absorbability of the UV-PF may own to the benzene structure, C O bonds, C C bonds in the constituents of the extractives, which all have strong absorption in the near UV-region (200–400 nm). Graphical abstract Diethyl ether extractives were isolated from Phoebe zhennan wood and added into PLA matrix for the preparation of UV protective films. The prepared UV protective films with the addition of 24 wt% extractives showed complete absorption of UV-C and UV-B (280–315 nm) and more than 90% absorption of UV-A (315–400 nm), indicating the addition of extractives into PLA contributed to the super UV resistant ability of the PLA based films. The UV absorbability of the UV protective films may own to the benzene structure, C O bonds, C C bonds in the constituents of the extractives, which all have strong absorption in the near UV-region (200–400 nm). Unlabelled Image [ABSTRACT FROM AUTHOR]

In order to evaluate the significant effects of curing temperature, solid content, and pH on the pre-curing behavior of the UF resin, the isothermal and non-isothermal thermal behaviors were discussed by differential scanning calorimetry in this work. The results indicated that the temperature and pH showed significant influence on the whole shape of the DSC curves and the conversion at the same time of the UF resin. Meanwhile, the non-isothermal thermal behavior showed that when the UF resin pre-cured for the same time of 30 s, the onset and peak and end temperature of the DSC curves were decreased, and the activation energy and the conversion was also increased with the increasing curing temperature or decreasing pH. Based on the analysis of the contribution rate of the temperature, solid content, and pH on the conversion and heat of pre-curing UF resin, the results indicated that the pH and temperature showed significance effect on the pre-curing action than solid content. [ABSTRACT FROM AUTHOR]

Soy-based adhesives are considered to be a substitute for toxic petroleum-based adhesives in wood industry because of its environmentally-friendly property. However, their application range is limited by the lack of high wet bond strength and high toughness. While it is possible to impart these properties to soy-based adhesives by adding a variety of corresponding modifiers, it is difficult to do so by adding a single modifier. In this work, a multifunctional cross-linking agent dodecanedioic acid diglycidyl ester (DADE) with high reactivity, toughening, and hydrophobic effects was synthesized and incorporated into soy-based adhesive to ameliorate the bonding performance of the adhesives. The reaction process between DADE and protein was confirmed by instrumental analyses. Results revealed that the introduction of 4% DADE increased the wet bond strength of the soy protein adhesive by 140% to 1.57 MPa, whereas the wet bond strength (1.11 MPa) of soybean meal adhesive containing 4% DADE was comparable to that of MUF resin. The micrographs of the fracture surface and the force-distance curves of the shear strength test showed that the toughness of the adhesives was significantly improved by DADE. These improvements were attributed to the long hydrophobic aliphatic chains and highly reactive groups from DADE. This modification method avoided using large amounts of chemical additives. This work may provide an efficient and low-consumption method for producing bio-based adhesives with excellent bonding properties. [Display omitted] • The resulting soy-based adhesive was an environmentally-friendly wood adhesive. • A multifunctional crosslinker with toughening and hydrophobic effects was developed. • The use of DADE avoided the addition of additional hydrophobic and toughening agents. • The strength of the SPD adhesive was higher than that of formaldehyde-based resin. [ABSTRACT FROM AUTHOR]

Dioecious plant species exhibit sexual dimorphism in morphology and physiology under water deficit conditions, but the metabolic and molecular mechanisms underlying such differences are barely explored. In this study, we integrated metabolome and transcriptome analyses of female and male full-sibs of Populus deltoides that featured different drought tolerance in response to moderate and severe water shortage conditions. The results showed that male poplars had higher chlorophyll content and photosynthetic capacity, which result in a better growth performance than female poplars under drought conditions. The metabolome profiling revealed that both the quantification and qualification of differentially expressed metabolites in male poplars were higher than those in females. The transcriptome analysis revealed that the KEGG pathway was enriched in plant hormone signal transduction and carotenoid biosynthesis pathway in both male and female poplars under water deficiency. Moreover, the number of differentially expressed genes (DEGs) that were altered by plant sex was much lower than that by drought treatment. Simultaneously, most of these DEGs were up-regulated in male poplars, especially the key genes that involve in ABA synthetic pathway. The results revealed the metabolic and molecular mechanisms underlying the better ability of drought resistance observed in male poplar plants. • Male poplars grew better than female conspecifics under water deficit condition. • Male poplars enriched higher differentially expressed metabolites than females. • Key genes involved in ABA synthetic and signal pathway were up-regulated more in male poplars. [ABSTRACT FROM AUTHOR]

