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141.
Jun Tanabe Akira Tamura Mika Hamanaka Futoshi Ishiguri Yuya Takashima Jyunichi Ohshima Kazuya Iizuka Shinso Yokota 《Journal of Wood Science》2014,60(5):297-304
This study aimed to evaluate radial and among-family variations of wood properties in Picea jezoensis. A total of 174 trees were randomly selected from 10 open-pollinated families in a progeny trial for measuring stem diameter, dynamic Young’s modulus of log (DMOElog), annual ring width (ARW), air-dry density (AD), modulus of elasticity (MOE), and modulus of rupture (MOR). Mean values of DMOElog, AD, MOE, and MOR were 9.60 GPa, 0.41 g/cm3, 9.44 GPa, and 76.6 MPa, respectively. Significant differences among families were observed in all properties. F values obtained by analyzing variance in wood properties were higher than those generally observed in growth traits. In addition, F values in wood properties remained relatively higher from the 1st to 25th annual ring from the pith, although F value in ARW rapidly decreased with each increase in annual ring number. These results indicate that genetic factors largely contributed to the variance in wood properties compared with the growth traits. 相似文献
142.
Iris Brémaud Nadine Amusant Kazuya Minato Joseph Gril Bernard Thibaut 《Wood Science and Technology》2011,45(3):461-472
Extractives can affect the vibrational properties tanδ (damping coefficient) and E′/ρ (specific Young’s modulus), but this
is highly dependent on species, compounds, and cellular locations. This paper investigates such effects for African Padauk
(Pterocarpus soyauxii Taub.), a tropical hardwood with high extractives content and a preferred material for xylophones. Five groups of 26 heartwood
specimens with large, yet comparable, ranges in vibrational properties were extracted in different solvents. Changes in vibrational
properties were set against yields of extracts and evaluation of their cellular location. Methanol (ME) reached most of the
compounds (13%), located about half in lumen and half in cell-wall. Water solubility was extremely low. tanδ and E′/ρ were
very strongly related (R
2 ≥ 0.93), but native wood had abnormally low values of tanδ, while extraction shifted this relation towards higher tanδ values.
ME extracted heartwood became in agreement with the average of many species, and close to sapwood. Extractions increased tanδ
as much as 60%, irrespective of minute moisture changes or initial properties. Apparent E′/ρ was barely changed (+2% to −4%)
but, after correcting the mass contribution of extracts, it was in fact slightly reduced (down to −10% for high E′/ρ), and
increasingly so for specimens with low initial values of E′/ρ. 相似文献
143.
To clarify the role of lignin in the affinities of acetylated wood for organic solvents, the effects of delignification on
the solvent adsorption of acetylated wood were investigated. Acetylated wood meals rapidly adsorbed organic solvents that
were hardly adsorbed by unmodified wood. For nonpolar and low-polarity organic solvents, a clear positive correlation was
observed between the amount of adsorption and the lignin content. This indicated that acetylated lignin was responsible for
the excellent affinities of acetylated wood for hydrophobic organic solvents. On the other hand, for lower alcohols and water,
the amount of adsorption reduced with an increase in the lignin content. It was suggested that the adsorption of such polar
solvents was dominated by insufficiently acetylated hydrophilic polysaccharides. 相似文献
144.
Wood specimens were prepared in a swollen state using solvent exchange (PS) treatment. The swollen wood specimens were acetylated
using acetic anhydride by heating at 80–120°C. At the beginning of heating, the weight percent gain (WPG) of PS-treated wood
was greater than that of conventionally acetylated wood. This acceleration effect of the PS treatment was explained by the
introduction of treating reagent into the wood polymers where the intermolecular hydrogen bonds were previously broken. On
the other hand, the PS treatment had no influence on the final WPG and moisture sorption characteristics of acetylated wood.
This indicated that the intrinsic reactivity of wood constituents was unaffected by the PS treatment. The acetylation of PS-treated
wood produced greater bulking and slightly higher dimensional stability than that in the case of conventional acetylation
at the same WPG. It was speculated that the expansion of cell lumina due to the PS treatment resulted in greater bulking on
acetylation and lesser swelling of acetylated wood with moisture sorption. 相似文献
145.
In order to examine the contribution of wood components to the acetylation of wood, we acetylated wood meal that had been
partially delignified. The results were analyzed in terms of the reaction kinetics. The first-order rate equation was successfully
adjusted to the weight gain data. The rate constant for acetylation initially increased with progress of lignin elimination
and then turned to decrease; the apparent activation energy showed the reverse tendency and ranged from about 90 to 130 kJ/mol.
These results suggest that lignin elimination brings not only separation of lignin but also drastic change of the chemical
and/or physical structure in the residual lignin, and this affects the reactivity of wood meal as a whole. The ultimate weight
gain estimated by the regression of the rate equation showed a minimum when lignin was moderately eliminated, which was explained
in terms of enhanced reactivity of lignin and lower accessibility for holocellulose than predicted. The equilibrium moisture
content had a maximum when lignin was moderately eliminated. This tendency is the opposite of that observed for the ultimate
weight gain, and suggests that the sites for acetylation do not always correspond to those for moisture adsorption.
Part of this report was presented at the 54th Annual Meeting of the Japan Wood Research Society, Sapporo, August 2004 相似文献
146.
