Effects of silver nanoparticles and fungal degradation on density and chemical composition of heat-treated poplar wood (Populous euroamerica)

Effects of silver nanoparticles and fungal degradation on the weight loss and chemical composition of heat-treated poplar wood were studied. Wood blocks were impregnated with a 400 ppm nanosilver suspension under 3 bar pressure for 20 min using Lowry process (edited empty cell). Heat-treatment was carried out at 135, 160 and 185 °C. Specimens were divided into 4 groups; control, nanosilver impregnated, heat-treated and impregnated- heat treated specimens (135, 160 and 185 °C). All samples from the internal and superficial parts of the blocks were exposed to the white rot fungus Trametes versicolor. The results of heat-treated samples indicated higher amount of Klason lignin and extractives, but lower holocellulose and cellulose content. Furthermore, heat-treatment illustrated an increasing effect on the fungal resistance. For all the properties, significant difference was found between the internal and superficial test specimens. Nanosilver impregnation had an intensifying effect on the results of the heat-treatment.     

Study on infection behavior and characteristics of poplar wood dyed by Lasiodiplodia theobromae

European Journal of Wood and Wood Products - The technology of dyeing wood by microorganisms is a kind of pollution-free and sustainable wood dyeing technology. To achieve fast and rich dyeing of...     

Effects of chemical modification on the mechanical properties of wood

Chemical modification has been recognized as an efficient strategy for dimensionally stabilizing wood and protecting it from environmental damage, such as deterioration due to weathering and fungal decay during the service period. Studies reported in the literature mainly concern the establishment of workable modification techniques, testing methodologies, and assessment of the durability of modified wood. The development of wood modification techniques has recently been reviewed; limited information is however given on the effects of chemical modification on the mechanical properties of wood that are of importance to it as an engineering material. This paper reviews the effects of wood modification, typically by heat treatments and impregnation with low molecular weight resins, reactive monomers, or hot melting paraffins on the mechanical properties of wood. The modifying variables associated with mechanical properties of wood such as wood species, treating temperature and time, catalyst, type of solvent, weight percent gain, and molecular structures of the modifying agent were analysed and the results interpreted. The reasons for changes in the mechanical properties of wood are discussed.     

Chemical,morphological and structural characteristics of crossbred wool fibers

Abstract

Crossbreeding of a local sheep called Ghezel thick wool with Arkharmerino fine wool is one of the interest studies in the last decade to improve the local sheep’s products quality. In this study, the chemical and mechanical properties of Arkharmerino, Ghezel and their first and second-generation wool fibers were investigated. The diameter, length and tensile properties of wool fibers were studied. The Fourier transform infrared spectroscopy, scanning electron microscope, X-ray diffraction and energy dispersive X-ray spectrum were also performed to evaluate the morphological and physical characteristics of all samples. The results showed that crossbreeding Ghezel ewes with Arkharmerino rams led to improving the wool fiber characteristics from chemical and physical properties points of view in the final application. The higher fineness, higher length, lighter color and higher tenacity were resulting from Arkharmerino–Ghezel in the second generation in comparison with Ghezel wool fibers.     

压缩预处理中压缩速率对杨木浸注性能的影响研究

以杨木为研究对象,利用压缩预处理的方法,选用0.5mm/min、1mm/min、3mm/min、5mm/min和10mm/min五种压缩速率将木材压缩到压缩率60%,研究其对浸注性能的影响.结果表明:不同的压缩速率均可以有效提高木材的浸注效率,但综合浸注量、恢复率及力学性能各方面因素考虑,3mm/min为最佳的压缩浸注速率     

