Simple method for synthesizing phenolicβ-O-4 dilignols

A modified synthetic method for phenolic-O-4 lignin substructure model dimers was developed involving protection of the phenolic hydroxyl group of acetophenons with benzoyl chloride, bromination with 4-dimethylaminopyridiniumbromide perbromide, condensation with phenols in the presence of 18-crown-6-ether, condensation with paraformaldehyde, reduction with NaBH₄ and debenzoylation. This method results in shorter reaction times and increasing yields without the application of strict anhydrous and drastic conditions or chloric solvents. This alternative route could be applied to the-O-4 dilignol syntheses of four combinations of guaiacyl and syringyl derivatives.     

Mathematical Simulation of Small Log Ripped by Slasher Saw

Withthesmallsawlogwidespreadused,theuncut-boardsandslabsarecutbythemulti-bitrippingedgerinthejhoberindustw.AfersawingripPed,theunedgedboedaccuratelyvolumeisfAnotherparametCrsaredefinitebyadrawing,theaPProimatevolumeforn1ulateofunedgedboardistx,y,~inatC,x'…     

Locating and identifying sound knots and dead knots on sugi by the rule-based color vision system

Knowledge of the occurrence of sound and dead knots on the surface of sugi is important for the classification and application of the material. This study examined a color vision system for detecting sound and dead knots on sugi. The system can be conceptually divided into three components: a CCD-camera scanning system, an image-segmenting module, and a rule-based defect identifying module. The results showed that the potential defect regions could be located by Otsus threshold algorithm in conjunction with t-test analysis. The accuracies of locating sound knots and dead knots were 92.6% and 97.1%, respectively. The rule-based approach was used to identify sound and dead knots and the identifying accuracies for sound knots and dead knots were 92.0% and 94.1%, respectively. The overall detection accuracy of the system was 87.6%. The results indicated that the rule-based color vision system is an efficient means of detecting sound knots and dead knots on sugi.     

Effect of tool angles on the chips generated during milling of wood by straight router-bits

 The effect of tool angles on the shapes of chips generated by parallel-to-grain and end-grain milling was explored for China fir and maple under fixed spindle and feed speeds and cutting depth. The milling path was up-milling by straight router-bits with a diameter of 12 mm. The chip shapes could be distinguished as five types: spiral, splinter, flow, thin, and granules or powder. The flow and thin chips were generated most often (on a weight percentage basis) for all tool angles investigated for parallel-to-grain and end-grain milling of China fir and maple. More granule chips were produced with parallel-to-grain milling than with end-grain milling for both woods. The measured chip thickness (t′) was thicker than the calculated thickness (t _max). Thicker and longer maple chips were produced by end-grain milling than by parallel-to-grain milling. The tool geometries of 40°/15° (sharpness of the angle–rake angle), 50°/15°, and 60°/15° for China fir and 40°/25°, 50°/5°, and 60°/5° for maple produced relatively more flow chips with parallel-to-grain milling. Furthermore, the tool geometries of 40°/5°, 50°/15° and 60°/25° produced more flow chips (weight percentage) by end-grain milling of China fir and maple. Received: May 23, 2001 / Accepted: June 28, 2002 Acknowledgment This study was supported by a grant from the National Council of Science, Taiwan (NSC89-2313-B-415-011).     

Maternal Liver Damage Delays Meiotic Resumption in Bovine Oocytes through Impairment of Signalling Cascades Originated from Low p38MAPK Activity in Cumulus Cells