The dependence of the reaction parameters of acetylation on the reaction mixture was compared among uncatalyzed, acetic anhydride-xylene mixed, and acetic anhydride-pyridine mixed solutions. Wood meal and blocks were used to examine the effect of sample size. A first-order rate equation was applied to the data, and a rate constant and leveling off value of weight gain (WG) were estimated. The rate-determining step was examined from the viewpoint of activation energy. The results were as follows: (1) Regarding the magnitude of the rate constant, the order was pyridine system > uncatalyzed system > xylene system. (2) The ultimate value of WG was lower in the uncatalyzed and xylene systems than the pyridine system, probably because of the swelling ability of pyridine. (3) The activation energies of acetylation estimated for wood meal were 120, 135, and 110kJ/mol for the uncatalyzed, xylene, and pyridine systems, respectively. (4) The characteristics of the diffusion-controlled reaction became marked when the acetylation was carried out in the pyridine system, at elevated temperature, and for wood blocks. Under these conditions, the supply of reagent to the reaction site might not be sufficient to fuel the reaction.Part of this report was represented at the 52nd Annual Meeting of the Japan Wood Research Society, Gifu, April 2002 相似文献
147.
Participation of lignin in the reaction between vapor-phase formaldehyde and wood was examined by using gradually delignified
wood meal. A fi rst-order rate equation was successfully applied to the weight gain data. From the estimated reaction parameters
such as rate constant, k, and ultimate weight gain, a, the reactivity toward formaldehyde was discussed among wood components, and compared with that for acetylation. k decreased monotonously with progress of the elimination of lignin, suggesting that the reaction rate of lignin is dominant
over that of whole wood, and the decrease in the ratio of lignin retarded the reaction of wood as a whole. On the other hand,
a increased with decreasing lignin content. This may be attributable to the enhanced reactivity of the remaining lignin due
to some structural changes and to the increase in the number of reactive sites in polysaccharides as a result of their exposure
accompanying the elimination of lignin. The dependencies of k and a on the lignin content were not similar to the case for acetylation, probably because of the difference in the reaction phase.
In vapor-phase formaldehyde treatment, the remaining lignin reacts as it is, whereas in liquid-phase acetylation it would
undergo rearrangement or swelling of the structure in the reaction solution. 相似文献
148.
The vapor phase reaction of wood with maleic anhydride (MA) was investigated from the aspect of the mechanism of dimensional
stabilization. Notably the existence of cross-links was examined by detailed analyses of dimensional stability and related
properties, diffuse reflectance infrared Fourier transform (DRIFT) spectra, and changes in mechanical properties such as creep
property and vibrational property. Higher reaction temperature resulted in less leaching of reagent. Also a peak in DRIFT
spectra at 1730 cm−1 showed the esterification of wood components with MA, while that at around 1780 cm−1, which became remarkable with increasing reaction temperature, suggested the formation of cross-linking. The loss tangent
decreased and the creep deformation was restrained for the specimens treated at high temperature. From these results it is
plausible that MA mainly forms monoester with wood components at lower temperature; however, at elevated temperature cross-linking
appears in addition to formation of the monoester. 相似文献
149.
Satoshi Furukawa Yumiko Hoshikawa Kota Irie Yusuke Kuroda Kazuya Takeuchi 《Journal of toxicologic pathology》2021,34(1):107
Swim bladder tumors were detected in three out of 28 wavy medakas aged about 2 years old, all of which displayed abnormal swimming patterns caused by their spinal curvature. The tumors were located in the dorsal abdominal cavity. The swim bladder lumen was not detected in the region where it was originally assumed to be located, and that region was replaced with adipose tissue. The tumors were non-invasive, expansile, and encapsulated solid masses composed of a homogenous population of well-differentiated, densely packed, gas glandular epithelium-like cells. The tumor masses were connected to the rete mirabile, but the tumor cells did not infiltrate into them. Histopathologically, these tumors were diagnosed as adenomas originating from the gas glandular epithelium of the swim bladder. Spontaneous swim bladder tumors are rare in medaka, with an incidence of 0.02%; however, in the present study of wavy medaka, the incidence was much higher (10.7%). The long-term physical effects on the gas gland caused by swim bladder deformation considered to be a secondary effect of the spinal curvature may be an important factor in the proliferation of the gas glandular epithelium in the wavy medaka, resulting in the higher incidence of swim bladder tumors. 相似文献
150.
Yuto SANO Kanae SEKI Kenjirou MIYOSHI Toshikazu SAKAI Tsuyoshi KADOSAWA Kazuya MATSUDA 《The Journal of veterinary medical science / the Japanese Society of Veterinary Science》2021,83(5):876
Mediastinal masses in dogs were diagnosed as basaloid carcinoma associated with multiple thymic cysts (MTCs). The masses were composed of MTCs and proliferating intracystic neoplastic basaloid cells, which immunohistochemically diffusely expressed p63 and cytokeratin 19. A gradual transition from the basal cell layers lining the cysts walls to the neoplastic cells was seen, and it was indicated that the neoplastic cells had originated from the basal cell layers of the cysts. To the best of our knowledge, this is the first report of basaloid carcinoma occurring in the mediastinal cavity in dogs. Although these tumors were demonstrated to be rare origins, basaloid carcinoma should be included in the differential diagnoses for canine mediastinal tumors. 相似文献