Sorption of PAHs by aspen wood fibers as affected by chemical alterations

Sorption and desorption experiments for phenanthrene and pyrene, using untreated (UTR) and treated (bleaching and hydrolysis) aspen wood fibers, were examined to understand their sorption mechanisms. The wood was characterized by elemental and porosity analysis, solid-state 13C NMR, and diffuse reflectance infrared Fourier transform spectroscopy. Bleaching removed aromatic components, yielding the highest polarity and increased porosity, whereas hydrolysis removed a large percentage of hemicellulose and parts of amorphous cellulose, producing a matrix with more aromatic moieties, lower polarity, and higher porosity than that of the UTR wood fibers. All isotherms fitted well to the Freundlich equation and the N values had a decreasing trend from bleached (BL), UTR, low-temperature hydrolyzed to high-temperature hydrolyzed (HHY) wood fibers. BL fibers had the lowest sorption capacity (Koc) for both phenanthrene and pyrene. HHY had the highest Koc because of its high aromatic carbon content and low polarity. The results suggest that aromatic moieties and polarity of wood fibers play significant roles in polycyclic aromatic hydrocarbon (PAHs) sorption and desorption. Thus, both aromatic components and polarity should be considered when predicting the PAHs sorption/desorption by aspen wood fibers. This study demonstrated that aspen wood fibers are a potential sorbentfor PAHs and that chemical modifications of the wood matrix can effectively increase its sorption efficiency. These results may have implications for the treatment of stormwater runoff and other PAH-contaminated liquids.     

Effects of growth rate, sex and slaughter weight on fat characteristics of pork bellies

A total of 119 Duroc × (Landrace × Yorkshire) commercial pigs were used to investigate the effect of growth rate (fast vs slow), sex (barrows vs gilts) and slaughter liveweight (107, 115 and 125 kg) on the fat characteristics of bellies. Backfat thickness increased with weight (P < 0.01). Fat firmness score was only affected by sex (P < 0.05), with gilts showing softer bellies than barrows. Fat from gilts and slow growing pigs showed a lower proportion of saturated fatty acids (SFA; P < 0.001 and P < 0.01, respectively), a higher proportion of linoleic fatty acid (C18:2 n-6; P < 0.01), a higher proportion of total polyunsaturated fatty acids (PUFA; P < 0.001 and P < 0.01, respectively), and an increased iodine value (P < 0.001). Consequently, the fat from these bellies had higher PUFA:SFA ratios (P < 0.001) and n-6:n-3 ratios (P < 0.01 and P < 0.001, respectively) than that from the bellies of barrows and fast growing pigs. The belly fat from barrows and fast growing pigs had higher stearic fatty acid (C18:0; P < 0.01) and SFA proportions (P < 0.001 and P < 0.01, respectively) than that from gilts and slow growing pigs. The belly fat from gilts and slow growing pigs would better meet the health requirements of consumers, but it is more prone to rancidity during storage leading to a potentially reduced bacon shelf-life.     

速生杨木热压处理的研究

采用试验用热压机对速生杨木进行热压处理,比较不同条件下压缩对试材主要物理力学性能的影响。试验表明:热压处理对压缩木材的变形回复有较大的抑制作用,而且随着压缩率的增大,杨木试件的物理力学性能有明显改善。     

Modulus of elasticity of I-214 young poplar wood from standing trees to sawn timber: influence of the age and stand density

The poplar wood industry chain from planted forests takes a strategic position for the creation of a competitive, profitable, and highly technological bioeconomy in the world. Niche sectors such as buildings can find in poplar wood an effective ally to reduce its carbon footprint and ecological backpack. For the poplar wood, it is important to understand the huge significance of the proper silvicultural management of a plantation and to characterize the raw material. In this context, this paper carries out such characterization for the particular case of young plantations of the clone I-214 (Populus × euroamericana (Dode) Guinier), commonly used for its high growth rate. The acoustic non-destructive characterization of poplar wood is carried out from standing trees, logs and sawn timber and then compared with the one obtained through destructive mechanical tests. The study shows that growth parameters are highly affected by the age and moderately affected by stand density, while mechanical properties are strongly affected by the age and less affected by the stand density. The study also shows high values of the linear regression coefficients between the mechanical properties obtained on standing trees, logs, and sawn timber using non-destructive and destructive methods (R²?=?0.7 for all three cases), greater than those obtained for other species. A good linear fitting was obtained between the tree and log velocities (R²?=?0.76) and between the tree and log elastic moduli (R²?=?0.85). Consequently, the evaluation of the mechanical properties employing the optimized acoustic protocol provides a reliable characterization for the poplar wood.

