Akita Prefectural University

About: Akita Prefectural University is a education organization based out in Akita, Japan. It is known for research contribution in the topics: Magnetic field & Starch. The organization has 1631 authors who have published 3107 publications receiving 45764 citations. The organization is also known as: Akita kenritsu daigaku.

The Effect of Measurement Time When Evaluating Static Muscle Endurance during Sustained Static Maximal Gripping

Abstract: The purpose of this study was to examine the useful measurement time when evaluating static muscle endurance by comparing various parameters during sustained static gripping for 1, 3 and 6 min. Fifteen males (mean +/- SD age 20.8 +/- 1.3 yr, height 172.9 +/- 4.6 cm, body mass 67.7 +/- 5.7 kg) and fifteen females [mean +/- SD age 20.2 +/- 0.9 yr, height 158.5 +/- 3.2 cm, body mass 55.9 +/- 4.6 kg] volunteered to participate in this study. The subjects performed the sustained static maximal grip test with a sagittal and horizontal arm position for 1, 3 and 6 min on different days. Eleven force-time parameters were selected to evaluate static muscle endurance. The trial-to-trial reliability of each measurement time of sustained static maximal gripping was very high (rxy = 0.887-0.981 (1 min), 0.912-0.993 (3 min), 0.901-0.965 (6 min)). The errors of exertion values between trials were very small (below 10%). A significant correlation was found in the following parameters: the final strength and the exponential function between 1 min and 3 min, all parameters except for the time required to reach 80% of maximal grip, the regression coefficient at post-inflection between 3 min and 6 min, and the decreasing rate between all measurement times (1 min, 3 min, and 6 min). Significant differences between the measurement times were found in all parameters except for the time to 60, 70, and 80% force decreases, and the regression coefficient of pre-inflection. There was a tendency that the longer the measurement time, the larger the decreasing force. It is suggested that for the 6 min measurement, the subjects unconsciously restrained the maximal gripping force, influenced by a psychological factor as the pain became greater. The 1 min measurement may evaluate only the remarkable decreasing phase of the decreasing force, and not evaluate the phase of an almost steady state.

Relationship between formation of earlywood vessels and leaf phenology in two ring-porous hardwoods, Quercus serrata and Robinia pseudoacacia, in early spring

Abstract: In deciduous ring-porous hardwoods, three-dimensional networks of the current year’s earlywood vessels play an important role in the movement of water. In the present study, we analyzed the formation of earlywood vessels along the main stem and leaf phenology in two deciduous ring-porous hardwoods, Quercus serrata and Robinia pseudoacacia. We introduced a dye in an effort to monitor the timing of initial water conduction through the network of the current year’s earlywood vessels. The formation of earlywood vessels began before bud break. At bud break, perforation of the first earlywood vessels was evident at the top of the stem but not at other positions within the stem. Perforations were observed along the entire stem when small leaves became visible and then leaves continued to develop. These results suggest that conduction of water via the network of the first earlywood vessels of the current year might not contribute to the initial growth of buds but might play an important role in the development of the current year’s leaves and shoots.

Cesium Uptake by Rice Roots Largely Depends Upon a Single Gene, HAK1, Which Encodes a Potassium Transporter

Abstract: Incidents at the Fukushima and Chernobyl nuclear power stations have resulted in widespread environmental contamination by radioactive nuclides. Among them, 137cesium has a 30 year half-life, and its persistence in soil raises serious food security issues. It is therefore important to prevent plants, especially crop plants, from absorbing radiocesium. In Arabidopsis thaliana, cesium ions are transported into root cells by several different potassium transporters such as high-affinity K+ transporter 5 (AtHAK5). Therefore, the cesium uptake pathway is thought to be highly redundant, making it difficult to develop plants with low cesium uptake. Here, we isolated rice mutants with low cesium uptake and reveal that the Oryza sativa potassium transporter OsHAK1, which is expressed on the surfaces of roots, is the main route of cesium influx into rice plants, especially in low potassium conditions. During hydroponic cultivation with low to normal potassium concentrations (0-206 µM: the normal potassium level in soil), cesium influx in OsHAK1-knockout lines was no greater than one-eighth that in the wild type. In field experiments, knockout lines of O. sativa HAK1 (OsHAK1) showed dramatically reduced cesium concentrations in grains and shoots, but their potassium uptake was not greatly affected and their grain yields were similar to that of the wild type. Our results demonstrate that, in rice roots, potassium transport systems other than OsHAK1 make little or no contribution to cesium uptake. These results show that low cesium uptake rice lines can be developed for cultivation in radiocesium-contaminated areas.

Proposal of a tilted helical milling technique for high quality hole drilling of CFRP: kinetic analysis of hole formation and material removal

Abstract: Carbon fiber reinforced plastic (CFRP) is used for various mechanical structures because of its superior mechanical and physical properties. Industrial applications of CFRP require high quality, efficiently drilled holes. However, it is difficult for conventional methods, such as drilling, helical milling, and so on to meet industry requirements. Therefore, this study proposed a novel method for drilling holes in CFRP products. This new method is performed by replacing the revolving motion of the tool in conventional helical milling (CHM) with conical pendulum motion, in which the tool axis is tilted toward the hole axis at a certain angle, consequently called tilted helical milling (THM). As a step toward the establishment of the new method, in this work, the hole formation process, the cross-sectional area of work materials removed per tool revolution, and the zero cutting speed point problem in THM were theoretically compared with those in CHM. Then, experiments were performed to confirm the theoretical analysis in terms of the variations in the cross section profile of the drilled hole, the drilling forces, the hole quality at entrance/exit, and the chip removal. The obtained results revealed that during hole drilling by THM, a circumferential V-groove exists between the end face of the tool and the bottom of the hole, whereas in CHM, this phenomenon does not occur. This fact is beneficial to timely chip removal, drilling force reduction, and zero cutting speed point problem avoidance. Subsequently, high quality holes can be successfully obtained with high efficiency by THM.

Extraction of magnetic particle clusters self-assembled by a magnetic field

Abstract: For the purpose of particle assembly on a nano- or microscale produced by metal particles, we proposed a method of extracting magnetic clusters in the shapes of rods or needles that have been produced in sizes ranging from macroscopic to microscopic. We also succeeded in freely controlling the scale of the magnetic cluster in this size range, with the form remaining stable without the presence of a magnetic field through the use of hydrophilic monomers of oleic acid. We discovered an algebraic rule governing the relation between the scale of the magnetic cluster and the strength of the applied magnetic field.