ENERGETICS APPROACH TO FATIGUE BEHAVIOR OF WOODEN JOINT USING DOUBLE-SIDED ADHESIVE TAPE

The authors have previously studied the possibility of the use of industrial double-sided adhesive tape as a method for jointing wooden panel to wooden framework. The mechanical performance of joints formed by such methods is comparable to that of nailed joint under static load conditions. However, the mechanical performance of such joints has not been evaluated under cyclic load conditions. This study was conducted to investigate this aspect of their performance. Double-shear specimens were prepared by bonding wooden panel to wooden framework using two types of adhesive tape with different substrates. Specimens were also prepared with wooden dowels to strengthen their jointing performance. The joint specimens were subjected to cyclic shear loading testing. The results of the tests were analyzed from an energetics perspective, and the shear deformability of the specimens at failure was estimated. The test results indicate that both the specimens formed using adhesive tape and those formed using wooden dowels had fatigue properties comparable to nailed joint specimens. A tendency for the shear deformability caused by cyclic loading to increase with the stress level was observed. It was possible to estimate the shear deformability by evaluating the energy absorption capacity of the joints from an energetics standpoint

The Migration, Culture, and Lifestyle of the Paleolithic Ryukyu Islanders

Roughly 35,000 years ago, hunting-fishing-gathering people occupied the Ryukyu Islands of Japan, a chain of small-sized islands in the western Pacific. There are Paleolithic sites scattered over most of the relatively large islands, thereby suggesting an extensive human dispersal over the sea at least 30,000 years ago. Recent morphological and genetic studies of the human fossils found in this area revealed that Paleolithic occupants might have an affinity with the modern and prehistoric populations of Southeast Asia. Recent excavation of Paleolithic sediments at Sakitari Cave, Okinawa Island, provided a variety of shell artifacts, including beads, scrapers, and fishhooks, and evidence of seasonal consumption of aquatic animals, especially freshwater crabs. The Paleolithic Ryukyu Islanders’ culture and lifestyle, which made use of unique resources, demonstrate behavioral adaptations to living on relatively small islands

High-temperature thermoelectric properties of the double-perovskite ruthenium oxide (Sr1−x_{1-x}Lax_x)2_2ErRuO6_6

We have prepared polycrystalline samples of (Sr$_{1-x}$La$_x$)$_2$ErRuO$_6$ and (Sr$_{1-x}$La$_x$)$_2$YRuO$_6$, and have measured the resistivity, Seebeck coefficient, thermal conductivity, susceptibility and x-ray absorption in order to evaluate the electronic states and thermoelectric properties of the doped double-perovskite ruthenates. We have observed a large Seebeck coefficient of -160 $\mu$V/K and a low thermal conductivity of 7 mW/cmK for $x$=0.1 at 800 K in air. These two values are suitable for efficient oxide thermoelectrics, although the resistivity is still as high as 1 $\Omega$cm. From the susceptibility and x-ray absorption measurements, we find that the doped electrons exist as Ru$^{4+}$ in the low spin state. On the basis of the measured results, the electronic states and the conduction mechanism are discussed.Comment: 6 pages, 4 figures, J. Appl. Phys. (accepted

Surprising increase in yield stress of Mg single crystal using long-period stacking ordered nanoplates

Mg–Zn–Y ternary alloys containing the long-period stacking ordered (LPSO) phase exhibit superior mechanical properties. This is believed to be originating from the LPSO phase acting as the strengthening phase. However, we first clarify that the mechanical properties of the matrix Mg solid solution in the Mg/LPSO two-phase alloy are significantly different from those of pure Mg. The yield stress of a Mg99.2Zn0.2Y0.6 single crystal (matrix Mg solid solution) is almost the same as that of an LPSO single-phase alloy. This is ascribed to the formation of thin stacking-fault-like defects, named “LPSO nanoplate”. In Mg99.2Zn0.2Y0.6, kink-band formation is induced in the same manner as that in the LPSO phase in deformation, resulting in high strength accompanied with increased ductility. Our results suggest that the strengthening mechanism of the Mg/LPSO two-phase alloy must be reconsidered depending on the microstructure. Furthermore, the results suggest that new ultrahigh-strength Mg alloys, which have much lower Zn and Y contents but the mechanical properties are comparable or superior than the present Mg/LPSO two-phase alloys, are expected to be developed via the appropriate control of LPSO nanoplate microstructures.Hagihara K., Ueyama R., Yamasaki M., et al. Surprising increase in yield stress of Mg single crystal using long-period stacking ordered nanoplates. Acta Materialia, 209, 116797. https://doi.org/10.1016/j.actamat.2021.116797

