Effect of hygrothermal treatment on wood properties: color changes and kinetic analysis using four softwood and seven hardwood species

May 13, 2016, 12:00 am

≫ Next: Hygrothermal recovery of compression wood in relation to elastic growth stress and its physicochemical characteristics

≪ Previous: Continuum contraction of tension wood fiber induced by repetitive hygrothermal treatment

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Abstract

Color changes of four softwood and seven hardwood species during hygrothermal treatment were compared among species and kinetically evaluated. Treatment temperature ranged from 70 to 120 °C, and the durations were 5–150 h. Generally, the \(L^{*}\) (lightness) decreased and the total color differences \((\Delta E_{\text{ab}}^{*})\) increased irrespective of the treatment temperature. \(a^{*}\) and \(b^{*}\) (redness and yellowness) values varied spuriously based on the wood species. Kinetic analysis using the time–temperature superposition principle, which uses the whole data set, was successfully applied to the color changes. The apparent activation energies of the color changes calculated from \(\Delta E_{\text{ab}}^{*}\) were 24.3–40.8 kJ/mol for softwood and 32.3–61.3 kJ/mol for hardwood. The average apparent activation energy for hardwood was higher than for softwood. These values were lower than those calculated from other material properties. The obtained results will contribute to assess the color changes during the early stage of kiln drying and hygrothermal modification of wood.

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Hygrothermal recovery of compression wood in relation to elastic growth stress and its physicochemical characteristics

May 31, 2016, 12:00 am

≫ Next: Is hygrothermal recovery of tension wood temperature-dependent?

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Abstract

Hygrothermal recovery (HTR), the dimensional changes in wood induced by hygrothermal treatment, was investigated using both compression and normal wood of sugi (Cryptomeria japonica). The elastic released strain of growth stress was measured on living tree surfaces; subsequently, the specimens were taken from the same position to measure HTR. HTR was measured as dimensional changes due to treatment at 20, 40, 60, 80, and 100 °C in hot water ranging from 200 min to 177 days. The intensity of HTR had a positive relationship with elastic released strain of growth stress. This result suggests that HTR is the relaxation of the viscoelastic component of growth stress accumulated during the maturation process of trees. The rate of HTR clearly showed a time–temperature dependency: higher at higher treatment temperatures and lower at lower treatment temperatures. Based on kinetic analysis, the apparent activation energy (E_a) was calculated as 407 kJ/mol, which is similar to the published E_a of lignin softening implying that the HTR is a lignin-related phenomenon.

Is hygrothermal recovery of tension wood temperature-dependent?

July 1, 2016, 12:00 am

≫ Next: A Study on the Falls Prevention System in an Acute Hospital

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Abstract

When a green wood specimen is hygrothermally treated, it often shows dimensional changes in the longitudinal and transversal directions, which is called hygrothermal recovery of wood. Hygrothermal recovery of tension wood is assumed to be behind the unusual contraction of gelatinous layer along the longitudinal axis. This study investigated whether hygrothermal recovery of tension wood was temperature-dependent. Hygrothermal treatment at 80, 100 and 120 °C was given to green Quercus serrata tension wood, and longitudinal and tangential dimensions were recorded. In the longitudinal direction, the trend line obtained after 10 times of 10-min hygrothermal treatments at respective temperatures unraveled that it was comprised of initial recovery and continuum contraction at 100 and 120 °C, but no initial recovery was recognized at 80 °C. In the tangential direction, both the initial and the continuum deformations were expansive, and initial recovery was smaller at 80 °C. The results of multiple comparison test revealed that the parameters characterizing the trend line differed significantly among three temperature sets. Further, the result highlighted the existence of breakage of hygrothermal recovery mechanism at temperature between 80 and 100 °C.

A Study on the Falls Prevention System in an Acute Hospital

January 1, 2017, 12:00 am

≫ Next: Delayed recovery of growth stress in tension wood induced by drying and subsequent wetting treatment

≪ Previous: Is hygrothermal recovery of tension wood temperature-dependent?

