Shogo Okumura

Assessment of wood surface roughness: comparison of tactile roughness and three-dimensional parameters derived using a robust Gaussian regression filter

Japanese oak and Japanese beech were sanded by hand with abrasive papers of varying grit number. Two three-dimensional parameters selected to characterize their surface roughness – one parameter for the distribution of roughness-profile peaks and the other for the relative area of the roughness-profile peaks above the threshold height – were compared against tactile roughness. The parameters were obtained from roughness profiles as determined by a robust Gaussian regression filter (RGRF) using seven cutoffs. The RGRF filtering process was adjusted specifically for the evaluation of wood surface roughness. Except for a cutoff wavelength of 0.25 mm, the RGRF lent itself well to the determination of roughness profiles. No distortion of roughness profiles occurred around deep valleys, and there was a good correlation between the parameters and tactile roughness.

Relationship between roughness parameters based on material ratio curve and tactile roughness for sanded surfaces of two hardwoods

The roughness parameters on the material ratio curves were related to tactile roughness for samples of buna and mizunara. The surfaces of the samples were sanded using various grades of coated abrasives and the roughness parameters, reduced peak height (Rpk), core roughness depth (Rk), and reduced valley depth (Rvk), were estimated on the material ratio curves, which were obtained from roughness profiles determined using robust Gaussian regression filter. The values of Rpk and Rk were almost the same for buna and mizunara under the same sanding conditions and increased exponentially with tactile roughness. The coefficients of determination of those parameters and tactile roughness were higher than 0.79 at all cutoff wavelengths. On the other hand, the value of Rvk for mizunara was significantly larger than that for buna because of the deep local valleys. There was no relationship between Rvk and tactile roughness for both species.

Wear of tungsten carbide tipped circular saws in cutting particleboard: Effect of carbide grain size on wear characteristics

SummaryIn order to study the wear of tungsten carbide tipped circular saws, three kinds of carbide tips (fine, medium and coarse grained ones) were employed, when sawing particleboards. The saw with coarse grained carbide tips showed the longest working life, while the fine-grained carbide tipped saw retained its usefulness for only a short period of sawing. In an experiment using a saw with all three kinds of carbide tips, it was also confirmed that the fine grained tips wore most and the coarse least. From the observations of the worn tips, it was found that the wear boundary on the clearance face was quite distinct for these tips, although for the fine grained one it was remarkably indented. There were many striations on the wear surface of the fine grained tip, but they scarcely appeared on those of the other two tips. The wear mechanism and the wearing process of the carbide tips are discussed.

para-Selective Alkylation of Sulfonylarenes by Cooperative Nickel/Aluminum Catalysis

A method for the para-selective alkylation of a variety of arenesulfonamides and aromatic sulfones with 1-alkenes by cooperative nickel/aluminum catalysis has been developed. Taking advantage of the sulfornyl functionality serving as a removable ortho-directing group, the reaction can be applied to facile access to 1,3-dialkyl-substitued benzenes.

Thickness variation of the G-layer along a mature and a differentiating tension wood fiber in Populus euramericana

SummaryThe thickness variation of the secondary wall layers along a mature tension wood fiber was examined, using serial transverse sections, and that of the gelatinous layer along a differentiating fiber was also studied. In a mature gelatinous fiber the G-layer was the thickest in the central region of the fiber and decreased in thickness toward the tips. The thickness of the S2 layer also decreased from the center toward the tips, whereas the S1 layer showed a uniform thickness throughout the fiber length. From the observations of some differentiating fibers it was concluded that the G-layer possesses a uniform thickness along the length of a fiber at the earliest stage of G-layer formation and that the more the fiber develops, the greater is the reduction in thickness of the G-layer from the center of the fiber toward the tips. The thickening process of secondary wall layers is discussed.

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.

Site‐Selective Linear Alkylation of Anilides by Cooperative Nickel/Aluminum Catalysis

We report meta- and para-selective linear alkylation reactions of anilides with alkenes by nickel/N-heterocyclic carbene (NHC) and aluminum catalysis. With a less bulky NHC, the alkylation reaction of N-methyl-N-phenylcyclohexanecarboxamides proceeded mainly at the meta position. In contrast, a bulky NHC ligand led to the para-selective alkylation of N-sec-alkyl anilides.

Difference in mass concentration of airborne dust during circular sawing of five wood-based materials

The object of this study was to compare the mass concentration of airborne dust during circular sawing of five wood-based materials: solid sugi (Cryptomeria japonica) lumber, tropical hardwood plywood, softwood plywood, particleboard, and medium-density fiberboard. Specimens were sawn at a constant feed per tooth (0.05 mm) using two saw speeds. The mass concentration of airborne dust of diameter 7.07 μm or less (respirable dust) was measured with a light-scattering dust monitor. The mass concentration showed a log-normal distribution, and the geometric means of mass concentration at saw speeds of 2000 and 3000 rpm were 2.33 and 2.89 mg/m3 for tropical hardwood plywood, 1.13 and 2.84 mg/m3 for particleboard, 0.91 and 2.28 mg/m3 for medium-density fiberboard, 1.09 and 1.38 mg/m3 for softwood plywood, and 0.32 and 0.66 mg/m3 for sugi lumber. The mass concentration for all five wood-based materials increased with the revolution speed of the circular saw.

Polarizing Microscope Study on the Concentric Orientation of nγ in the Pit Border Region of Softwood Tracheids

It has been often stated that the cellulose molecules in the pit border region of the bordered pits in softwood tracheids have a concentric orientation around pit apertures. However, this concept only results from the observation of the double wall of tracheids, and it is not consistent with the streamline pattern of the microfibrils in the S2 and S3 layers in the pit border. In order to clarify how the pit border region of double wall tracheids shows the concentric orientation of ny, mature and differentiating tracheids in Pinus densiflora Sieb, et Zucc. were studied using polarizing microscopy. Examination of the pit border region in the single wall of mature earlywood tracheids showed the distinct orientation of ny which is perpendicular to the microfibril direction of the S2 layer, near both ends of the spindle-shaped pattern of this layer. From observations of the double and single walls of tracheids at the various developmental stages, it has been concluded that the remarkable orientation of ny near both ends of the spindle-shaped pattern of the S? layer is due to the predominance of microfibril orientation in the Sx or BT layer. Consequently, it has become clear that two adjacent single walls which show the above mentioned orientation of ny give the concentric orientation of ny in the pit border region in double wall.