scholarly journals Flexural anisotropy of rift-sawn softwood boards induced by the end-grain orientation

2021 ◽  
Vol 67 (1) ◽  
Author(s):  
Sung-Wook Hwang ◽  
Hiroshi Isoda ◽  
Takafumi Nakagawa ◽  
Junji Sugiyama
Keyword(s):  
Cell Walls ◽  
Grain Orientation ◽  
Cryptomeria Japonica ◽  
Chamaecyparis Obtusa ◽  
The Other ◽  
Deformation Mechanisms ◽  
Curved Surfaces ◽  
Hardwood Species ◽  
Populus Suaveolens ◽  
Softwood Species

AbstractInspired by the use of rift-sawn softwood board for covering curved surfaces in Kokerabuki, a traditional Japanese roofing method, we investigated the flexural anisotropy of wood caused by its end-grain orientation. We measured the flexural displacement of softwood species, Chamaecyparis obtusa and Cryptomeria japonica, and hardwood species, Populus suaveolens and Cerasus serrulata. For the softwood species, this was approximately five times longer for the rift-sawn specimens than for the other grain patterns. Using the replica method to measure the softwood tracheid deformation with different flexural displacements, we confirmed the different deformation mechanisms of the tracheid in the flat- and quarter-sawn specimens, and rift-sawn specimens. In the flat- and quarter-sawn woods, on-axis loading was generated, in which the stress was concentrated on the radial and tangential cell walls parallel to the direction of tension or compression. By contrast, in the rift-sawn wood, off-axis loading was generated, in which the stress was evenly distributed throughout the corner cell walls without the wall directly resisting the tensile and compressive forces. We also concluded that the tapered shape of the tracheid walls contributes to the excellent flexibility of rift-sawn softwood.

Contact And Non-Contact Proportions Between Axial Elements and Rays

IAWA Journal ◽  
2003 ◽  
Vol 24 (3) ◽  
pp. 247-255 ◽  
Author(s):  
Chunhua Zhang ◽  
Minoru Fujita ◽  
Keiji Takabe
Keyword(s):  
Cryptomeria Japonica ◽  
Chamaecyparis Obtusa ◽  
Pinus Thunbergii ◽  
Wood Fibers ◽  
Paulownia Tomentosa ◽  
Axial Parenchyma ◽  
Albizia Julibrissin ◽  
Contact Rates ◽  
Hardwood Species ◽  
Softwood Species

Proportions ofaxial elements without any spatial contacts with rays were investigated. Non-contact rates between rays and fusiforrn initials or axial parenchyma strands were examined in tangential sections of cambial or axial parenchyma zones in 21 hardwood species . The noncontact rates were very different among species, ranging from 0% to 76%. Serial trans verse sections of xylem were used to deterrnine the non-contact rates between rays and wood fibers in 3 of the 21 hardwood species having high non-contact rates of parenchyma strands . The noncontact rate of wood fibers was 49% in Albizia julibrissin (non-storied cambium), 30% in Paulownia tomentosa (non-storied cambium), and 52% in Pterocymbium beccarii (storied cambium). Tangential seetions of three softwood species, Pinus thunbergii, Cryptomeria japonica, and Chamaecyparis obtusa were used to investigate the contacts between rays and tracheids. All tracheids in the three species had contact with at least one ray, ranging from 1 to 15 rays.

Influence of grain direction in vibrational wood welding

Holzforschung ◽  
2005 ◽  
Vol 59 (1) ◽  
pp. 23-27 ◽  
Author(s):  
Milena Properzi ◽  
Jean-Michel Leban ◽  
Antonio Pizzi ◽  
Stephanie Wieland ◽  
Frederic Pichelin ◽  
...  
Keyword(s):  
Cell Walls ◽  
Grain Orientation ◽  
Marked Effect ◽  
Fibre Orientation ◽  
The Other ◽  
Matrix Composites ◽  
Lower Strength ◽  
Wood Grain ◽  
Strength Result ◽  
Fibre Matrix

