Microwave pyrolysis of cellulosic materials for the production of anhydrosugars

Large-scale microwave rapid pyrolysis of cellulosic materials has been investigated. Levoglucosan (1,6-anhydro--d-glucopyranose) was obtained from a larch log as the main anhydrosugar in 2.6% yield on the basis of dry wood weight. This yield would be much higher than that obtainable by conventional pyrolysis in the largescale reaction. Levoglucosenone (1,6-anhydro-3,4-dideoxy--D-glycero-hex-3-enopyranos-2-ulose) was found to be produced in one-quarter the amount of levoglucosan. Other anhydrosugars, such as mannosan (1,6-anhydro--D-mannopyranose), galactosan (1,6-anhydro--d-galactopyranose), and xylosan (1,4-anhydro--d-xylopyranose), were also confirmed to be produced as minor components depending on the proportion of the monosaccharide content in the larch. When microwave pyrolysis of used papers and filter papers was performed, the yields of levoglucosan were about 6% and 12%, respectively, suggesting that a higher content of cellulose gives a larger amount of levoglucosan.     

Effects of complex stress of chronic acid fog exposure with rhizosphere aluminum on nutrient status in Abies firma seedlings

We exposed momi fir (Abies firma Sieb. et Zucc.) seedlings to simulated acid fog of pH 3.0 for about 3 years (from July 1999). During the last year of acid fog exposure, half of the seedlings were subjected to rhizosphere Al stress (complex stress) and the nutrient status of seedlings was determined. Chronic acid fog exposure decreased Fe and Zn concentrations in current-year and 1-year needles, and Al in 1-year needles, but had little effect on major element concentrations. Aluminum treatment had a broad impact on nutrient status in fine roots and needles. In fine roots, increases in Al and Cu concentrations and decreases in B, Mn, and Zn concentrations were observed. In 1-year needles, Al treatment increased Al, B, and Mn concentrations and decreased Cu concentration. The complex effect of acid fog with aluminum on nutrient status was relatively slight. These results show that changes in nutrient status under chronic acid fog exposure and/or Al stress are induced before the decline of photosynthesis in momi fir seedlings, mainly due to Al stress.     

Stand structure and composition of a 60-year-old larch (Larix kaempferi) plantation with retained hardwoods

Tree retention is understood as a key practice in creating complexity, leading to heterogeneity in resources and habitats in managed stands. In this article, we clarify the long-term effects of tree retention on stand structure and tree-species composition in a 60-year-old Larix kaempferi plantation in central Japan. In our study plot (1.5 ha) there were 18 stems/ha of retained trees (determined by tree-ring analysis), mostly Quercus crispula. We conducted spatial analyses and tested the hypothesis that tree abundance, size structure, and species composition and diversity change with distance from the retained trees. Near the retained trees, L. kaempferi showed a reduction of 40%–60% in basal area, due presumably to the shading effect. In contrast, the nearby area showed greater species diversity in the canopy layer. The retained trees created patches of different species composition in the understory. The spatial gradient of shade and colonization opportunity provided by retained trees greatly affect the distribution of the colonized species, according to their shade tolerance and seed-dispersal ability, which resulted in the stand structure with a heterogeneous shrub-layer vegetation. Retention proved particularly important for the enhancement and long-term maintenance of structural and compositional complexity in L. kaempferi plantations.     

Generation process of growth stresses in cell walls: Relation between longitudinal released strain and chemical composition

Summary To advance the discussion on the evolution mechanism of tree growth stresses, the relation between released strain and the chemical components was investigated experimentally. The expansive released strain in the longitudinal direction assumed large values as the lignin content increased in the compression wood, but there was no relation between released strain and lignin content in the normal wood region. The contractive released strain assumed large values as the cellulose content and its crystallinity increased. Their correlation was very high and clear. From these facts, it is considered that the lignin deposition plays an important role in the generation of the growth stresses in compression wood but is not important in normal or tension wood regions. Cellulose microfibrils contract along their longitudinal axis during cell maturation, and the stress included by the contraction creates a longitudinal growth stress in normal and tension woods.The authors thank Prof. R. R. Archer, University of Massachusetts, for his valuable advice. A part of this research was supported by a grant under the Monbusho International Scientific Research Program     

The effect of day length on diurnal differences in the innermost surface of the S2 layer in differentiating tracheids

This article describes the effect of day length during the photoperiodic cycle on the diurnal differences in the innermost surface of developing secondary walls. Saplings of Cryptomeria japonica D. Don. were grown in growth chambers at constant temperature and relative humidity, but with different photoperiods. Samples of differentiating xylem were collected during the light and dark periods. The innermost surface of developing secondary walls in differentiating tracheids were observed using field emission scanning electron microscopy, and observations made during the light and dark periods were compared. In the saplings grown under long-day or short-day conditions, diurnal differences in aspects of the innermost surface of developing secondary walls were observed. Cellulose microfibrils were observed on the innermost surface of developing secondary walls during the light period when the volumes of differentiating cells were low, and amorphous material was observed during the dark period, when differentiating tracheids were turgid. The amorphous material was labeled with antiglucomannan antiserum. These results suggest that the range of day-length conditions set in this study does not affect the diurnal periodicity in the supply of cell wall components to the innermost surface of developing secondary walls.     