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Preventing falls is one of the clinical problem and causes patients’ significant problem, since it may cause serious injuries such as an abrasion and fractures. An assessment score sheet for inpatients is one of the falls prevention system. In this paper, we focus on sheet for inpatients’ fall risk. In this paper, we validate the appropriateness of the falls estimate in patients hospitalising. We reassessed the score of 84 cases which consist of 42 sets of the actual patient data for patients who have fallen and 42 sets of the data for those who have not from seven wards from October 2013. The results showed four items as greatly influence the falls. With these items, we calculated fall probabilities of each patients, and compared them of patients who have fallen and those who have not. Then, we could not recognise the difference between two groups since the number of people whose probability of fall is more than 60% are 34 cases in patients who fallen and 24 cases who did not fall. From the result of the analysis, we discuss it is not enough that nurses estimate the patient’s fall risk only using the assessment in patients at the time of hospitalising. Instead, the importance of daily assessment is shown.

Delayed recovery of growth stress in tension wood induced by drying and subsequent wetting treatment

July 1, 2018, 12:00 am

≫ Next: Changes in vibrational properties of compression wood in conifer due to hygrothermal treatment and their relationship with hygrothermal recovery strain

≪ Previous: A Study on the Falls Prevention System in an Acute Hospital

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The delayed recovery of the longitudinal length in biomechanically pre-stressed wood, specifically tension wood with a conspicuous gelatinous layer in the cell wall structure, was generally induced by hygrothermal treatment. However, hygrothermal treatment should not be the sole method to induce delayed recovery in tension wood. In order to broaden our understanding of the mechanism underlying delayed recovery, tension wood of Quercus serrata was treated by drying and subsequent rewetting over many times. Interestingly, the longitudinal deformation over repeated drying and subsequent rewetting treatments (dry–wet treatments) was identical to the response of the tension wood during repetitive hygrothermal treatments. Hence, the longitudinal delayed recovery in pre-stressed tension wood was concluded to be induced not only by hygrothermal treatment but also by the dry–wet cycles.

Changes in vibrational properties of compression wood in conifer due to hygrothermal treatment and their relationship with hygrothermal recovery strain

February 1, 2019, 12:00 am

≫ Next: Evaluation of Systematic Errors in the Compact Absolute Gravimeter TAG-1 for Network Monitoring of Volcanic Activities

≪ Previous: Delayed recovery of growth stress in tension wood induced by drying and subsequent wetting treatment

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To clarify the mechanism of irreversible dimensional changes due to the hygrothermal treatment of green wood, i.e., the hygrothermal recovery (HTR), the changes in vibrational properties of compression wood and normal wood were measured after hygrothermal treatment at 60 °C, 80 °C, and 100 °C. In addition, the relationship between those changes and HTR strains were discussed. The hygrothermal treatment induced an increase in mechanical loss tangent (tanδ) and decrease in specific dynamic Young’s modulus (E′/ρ). It seems that the changes in vibrational properties due to hygrothermal treatment had a time–temperature dependency: Higher temperatures and longer treatment durations induce larger increases in tanδ and larger decreases in E′/ρ. In contrast to the quenching effect, tanδ and E′/ρ did not recover to their original state even after 60 days of conditioning in water at 20 °C. For compression wood with a large microfibril angle (MFA), there was a clear relationship between the changes in vibrational properties and HTR strains. The tanδ increased and E′/ρ decreased with hygrothermal treatment, corresponding to dimensional changes in the L-direction. This suggests that structural changes in wood components are responsible for HTR. The most likely mechanism for HTR is that the hygrothermal treatment softens the lignin to release locked-in growth stress. Subsequently, irreversible structural changes in lignin induce both the changes in vibrational properties and HTR. For normal wood, because of the small MFA, the structural changes in lignin in the L-direction are possibly restricted by crystalline cellulose. As a result, the relationship between the changes in vibrational properties and HTR is uncertain.

