<Original>Studies on Hemicelluloses in Tension Wood : II. Structural Studies on Xylans from Tension, Opposite and Side Woods of Japanese Beech (Fagus crenata Blume)

この論文は国立情報学研究所の学術雑誌公開支援事業により電子化されました。Structural differences in three 4-0-methyl-glucuronoxylans from tension, opposite and side woods of Japanese beech (Fagus crenata Blume) were investigated. Each 4-0-methyl-glucuronoxylan was isolated from the 1 % potassium hydroxide extract and purified by gel filtration on Sepharose 4B. The weight average molecular weights of three xylans were similar and estimated to be in the range of 20,000-25,000 by gel filtration. A structural analysis by the methylation method and ^C-n.m.r. spectroscopy showed that no substantial differences were detected between these three xylans. ^C-N.m.r. spectroscopy was used in determination of the ring size, anomeric configuration, the position of 0-glycosidation and the purity of these xylans, suggesting the effectiveness of this technique for characterization of polysaccharides in wood

Chronic Exposure to Low Frequency Noise at Moderate Levels Causes Impaired Balance in Mice

We are routinely exposed to low frequency noise (LFN; below 0.5 kHz) at moderate levels of 60–70 dB sound pressure level (SPL) generated from various sources in occupational and daily environments. LFN has been reported to affect balance in humans. However, there is limited information about the influence of chronic exposure to LFN at moderate levels for balance. In this study, we investigated whether chronic exposure to LFN at a moderate level of 70 dB SPL affects the vestibule, which is one of the organs responsible for balance in mice. Wild-type ICR mice were exposed for 1 month to LFN (0.1 kHz) and high frequency noise (HFN; 16 kHz) at 70 dB SPL at a distance of approximately 10–20 cm. Behavior analyses including rotarod, beam-crossing and footprint analyses showed impairments of balance in LFN-exposed mice but not in non-exposed mice or HFN-exposed mice. Immunohistochemical analysis showed a decreased number of vestibular hair cells and increased levels of oxidative stress in LFN-exposed mice compared to those in non-exposed mice. Our results suggest that chronic exposure to LFN at moderate levels causes impaired balance involving morphological impairments of the vestibule with enhanced levels of oxidative stress. Thus, the results of this study indicate the importance of considering the risk of chronic exposure to LFN at a moderate level for imbalance

<Original>Studies on Hemicelluloses in Tension Wood : I. Chemical Composition of Tension, Opposite and Side Woods of Japanese Beech (Fagus crenata Blume)

この論文は国立情報学研究所の学術雑誌公開支援事業により電子化されました。Three different types of woods, tension, opposite and side woods, were isolated from Fagus crenata Blume and their anatomical and chemical properties were compared. Tension wood was composed of well developed gelatinous fibers and was characteristic in its low lignin and pentosan contents as well as its high ash, alpha-cellulose and uronic acid contents. Carbohydrate portion of tension wood has been found to be peculiar in that tension wood contains the highest amount of galactose in contrast to the lowest amount of mannose among three types of wood. Each wood was further subjected to sequential fractional extractions. The peculiarity of the chemical composition of the tension wood reflected the differences in the carbohydrate compositions of the extracted hemicelluloses. In analysing the molecular weight distribution of the extracted hemicelluloses by gel nitration on Sepharose 4B, it has been found that all components included in the gel matrices have quite similar molecular weights in spite of the differences in the carbohydrate compositions. These results may give a clue in ellucidation of the distribution and function of hemicelluloses in wood

Characterization and Prediction of the Gas Hydrate Reservoir at the Second Offshore Gas Production Test Site in the Eastern Nankai Trough, Japan

Following the world’s first offshore production test that was conducted from a gas hydrate reservoir by a depressurization technique in 2013, the second offshore production test has been planned in the eastern Nankai Trough. In 2016, the drilling survey was performed ahead of the production test, and logging data that covers the reservoir interval were newly obtained from three wells around the test site: one well for geological survey, and two wells for monitoring surveys, during the production test. The formation evaluation using the well log data suggested that our target reservoir has a more significant heterogeneity in the gas hydrate saturation distribution than we expected, although lateral continuity of sand layers is relatively good. To evaluate the spatial distribution of gas hydrate, the integration analysis using well and seismic data was performed. The seismic amplitude analysis supports the lateral reservoir heterogeneity that has a significant positive correlation with the resistivity log data at the well locations. The spatial distribution of the apparent low-resistivity interval within the reservoir observed from log data was investigated by the P-velocity volume derived from seismic inversion. The integrated results were utilized for the pre-drill prediction of the reservoir quality at the producing wells. These approaches will reduce the risk of future commercial production from the gas hydrate reservoir

Prediction and validation of gas hydrate saturation distribution in the eastern Nankai Trough, Japan: Geostatistical approach integrating well-log and 3D seismic data

Accurate reservoir potential evaluation requires reliable 3D reservoir models. Geostatistical simulation techniques can reproduce the heterogeneity and quantify the uncertainty in a reservoir. We have applied sequential Gaussian simulation with collocated cokriging to generate the spatial distribution of gas hydrate (GH) saturation around a gas production test site in the eastern Nankai Trough. The simulation was performed using well-log data obtained from the exploration and production tests as a primary variable and inversion-derived seismic impedance data as a secondary variable under the good correlations between two variables. The integrated model adequately described the reservoir heterogeneity and effectively interpolated the seismic trend with respect to the well data. To confirm the usability of the seismic data for the accurate representation of the GH saturation distribution, we ran two model simulations: one using well data only and the other using well and seismic data. Each model was validated using the well-log data obtained at the production test site that were not included during the simulation. The model generated using well and seismic data appropriately reproduced the trend of well-log data at the production test site, especially for the low-GH-saturation unit within the reservoir. However, the model generated using well data only was insufficient to predict the trend of the well data. The results demonstrated that the seismic data were effective for the prediction of the GH saturation distribution, and integration of the well and seismic data could improve the accuracy of the reservoir model