scholarly journals Comparative studies on wood structure and microtensile properties between compression and opposite wood fibers of Chinese fir plantation

2021 ◽  
Vol 67 (1) ◽  
Author(s):  
Zhu Li ◽  
Tianyi Zhan ◽  
Michaela Eder ◽  
Jiali Jiang ◽  
Jianxiong Lyu ◽  
...  
Keyword(s):  
Cellulose Microfibril ◽  
Microfibril Angle ◽  
Tensile Modulus ◽  
Scientific Basis ◽  
Ultimate Tensile Stress ◽  
Chinese Fir ◽  
Cellulose Content ◽  
Wood Fibers ◽  
Opposite Wood ◽  
Chinese Fir Plantation

AbstractThe microtensile properties of mechanically isolated compression wood (CW) and opposite wood (OW) tracheids of Chinese fir (Cunninghamia lanceolata) were investigated and discussed with respect to their structure. Major differences in the tensile modulus and ultimate tensile stress were found between CW and OW fibers. Compared to OW, CW showed a larger cellulose microfibril angle, less cellulose content and probably more pits, resulting in lower tensile properties. These findings contribute to a further understanding of the structural–mechanical relationships of Chinese fir wood at the cell and cell wall level, and provide a scientific basis for better utilization of plantation softwood.

scholarly journals Screening, Identification and Growth-Promotion Products of Multifunctional Bacteria in a Chinese Fir Plantation

Forests ◽  
2021 ◽  
Vol 12 (2) ◽  
pp. 120
Author(s):  
Guangyu Zhao ◽  
Yihui Wei ◽  
Jiaqi Chen ◽  
Yuhong Dong ◽  
Lingyu Hou ◽  
...  
Keyword(s):  
High Efficiency ◽  
Growth Promotion ◽  
Nitrogenase Activity ◽  
Acc Deaminase ◽  
Inorganic Phosphorus ◽  
Chinese Fir ◽  
Biochemical Tests ◽  
Growth Promoting ◽  
Chinese Fir Plantation ◽  
Physiological And Biochemical

Purpose: This research was aimed to screen and identify multifunctional phosphorus-dissolving bacteria of a Chinese fir (Cunninghamia lanceolata) plantation and study its phosphorus-dissolving characteristics in order to provide strain resources and a theoretical basis for developing the appropriate bacterial fertilizer of a Chinese fir plantation. Methods: First, phosphorus-dissolving bacteria were isolated from the woodland soil of a Chinese fir plantation by Pikovskava inorganic phosphorus medium (PVK). Then, some growth-promoting indicators of primary screening strains were determined, including the capacity of phosphorus-solubilized, nitrogenase activity, 1-aminocyclopropane-1-carboxylic acid (ACC) deaminase activity, production of indole-3-acetic acid (IAA), secretion of iron carrier and so on. Finally, the screening multifunctional phosphorus-dissolving bacteria were identified, which were combined with colony characteristics, physiological and biochemical tests and molecular biotechnology. Results: (1) Thirteen phosphorus-dissolving bacteria were isolated and screened in total, and P5 (195.61 mg·L−1) had the strongest capacity of phosphorus-solubilized. Five phosphorus-dissolving bacteria were provided with nitrogenase activity, and the highest activity of nitrogenase was P10 and P5 (71.90 C2H4 nmol·mL−1·h−1 and 71.00 C2H4 nmol·mL−1·h−1, respectively). Four strains were provided with ACC deaminase activity, and the highest activity of ACC deaminase was P5 and P9, (0.74 μmol·mg−1·h−1 and 0.54 μmol·mg−1·h−1, respectively). Most strains could secrete IAA, and three strains of bacteria had a strong secretory ability, which could secrete IAA with a concentration greater than 15 mg·mL−1, and P5 was 18.00, P2 was 17.30, P6 was 15.59 (mg·mL−1). P5 produced carriers of iron better than others, and the ratio of the diameter of the iron production carrier ring to the diameter of the colony was 1.80, respectively, which was significantly higher than other strains. Combining all kinds of factors, P5 multifunctional phosphorus-dissolving bacteria were screened for eventual further study. (2) Strain P5 was identified as Burkholderia ubonensis, based on the colony characteristics, physiological and biochemical tests, 16SrDNA sequence analysis and phylogenetic tree construction. Conclusion: P5 has a variety of high-efficiency growth-promoting capabilities, and the ability to produce IAA, ACC deaminase activity and siderophore performance are significantly higher than other strains, which had great potential in the development of microbial fertilizer.

scholarly journals Dielectric Properties of Wood-Polymer Composites: Effects of Frequency, Fiber Nature, Proportion, and Chemical Composition