Evaluation of Systematic Errors in the Compact Absolute Gravimeter TAG-1 for Network Monitoring of Volcanic Activities

April 29, 2020, 12:00 am

≫ Next: Effect of residual stress distribution in a log on lumber warp due to sawing: a numerical simulation based on the beam theory

≪ Previous: Changes in vibrational properties of compression wood in conifer due to hygrothermal treatment and their relationship with hygrothermal recovery strain

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Volcanic activities sometimes involve gravity changes, and this research is intended to establish an observation network surrounding an active volcano using compact absolute gravimeters. To simplify the configuration of absolute gravimeters, they are preferably operated with a light source distributed from a telecom band (wavelength of 1.5 μm) laser through optical fibers. To evaluate the accuracy of the absolute gravimeter with the telecom band laser, we conducted observations using a prototype gravimeter (TAG-1) with frequency-stabilized lasers at both 1.5 μm and 633 nm, and compared these results with the expected gravity at the site. Initially, both results showed offsets −187 μGal and −9.6 μGal for the 1.5-μm laser and the 633-nm laser, respectively (1 Gal = 10⁻⁸ m/s²). By correcting the systematic errors of the photo detectors measured by the synthetic chirp signal, the obtained absolute gravity was consistent with the expected value for both wavelengths; offsets from the expected gravity were reduced to 6.6 μGal and 5.4 μGal for 1.5 μm and 633 nm, respectively. We also evaluated the errors associated with long-distance transmission of the 1.5-μm laser using a reeled optical fiber (26 km) and an optical amplifier and found no degradation in the gravity data from the case of short transmission (10 m). These results allow networking of compact absolute gravimeters connected by telecom optical fibers that are operated using a common laser and expansion to volcanic areas to monitor the gravity change associated with volcanic activities.

Effect of residual stress distribution in a log on lumber warp due to sawing: a numerical simulation based on the beam theory

November 11, 2020, 12:00 am

≫ Next: Hygrothermal recovery behavior of cellulose-rich gelatinous layer in tension wood studied by viscoelastic vibration measurement

≪ Previous: Evaluation of Systematic Errors in the Compact Absolute Gravimeter TAG-1 for Network Monitoring of Volcanic Activities

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When a squared lumber such as a beam and/or a bearer is produced from a log, they often show warps. Warp of the sawn lumber is practically not serious when the pith is located at the center of the cross-section, as in the lumber-with-pith, but causes serious problems in the lumber-without-pith. In the present study, a mechanical model was introduced to explain lumber warping based on beam theory, and a numerical simulation using the introduced model examined how the magnitude and type of the residual stress distribution would affect the warps of the lumbers sawn from the four-sided cants with various sizes and shapes in their cross-sections, and how the different sawing patterns would affect the production efficiency of the straight lumber, which is manufactured from the four-sided cant by quartering and subsequent correction sawing. As a result, the following suggestions were obtained. The warp of the sawn lumber is affected by the type and the magnitude of the inherent strain distribution in the log and furthermore by the cross-sectional shape and/or size of the four-sided cant. Production efficiency of the straight lumbers differs depending on the sawing patterns. In the present study, two types of sawing patterns (a) and (b) were assumed. The sawing pattern (a) gave better production efficiency than the sawing pattern (b) in the sense that straight lumbers are produced with higher volumes as well as with less variation in dimension of the cross-section.

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Hygrothermal recovery behavior of cellulose-rich gelatinous layer in tension wood studied by viscoelastic vibration measurement

April 20, 2021, 12:00 am

≫ Next: Measuring the tensile strain of wood by visible and near-infrared spatially resolved spectroscopy

≪ Previous: Effect of residual stress distribution in a log on lumber warp due to sawing: a numerical simulation based on the beam theory

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Hygrothermal treatment induces irreversible dimensional changes of green wood i.e. hygrothermal recovery (HTR). To understand what happened to cellulose-rich gelatinous (G-) layer in green tension wood during HTR, changes in vibrational properties of konara oak (Quercus serrata Thunb. ex Murray) tension wood (TW) and normal wood (NW) collected from sapwood after hygrothermal treatment were tested regarding HTR. After this treatment, all specimens were air-dried, and their vibrational properties and dimensions were measured in this dried state. The hygrothermal treatment induced an increase in mechanical loss tangent (tanδ) and a decrease in specific dynamic Young’s modulus (E’/ρ). Changes in vibrational properties due to hygrothermal treatment appeared to depend on treatment time and temperature with higher temperatures and longer treatment durations producing larger increases in tanδ and larger decreases in E’/ρ. In TW with a G-layer, a clear correlation between changes in vibrational properties and HTR strains was identified. Tanδ increased and E’/ρ decreased corresponding to HTR strains. Contraction of the G-layer in TW cell walls due to release of locked-in growth stress by hygrothermal treatment seems to be the most plausible mechanism underlying changes in vibrational properties and generation of HTR. In NW without a G-layer, HTR strain was below the limit of detection, which obscures potential correlations. Differences in the intensities of changes in vibrational properties after 120 min hygrothermal treatments at 60, 80, and 100 °C were not significant after drying; however, the difference in the intensities of HTR strains apparently remained after drying.

