Evaluation of the invariant reactions in the Ta-rich region of the Ta-B system

Invariant reactions in the Ta-rich side of the Ta-B system were evaluated. The alloys were arc melted from pure materials. Pellets prepared from powder mixtures of Ta and TaB were heat treated under vacuum at 1900 and 1950 °C. The microstructures of the alloys were characterized through scanning electron microscopy images and x-ray diffraction (XRD). The microstructural analyses confirmed the type of reactions occurring in Ta-rich region; however, the composition of the liquid phase should be altered: (a) L ↔ Ta_SS+Ta₂B from 23 to 18 at.% B and (b) L+TaB↔Ta₂B from 27 to 22.5 at.% B. The formation of Ta₃B₂ was confirmed as the understoichiometry of Ta₂B. The decomposition of Ta₂B occurs between 1900 and 1950 °C. The XRD data for alloys with composition between 34 and 50 at.% B indicate the existence of a new high-temperature phase.     

Evaluation of recycle P&T treatment by using BWR to perform geologic disposal

Geologic disposal scenario combined with multiple-recycle P&T (partitioning and transmutation) treatment of MA (minor actinide) was thought to have an important potential merit to carry out the geologic disposal. P&T treatment was thought to have a role to avoid an uncertainty caused by geologic behavior, such as underground water migration rate, reductive and inorganic environment in a super-long time. Partitioning and grouping of LLRN (long-lived radionuclide), i.e. MA and LLFP (long-lived fission product), has an essential role to the transmutation treatment. B/T (burning and/or transmutation) treatment of MA, with R&P (reprocessing and partitioning) process, could be recycled and SLFP (short-lived fission product) was removed to immobilize in GSC (glass solidified canister). If R&P has a high performance, the multi-recycle system which combines B T-BWR (B/T boiling water reactor) and R&P can transmute of U&Pu, MA and LLFP etc. with small inventory. B/T fraction of MA is high in case of multi-recycle system, and then the remain of mass of MA or LLFP is recycled many times with low inventory. The B/T fraction of MA or LLFP could be high, if the flux is high, i.e. the time needed for high B/T fraction is relatively short in case of high flux BWR, or long in case of normal BWR. The optimum period for discharge of B/T fuel could be determined by the net difference between the reduced mass of MA burned and/or transmuted in the B/T fuel and the accumulated mass of MA in the normal fuel, and with the additional mass of MA accumulated by U&Pu, which was unrecovered in the reprocessing existed in B/T fuel.     

Biochemical and molecular biological analyses of space-flown nematodes in Japan, the first international caenorhabditis elegans experiment (ICE-First)

The first International Caenorhabditis elegans Experiment (ICE-First) was carried out using a Russian Soyuz spacecraft from April 19–30, 2004. This experiment was apart of the program of the DELTA (Dutch Expedition for Life science Technology and Atmospheric research) mission, and the space agencies that participate in the International Space Station (ISS) program formed international research teams. A Japanese research team that conducted by Japan aerospace Exploration Agency (JAXA) investigated the following aspects of the organism: (1) whether meiotic chromosomal dynamics and apoptosis in the germ cells were normal under microgravity conditions, (2) the effect of the space flight on muscle cell development, and (3) the effect of the space flight on protein aggregation. In this article, we summarize the results of these biochemical and molecular biological analyses.     

Approaches to suppressing shaft voltage in brushless DC motor driven by PWM inverter

This paper describes the approaches to suppressing the shaft voltage and bearing current by electrostatically shielding the stator end windings of the brushless DC motor driven by PWM inverter. At first, measured shaft voltage and bearing current are compared with those calculated waveforms to verify the common mode equivalent circuit of the brushless DC motor. Next, the relationship between shaft voltage and stator winding to rotor capacitance is calculated using the common mode equivalent circuit. Finally, the electrostatic shielding of the stator end windings is evaluated to reduce the shaft voltage by experiments and calculations. ©2008 Wiley Periodicals, Inc. Electr Eng Jpn, 166(4): 73–79, 2009; Published online in Wiley InterScience ( www.interscience.wiley.com ). DOI 10.1002/eej.20701     

A new semi-phenomenological approach to predict the stress relaxation behavior of thermoplastic elastomers

