Youki Suzuki

Twisting force during drying of wood

The object of this study is to investigate when wood begins to twist and the extent of the twisting force during drying. Japanese larch (Larix leptolepis Gord.) and hiba (Thujopsis dolabrata Sieb. et Zucc. var. hondae Makino) which tend to twist significantly when drying, were used in experiments to obtain multiple examples of grain angle (GA) variation in the R-direction. A measuring system to measure the twisting force during the drying of wood in real time was developed. It is thought that the time when twisting of timber by drying starts is subject to the variation in R-direction of GA; timber begins to twist when the portion with large GA begins to dry. There is concern that timber with large GA in the inner portion may become twisted during storage after kiln drying. The twisting stress measured in this study is effective for examining the load on the timber to control the twisting.ZusammenfassungIn dieser Studie wird untersucht, wann sich Holz beim Trocknen zu verdrehen beginnt und welche Kraft beim Verdrehen wirkt. Für die Versuche wurden japanische Lärche (Larix leptolepis Gord.) und der Hiba-Lebensbaum (Thujopsis dolabrata Sieb. et Zucc. var. hondae Makino), die beide beim Trocknen zu starken Verdrehungen neigen, verwendet, um gute Beispiele für Faserwinkelvariationen (GA) in radialer Richtung untersuchen zu können. Es wurde ein Messsystem zur Echtzeit-Messung der Verdrehungskraft beim Trocken von Holz entwickelt. Es wird angenommen, dass der Zeitpunkt, an dem sich das Holz beim Trocknen zu verdrehen beginnt, vom Faserwinkelverlauf in radialer Richtung abhängt. Holz fängt an sich zu verdrehen, wenn der Bereich mit großem Faserwinkel zu trocknen beginnt. Es bestehen Bedenken, dass sich Holz mit großer Faserabweichung im inneren Bereich erst nach der technischen Trocknung bei der Lagerung verdrehen könnte. Die in dieser Studie gemessene Verdrehungskraft ist geeignet, um zu bestimmen, wie Holz bei der Trocknung zur Kontrolle der Verdrehung belastet werden muss.

Shear modulus of several kinds of Japanese bamboo obtained by flexural vibration test

The vibrational properties of Japanese bamboo were examined. To obtain the Young’s modulus and shear modulus, a flexural vibration test and a longitudinal vibration test were conducted. The Young’s modulus with vibration in the R-direction was smaller than that measured in the longitudinal vibration test El. This was due to the shift of the neutral axis to the outer layer. On the other hand, the Young’s modulus with vibration in the T-direction was close to El. Hence, an adequate Young’s modulus should be used for each use of bamboo. The shear moduli of the LR and LT planes of bamboo were similar to those of beech. There were high correlations between shear moduli of the LR and LT planes and density.

Electrical properties of composite cyanoethylated pullulan film

We have investigated the electrical properties of cyanoethylated cellulose to expand the field of wood utilization. Electrical properties of cyanoethylated cellulose that have been reported so far include dielectric properties, conductivity, and piezoelectricity. Hirai et al. reported that the high drawing cyanoethylated hydroxyethyl cellulose film had a high piezoelectric constant d that was 10–20 (pC/N) as large as that of PVDF film. Its ferroelectricity has not be determined. The cyanoethyl groups contribute more to polarization than other groups, and their introduction has been effective in improving electrical properties. Chemical treatment alone is not able to improve the electrical properties. It has been necessary to apply an orientation method, such as drawing, to a film, but this is difficult because cyanoethylated film is extremely fragile. In general, ferroelectric materials such as BaTiO3 have a high dielectric constant, so they are combined with cellulose and this composite was expected to improve the electrical properties. A compound of cellulose and BaTiO3 did not exhibit the ferroelectric phenomenon; but when samples were subjected to high voltage at high temperature, the electrical properties appear to have been markedly changed. We therefore tried to induce ferroelectricity of cyanoethylated pullulan with piezoelectric ceramics by applying high voltage at high temperature. Materials and methods