Different spatial locations provide different external conditions for root decomposition, while species and root order cause obvious differences in root substrate quality. Both differences in internal and external conditions may determine root decomposition rate. We explored the effects of decomposition position, root order, and species differences on root decomposition, and determined the role of manganese (Mn) in root decomposition. We conducted a fine root decomposition experiment using roots from Schima superba , Cleyera japonica, and Eurya loquaiana (separated into orders 1−3, 4−5, and 6) in the litter layer, and at 0−10 cm, 20−30 cm, and 40−50 cm soil depth in a subtropical forest. Root mass and concentration of C, N, P, Mn, condensed tannins and total phenolics were measured during two years of decomposition. Root decomposition rates decreased with increasing soil depth for all root samples. Compared to decomposition at 0−10 cm soil depth, remaining mass (% of initial) declined by 7%–34% in the litter layer and increased by 17%–37% at 40−50 cm soil depth. Lower-order roots had a higher decomposition rate than higher-order roots in the litter layer, but at 40−50 cm soil depth, we observed the opposite. Root litter Mn concentration and remaining mass were negatively correlated during the whole decomposition period including the early, middle, and late stages. Initial root Mn content was negatively correlated with remaining mass after two years of decomposition in the litter layer, and at 20−30 cm, 40−50 cm soil depth. However, no significant relationship between mass remaining and initial root N, P, condensed tannins and total phenolics were observed in the subsoil. Variance partitioning showed that the soil layer contributes significantly to the variance in remaining root mass, C, and Mn, whereas root order group contributed more than the soil layer to remaining root N and P. Our results indicate that soil depth is more important than root order for fine root decomposition rate at a site scale. Relative root decomposition rate between lower- and higher-order roots depends on the decomposition environment. Overall, this study strongly suggests that root Mn concentration (whether in initial or other decomposition stages) was much more consistently correlated with mass remaining than traditional predictors of N, P, condensed tannins, or total phenolics. Root Mn concentration greatly indicates root decomposition rates across soil layers, root orders, and species. Initial root Mn concentration and Mn supply capacity of the decomposition environment jointly control root decomposition rates throughout the decomposition process. • Fine root was decomposed by root order in litter layer, and at different soil depth. • Root Mn content and remaining mass were negatively correlated during decomposition. • Root decomposition rate is more affected by soil depth than root order. • Root Mn content controls root decomposition rates across soil layer and root order. [ABSTRACT FROM AUTHOR]

Supramolecular structure of cellulosic materials from microwave treatment were throughly investigated for production of lignin-containing nanocellulose. The results revealed that both the intermolecular and intramolecular hydrogen bonds were altered by microwave irradiation. Cellulose I β was the main component in microwave treated bamboo (MTB) with smaller interplanar spacing, and the cellulose molecules were loosely connected resulting in a loose structure. Thereafter, MTB was used to produce lignin-containing nanocellulose by using oxalic acid dihydrate (OAD) to test the feasibility on its efficiency. The chemical consumed for the preparation of lignin-containing nanocellulose (LCN) with a comparable yield (68.08–82.33 %) from MTB was merely 1/10 that from conventional cellulosic materials, indicating the supramolecular structural changes of bamboo cellulose induced by microwave treatment provided suitable conditions for the subsequent hydrolysis of OAD to prepare LCN. The LCN was further added into the polyvinyl alcohol (PVA) matrix endowed excellent UV shielding property and thermal stability for the PVA/LCN films. This study was aimed to provide an environmentally friendly method on the production and application of LCN from bamboo by employing microwave treatment from the perspective of supramolecular level. [Display omitted] • Both the intermolecular and intramolecular hydrogen bonds were altered. • Cellulose molecules were loosely connected with smaller interplanar spacing. • LCN was produced from MTB with lower chemical consumption. [ABSTRACT FROM AUTHOR]