Loading orientation dependence of the formation behavior of deformation kink bands in the Mg-based long-period stacking ordered (LPSO) phase

The variation in the deformation behavior of a directionally solidified (DS) Mg-based long-period stacking ordered (LPSO)-phase crystal depending on the loading orientation was examined. The frequency of formation of the beak-like shape of the deformation band, which is known as one of the important deformation mechanisms in the LPSO phase, monotonically decreased as the inclination angle of the loading orientation with respect to the crystal growth direction in the DS crystal increased, and was accompanied by a decrease in the yield stress due to the activation of basal slip. Deformation bands formed along a direction approximately perpendicular to the grain boundary independent of the loading orientation. The crystal rotation axes selected in the deformation bands were perpendicular to [0001] in almost all grains, independent of the loading orientation. However, the rotation axes in the bands were not fixed but varied between h1010 - i and h1120 - i; this variation was correlated with the loading axis. These observed features strongly suggest that the deformation bands formed in the LPSO phase are predominantly deformation kink bands and that the formation mechanism itself does not vary with the loading orientation but instead its details. The selectivity of the crystal rotation axis in the kink band is strongly affected by the loading orientation.Hagihara K., Okamoto T., Ueyama R., et al. Loading orientation dependence of the formation behavior of deformation kink bands in the Mg-based long-period stacking ordered (LPSO) phase. Materials Transactions 61, 1821 (2020); https://doi.org/10.2320/matertrans.MT-MM2019001

Quantitative estimation of kink-band strengthening in an Mg–Zn–Y single crystal with LPSO nanoplates

Kink-band strengthening was first quantitatively evaluated using an Mg–Zn–Y single crystal containing long-period stacking ordered (LPSO) nanoplates. The ability of a kink-band boundary to act as a barrier that hinders the motion of dislocations is high and comparable to that of a general random grain boundary. Nevertheless, a kink-band boundary is regarded as a simple tilt boundary in the dislocation model. One reason for the anomalous ability of kink-band boundary acting as barriers is related to its peculiar hierarchical structure, in which many small kink bands with high crystal rotation angles accumulate in a localized region.Hagihara K., Ueyama R., Tokunaga T., et al. Quantitative estimation of kink-band strengthening in an Mg–Zn–Y single crystal with LPSO nanoplates. Materials Research Letters, 9, 11, 467. https://doi.org/10.1080/21663831.2021.1974593

Uranium dioxides and debris fragments released to the environment with cesium-rich microparticles from the Fukushima Daiichi Nuclear Power Plant

International audienc

Morphologic studies of bone marrow cells exposed to the phospholipid fraction from the liver of irradiated animal, an experiment in vitro

With the purpose of revealing the biological effects of the X-ray irradiation the authors extracted phospholipids from the liver of irradiated animals and proved that this substance has the action to inhibit the growth of the bone marrow cells, the motility of pseudo-eosinophilis and the erythropoiesis in tissue culture, suggesting that the injury will mainly be induced by the toxic substances produced by irradiation.</p

Novel Method of Quantifying Radioactive Cesium-Rich Microparticles (CsMPs) in the Environment from the Fukushima Daiichi Nuclear Power Plant

Highly radioactive cesium-rich microparticles (CsMPs) were released from the Fukushima Daiichi nuclear power plant (FDNPP) to the surrounding environment at an early stage of the nuclear disaster in March of 2011; however, the quantity of released CsMPs remains undetermined. Here, we report a novel method to quantify the number of CsMPs in surface soils at or around Fukushima and the fraction of radioactivity they contribute, which we call “quantification of CsMPs” (QCP) and is based on autoradiography. Here, photostimulated luminescence (PSL) is linearly correlated to the radioactivity of various microparticles, with a regression coefficient of 0.0523 becquerel/PSL/h (Bq/PSL/h). In soil collected from Nagadoro, Fukushima, Japan, CsMPs were detected in soil sieved with a 114 μm mesh. There was no overlap between the radioactivities of CsMPs and clay particles adsorbing Cs. Based on the distribution of radioactivity of CsMPs, the threshold radioactivity of CsMPs in the size fraction of <114 μm was determined to be 0.06 Bq. Based on this method, the number and radioactivity fraction of CsMPs in four surface soils collected from the vicinity of the FDNPP were determined to be 48–318 particles per gram and 8.53–31.8%, respectively. The QCP method is applicable to soils with a total radioactivity as high as ∼106 Bq/kg. This novel method is critically important and can be used to quantitatively understand the distribution and migration of the highly radioactive CsMPs in near-surface environments surrounding Fukushima