     

Effect of heat treatment duration on the thermal conductivity of spruce and poplar wood

Changes in the thermal conductivity and density of Pannónia poplar (Populus x euramericana cv. Pannónia) and spruce (Picea abies) caused by heat treatment were examined. The specimens were treated at 180?°C for 15, 25 and 35 h. Treatment duration had different impact on both the density and the thermal conductivity of poplar and spruce. The density of poplar decreased by 9.1, 12.1 and 13.4%, and the thermal conductivity decreased by 16.9, 24.0, 29.1% after 15, 25 and 35 h of treatment, respectively. In the case of spruce, the density decreased by 5.2, 7.6 and 8.7%, and the heat conductivity by 7.4, 14.1 and 22.0%, respectively.     

Effects of laser parameters on the width of color change area of poplar wood surface during a single irradiation

Due to the high efficiency, flexible moving trajectory and good controllability, laser surface treatment is a modification method used for wood materials, which could be applied to change the wood properties of color, wettability, surface roughness, etc. These surface properties directly affect the wood products coating performance, such as coating adhesion and surface gloss. To reveal the width of the heat-affected zone under laser treatment with different laser parameter combinations, the width of color change area (WCCA) during a single irradiation was measured. The laser power, feed speed and focus plane position were chosen as input parameters. The response surface methodology was selected to arrange the experiments, analyze the influences of laser parameters on WCCA and establish a relationship between laser parameters and WCCA. The results showed that the laser power and focus plane position had significant influences on WCCA. The values of WCCA increased with increased laser power and focus plane position within certain limit. The quadratic model for establishing the relationship between laser parameters and WCCA was significant. The value of correlation coefficient (R²) is very close to 1, which means that the model could give an accurate prediction of WCCA under variable modification parameter combinations.

     

Effects of autografting ovarian tissue,ovariectomy and implanting on growth rate and carcass characteristics of feedlot heifers

Ninety heifers sired by Charolais or Red Poll bulls were utilised in two trials involving ovariectomy, ovarian tissue transplants (autografts) andlor an anabolic implant. In trial 1, four treatments were imposed upon 60 heifers: (1) autograft, (2) autograft plus Synovex-H® implant, (3) vaginal ovariectomy plus implant, and (4) intact plus implant. Three replications of five heifers per treatment were fed a finishing diet until heifers weighed approximately 432 kg. Autografed-implanted heifers exhibited a greater average daily gain than non-implanted autografted heifers (P < 0.05). No treatment effects were detected for feed eficiency or dressing percentage. Carcasses from autografted heifers merited higher marbling scores and USDA quality grades than did those of ovariectomised-implanted heifers. Fat thickness tended to be greater for autografted heifers than for heifers in the implant treatment groups (P <0.l0). Non-implanted autografted heifers had smaller ribeye areas, more kidney, pelvic and heart fat, and higher numerical USDA yield grades. Shear force values and taste panel scores for meat favoured non-implanted autografted heifers. In trial 2, 30 heifers were autografted, ovariectomised via high lumbar laparotomy, or left as intact controls. Heifers in trial 2 were fed a finishing diet until heifers reached 1.2 ern average backfat thickness. Intact heifers tended to gain weight more rapidly than did ovariectomised heifers. Ovarian cell types were detected at the graft sites of only four of the 10 autografted heifers upon post-mortem histological examination. Very low levels of oestrogen were present in the fluid aspirated from three of the apparently successful grafts. However, growth rate was not superior for these three heifers.     

坡向对马占相思人工林生长和材质的影响

通过对阴坡和阳坡马占相思人工林生长特性和木材物理力学性质的测定和比较分析，结果表明：阳坡马占相思人工林林分胸径、冠幅、树高和枝下高大于阴坡；阴坡马占相思人工林木材密度、干缩系数和各项力学性质指标均小于阳坡马占相思人工林；阴坡马古相思人工林木材物理力学性质的分散程度略大于阳坡马占相思人工林，差异显著性t检验表明：阴坡和阳坡马古相思人工林林分胸径、树高、冠幅和枝下高以及差异干缩、顺纹抗压强度、抗弯强度、抗弯弹性模量、弦面抗劈力差异均为极显著或显著；而木材密度、径向干缩系数、弦向干缩系数和体积干缩系数以及顺纹抗剪强度、硬度、径面抗劈力和冲击韧性均差异不显著。研究结果为马占相思人工林培育和木材合理利用提供科学依据。     