Microwave-assisted liquefaction of rape straw in methanol was conducted to collect the liquefied residues for the extraction of cellulose nanocrystals (CNCs). The liquefied residue with content of 23.44% from 180°C/7.5 min was used to fibrillate CNCs with dilute alkali (2% NaOH) and hydrogen peroxide (5% H2O2) treatments, followed by ultrasonication for 15 min. The FT-IR spectra and SEM images revealed that the liquefied residue from 180°C/7.5 min exhibited a relatively homogeneous texture and a huge surface with cellulose as core structure. The retained hemicelluloses and other impurities in the liquefied residue were eliminated by 2% NaOH treatment, and the surface and accessibility of the alkali treated sample were significantly increased by 5% H2O2 treatment. The TEM images confirmed the CNCs had an average diameter of 12.59 nm. The CNCs had good thermal stability with a maximum weight loss temperature of 376.5°C. [ABSTRACT FROM AUTHOR]

Ethanol and hexane mixture agent microwave-assisted extraction ( MAE) method was conducted to extract peony ( Paeonia suffruticosa Andr.) seed oil ( PSO). The aim of the study was to optimise the extraction for both yield and energy consumption in mixture agent MAE. The highest oil yield (34.49%) and lowest unit energy consumption (14 125.4 J g−1) were obtained under optimum extraction condition: solid-liquid ratio 0.37 g mL−1, extraction time 3.72 min, extraction temperature 80.92 °C, ethanol ratio 20.00%. GC- MS results showed that unsaturated fatty acids ( UFAs) accounted for 88.60% of total fatty acids in PSO. Moreover, linolenic acid content of 37.35% was the highest UFA and caused PSO to possess good nutrition. PSO in DPPH radical scavenging experiment showed that IC50 value of 28.80 ± 2.13 mg mL−1 exhibited strong antioxidant property. All experiments proved that mixed solvent MAE is an efficient and promising method to extract PSO. This method can effectively reduce the energy consumption and extraction time. [ABSTRACT FROM AUTHOR]

Sand blasting was proposed as a surface modification approach on the small diameter and thin culm wall bamboo species of Neosinocalamus affinis for the fabrication of laminated bamboo composites. The results revealed that sand blasting modification could almost wipe off the wax and silicons deposited on the green and yellow surfaces by removing or damaging the suberized and siliceous cells, pith membrane, and compact arranged sclereid, resulting in the uncovering of the porous structure. Meanwhile, the surface roughness was also increased by the sand blasting modification, which provided appropriate surface characteristics for resin permeability. The weight loss after sand blasting modification was merely 4.3%, and the internal structure was mostly preserved. Average modulus of rupture, modulus of elasticity, and compressive strength of the laminated bamboo composites fabricated from Neosinocalamus affinis were comparable to previous reported similar products and were higher than those from Phyllostachys pubescens and Phyllostachys bissetii. The findings in this study revealed that sand blasting modification could be used as an efficient and environmentally friendly approach on the high yield production of laminated bamboo composites from small diameter and thin culm wall bamboo species. • Sand blasting was efficient in cleaning up non-lignocellulosic substances on bamboo surfaces. • Laminated bamboo composites with yield of 96% was successfully fabricated. • The composites showed comparable mechanical strength with previously reported products. • Sand blasting surface modification was suitable for small diameter bamboo utilization. [ABSTRACT FROM AUTHOR]

