Keizo Okamura

Characterization of cellulose in compression and opposite woods of a Pinus densiflora tree grown under the influence of strong wind

SummaryStructural factors in a Pinus densiflora tree grown under the influence of strong wind were measured. No

DSC study on regioselectively substituted cellulose heteroesters

\overline {DP}

Molecular and crystal structure of the regenerated form of (1→3)-α-d-glucan☆

difference for cellulose molecules was noticed between compression and opposite wood, but the

Molecular and crystal structure of cellulose acetate dipropanoate (CADP, 6-O-acetyl-2,3-di-O-propanoyl cellulose)

\overline {DP}

Single crystals of regio-selectively substituted cellulose hetero-esters

was somewhat lower in the region where the compression wood was concentrated. The degree of crystallinity of cellulose was 45–50% in compression wood, about 50% in normal wood, and 50–60% in opposite wood. The crystallinity decreased with increasing height above the ground. The maximum point of crystallographic b-axis (fiber axis) orientation distribution for cellulose crystallites in compression wood was located at ϕ≅30°, in normal wood at ϕ≅25° and in opposite wood at ϕ≅0°. The cellulose crystallite dimension in the transverse direction was 3.2 nm, corresponding to four cellulose unit cells, a value that was almost constant throughout the wood. In the longitudinal direction, there were large differences in cellulose crystallite dimensions between compression and opposite woods. In compression wood the cellulose crystallite dimensions was 12 nm corresponding to 11–12 cellulose unit cells. In opposite wood it was 17–32.5 nm corresponding to 17–32 cellulose unit cells. These structural factors were apparently affected by the environmental conditions, and the mechanical properties of the wood were influenced by these factors. Opposite wood had longer crystallites, a higher degree of crystallinity and a better orientation distribution of cellulose crystallites in the longitudinal direction. Compression wood, on the other hand, had shorter crystallites, a lower degree of crystallinity and a large angle between the stem and the direction of the crystallites.

X-ray diffraction data for (1→3)-α-d-glucan triacetate

Xyloglucan isolated from the elongating regions of pea stems was examined using X-ray diffraction and energy calculations. The X-ray fibre pattern suggested that the backbone (1----4)-beta-D-glucan takes an extended two-fold helix similar to common cellulose. In order to study side chains (xylosyl or fucosyl-galactosyl-xylosyl residues) of the polysaccharide, energetically preferable conformations were searched by calculation of interactions between non-bonded atom pairs. A stepwise calculation for the conformation of fucosyl-galactosyl-xylosyl residue gave 10 allowed area (phi-psi) maps which are useful to deduce xyloglucan conformations of both monocotyledons and dicotyledons in the walls of growing plant cells.