Soichi Tanaka

Poikiloderma-Like Cutaneous Amyloidosis

Cases of cutaneous amyloidosis which exhibit poikiloderma-like skin changes are extremely rare. There are at least two clinical forms of poikiloderma-like cutaneous amyloidosis (PCA): (1) the ordinary

Effect of grain direction on transmittance of 100-GHz millimeter wave for hinoki (Chamaecyparis obtusa)

The attenuation coefficients of 100-GHz millimeter waves polarized linearly were measured for cross-cut, quarter-sawn, and flat-sawn boards of hinoki (Chamaecyparis obtusa) that were 0.2–2.0 cm thick. This was done to examine the applicability of free-wave propagation theory for applying electromagnetic waves to wood. It was found that the transmittance of a millimeter wave through the specimen boards was lower when the fiber direction of a board was parallel to the direction of the electric field of the incident wave than when the fiber direction was perpendicular to the electric field, and there was little difference in the transmittance between the tangential and radial directions for the former case. These findings can be quantitatively explained by using propagation theory and the dielectric properties of wood.

溶液含浸木材の養生過程における細胞壁への溶質拡散機構の検証: 相対湿度がポリエチレングリコール水溶液含浸木材の膨潤・収縮挙動に及ぼす影響

To control the amount of solute in cell walls of solution impregnated wood using the conditioning process, the mechanisms of solute diffusion into the cell walls and of solvent evaporation from wood under the process were verified. The effect of relative humidity (RH) on temporal variability of swelling, shrinkage, and mass of wood impregnated with an aqueous solution of polyethylene glycol (PEG1540) was examined. The impregnated wood specimen swelled under the conditioning at the RH over 75%. The specimen was indicated to swell when the amount of the PEG polymers in the cell walls increase in this RH range. On the basis of this indication, the temporal variability of increasing rate of the polymers in the cell walls and of evaporating rate of water from the specimen under the conditioning was well explained by the mechanisms of the solute diffusion and the solvent evaporation, respectively. In the RH range, the increasing amount of the polymers in the cell walls increased with the evaporating amount of the water, which increased with the decrease in the RH. These results were supported by the mechanisms of the solute diffusion and the solvent evaporation, respectively. The diffusion mechanism also supported the effect of the history of the RH on the polymer amount in the cell walls throughout the conditioning and subsequent drying in a vacuum. It was concluded from these findings that the solute diffusion into cell walls is able to be controlled by the surrounding vapor pressure of solvent when the polymers (PEG1540) and water are employed as the solute and solvent, respectively.

Solute diffusion into cell walls in solution-impregnated wood under conditioning process III: effect of relative humidity schedule on solute diffusion into shrinking cell walls

This study has focused on solute diffusing into cell walls in solution-impregnated wood under conditioning, process of evaporating solvent. The purpose of this paper was to clarify the RH- (relative humidity-) schedule that promotes the solute diffusion into shrinking cell walls during conditioning. The wood samples impregnated with a 20 mass% aqueous solution of polyethylene glycol (PEG1540) was conditioned with a temperature of 40 °C to the equilibrium point at the RH where the samples swelled maximally. The samples were subsequently conditioned at 40 °C under the schedules including four ways of RH-decrease steps where the cell walls shrunk. The amount of solute (PEGs) diffused into cell walls during the conditioning logarithmically increased with increasing the number of the RH-decrease steps. This was well explained by the theoretical model that describes the solute diffusion into shrinking cell walls. It is clarified from the model that the RH, or moisture content of the sample, should be decreased as gradually as possible to increase the total amount of diffused solute into shrinking cell walls, and that the amount of diffused solute is smaller for the lower moisture content. The model also suggests that effect of change in RH schedule on change in total amount of diffused solute does not depend on solute diffusivity in the sample under drying in a vacuum over phosphorous pentoxide, and that impregnated wood should be conditioned under natural convection rather than forced convection for promoting the diffusion into shrinking cell walls.