Soy protein-based adhesives are biodegradable and renewable and are widely used in wood based products. However, the application of soy protein (SP) adhesives is also limited by its poor mildew resistance, water resistance and bonding strength, so it is necessary to find ways to promote the comprehensive performance of SP adhesives. In this study, hydroxymethyl l -tyrosine (TYF) synthesized from l -tyrosine and formaldehyde was used to enhance the mildew resistance and bonding strength of the SP adhesive. The results showed that the cross-linking reactions of TYF and SP molecules and the condensation reactions between an appropriate amount of TYF molecules enhanced the force between SP molecules and made the cross-linked structure more stable and compact, resulting in a significant increase in the bonding strength of the SP adhesive modified by TYF. Compared with the plywood prepared by the SPI adhesive, the SP adhesive modified with 6 wt% TYF had the best bonding performance, and its dry and wet shear strength were increased by 49.3% and 110.1%, respectively. In addition, l -tyrosine Schiff base, which had antibacterial, bactericidal and antiviral effects, was produced by dehydration of TYF molecules, so the mildew resistance of SP adhesives modified by TYF was effectively enhanced. [ABSTRACT FROM AUTHOR]

Although soy protein (SP) adhesives have shown great potential in promoting the green and sustainable development of the wood industry, the practical application of SP adhesives is limited by poor performance (bonging strength, mold resistance and water resistance). Cross-linking modification is considered to be the most effective modification method for SP adhesives. In this work, non-antibacterial l -tyrosine (TYR) was treated with epichlorohydrin to graft multiple epoxy groups and transformed into tetraepoxy l -tyrosine (ETY). Interestingly, ETY exhibited obvious antifungal properties with a bacteriostatic rate as high as 98.3%. Adding a low amount (3 wt%) of ETY, the wet shear strength of the modified adhesive was 169.1% higher than that of the pristine SP adhesive, reaching 1.83 MPa. Moreover, in an environment of 28 °C and 80% humidity, both uncured and cured SP adhesives (with 3 wt% ETY) exhibited an anti-mold period of more than 30 days. Therefore, this work reveals that non-antibacterial bio-based materials may be endowed with antibacterial properties through epoxidation and transformed into multifunctional modifiers, and provides a new way for the development of high-strength antibacterial bio-based adhesives. • Non-antibacterial bio-based materials may be endowed with antibacterial properties through epoxidation. • The antibacterial rate of tetraepoxy l -tyrosine is as high as 98.3%. • High performance adhesive modified by low amount of ETY. • The wet shear strength of the adhesive (with 3 wt% ETY) increased by 169.1% to 1.83 MPa. • Modified adhesives (with 3 wt% ETY) showed an anti-mold period of more than 30 days. [ABSTRACT FROM AUTHOR]

[Display omitted] • The fracture toughness of bamboo increased with the water content. • One function of water in bamboo was to soften the cell wall, which increased the plastic deformation of bamboo and impeded the propagation of cracks. • The other function of water in bamboo was to make the fracture surface smooth, which indicates that cracks propagated easily. • These two functions of water also affected the fracture toughness of other materials. Most engineering materials are chosen based on their fracture toughness rather than their strength. However, water molecules in air would interact with these materials and affect their fracture toughness, especially for the biomass materials. Bamboo is an excellent engineering material, and the effect of water content on its fracture toughness was still unknown. Thus, in this study, the effect of water on bamboo's fracture toughness was investigated, and the mechanism behind it was discussed. The results showed that the growth fracture toughness increased by 7.6 J/m2 per 1 % increase of environmental relative humidity. The effect of the water includes both promoting and impeding crack growth. The hydrated amorphous layer in cell wall impeded the propagation of cracks, while the water layer on cell wall promoted the propagation of cracks. The former effect was the stronger one in bamboo, and thus the fracture toughness increased. This competition mechanism stemmed from water was also found useful to explain the fracture properties of other kinds of materials, such as wood, stone, and clay. Therefore, a reasonable hypothesis to explain the mechanism of water content on fracture toughness of bamboo and even other materials was concluded in this study. [ABSTRACT FROM AUTHOR]

