Mapping of microfibril angles and chemical compositions in a tree.

木材细胞壁是一种复合材料，由纤维素、半纤维素、木质素和其他少量成分（如果胶和提取物）组成。S2层（最厚层）的纤维素微纤维角（MFA）和化学成分决定了细胞壁的杨氏模量和生长应力等功能特性。本研究采用小角x射线散射（SAXS）和傅里叶红外光谱（FT-IR）研究了MFA和化学成分的变化。综上所述，从茎干到茎尖和上部，纤维素含量不断降低。部分通常比下部有更多的纤维素。观察到MFA的变化和细胞壁化学成分的微小变化。在软木和硬木中，这些变化似乎得到了很好的调节，以表现出机械功能，以保持树枝的理想方向。我们检查了mfa，化学成分和三个波数测量的峰高之间的相关性。在1034cm-1（纤维素）处的峰值用于软木和硬木。在1219cm-1处（木质素）的峰值为软木。木聚糖在1239 cm-1处的峰是硬木中特有的，用于硬木。在软木中，MFAs与木质素含量呈正相关。另一方面，MFAs与纤维素含量呈负相关。在。硬木中MFAs含量与纤维素含量无显著相关，但与木聚糖含量呈正相关。sr - x射线实验在日本Harima， Spring-8， BL40B2上进行，项目编号2002A0250和2002B0440。

Wood cell walls are a composite material consisting of cellulose, hemicellulose, lignin and other minor components, such as pectin and extractives. Two main factors, cellulose microfibril angle (MFA) in S2 layer (thickest layer) and chemical composition, govern functional properties of the cell wall such as Young's modulus and growth-stress. In this study, change of MFA and chemical composition were investigated by small angle X-ray scattering (SAXS) and FT-IR. In summary, cellulose content decreases continuously from the trunk to the tip and upper. parts had generally more cellulose than, lower parts. Variation of MFA and small changes of chemical composition in cell wall were observed. In both softwood and hardwood, these changes seemed to be well regulated to manifest the mechanical function in order to keeping the branch in its ideal orientation. We examined the correlations between MFAs, chemical components and measured peak height at three wavenumbers. The peak at 1034cm-1 (cellulose) was used for both softwood and hardwood. Moreover, the peak at 1219cm-1 (lignin) was used for softwood. The peak at 1239 cm-1 (xylan), which appeared characteristically in hardwood, was used for hardwood. In softwood, the correlation of MFAs with lignin content was positive relationship. On the other hand, there was a negative correlation between MFAs and cellulose content. In. hardwood, although apparent correlation between MFAs and cellulose was not shown, the positive correlation between MFAs and xylan content could be seen. The SR-X-ray experiments were performed at BL40B2, Spring-8, Harima, Japan, Project number, 2002A0250 and 2002B0440.