Masafumi Inoue

Time‐resolved D‐band luminescence in strain‐relieved SiGe/Si

Temporal decay characteristics of dislocation‐related luminescence bands (D1–D4) were explored in strain‐relieved epitaxial SiGe/Si(100). Close similarity of the decay profiles was observed not only between D1 and D2 bands but also between D3 and D4 bands. The decay transients of the D1 and D2 bands at low temperatures are characterized by long decay times, τ≳200 ns, whereas the D3 and D4 bands exhibit even sharper transients with τ<60 ns. Temperature dependence of ‘‘radiative’’ lifetimes implies a free‐to‐bound nature of the D1 and D2 bands, while a bound‐to‐bound character of the luminescence origins for the D3, D4 bands.

Mechanism of water adsorption capacity change of bamboo by heating

AbstractThe water adsorption capacity of moso bamboo (Phyllostachys pubescens)n heated at 200xa0°C in air for various times was examined. The samples were subsequently placedn in various humidities at 20xa0°C to obtain relevant isotherms. They were analyzed using the Hailwoodn and Horrobin theory, derived for hydrophilic macromolecules, and the Dubinin and Radushkevich theory, previouslyn used to describe the behavior of microporous carbons. The results show that the water adsorption capacitiesn of the samples changed after heating for 2 to 5xa0hrs, and imply that over this time the number of hydroxyln groups decreased markedly while the number of micropores formed increased.n ZusammenfassungUntersucht wurde das Wasseradsorptionsvermögen von Mosobambus (Phyllostachysn pubescens) nach unterschiedlich langer Wärmebehandlung in heißer Luft bei 200xa0°C.n Die Proben wurden anschließend bei unterschiedlicher Luftfeuchte und 20xa0°C konditioniert,n um die entsprechenden Sorptionsisothermen zu erhalten. Diese wurden anhand der für hydrophile Makromolekülen abgeleiteten Hailwood und Horrobin Theorie sowie der bereits früher zur Beschreibung des Verhaltensn mikroporöser Kohlenstoffe verwendeten Theorie von Dubinin und Radushkevich analysiert. Die Ergebnissen ergaben, dass sich das Wasseradsorptionsvermögen der Proben nach einer Wärmebehandlung von 2 bisn 5xa0Stunden geändert hat. Daraus lässt sich schließen, dass in dieser Zeit die Anzahln der Hydroxylgruppen deutlich abgenommen hat und gleichzeitig die Anzahl der sich gebildeten Mikroporen angestiegenn ist.n

Electronically enhanced kink motion on 30° partial dislocations in Ge directly observed by plan-view high resolution electron microscopy

In the high resolution electron microscopic (HREM) images of dislocations in Ge obtained with the electron beam incident normal to the slip plane, 30° partial dislocation lines were extracted by image processing, and kinks in them were identified at atomic resolution. Analysis of sequential images taken from the same dislocation lines revealed that (1) geometrical kinks of different signs, 30° (left) and 90° (right) kinks, are both mobile even at room temperature (2) generation of kink pairs occurs, albeit less frequently, in the course of HREM observations. These results are reasonably understood when considering that the migration of kinks, at least one of the two types, and the formation of the smallest double kinks are enhanced by the electronic excitation that is caused by the electron beam used for the HREM observations.

Time-resolved dislocation-related luminescence in strain-relaxed SiGe/Si

Abstract Time-resolved photoluminescence (PL) of dislocation-related features (D1–D4) was studied in strain-relaxed molecular beam epitaxy SiGe/Si(100). Low-temperature decay transients are essentially non-exponential for all D bands. The D1, D2 bands are characterized by long ( τ >200 ns) decay times while short ( τ

Water adsorption process of bamboo heated at low temperature

Water adsorption capacities were evaluated for moso bamboo samples that were heated at 200°C for various times and conditioned in a closed container at 97% relative humidity at 20°C. Logistic regression analysis was used for curve fitting to the adsorption data and its parameters were analyzed. These parameters were compared with those derived previously from the Dubinin and Radushkevich theory. The properties of the heat-treated samples changed after 5 h of heating. With less than 5 h of heating, hydroxyl groups provided the main adsorption sites but their numbers decreased on heating. After 5 h, gasifi cation of the bamboo increased and capillaries formed.