The effect of carbon fibers, glass fibers and nanoclay on wood flour-polypropylene composite properties

This study investigates the influence of different types of reinforcing fillers on the mechanical properties and wettability of wood–plastic composite material. Micro-sized glass fibers (GF) and carbon fibers (CF) and nano-sized montmorillonite (MMT) were used to reinforce a polypropylene/wood flour composite. Clear improvement of the tensile strength and modulus, up to 20 and 29 %, respectively, was observed when GF was loaded; the impact strength was reduced by 7 %; the hardness of the composite was improved by up to 7 %. No significant change in the tensile strength was observed after the CF loading; the tensile modulus was improved by 18 %; the impact strength of the composite was reduced and hardness was improved by 19 and 7 %, respectively. The MMT enhanced the tensile modulus by 34 %; the other studied mechanical properties, tensile and impact strengths, as well as the hardness of the composite decreased by 12, 32 and 15 %, respectively. The water absorption level decreased with all three filler type loadings. The morphology of the composites was examined using a scanning electron microscope (SEM).     

西南桦木材化学成分及其变异的研究

按照我国木材化学成分分析标准,对人工林西南桦木材化学成分进行了测定,结果表明含量分别为:纤维素47.31%,多戊糖23.99%,木质素24.57%,热水抽提物4.41%,1%NaOH抽提物15.15%,笨醇抽提物1.80%,pH值4.61;以上7个指标在树干不同高度的差异均未达到显著性水平;热水、1%NaOH抽提物含量和pH值在不同树龄间的差异达到了1%显著性水平;苯醇抽提物含量达到5%显著性水平.主要化学成分含量的差异不显著.比较分析认为,就木材化学成分而言,西南桦是比较理想的板材和造纸原料.     

干燥对二次纤维微观结构及其角质化的影响

通过改变干燥时间,研究了纤维微观结构的变化与二次纤维角质化的关系。结果表明：随着干燥时间的增加,纤维平均长度变化不大,卷曲指数和平均扭结指数呈现下降趋势,纤维变直。干燥过程中角质化主要发生在前10min,从干燥开始到干燥10min时,角质化程度从23.7%上升至28.4%。纤维N.O’KI值的变化趋势与纤维角质化的变化趋势相同。干燥过程对二次纤维的微观结构及角质化产生不可逆的影响,这种影响不会因为纤维的再润湿而得到完全恢复。随着干燥时间的增加,纤维间内酯含量增加。从干燥5min到20min时,内酯含量增加了178.2%,且在再润湿后干燥的过程中,内酯含量进一步增加。     

Combined effect of organosolv delignification/polymerization on the set recovery of densified poplar wood

European Journal of Wood and Wood Products - According to recent literature, delignification could be a new approach to enhance mechanical properties of densified wood. In the present study, the...     

Properties of fast-growing poplar wood simultaneously treated with dye and flame retardant

Simultaneous dyeing and inflaming retarding treatment improves both the aesthetic aspects and the safety value of fast-growing tree species. This study investigated the effects of water bath temperature, dye concentration, flame retardant concentration and dipping time on dye uptake and limited oxygen index of simultaneously dyed and fire-retardant-treated wood veneer. Through comprehensive analysis, an improved process was obtained and wood with these improved properties was prepared. Analyses of chemical structure and thermal stability of prepared wood samples were conducted, as well as crystallinity and microscopic morphologies using Fourier transform infrared spectroscopy, thermogravimetric, plus X-ray diffraction and scanning electron microscopy and energy-dispersive X-ray spectroscopy. Results showed that dye uptake and limited oxygen index had a similar increasing tendency with increased water bath temperature and dipping time. Moreover, dye uptake improved upon addition of flame retardant, while limited oxygen index decreased as dye concentration increases. Flame retardant combined with the wood fiber and was in the absence of chemical reaction with the dye used. Dye and flame retardant molecules diffused into the cell cavity, wood vessel and aperture. Furthermore, the fire-retardant properties and crystallinity of wood simultaneously treated with dye and flame retardant were both improved.