The main objective of the present study is to investigate the molecular mechanism underlying the delay in progression of nuclear maturation in oocytes derived from cows with damaged livers (DL cows), which was previously reported. In present study, delayed progression of nuclear maturation of oocytes derived from DL cows relative to oocytes derived from cows with healthy livers (HL cows) was accompanied by low maturation promoting factor (MPF) activity (0.43 fold, p < 0.05). When cumulus cells were removed from cumulus‐oocyte complexes and the denuded oocytes were cultured, there was no difference in the progression of nuclear maturation between the two liver conditions. In addition, gap junctional communication (GJC) between the oocyte and cumulus cells was higher in DL cows than in HL cows at 3 and 7 h of in vitro maturation (IVM) (p < 0.05). Supplementation of IVM medium with epidermal growth factor (EGF) increased the ratio of germinal vesicle breakdown (GVBD) of oocytes derived from DL cows to the level seen in oocytes derived from HL cows. Additionally, the level of p38MAPK phosphorylation at 0 h of IVM was significantly lower in cumulus cells derived from DL cows than in cumulus cells derived from HL cows (HL cows, 53.5%; DL cows, 28.9%; p < 0.05). Thus, a low level of p38MAPK phosphorylation in cumulus cells induced slow GJC closure between oocyte and cumulus cells, which resulted in slow meiotic maturation of oocytes derived from DL cows.     

Applicability of effective medium theory to wood density measurements using terahertz time-domain spectroscopy

The use of an effective medium theory is important when accurately measuring wood density using millimeter and terahertz wave techniques. To confirm the applicability of this theory to the evaluation of wood density, the relative permittivity and dielectric loss of oven-dry flat-sawn specimens of 11 different wood species were measured in a frequency range of 0.15–1.2 THz using a transmission measurement system for terahertz time-domain spectroscopy. A mixture model based on the effective medium theory well explained the density dependence of relative permittivity over the entire frequency range, while it did not fully explain that of dielectric loss, especially for higher frequencies. This indicates that wood scatters the terahertz wave with a wavelength close to the transverse sectional dimensions of the pores in wood in the same way as Mie scattering. It was found from the dielectric loss spectrum of wood substance that the frequency around 0.23 THz was preferable for the nondestructive evaluation of wood.     

Effect of pore conformation on dielectric anisotropy of oven-dry wood evaluated using terahertz time-domain spectroscopy and eigenvalue problems for two-dimensional photonic crystals

To clarify the effect of pore conformation on the dielectric anisotropy of wood, the relative permittivity along the longitudinal and tangential axes of flat-sawn oven-dry specimens of 12 different wood species was measured using terahertz time-domain transmission spectroscopy and compared with the values calculated using the eigenvalue problem for two-dimensional photonic crystals. The measured dielectric anisotropy, which is the ratio of the relative permittivity along longitudinal axis to that along the tangential axis, was well explained by the calculated value. It was concluded that the ratio of tangential to radial widths of wood pores affects the relative permittivity along the tangential axis, and that the dielectric anisotropy decreased with an increase in the ratio. This discussion can also be applied to the relative permittivity in frequencies below 0.15 THz. These findings show promise as a new method for evaluating the porous structure of wood.     

Does future climate change facilitate expansion of evergreen broad-leaved tree species in the human-disturbed landscape of the Korean Peninsula? Implication for monitoring design of the impact assessment

To quantitatively assess future change of evergreen broad-leaved tree species’ distributions in human-disturbed landscapes of the Korean Peninsula under climate change, potential habitats (PHs) were projected for four important evergreen broad-leaved tree species (Quercus acuta, Castanopsis sieboldii, Machilus thunbergii, and Neolitsea sericea) by species distribution models (SDMs). The distribution data (presence/absence) of the target species in Korea and Japan were used as response variables for SDMs, and climatic data were used as explanatory variables. Three general circulation models under A2 emission scenarios were used as future climate scenarios for the years 2070–2099. Potential habitats masked by land-use data (PHLUs) were projected to assess the impact of anthropogenic activities. Highly accurate SDMs were obtained for all the target species. The current PHs were decreased to 21–35 % by the anthropogenic activities. Future PHLUs for all the target species were projected to increase by 2.0–18.5 times of current PHLUs. These results suggest that all the target species are applicable as indicator species for monitoring in the Korean Peninsula, even if anthropogenic effects are incorporated. Variation of the increasing rate was caused by the differences in the response to temperature changes. M. thunbergii responded sensitively to the increase of minimum temperature of coldest month and had a largest increase in PHLUs under future climate. Therefore, M. thunbergii is considered to be most appropriate species for monitoring the changes of horizontal distributions above all focal evergreen broad-leaved tree species.