Measuring the tensile strain of wood by visible and near-infrared spatially resolved spectroscopy

November 1, 2021, 12:00 am

≫ Next: Suppressive effects of processed aconite root on dexamethasone-induced muscle ring finger protein-1 expression and its active ingredients

≪ Previous: Hygrothermal recovery behavior of cellulose-rich gelatinous layer in tension wood studied by viscoelastic vibration measurement

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Strain measurement is critical for wood quality evaluation. Using conventional strain gauges constantly is high cost, also challenging to measure precious wood materials due to the use of strong adhesive. This study demonstrates the correlation between the light scattering degrees inside the wood during tension testing and their macroscopic strain values. A multifiber-based visible-near-infrared (Vis–NIR) spatially resolved spectroscopy (SRS) system was designed to rapidly and conveniently acquire such light scattering changes. For the preliminary experiment, samples with different thicknesses, from 2 to 5 mm, were measured to evaluate the influence of sample thickness. The differences in Vis–NIR SRS spectral data diminished with an increase in sample thickness, suggesting that the SRS method can successfully measure the wood samples' whole strain (i.e., surface and inside). Then, for the primary experiment, 18 wood samples were each prepared with approximately the same sample thickness of 2 mm and 5 mm to construct strain calibration models, respectively. The prediction accuracy of the 2-mm samples was characterized by a determination coefficient (R²) of 0.81 with a root mean squared error (RMSE) of 343.54 με for leave-one-out cross-validation; for test validation, the validation accuracy was characterized by an R² of 0.76 and an RMSE of 395.35 με. For the validation accuracy of the 5-mm samples, R²_val was 0.69 with 440.78 με RMSE_val. Overall, the presented calibration results of the SRS approach were confirmed to be superior to the standard diffuse reflectance spectroscopy.

Suppressive effects of processed aconite root on dexamethasone-induced muscle ring finger protein-1 expression and its active ingredients

February 18, 2022, 12:00 am

≫ Next: Comprehensive study of distributions of residual stress and Young’s modulus in large-diameter sugi (Cryptomeria japonica) log

≪ Previous: Measuring the tensile strain of wood by visible and near-infrared spatially resolved spectroscopy

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Processed aconite root (PA), the tuberous root of Aconitum carmichaelii prepared by autoclaving, is a crude drug used in Japanese traditional Kampo medicine and traditional Chinese medicine for the symptoms of kidney deficiency, that is related to the muscle atrophy in modern medicine. The objective of the present study is to evaluate the effectiveness of PA on muscle atrophy and to find its active ingredients using dexamethasone-induced muscle ring finger protein-1 (MuRF1) mRNA expression in murine myoblast C2C12 cells. Dexamethasone-induced MuRF1 expression was significantly suppressed by methanol-soluble part of boiling water extract of PA in a concentration-dependent manner with its IC₅₀ value of 1.5 mg/ml. By the activity-guided fractionations of PA extract using the partition between organic solvents and its aqueous solution, the activity of PA did not transfer into the fraction containing aconitine-type diterpenoid alkaloids but into BuOH layer. Then, we found higenamine and salsolinol as the active ingredients in PA. Higenamine and salsolinol significantly suppressed dexamethasone-induced MuRF1 expression, and their IC₅₀ values were 0.49 and 50 µM, respectively. The contents of higenamine and salsolinol in the decoctions of commercially available fourteen PA products are 0.12 and 14 µg/ml as the average values, and varied with the coefficient of variation (CV) values of 97 and 63%, respectively. Higenamine also significantly suppressed dexamethasone-induced mRNA expressions of muscle atrophy F-box protein (MAFbx)/atrogin1, casitas B-lineage lymphoma-b (Cbl-b), troponin, branched-chain amino acid aminotransferase 2 (BCAT2), and Bcl-2 binding and pro-apoptotic protein3 (Bnip3). Although the quality control of PA is regulated by the contents of diterpene alkaloids, salsolinol and higenamine can be used as the marker compounds to certificate the pharmacological activities of PA.