Tree regeneration in partially cut conifer–hardwood mixed forests in northern Japan: roles of establishment substrate and dwarf bamboo

We assessed the relationship of the regeneration (seedling and sapling) densities of seven representative tall-tree species to the past partial cutting and current stand structure. We also determined if differences in tree regeneration were associated to establishment substrates (coarse woody debris (CWD) and root throws) and understory inhibitor vegetation (the dwarf bamboo species: Sasa senanensis). The study was conducted in 17 conifer–hardwood mixed stands in a heavy snowfall region in Hokkaido, northern Japan. The results suggest that stand structure, rather than logging intensity, is the primary factor influencing regeneration densities. Total conifer basal area was positively correlated with the regeneration density of individual tree species, including two conifers and three hardwoods. These patterns differ from those observed in old-growth stands in the region. A negative correlation between total conifer basal area and dwarf bamboo coverage suggests that the presence of dense conifer canopies causes an increase in regeneration density of tall-tree species by preventing domination of dwarf bamboo. Picea glehnii, a species that depends for its establishment strongly on CWD, has lower seedling and sapling density in stands with higher logging intensity. This seems to be a result of the decrease in the volume of CWD with increasing logging intensity in these stands. We suggest that both reducing logging intensity and retaining overstory conifers should be considered to develop a sustainable silvicultural system in this region. Providing sufficient CWD and root throws may also be important to ensure natural regeneration of tree species that require these as an establishment substrate.     

棕榈藤的热软化:半纤维木素基质的影响

利用蠕变柔量实验检测8种棕榈藤植物细胞壁的半纤维素木素基质，了解其对棕榈藤热软化影响。首先用乙醇-苯准备提取的单体样本，随后是用在木材上使用的标准程序对藤细胞进行化学分析。结果显示为细胞壁是42％～53％α-纤维素，19％～27％半纤维素和20％～40％木素。蠕变柔量实验表明，样品软化程度取决于热量的提供情况。提取的单体软化是在70～85℃时开始的，全纤维素在75～95℃时软化，而α-纤维素样品在100℃时软化。8种品种的热软化程度差异也被观测到。它们的差异取决于品种间半纤维素木素的比例的不同：基质的容量越大，分子运动越剧烈。同时还注意到从提取的单体的原料到全纤维素再到α-纤维素样品在热软化中的还原性差异。它取决于基质的还原量，因为木素去除了。α-纤维素还有其它的运动。这些运动仅衍生于纤维素链中的晶体-非晶体区域。物质的晶体越多，可观测的分子运动越小。     

The generation of longitudinal maturation stress in wood is not dependent on diurnal changes in diameter of trunk

A hypothetical mechanism for the generation of maturation stress in wood was tested experimentally. The hypothesis was that the maturation stress could partly originate in a physical mechanism related to daily changes in water pressure and associated diurnal strains. The matrix of lignin and hemicellulose, deposited in the cell wall during the night, would be put in compression by the effect of water tension during the next day. The cellulose framework, crystallizing during the day, would be put in tension by the decrease in tension at night and subsequent cell-wall swelling. This was tested on young saplings of sugi and beech. Half of the saplings were submitted to continuous lighting, which canceled diurnal strains. Saplings were tilted 40 degrees, and their uprighting movement was measured. The uprighting movement is directly due to the production of reaction wood and the concomitant development of large longitudinal maturation stress. It occurred in the continuously lighted plants at least as much as in control plants. We conclude that the generation of longitudinal maturation stress in tension or compression wood is not directly related to variations in water pressure and diurnal strains.     

Comprehensive analytical method for the determination of hydrophilic metabolites by high-performance liquid chromatography and mass spectrometry

A method for the comprehensive analysis of hydrophilic metabolites, based on a combination of high-performance liquid chromatography and mass spectrometry, is described. We evaluated three types of stationary phases to achieve the separation of highly hydrophilic metabolites. Good chromatographic retention and separation of these metabolites were achieved on a pentafluorophenylpropyl-bonded silica column with gradient elution, using 0.1% aqueous formic acid and acetonitrile as the mobile phase. The optimized conditions allowed the comprehensive determination of the standard 49 kinds of amino acids, 6 kinds of amines, 45 kinds of organic acids, 18 kinds of nucleic bases, 5 kinds of nucleosides, and 14 kinds of nucleotides, and then the linearity, dynamic range, detection limit, and precision of the retention time and the peak area were validated. We applied this method for the targeted analysis of the components in soy sauce. The results from the quantitative determination of amino acids were compared to those obtained with an amino acid analyzer, and the accuracy was in the range between 85 and 119%. The accuracy of other detected components was confirmed to be 105-133% by the recovery rate after the addition of standard compounds. We also applied the method for the nontargeted metabolic profiling of the components in several kinds of soy sauces with the principal component analysis. They were classified by the manufacturing methods, and the components that corresponded to the differences were identified. This method could be useful for the targeted analysis of hydrophilic metabolites as well as their nontargeted metabolic profiling.