2021 ◽  
Vol 5 (6) ◽  
pp. 141
Author(s):  
Imen Elloumi ◽  
Ahmed Koubaa ◽  
Wassim Kharrat ◽  
Chedly Bradai ◽  
Ahmed Elloumi
Keyword(s):  
Dielectric Properties ◽  
Polymer Composites ◽  
Wide Frequency Range ◽  
Dielectric Constants ◽  
Cellulose Content ◽  
Wood Fibers ◽  
Low Frequencies ◽  
Wood Polymer ◽  
Wood Polymer Composites ◽  
New Applications

The characterization of the dielectric properties of wood–polymer composites (WPCs) is essential to understand their interaction with electromagnetic fields and evaluate their potential use for new applications. Thus, dielectric spectroscopy monitored the evolution of the dielectric properties of WPCs over a wide frequency range of 1 MHz to 1 GHz. WPCs were prepared using mixtures of different proportions (40%, 50%, and 60%) of wood and bark fibers from various species, high-density polyethylene, and maleated polyethylene (3%) by a two-step process, extrusion and compression molding. Results indicated that wood fibers modify the resistivity of polyethylene at low frequencies but have no effect at microwave frequencies. Increasing the fiber content increases the composites’ dielectric properties. The fibers’ cellulose content explains the variation in the dielectric properties of composites reinforced with fibers from different wood species. Indeed, composites with high cellulose content show higher dielectric constants.

Differences in the viscoelastic properties between earlywood and latewood in the growth rings of Chinese fir as analyzed by dynamic mechanical analysis (DMA) in the temperature range between −120°C and 120°C

Holzforschung ◽  
2019 ◽  
Vol 73 (3) ◽  
pp. 241-250 ◽  
Author(s):  
Anxin Li ◽  
Jiali Jiang ◽  
Jianxiong Lu
Keyword(s):  
Dynamic Mechanical Analysis ◽  
Microfibril Angle ◽  
Mechanical Analysis ◽  
Chinese Fir ◽  
Individual Growth ◽  
Tree Age ◽  
Dry Density ◽  
Mechanical Relaxation ◽  
Growth Rings ◽  
Dynamic Mechanical

AbstractTo clarify the viscoelasticity of earlywood (EW) and latewood (LW) within different growth rings of Chinese fir, the following data were determined: absolute dry density, percentage of tracheid cell wall, microfibril angle (MFA), modulus of elasticity (MOE), storage modulus (E′) and loss modulus (E″) within the 3rdand 6thgrowth rings (in heartwood, hW) and the 14thand 18thgrowth rings (in sapwood, sW). The E′ and E″ data were obtained by dynamic mechanical analysis (DMA) between −120°C and 120°C, at a heating rate of 1°C min−1at the frequencies of 1, 2, 5 and 10 Hz under a dynamic load amplitude of 10 μm. All measured data were different between EW and LW. In the same growth ring, LW had a greater MOE and larger E′ than those of EW due to the higher density of LW. The MOE and E′ increased for both EW and LW with increasing tree age. The variation of MFA in different growth rings of EW influenced the MOE and E′. Both density and the MFA affected the MOE and E′ in LW. The profiles of E″ plots vs. DMA temperature reveal two maxima around −12°C (β mechanical relaxation process, βMRP) and 12°C (αMRP). The LW-MRP maxima are higher than those of EW, but in both cases increased with tree age. No frequency dependence was seen for the αMRP, whereas the loss peak temperature (LPT) of the βMRP increased with increasing frequency of DMA. Almost no difference in αLPT was observed between the four EW growth rings, and their βLPTs were similar. The LW-αLPT was almost the same in the four growth rings, but the hW-βLPT was higher than that of sW. In addition, the apparent activation energy (ΔH) of the hW-βMRP was greater than that of sW in both EW and LW, and the EW data>LW data in individual growth rings. These differences can be explained tentatively that hW and EW contain more extractives than sW and LW, and the deposited of extractives limit the motion of molecular segments within the cell walls.

