Investigation of wood properties that influence the final moisture content of air-dried sugi (Cryptomeria japonica) using principal component regression analysis
Sugi (Cryptomeria japonica D. Don) lumber is known to have a large variability in final moisture content (MCf) and is difficult to dry. This study investigated the variability in MCf of sugi in relation to wood properties. The wood property variables included initial moisture content (MCi), basic density (BD), annual ring orientation (ARO), annual ring width (ARW), heartwood ratio (HR) and CIE L* color (L*). Sugi samples were cut from flat-sawn lumbers and air-dried; a principal component regression (PCR) model for predicting MCf was developed with the wood property variables. The wood properties that contributed to the prediction of MCf were evaluated by PCR analysis. Significant positive regression coefficients of the PCR model were observed in the MCi, BD, ARO and HR, whereas negative ones in the L*. There were no significant regression coefficients in the ARW. These results suggest that the MCi, BD, ARO and HR had a positive influence, the L* had a negative influence, and the ARW had little influence on the MCf of air-dried sugi wood. This finding is in line with the general view on the drying characteristics in relation to these wood properties.
Bordered Pit Aspiration in the Wood of Cryptomeria Japonica in Relation to Air Permeability
Aspiration of bordered pits in Cryptomeria japonica (L. f.) D. Don was studied in relation to the air permeability in sapwood, transition zone wood, and heartwood. The percentage of aspirated pits relative to the total number of bordered pits with observable tori was determined in samples that were epoxy-embedded and thin sectioned. Air permeability of air-dried and freeze-dried wood samples was measured following the method described by Siau (1984). Pit membrane structure of air-dried and freeze-dried samples was investigated by scanning electron microscopy on split radial surfaces. It is proposed that pit aspiration progresses during heartwood formation as already reported, but the pit aspiration was frequently incomplete and the percentage varied between individuals. The pit aspiration percentage was not obviously related to the sample's initial green moisture content or heartwood color. The results from permeability measurement and SEM observation on air- and freeze-dried samples suggest that pit aspiration occurred in sapwood samples (the initial moisture content of which ranged from 200 to 300%) during air-drying and caused a significant decrease in permeability confirming the pit aspiration mechanism proposed by Hart and Thomas (1967). In the heartwood, encrustation of pit membranes prevented aspiration during air-drying.
AMERICAN WESTS: PREFACE TO A GEOGRAPHICAL INTERPRETATION
ABSTRACT Geographers might make a very significant contribution to the interpretation of the American West and of the American nation by a systematic investigation of the West as a set of dynamic regions. The outline offered suggests a focus upon four categories of regional features (population, circulation, political areas, and culture) to be examined as complexes changing through four recognizable stages (nuclear, regional, regional-national, metropolitan-national) from initial European colonization to the present with projections into the future.