Solute diffusion into cell walls in solution-impregnated wood under conditioning process II: effect of solution concentration on solute diffusion

This study focused on solute diffusing into cell walls in solution-impregnated wood during conditioning, process of moderate drying of solvent. To clarify the effect of solution concentration on the diffusion during the conditioning, weight percent gain (WPG) and relative swelling of the wood sample impregnated with an aqueous solution of polyethylene glycol (PEG) polymers at a concentration of 10, 20, 30, 40, or 50 mass% were examined during the conditioning and subsequent drying processes. The relation between the concentration and the relative swelling after all processes, an indicator of the amount of the polymers in cell walls, exhibited a concave-downward curve with a maximum value at 20 mass%. The estimated mass of the polymers in cell walls just before conditioning increased with the concentration. This indicates that the distribution of the polymers changed during conditioning. The estimated mass just before conditioning and the relative swelling after all processes were normalized to the packing ratios of the polymers in cell walls. The ratio after all processes subtracted by that just before conditioning was larger than the ratio just before conditioning, and increased with the concentration up to 20 mass%; after which it decreased. This indicates that the majority of the polymers in cell walls increased during conditioning, and that the amount of the polymers that diffused into cell walls was at the maximum at concentration of 20 mass%. This was explained by two factors: the decrease in the diffusivity into cell walls and in the concentration difference of the polymers between cell walls and cell cavity with the concentration, based on the behavior of WPG during conditioning; and the estimated minimum concentration at which the solution contains the least amount of polymers to fill the cell walls.

Rock physical interpretation of the compressive strength–seismic velocity relationship for sedimentary rocks

Estimating the strength, especially compressive strength, of rocks is one of the major problems in many civil engineering applications. Compressive strength of a rock is usually measured in a laboratory test of rock specimens obtained in boreholes drilled in the investigation site. If seismic velocity can be used for estimating rock strength, the seismic method can be employed effectively for profiling strength of a large rock mass because it is capable of determining subsurface seismic properties over a large area. Rock strength is often estimated from seismic velocity using correlations between data of each property, measured in the specific rock mass, or by using existing empirical relations. These techniques, however, have problems in accuracy and reliability of their estimates, because the correlations between measured data generally are made with a small number of data, and empirical relations are restricted for applicable rock types. In this study, a rock physics model is studied to estimate the compressive strength from seismic velocity more accurately and reliably. The confined compressive strength–seismic velocity relationship is modelled by combining two effective-medium models for (1) the confined compressive strength v. porosity and (2) seismic velocity v. porosity. The model is applied to S-wave velocity log data in soft sedimentary rocks, and the model predictions are compared with confined compressive strength, measured with the triaxial compression test on rock cores sampled in the same borehole as that used for the velocity logging. The model is also applied to ultrasonic P-wave velocity and confined compressive strength data measured in the laboratory, using core samples of sedimentary rocks collected from various sites in Japan. Good agreement between model-calculated and measured data in the confined compressive strength–seismic velocity relationships in these cases reveals that the confined compressive strength can be estimated from seismic velocity using a rock physics model.

Feasibility of millimeter wave imaging as tool for nondestructive inspection of wood and wooden structures

Dielectric properties of wood were estimated by a reflection imaging using monostatic system of millimeter wave of 100GHz and by a transmission imaging using bistatic system, respectively. The influence of cellular structure, moisture content and inner defect on the imaging performance was clarified. The feasibility of the millimeter imaging as the tool for nondestructive evaluation of quality and deterioration of wood and wooden structure was confirmed.

Visualization of solute diffusion into cell walls in solution-impregnated wood under varying relative humidity using time-of-flight secondary ion mass spectrometry

The purpose of the present study is to clarify the diffusion of non-volatile substances into cell walls during the conditioning procedure under varying relative humidities (RH). In this paper, wood blocks were impregnated using an aqueous solution of melamine formaldehyde (MF), and they were subsequently conditioned under RHs of 11, 43, and 75%. The solute that diffused into the cell walls was visualized using time-of-flight secondary ion mass spectrometry (TOF-SIMS). The volumetric relative swelling of the samples during the conditioning procedure was calculated. The results showed increased cell wall swelling at higher RH, which may have been caused by higher MF diffusion into the cell walls and/or higher moisture content. Cryo-TOF-SIMS measurements showed that more cell cavities were unfilled with MF at higher RH, indicating that most of the MF diffused from the cell cavities into the cell walls. The relative intensity of MF in the cell walls of the cured samples was evaluated from dry-TOF-SIMS images, which showed a higher relative intensity of MF in the cell walls at higher RH. With the ability to visualize and semi-quantitatively evaluate the solute in cell walls, TOF-SIMS will serve as a powerful tool for future studies of solute diffusion mechanisms in solution-impregnated wood.