Reliable image processing that can extract an atomically-resolved line shape of partial dislocations in semiconductors from plan-view high-resolution electron microscopic images

In this paper we have proposed a reliable methodology to extract partial dislocation lines in atomic resolution from high-resolution electron microscopic (HREM) images obtained with an electron beam incident normal to the slip plane. A previous scheme, which is based on imaging stacking faults (SF) which separate Shockley partial dislocations, is likely to be ambiguous in regard to the choice of the threshold in the image binarization process. Our scheme allows us to uniquely extract 30° partial dislocation lines at atomic resolution by tracing inflection points on the (1 1 0) lattice fringes that cross the partials. The dislocation line thus deduced on the atomic scale coincides in good fidelity with the real core of the 30° partial. The fringe inflection or shift is stable against unintentional misorientation of the sample from exact on-axis geometry. The movement of extracted dislocations is rational, which provides more evidence as to the reliability of this methodology.

Study of mechanical properties of wooden bolt-nut connector I: effect of size and shape of thread on withdrawal strength

The withdrawal strength of a bolt-nut connector made from wood-based material was evaluated. The thread strength of the wooden bolt-nut connector was tested to select various parameters of the connector and the type of wood material; the wood materials tested were hard maple, white oak, ebony, glue-laminated bamboo, and densified Japanese cedar. A plane model of wooden threads with various thread angles was also evaluated. The results showed that the maximum failure load of the thread increased with increasing bolt density and connection area, which was calculated from the diameter of the bolt and the thickness of the nut. The withdrawal resistance after reaching the maximum load underwent a graded decrease because the bolt threads were broken one by one. In addition, the thread strength depended on the thread angle. In the model with a thread angle of 90°, compressive deformation in the transverse direction occurred prior to shear deformation along the root of the threads; the model with this thread angle thus had higher strength than those with other angles.

Mechanism of partial fixation of compressed wood based on a matrix non-softening method

Abstract Three different mechanisms to explain the partial fixation of the compressive deformation of wood are postulated: non-softening, cross-linking and stress relaxation. This study attempted to fix the compressive deformation of wood by the non-softening mechanism of the cell-wall matrix using acetylation of the cell wall making it more hydrophobic. In this method, partial recovery of compressive deformation by wetting decreased at room temperature as the acetyl content increased. However, almost complete recovery occurred by boiling the compressed wood in water or soaking in acetone. This is due to the ability of boiling water or acetone to soften the cell-wall matrix of acetylated wood enough to enable recovery from compression. It is, therefore, possible to partially fix the compressive deformation of wood, preventing the resoftening of the cell-wall matrix in water.

Dimensional stabilization of compressed laminated veneer lumber by hot pressing in an airtight frame

Abstract The purpose of this study was to evaluate the dimensional stability and strength properties of compressed laminated veneer lumber (LVL) produced using a closed hot pressing system. LVL specimens were produced with varying number of veneers using either diphenylmethane diisocyanate (MDI) or a water-soluble phenol formaldehyde (PF) resin at varying temperatures (160–200°C), pressures (0.5–3 MPa) and hot-pressing times (2–16 min). Results show that the heating process decreases the recovery of compressive deformation in the veneers when subjected to cyclic moisture and heat conditions. Thickness swelling was approximately 5% after a drying, wetting and boiling cyclic test for LVL using the MDI resin and hot pressed at 200°C for 8 min. Modulus of elasticity and rupture increased for samples produced in both an open press and the closed press with an increase in the number of veneers and density, as did the absorbed energy in impact bending.

A new procedure for treating wood

Abstract A new procedure has been developed to treat wood with aqueous solutions, microemulsions or other fluids using a roller-press. Green lumber is used which eliminates the need for predrying before treatment. Compressing the green wood to 50–60% of its thickness in a roller-press submerged in a phenol formaldehyde solution resulted in weight gains of 40% resin with an antishrink efficiency of 80%. Specimen length, thickness, compression rate and feed speed were studied, and Japanese cedar, spruce and Douglas fir were successfully treated at different initial wood moisture contents.