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growth ring-dependent Fracture Toughness of Sea Urchin Spines Estimated by Boundary Effect Model

Journal of Bionic Engineering 2022年第5期19卷 1472-1480页

作者： Xiaona Liu Simin Liang Yingying Li Hongmei Ji Xiaowu Li Department of Materials Physics and Chemistry School of Material Science and EngineeringNortheastern UniversityShenyang 110819China Key Laboratory for Anistropy and Texture of Materials Ministry of EducationNortheastern UniversityShenyang 110819China State key Laboratory of Rolling and Automation Northeastern UniversityShenyang 110819China

Although the fracture behavior of sea urchin spines has been extensively investigated,there is as yet a lack of quantitative estimation on the effect of growth rings on the fracture properties of sea urchin *** sea urchin spines,much denser pores present in growth rings rather than porous *** tensile strength and fracture toughness of sea urchin spine samples with different numbers of growth rings are measured by the Boundary Effect Model(BEM).The experimental results of single-edge notched three-point bending tests indicate that the BEM is an appropriate method to estimate the fracture toughness of the present porous sea urchin spines,and the number of growth rings plays an important role in the fracture properties of ***,the tensile strength and fracture toughness of sea urchin spines can be significantly improved with the increase in the number of growth rings,and their fracture toughness can even reach a relatively high value compared with some other porous materials with an identical *** present research findings are expected to provide a fundamental insight into the design of high-performance bionic materials with a highly porous structure.

关键词： Sea urchin spine growth ring Boundary Effect Model Porous structure Tensile strength Fracture toughness

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growth rings of Roots in Perennial Forbs in Duolun Grassland, Inner Mongolia, China

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Journal of Integrative Plant Biology 2007年第2期49卷 144-149页

作者： Yong-Bo Liu Qi-Bin Zhang Laboratory of Quantitative Vegetation Ecology Institute of Botany the Chinese Academy of Sciences Beijing 100093 China Graduate University of the Chinese Academy of Sciences Beijing 100049 China

Annual growth rings of roots in perennial forbs have been used in studies of climate change and the ecology of grasslands. However, little has been done in this aspect of research in China. In this study, we report the characteristics of growth rings in the main roots of 13 herb species sampled in Duolun of the Inner Mongolia grassland in northern China. The results show that around two thirds of the species possess clearly demarcated annual rings in the root xylem. Some species of the same genera show different patterns in anatomical structure of the root xylem. Standardized annual ring widths of three species, Potentilla anserine L., Cymbaria dahurica L. and Lespedeza daurica （Laxm.） Schindh, show a common linear trend, indicating a continued favorable growth condition in the sampling sites. Our results provide evidence that growth rings in roots of some perennial forbs in the Inner Mongolia grassland can serve as a new and useful indicator of past changes in the grassland environment.

关键词： China growth ring herb-chronology perennial forbs.

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Responses of radial growth, wood density and fiber traits to planting space in poplar plantations at a lowland site

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Journal of Forestry Research 2022年第3期33卷 963-976页

作者： Yanhua Zhang Shengzuo Fang Ye Tian Linlin Wang Yi Lv College of Forestry Nanjing Forestry UniversityNanjing210037People’s Republic of China Co-Innovation Center for Sustainable Forestry in Southern China Nanjing Forestry UniversityNanjing210037People’s Republic of China

Poplar is raw material for various panel, paper and fiber products. The 12 sample trees of clone Nanlin-895 from four spacings were destructively harvested after thirteen growing seasons to assess the influence of spacing on radial growth and wood properties. Spacing significantly affected tree-ring width and wood basic density (p ring width, wood basic density and fiber traits were observed among the four sampling directions in discs taken at 1.3 m for each spacing. growth rings from the pith and tree heights had significant effects on wood basic density and fiber anatomical characteristics, highlighting obvious temporal-spatial variations. Pearson correlation analysis showed a significantly negative relationship of tree-ring width to wood basic density, fiber length and fiber width, but a significantly positive relationship to hemicellulose. There was no relationship with cellulose and lignin contents. Based on a comprehensive assessment by the TOPSIS method, the 6 m × 6 m spacing is recommended for producing wood fiber at similar sites in the future.

关键词： Planting density growth ring Fiber morphology Chemical composition Temporal-spatial variation

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