Graphical abstract

Comprehensive study of distributions of residual stress and Young’s modulus in large-diameter sugi (Cryptomeria japonica) log

February 24, 2022, 12:00 am

≫ Next: Distribution of salicifoline in freeze-fixed stems of Magnolia kobus as observed by cryo-TOF-SIMS

≪ Previous: Suppressive effects of processed aconite root on dexamethasone-induced muscle ring finger protein-1 expression and its active ingredients

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Aged conifer forests in Japan are expected to produce large-diameter logs, defined as logs with a top-end diameter of 30 cm or more. However, the knowledge and techniques for industrial processing of large-diameter logs of Japanese wood species have not been sufficiently developed. This study was aimed at characterizing the longitudinal component of residual stress distribution of large-diameter logs of sugi (Japanese cedar, Cryptomeria japonica), a major tree species cultivated in Japan, as the processing yield of primary lumber from large-diameter logs is affected by the magnitude and distribution pattern of the residual stress. The radial distributions of the released strain of residual stress, tensile Young’s modulus, and residual stress were measured using 63 logs. The radial distributions of the released strain and residual stress showed typical patterns reported in previous studies: contraction near the bark and elongation near the pith in the released strain, tensile stress near the bark, and compressive stress near the pith. The radial distributions of Young’s modulus showed a typical pattern: low near the pith and high near the bark. The difference between the maximum and minimum released strains in each log varied widely among individuals, which was expected to result in a wide variation in crooking when rip sawing. The longitudinal uniformity and axial symmetry of the radial distribution of the released strain and residual stress were experimentally confirmed, which lays the groundwork for improved understanding of the residual stress in sugi logs.

Distribution of salicifoline in freeze-fixed stems of Magnolia kobus as observed by cryo-TOF-SIMS

July 19, 2017, 12:00 am

≫ Next: Microscopic mechanism of contraction of tension wood G-fiber due to boiling

≪ Previous: Comprehensive study of distributions of residual stress and Young’s modulus in large-diameter sugi (Cryptomeria japonica) log

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Alkaloids are basic nitrogen-containing chemicals that have important physiological and pharmacological characteristics. Many vascular plant species contain alkaloids, and their roles in planta are of interest. However, the detailed distribution of alkaloids remains unclear because of their low water solubility and low concentrations in plants. In this study, we visualized the distribution of salicifoline, a water-soluble quaternary ammonium alkaloid, in the freeze-fixed stems of Magnolia kobus by cryo time-of-flight secondary ion mass spectrometry. Most of the salicifoline was distributed in living phloem tissues. In the xylem, salicifoline was detected in ray cells, lignifying wood fibres, and in vessels in the latest annual ring. The salicifoline distribution in the xylem varied with the cell wall formation stage. These results provide new insights into the storage, transportation, and role of the alkaloid salicifoline in M. kobus.

Microscopic mechanism of contraction of tension wood G-fiber due to boiling

September 1, 2022, 12:00 am

≫ Next: Usefulness of large beam-shaping filters at different tube voltages of newborn chest CT

≪ Previous: Distribution of salicifoline in freeze-fixed stems of Magnolia kobus as observed by cryo-TOF-SIMS