Acute Effects of Carbon Monoxide and Cyanide on Hepatic Mitochondrial Function

SummaryThe effects of carbon monoxide and cyanide on the hepatic redox state and energy charge were investigated. Rats were used for the experiment under pentobarbital anesthesia. Immediately after laparotomy, a rat was placed in an animal chamber made of a transparent plastic box and exposed to a test gas for 3 min. Every test gas was produced in a gas chamber connected to the animal chamber with a flexible tube. HCN was produced from NaCN and H2SO4. In the CO inhalation experiment, various amounts of CO were introduced into the gas chamber. Immediately after an exposure, about 2g liver was frozen in situ with a precooled clamp. Oozed blood from the wound surface was sampled. Concentrations of ATP, ADP, AMP, acetoacetate, and β-hydroxybutyrate in hepatic mitochondria were determined, and the redox state and the energy charge were calculated. For cyanide as well as CO, significant negative correlations were found between the concentration in the blood and the redox state. The same held true for the energy charge. The redox state showed a slight increase at low concentrations of both gases; however, thereafter it began to decrease sharply with increases in concentrations. When concentrations of the toxicant in the blood reached certain levels, a kind of turning point, beyond which the redox state does not decrease any more, was observed. It was about 40% for HbCO and about 2.0μg/ml for cyanide, and the points seemed to be related to the concentrations, beyond which cells are irreversibly damaged. On the other hand, the energy charge did not change at low concentrations. With an increase in toxicant concentrations, the energy charge decreased drastically. The rate of decrease in the energy charge became higher when blood concentrations exceeded certain levels. It was about 40% for HbCO and 2.0μg/ml for cyanide. The presence of low levels of blood cyanide did not affect the relationship between the energy charge and the HbCO concentration.ZusammenfassungDer Einfluß von Kohlenmonoxid und Blausäure auf die Funktion der Lebermitochondrien wurde untersucht. Alle Versuche wurden an Ratten in Pentobarbitalnarkose durchgeführt. Unmittelbar nachdem die Bauchhöhle der Ratten geöffnet wurde, wurden einzelne Tiere in einer Versuchskammer aus transparentem Kunststoff für 3min einem Prüfungsgas ausgesetzt. Jedes Prüfungsgas wurde in einer durch ein Plastikrohr mit der Versuchskammer verbundenen Gaskammer hergestellt. HCN wurde aus NaCN und H2SO4 hergestellt. Bei CO-Versuchen wurden verschiedene Mengen von CO in die Kammer eingeführt. Unmittelbar nach den Versuchen wurden etwa 2g Leber in situ mit einer abgekühlten Klemme gefroren. Eine Blutprobe wurde von der Wunde entnommen. Die Konzentrationen des Azetoazetats, β-Hydroxybutyrats, Adenosintriphosphats, Adenosindiphosphats und Adenosinmonophosphats der Leber wurden bestimmt, und anhand von ihren Werten wurden “redox state” (ein Verhältnis von Azetoazetats zu β-Hydroxybutyrats) und “energy charge” (ein Verhältnis von Summa von ATP und 0.5 ADP zu Summa von ATP, ADP und AMP) berechnet. In vergifteten Ratten verminderten sich “redox state” mit der zunehmenden Konzentration der Toxika im Blut. Als die HbCO-Konzentration 40% überstieg, trat eine Art Wende, bei der die Geschwindigkeit der Verminderung sich reduziert, ein. Für Zyanid war diese Wende 2.0μg/ml. Im Vergleich zu “redox state” verminderte sich “energy charge” langsamer. Aber die Geschwindigkeit der Verminderung beschleunigte sich, wenn die Blutkonzentration der Toxika eine Grenze überschritt. Die o.g. Wenden waren 40% für HbCO und 2.0μg/ml für Zyanid. In kombinierten Versuchen wurden Tiere einem Gasgemisch (CO und niederer Konzentration von HCN) ausgesetzt. Es wurde angenommen, daß es keine Wechselwirkung zwischen CO und HCN gibt.

Longitudinal Vibration Test for the Use of a Circular Truncated Cone as a Log Model of Japanese Cedar

The appropriate diameter ratio of log top and butt ends when using a round bar (cylinder shape) as a log model for estimating the density and Young’s modulus of a log was investigated. Square timbers of Japanese cedar (Cryptomeria japonica D. Don) with a length of 1200 mm were used as specimens and were machined into circular truncated cones. A longitudinal vibration test was performed to obtain the Young’s moduli of the square timbers and the circular truncated cones. The Young’s moduli were calculated using the circular truncated cone model and the round bar model. The density and Young’s modulus calculated by the circular truncated cone model were similar to those of the square timbers. Hence, it is considered that the circular truncated cone was effective for estimating the densities and Young’s moduli of logs. The density and Young’s modulus calculated by the round bar model differed from those of the square timbers when the diameters of the top ends were small. However, it is considered that the round bar can be used as a log model for actual logs.

Measurement of the refining degree of bamboo charcoal by an alternating current method

We investigated a method for measuring the refining degree of bamboo charcoal using an alternating current. The bamboo charcoal was made under heating conditions of 400°–900°C (set temperature) and 0—3 h (holding time at each set temperature). The qualities of the bamboo charcoal could not be estimated from the yield, and electric tests were required. The effect of the variation in sample thickness on the impedance could be ignored. Attaching two plate electrodes to the same surface of a specimen enabled high accuracy and practical use. The impedance was found to be a suitable index for estimating the refining degree of the bamboo charcoal, such as the specific electric resistance. We believe that bamboo changes from an insulator to a conductor suddenly when processed at 600°–750°C for 0–2 h. It is possible that the integral of temperature with time in a specimen during heating is useful for approximately estimating impedance.

Radial variations of wood properties of an endangered species, Pinus armandii var. amamiana

A dead tree of Pinus armandii Franch. var. amamiana (Koidz.) Hatusima (abbreviated to PAAm) was obtained from a natural habitat on Tanega-shima Island and various properties of its wood were investigated. Grain angle was measured and soft X-ray analysis was undertaken to obtain the density in each annual ring. Unit shrinkage and dynamic properties were measured by shrinkage, bending, and compression tests. Variations of wood properties in the radial direction, relationships of wood properties to density, and annual ring width were examined. Roughly speaking, variations in the radial direction of the grain angle, twist angle by drying, Young’s modulus and strength in static bending, absorbed energy in impact bending, compressive Young’s modulus, compressive strength, and compressive proportional limit corresponded to the variation of annual ring width. As a result, it was determined that if PAAm is afforested artificially for the purposes of lumber production and conservation, the annual rings of logs should not be too widely spaced. Wood properties of PAAm were similar to those of Japanese black pine (Pinus thunbergii Parl.), which is another representative pine on Tanegashima Island.