This work prepared a double-cross-linked biohybrid aerogel (DCBA) bead biosorbent from waste bamboo paper and chitosan by sequential physical (hydrogen bonding and electrostatic interaction between -COO- and -NH 3 + groups) and chemical (polymerization reaction between -COOH and -NH 2 , dehydration condensation between Si-OH and -OH) cross-linkings. The resulting DCBA bead was applied to remove cationic (Methylene blue, MB) and anionic (Congo red, CR) dyes in both single and binary systems. The MB and CR adsorption capacities of DCBA bead increased with increasing adsorbent dosage, contact time, temperature and initial dye concentration. With increasing solution pH, the MB adsorption capacity increased, while that for CR increased first and then decreased. The maximal adsorption capacities for MB and CR were 653.3 and 559.6 mg/g, respectively, in the single system. The thermodynamic analysis results showed a spontaneous and endothermic adsorption process. DCBA bead had a good stability and reusability with the removal efficiencies of 49.4% and 60.6% for MB and CR, respectively, after five cycles of adsorption-desorption. In the binary system, the adsorption of MB was inhibited by CR, while the removal of CR was enhanced by MB. • DCBA biosorbent was prepared using double cross-linking method. • The DCBA bead exhibited excellent stability and recyclability. • The maximum adsorption capacities of MB was 653.3 mg/g. • The maximum adsorption capacities of CR was 559.6 mg/g. • The adsorption mechanisms in single and binary systems were investigated. [ABSTRACT FROM AUTHOR]

[Display omitted] • Micro-sized bamboo cells with lignin (4–10 %) were prepared via microwave liquefaction. • Nanocellulose with width less than 10 nm was obtained in TBAA/DMSO system. • Highly transparent films with good UVA (82 %) and UVB (99 %) absorbing were fabricated. Bamboo is a potential resource to produce renewable materials with replacement of plastic. In this study, cellulose-rich bamboo fibers and parenchyma with partial lignin (4–10 %) retained were prepared from microwave liquefaction, thereafter nanocellulose with uniform diameter (less than 10 nm) distribution were obtained by directly dissolving the cellulose-rich bamboo cells in TBAA/DMSO system. By solvent-casting, transparent nanocellulose films with efficient UV-absorbing ability especially the excellent UVA (82 %) and UVB (99 %) absorbing performance were fabricated. The films showed homogeneous network structure and had good tensile strength (15−25 MPa). Changes in cellulose crystallinity structure was observed during the film preparation process. Results also showed that the lignin in the cellulose-rich bamboo could distribute uniformly in the nanocellulose films and had effect on the film formation, UV-absorbing ability and physical-mechanical properties. Overall, microwave liquefaction coupling with TBAA/DMSO dissolving system could be selected as a facile and simple method to produce transparent nanocellulose films with UV-absorbing property. [ABSTRACT FROM AUTHOR]

In this work, ethyl acetate (EA) and trichloromethane (TR) extracts were extracted from Phoebezhennan wood residues and the extracts were then applied to the preparation of UV shielding films (UV-SF). The results revealed that substances including olefins, phenols and alcohols were found in both EA and TR extracts, accounting for about 45% of all the detected substances. The two extracts had similar thermal stability and both had strong UV shielding ability. When the relative percentage of the extract is 1 wt% in solution, the extract solution almost blocked 100% of the UV-B (280–315 nm), and UV-A (315–400 nm). Two kinds of UV-SF were successfully prepared by adding the two extracts into polylactic acid (PLA) matrix. The UV-SF with the addition of 24 wt% of the extractive blocked 100% of the UV-B (280–315 nm) and more than 80% of the UV-A (315–400 nm). Moreover, the UV shielding performance of the UV-SF was still stable even after strong UV irradiation. Though the addition of extracts could somewhat decrease the thermal stability of the film, its effect on the end-use of the film was ignorable. EA extracts had less effect on the tensile properties of the films than TR extracts as the content of the extract reached 18%. The results of this study could provide fundamental information on the potential utilization of the extracts from Phoebe zhennan wood residues on the preparation of biobased UV shielding materials. [ABSTRACT FROM AUTHOR]