Abstract Wood grain orientation differences in the two surfaces to be bonded yield bondlines of different strength in no-adhesives wood welding. Longitudinal wood grain bonding of tangential and radial wood sections yields an approximately 10% difference in strength results of the joint. Cross-grain (±90°) bonding yields instead a much lower strength result, roughly half that observed for pieces bonded with the grain parallel to each other. These differences can be explained by the very marked effect that homogeneity of fibre orientation is known to have on fibre–matrix composites. Oak yields lower results than beech and maple and is more sensitive to welding conditions. Differences in both anatomical and wood constituent composition can account for this difference in performance. Contrary to the other wood species, oak always presents joint bondlines where little or no increase in density at the interface is noticed. This explains its somewhat lower strength results. This is based on the different mode of bonding predominant in this species, while the other species present two different modes of bonding. Thus, two types of bondlines are observed by scanning electron microscopy (SEM): (i) bondlines where entangled fibre–matrix composites are formed at the interface and (ii) bondlines in which direct welding of the cell walls occurs, just by fused intercellular material or cell surface material. In this latter case the cells remain flat, without an entangled fibre–matrix composite being formed. This is the almost exclusively predominant case for oak. Both cases and even hybrid cases between the two have also been observed in beech.

Design of bending dominated lattice architectures with improved stiffness using hierarchy

2018 ◽  
Vol 233 (11) ◽  
pp. 3976-3993 ◽  
Author(s):  
Maen Alkhader ◽  
Mohammad Nazzal ◽  
Karim Louca
Keyword(s):  
Finite Element ◽  
Cell Walls ◽  
Detrimental Effect ◽  
Diamond Lattice ◽  
Finite Element Simulations ◽  
Deformation Mechanisms ◽  
Manufacturing Processes ◽  
Cellular Solids ◽  
Stiffness Anisotropy

Micro-architectured lattices are a promising subclass of cellular solids whose inner topologies can be tailored to enhance their stiffness. Generally, enhancing lattices' stiffness is achieved by increasing their connectivity. This strategy gives rise to a stiffer response by forcing lattices' ligaments to deform mainly in an axial manner. Conversely, this work is interested in developing micro-architectured lattices with enhanced stiffness, but whose cell walls deform in a flexural manner. Such structures can be more ductile and exhibit better energy mitigation abilities than their stretching dominated counterparts. Enhancing the stiffness of bending dominated lattices without increasing their connectivity can be realized by transforming them to hierarchical ones. This work explores, using experimentally verified finite element simulations, the effect of fractal-inspired hierarchy and customized nonfractal-based hierarchy on stiffness, anisotropy, and deformation mechanisms of an anisotropic bending dominated diamond lattice. Results show that fractal-inspired hierarchy can significantly enhance the stiffness of bending dominated lattices without affecting their deformation mechanisms or anisotropy level; ill-designed hierarchy can have a detrimental effect on lattice's stiffness; and customized hierarchy are more effective than fractal-inspired hierarchy in enhancing lattices' stiffness as well as can be more compatible with traditional, reliable, mass-producing manufacturing processes.

Über die quantitative Verteilung der Ascorbinsäure innerhalb der Pflanzenzelle

1964 ◽  
Vol 19 (12) ◽  
pp. 1146-1149 ◽  
Author(s):  
Wolfgang Franke ◽  
Ulrich Heber
Keyword(s):  
Ascorbic Acid ◽  
Acid Content ◽  
Cell Walls ◽  
Direct Evidence ◽  
Ascorbic Acid Content ◽  
The Other ◽  
Leaf Cell ◽  
Unequal Distribution ◽  
Freeze Dried ◽  
High Figure

Leaves, which had been killed in liquid air, were freeze dried and then fractionated by a nonaqueous method. Two fractions were obtained, one consisting of chloroplasts and the other of cytoplasm, vacuolar constituents, cell walls and residual chloroplasts. Calculation of the intracellular distribution of ascorbic acid based on the analysis of the two fractions revealed that 40 to 50% of the total ascorbic acid content of the cells is located within the chloroplasts. Since chloroplasts occupy less than 10% of the total volume of the cells, this high figure is direct evidence of an unequal distribution of ascorbic acid within the leaf cell.

scholarly journals The separation of softwood and hardwood in historical wooden statues of the Nazenji-temple in Japan using NIR spectroscopy

IAWA Journal ◽  
2020 ◽  
Vol 41 (4) ◽  
pp. 740-750 ◽  
Author(s):  
Hisashi Abe ◽  
Yohei Kurata ◽  
Ken Watanabe ◽  
Atsuko Ishikawa ◽  
Shuichi Noshiro ◽  
...  
Keyword(s):  
Near Infrared ◽  
Nir Spectroscopy ◽  
Principal Component ◽  
Forest Products ◽  
Chamaecyparis Obtusa ◽  
Score Plot ◽  
Hardwood Species ◽  
Cercidiphyllum Japonicum ◽  
Sciadopitys Verticillata ◽  
Second Derivative Spectra