Effect of particle size, fiber content, and surface treatment on the mechanical properties of maple-reinforced LLDPE produced by rotational molding

2020 ◽  
pp. 096739112091660
Author(s):  
Fatima Ezzahra Hanana ◽  
Denis Rodrigue
Keyword(s):  
Mechanical Properties ◽  
Particle Size ◽  
Surface Treatment ◽  
Tensile Modulus ◽  
Complete Characterization ◽  
Fiber Content ◽  
Wood Fibers ◽  
Interface Quality ◽  
Effect Of Particle Size ◽  
The Impact

In this work, composites based on linear low-density polyethylene and maple wood fibers with and without surface treatment with maleated polyethylene (MAPE) were prepared by dry blending, followed by rotomolding to study the effect of particle size, fiber content, and surface treatment. From the samples produced, a complete characterization of the morphological and mechanical properties was performed. The results obtained showed that MAPE surface treatment improved the fiber–matrix interface quality, which improved the homogeneity, the thermal stability, and the mechanical properties of the composites. The results showed that the effect of particle size was significant as the tensile modulus increased by 7%, 40%, and 73% for 125–250, 250–355, and 355–500 µm at 30 wt% of maple fibers. The tensile strength also increased by 114% at the same fiber loading (30 wt%) when the particle size increased from 125–250 µm to 355–500 μm. Finally, the impact strength with 355–500 µm particles was 52% higher than for 125–250 µm particles at 30 wt%

Loss of soil organic carbon following natural forest conversion to Chinese fir plantation

2019 ◽  
Vol 449 ◽  
pp. 117476 ◽  
Author(s):  
Zhijie Yang ◽  
Shidong Chen ◽  
Xioafei Liu ◽  
Decheng Xiong ◽  
Chao Xu ◽  
...  
Keyword(s):  
Organic Carbon ◽  
Soil Organic Carbon ◽  
Chinese Fir ◽  
Natural Forest ◽  
Forest Conversion ◽  
Chinese Fir Plantation

Long-term effects of harvest residue management on soil total carbon and nitrogen concentrations of a replanted Chinese fir plantation

2013 ◽  
Vol 33 (13) ◽  
pp. 4205-4213
Author(s):  
胡振宏 HU Zhenhong ◽  
何宗明 HE Zongming ◽  
范少辉 FAN Shaohui ◽  
黄志群 HUANG Zhiqun ◽  
万晓华 WAN Xiaohua ◽  
...  
Keyword(s):  
Chinese Fir ◽  
Residue Management ◽  
Total Carbon ◽  
Long Term Effects ◽  
Carbon And Nitrogen ◽  
Nitrogen Concentrations ◽  
Chinese Fir Plantation ◽  
Harvest Residue

Characteristics of nutrient translocation before branch and leaf abscission in a second-generation Chinese fir plantation at different stand ages

2019 ◽  
Vol 39 (5) ◽  
Author(s):  
吕中诚 LÜ Zhongcheng ◽  
康文星 KANG Wenxing ◽  
黄志宏 HUANG Zhihong ◽  
赵仲辉 ZHAO Zhonghui ◽  
邓湘雯 DENG Xiangwen
Keyword(s):  
Second Generation ◽  
Chinese Fir ◽  
Leaf Abscission ◽  
Nutrient Translocation ◽  
Chinese Fir Plantation

Land Use Patterns Effect on Soil Anti-Erodibility in Low Mountain-Hilly Region

2011 ◽  
Vol 383-390 ◽  
pp. 3768-3774
Author(s):  
Shu Qin He ◽  
Zi Cheng Zheng ◽  
Ling Wang
Keyword(s):  
Land Use ◽  
Aggregate Stability ◽  
Chinese Fir ◽  
Land Use Patterns ◽  
Abandoned Farmland ◽  
Eucalyptus Plantation ◽  
Use Patterns ◽  
Water Stable Aggregate ◽  
Hilly Region ◽  
Chinese Fir Plantation

Land use patterns effect on soil anti-erodibility was studied by the combinative means of field investigation and laboratory analysis in low mountain-hilly region. The results showed that he five land use patterns had high proportion of aggregates at the size of >2 mm after dry sieving and had high proportion of aggregates at the size of <0.5 mm after wet sieving. Soil dispersion was mainly reflected in aggregate at the size of 0.05- 0.001 mm under different land use patterns. It was significantly different to land use patterns effect on soil anti-erodibility. Soil anti-erodibility in Chinese fir plantation and Eucalyptus plantation were stronger than those of tea plantation, loquat orchard and abandoned farmland. Water-stable aggregate stability was the highest in Chinese fir plantation, followed by eucalyptus plantations and tea plantations, and water-stable aggregate stability was the lowest in loquat orchards and abandoned farmland. Except for coarse dust, the other soil particle content of the same size had the different change under different land use patterns. The change of status of aggregate and degree of aggregation was opposite to the change of dispersive coefficient under different land use patterns. Water stability index and soil organic matter content in Chinese fir plantation, eucalyptus plantation and loquat orchard was higher than that of abandoned farmland and tea plantation. So, land use patterns of Chinese fir plantation and eucalyptus plantation was reasonable in study area.

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