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Many woody eudicot plants form a secondary xylem composed of gelatinous fibers (G-fibers) called "tension wood" (TW) along the upper side of the tilted stem or branch. TW generates a large tensile growth stress in the longitudinal direction, allowing the tilted stem or a branch to develop negative-gravitropism in response to the strong gravitational stimulus. This is because the G-fiber tends to contract in the longitudinal direction as it matures. The matured G-fiber also contracts upon boiling in water (= hygrothermal treatment, i.e., HT-treatment), and moisture desorption (= drying treatment). These contractions occur in the cellulose-rich gelatinous layer (G-layer) as an innermost layer of the G-fiber. It is still an unsolved mystery how the G-layer, which is composed of highly crystallized and longitudinally oriented cellulose microfibrils (CMFs), contracts during maturation, boiling, and drying. In the present study, TW specimen of Konara oak (Quercus serrata L.) was subjected to HT-treatment under different temperature and time conditions, and strain due to treatment was followed. Besides, the mass loss due to HT-treatment was also followed. Obtained results are summarized as follows. (1) Green TW specimen of Konara oak contracted in the longitudinal direction when subjected to the HT-treatment at a treatment temperature higher than 40 °C, which eventually converged to a constant value according to each treatment temperature. Magnitude of the longitudinal HTR-strain in the TW specimen was positively correlated with the treatment temperature in the range from 40 to 120 °C, whereas in the normal wood (NW) specimen, it does not occur explicitly when the temperature is less than 100 °C. (2) Both TW and NW specimens showed mass loss when subjected to the HT-treatment. The mass loss rate increased rapidly by the HT-treatment at 120 °C, while it was only slight below 100 °C. There was no significant difference between the mass loss behavior of TW and NW by the HT-treatment. From analyzing those results, physical behavior of CMF and other non-cellulosic matrix components in the G-layer during the HT-treatment was estimated. The discussion was further developed to associate HT-contraction with microscopic mechanisms of the other two characteristic contractions of the G-fiber, i.e., maturation strain and drying shrinkage.

Graphical abstract

Usefulness of large beam-shaping filters at different tube voltages of newborn chest CT

January 12, 2023, 12:00 am

≫ Next: Correction to: Suppressive effects of processed aconite root on dexamethasone-induced muscle ring finger protein-1 expression and its active ingredients

≪ Previous: Microscopic mechanism of contraction of tension wood G-fiber due to boiling

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Background: To investigate optimizing the use of different beam shaping filters (viz. small, medium and large) when using different tube voltages during the newborn chest computed tomography (CT) on a GE Lightspeed VCT scanner. Methods: We used pediatric anthropomorphic phantoms with a 64 detector-row CT scanner while scanning the chest. A real-time skin dosimeter (RD − 1000; Trek Corporation, Kanagawa, Japan) was positioned into the phantom center of the body, the surface of the body back, and the right and left mammary glands. We performed and compared six scan protocols using small, medium, and large beam shaping filters at 80 and 120 kVp protocols. Result: There were no significant differences in the image noise for the chest scan among the different beam shaping filters. By using the large beam shaping filter at 80 kVp, it was possible to reduce the exposure dose by 5% in comparison with the small beam shaping filter, and by 10% in comparison with the medium beam shaping filter. By using the large beam shaping filter at 120 kVp, it was possible to reduce the exposure dose by 15% in comparison with the small beam shaping filter and by 20% in comparison with the medium beam shaping filter (p < 0.01). Conclusion: The large beam shaping filter had the most dose reduction effect during newborn chest CT on a GE Lightspeed VCT scanner. The additional copper filtration being present in the large bowtie filter of the GE Lightspeed CT scanner when using different tube voltages is more effective in reducing radiation exposure in children.

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Correction to: Suppressive effects of processed aconite root on dexamethasone-induced muscle ring finger protein-1 expression and its active ingredients

March 16, 2023, 12:00 am

≫ Next: Unique characteristics of residual stress distribution of large-diameter keyaki (Zelkova serrata) logs and examination of their measurement method

≪ Previous: Usefulness of large beam-shaping filters at different tube voltages of newborn chest CT

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Unique characteristics of residual stress distribution of large-diameter keyaki (Zelkova serrata) logs and examination of their measurement method

March 30, 2023, 12:00 am

≫ Next: Distribution of coniferin in freeze-fixed stem of Ginkgo biloba L. by cryo-TOF-SIMS/SEM