Abstract The applicability of near-infrared (NIR) spectroscopy to the identification of wood species of archaeologically/historically valuable wooden artifacts in a non-invasive manner was investigated using reference wood samples from the xylarium of the Forestry and Forest Products Research Institute (TWTw) and applied to several wooden statues carved about 1000 years ago. Diffuse-reflectance NIR spectra were obtained from five standard wood samples each of five softwood species (Chamaecyparis obtusa, Cryptomeria japonica, Sciadopitys verticillata, Thujopsis dolabrata, Torreya nucifera) and five hardwood species (Aesculus turbinata, Cercidiphyllum japonicum, Cinnamomum camphora, Prunus jamasakura, Zelkova serrata). A principal component analysis (PCA) model was developed from the second derivative spectra. The score plot of the first two components clearly showed separation of the wood sample data into softwood and hardwood clusters. The developed PCA model was applied to 370 spectra collected from 21 wooden statues preserved in the Nazenji-temple in Shizuoka Prefecture in Japan, including 14 made from Torreya spp. and 7 made from Cinnamomum spp. In the score plot, the statue spectra were also divided into two clusters, corresponding to either softwood (Torreya spp.) or hardwood (Cinnnamomum spp.) species. These results show that NIR spectroscopy combined with PCA is a powerful technique for determining whether archaeologically/historically valuable wooden artifacts are made of softwood or hardwood.

A new species and comparative morphology of Vesselowskya (Cunoniaceae)

2001 ◽  
Vol 14 (2) ◽  
pp. 175 ◽  
Author(s):  
Andrew C. Rozefelds ◽  
Richard W. Barnes ◽  
Belinda Pellow
Keyword(s):  
New Species ◽  
Cell Walls ◽  
New South ◽  
Comparative Morphology ◽  
Epidermal Cells ◽  
The Other ◽  
Abaxial Surface ◽  
South Wales ◽  
Central Column ◽  
A New Species

The vegetative and reproductive morphology of Vesselowskya Pampanini, southern marara, is described and illustrated in detail. The variation within V. rubifolia (F.Muell.) Pampanini sens. lat. is shown to be greater than has previously been recognised, with the differences identified supporting the recognition of a new segregate species, V. venusta Rozefelds, R.W.Barnes and Pellow sp. nov. Vesselowskya venusta occurs in the Barrington Tops Plateau of New South Wales and differs from V. rubifolia in possessing hairs on the abaxial surface of the sepals and lacking both a prominent distal connective protrusion on the anthers and colleters at the base of the stipules. The two Vesselowskya species are dioecious with a vestigial ovary in staminate flowers and reduced stamens in pistillate flowers. Dioecy is more pronounced in Vesselowskya, than in some Weinmannia species, and in both genera is expressed through reduction in the size of the ovaries in staminate flowers, and stamens in pistillate flowers. Vesselowskya shares with the other genera in the tribe Cunonieae (Pancheria, Weinmannia and Cunonia), a central column in the fruits, and Cunonia-type stipules, but differs from these genera in having valvate aestivation, digitate leaves, craspedodromous secondary venation with secondary veins terminating at a tooth, tuft domatia along the midrib, adaxial epidermal cells with strongly sinuous cell walls and the absence of hydathodes.

UV Absorption Microspectrophotometry and Histochemistry of Flax and Kenaf

1998 ◽  
Vol 4 (S2) ◽  
pp. 846-847
Author(s):  
D.E. Akin
Keyword(s):  
Microbial Degradation ◽  
Linum Usitatissimum ◽  
Cell Walls ◽  
Industrial Applications ◽  
Hibiscus Cannabinus ◽  
Fiber Cell ◽  
The Other ◽  
Uv Absorption ◽  
Bast Fibers ◽  
Histochemical Tests

Flax (Linum usitatissimum L.) and kenaf (Hibiscus cannabinus L.) are the sources of fibers used for textiles and other industrial applications. Both flax and kenaf produce fibers in the bast region (Fig. 1, 2) which must be separated from other tissues by retting. Although both flax and kenaf are bast fibers, their properties are vastly different. UV absorption microspectrophotometry and histochemistry elucidate their chemistry and structure related to enzymatic retting.Aromatics such as lignins are produced by plants for protection and strength, but their presence inhibits microbial degradation, which is necessary in retting. Histochemical tests indicated variations in the site and type of aromatics within these two plants (1,2). In flax, acid phloroglucinol but not chlorine-sulfite gave positive reactions occasionally in fiber cell walls in the bast. The other cell walls in the bast did not contain aromatics by these tests, although aromatics occurred in the cuticle.

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