In this paper we report on a new semi-phenomenological approach to predict the stress relaxation behavior of thermoplastic elastomers at long times. This approach relies on the method of Gurtovenko and Gotlib [J Chem Phys 115 (2001) 6785], which has originally been conceived to describe the relaxation dynamics of inhomogeneously crosslinked polymers forming agglomerations of crosslinks. In this work we demonstrate that the method can be extended to predict the stretched exponential stress decay of homogeneously crosslinked thermoplastic elastomers, which are subjected to an extensional strain pertaining to the nonlinear regime of mechanical properties. In our approach thermal fluctuations induce fluctuations in size of domains of crosslinks via a chain-pullout mechanism. We compare our theoretical predictions to the experimental measurements of Hotta et al. [Macromolecules 35 (2002) 271] performed on poly(styrene-isoprene-styrene) triblock copolymers, which are composed of hard domains of polystyrene embedded in a rubbery polyisoprene matrix. Our study confirm the importance of the chain-pullout mechanism in the stress relaxation process and demonstrates the involvement of multiple time- and structural-length-scales.     

Eating habits in childhood relate to preference for traditional diets among young Japanese

The present study investigated whether eating habits during childhood, specifically the type of food eaten for breakfast, is related to later attitudes toward traditional foods among young Japanese. In the experiment, participants were classified into two groups: one consisting of freshmen that habitually ate a Japanese-style breakfast during childhood (n = 28) and the other of freshmen that habitually ate a Western-style breakfast (n = 20). They were asked to complete a personalized implicit association test (IAT) and a self-report questionnaire, both of which measure attitudes toward Japanese and Western foods. Results demonstrated that implicit and explicit associations between Japanese food and attitude in the Japanese-style breakfast group were stronger than those between type of food and attitude in the Western-style breakfast group. Thus, positive attitudes toward traditional diets in young Japanese are likely related to the type of breakfast eaten in childhood.     

Applying Micro-Texture to Cast Iron Surfaces to Reduce the Friction Coefficient Under Lubricated Conditions

The tribological properties of cast iron have been investigated to determine the effects of micro-texturing the surfaces. The micro-textured surfaces were prepared by shot blasting or milling using a shaper. The surfaces with groove patterns and mesh patterns had higher friction coefficients than the flat surfaces. The surfaces with dimpled patterns had lower friction coefficients than the flat surfaces. The results indicated that the dimpled pattern had a beneficial effect by decreasing the friction.     

Relationships between lateral force and viscoelastic properties for amorphous polymer films based on lateral force microscopy

Summary. The relationships between lateral force and viscoelastic properties of amorphous polymer surfaces with Tg's lower and higher than room temperature (295 K, RT) and their blend systems have been studied on the basis of lateral force microscopic (LFM) measurement. Under the conditions of scanning rate of 10²–10⁵ nm sec^-1, normal load of 5 nN and RT, the lateral forces of poly(methyl methacrylate) (PMMA) and polyisoprene (PI) homopolymers with Tg's fairly higher and lower than RT, respectively, did not depend on the scanning rate. Whereas, the lateral force of poly(methyl acrylate) (PMA) with Tg ≤ RT decreased with an increase in the scanning rate. Also, poly(vinyl acetate) (PVAc) with Tg ≥ RT showed slight dependence on the scanning rate. The scanning rate dependence of lateral force was similar to the frequency dependence of mechanical loss modulus. The results indicate that the magnitude of lateral force strongly depends on the state of thermal molecular motion. The lateral force-viscoelastic properties of miscible polymer blends was also investigated by LFM. Received: 30 June 1997/Revised: 24 July 1997/Accepted: 29 July 1997     

Aspects of q-discretized Nahm equations

There is a conjecture by Ward that almost all of integrable equations are derived from (anti-)self-dual (ASD) Yang–Mills equations. This conjecture is supported by many concrete examples, e.g., the Nahm equations. In this work, we consider a situation that if the ASD conditions are slightly loosened, as to how it affects the integrability of the equations. For this purpose, we consider a q-analog of the Nahm equations, as a non-ASD system. The analysis is performed on the reduced system which is a q-analog of the Euler–Arnold top, by the singularity confinement test and the estimation of the algebraic entropy.