≪ Previous: Correction to: Suppressive effects of processed aconite root on dexamethasone-induced muscle ring finger protein-1 expression and its active ingredients

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Large-diameter keyaki (Zelkova serrata Makino) logs have long been used in Japan as high-quality material especially for traditional construction and furniture. However, unlike other major wood species in Japan, keyaki has been practically considered as a wood species of high difficulty when processing. Keyaki frequently shows processing defects due to sawing, such as warping, cracking, and so forth, which often reduces the production yield of logs. Furthermore, there are drastic differences in those behaviors between individual logs, so causing unexpected processing defects. A scientific approach is required to improve this situation, but data on the material characteristics of keyaki were scarce. This study aimed to characterize the radial pattern of the residual stress as one of the processing-related characteristics. The measurement method was also examined. This study used diametral planks obtained from large-diameter keyaki logs to measure released strain of residual stress from pith to the bark sides. The results showed the distribution of released strain often showed peculiar zig-zag patterns characterized with localized residual stress, unlike the smooth bell curve pattern seen in typical logs of other species. Because of the unique characteristics, some practical points related to the measuring methodology were investigated. The extent of influence of this residual stress in the longitudinal direction was limited to within 30 cm from the site of measurement of the strain. In addition, the length of log necessary to measure the released strain without being affected by crosscutting was more than four times the log diameter—greater than the diameter ratio theorized by previous studies.

Distribution of coniferin in freeze-fixed stem of Ginkgo biloba L. by cryo-TOF-SIMS/SEM

August 11, 2016, 12:00 am

≫ Next: The “chi-chi” of Ginkgo biloba L. grows downward with horizontally curving tracheids having compression-wood-like features

≪ Previous: Unique characteristics of residual stress distribution of large-diameter keyaki (Zelkova serrata) logs and examination of their measurement method

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To clarify the role of coniferin in planta, semi-quantitative cellular distribution of coniferin in quick-frozen Ginkgo biloba L. (ginkgo) was visualized by cryo time-of-flight secondary ion mass spectrometry and scanning electron microscopy (cryo-TOF-SIMS/SEM) analysis. The amount and rough distribution of coniferin were confirmed through quantitative chromatography measurement using serial tangential sections of the freeze-fixed ginkgo stem. The lignification stage of the sample was estimated using microscopic observations. Coniferin distribution visualized at the transverse and radial surfaces of freeze-fixed ginkgo stem suggested that coniferin is stored in the vacuoles and showed good agreement with the assimilation timing of coniferin to lignin in differentiating xylem. Consequently, it is suggested that coniferin is stored in the tracheid cells of differentiating xylem and is a lignin precursor.

The “chi-chi” of Ginkgo biloba L. grows downward with horizontally curving tracheids having compression-wood-like features

August 30, 2023, 12:00 am

≪ Previous: Distribution of coniferin in freeze-fixed stem of Ginkgo biloba L. by cryo-TOF-SIMS/SEM

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The old Ginkgo biloba L. trees often develop cylindrical woody structures that grow downward from the underside of the large branches near the trunks. This structure is traditionally called “chi-chi” (a breast) in Japan. The structure of chi-chi has not been investigated in detail because of the rarity of such old trees of G. biloba. This study examined the chi-chi from wood anatomy and chemistry viewpoints. After debarking, there were many woody bulges and latent buds. There were hollows corresponding to these latent buds on the inner side of the bark. In the transverse section obtained from the tip part of the chi-chi sample, we found tracheids curving in a horizontal plane, and the parenchymatous latent bud tissue is the center of the swirl. Microscopic observations and X-ray micro-computed tomography suggest the growing course of the chi-chi due to several swirls contiguous to each other. From these observations, the downward growth of the chi-chi starting from the cambium cell division might be driven by the woody bulges with latent buds. The cell walls of the curved tracheids were not thickened, not rounded, and had no intercellular spaces, but their S₃ layers disappeared. Furthermore, the results of thioacidolysis and acetyl bromide analyses exhibited p-hydroxyphenyl subunits deposition to lignin and high lignin content on the tip part of the chi-chi. These results suggest that the curved tracheids in the chi-chi have compression-wood-like properties to some extent.