Analysis of stable crack growth across welded fusion line: Japanese round-robin

Bimaterial CT specimens are numerically analyzed in the elastic-plastic states. By changing the material constants and the distance between the crack tip and the phase boundary, the parametric analyses are conducted. J integral evaluated by the line integration is compared with that obtained by the empirical formula by Merkel-Corten. The effects of the inhomogeneities on the accuracy of the J integral evaluation are discussed. Next the stable crack growth analyses are conducted. Using the relation between a and load-load line displacement obtained experimentally, the generation phase analyses are carried out. J integral, T^* integral and CTOA are evaluated and the effects of the fusion line are discussed.     

Development of the evaluation method for crack propagation due to thermal striping

The evaluation code “THERST” was developed to estimate the fatigue crack propagation behavior under thermal stresses due to high-frequency temperature fluctuations, called “thermal striping”. This paper presents fundamental formulations of the evaluation method and verifications of the evaluation method by FEM analyses. Experimental data were obtained in high cycle thermal fatigue tests and the effect of a multiple crack which is characteristic for a crack under thermal stress is discussed in addition to the results of the FEM analyses. A modification of the evaluation method was performed to take multiple crack effects into account.     

Realization of Large Electric Polarization and Strong Magnetoelectric Coupling in BiMn3Cr4O12

Magnetoelectric multiferroics have received much attention in the past decade due to their interesting physics and promising multifunctional performance. For practical applications, simultaneous large ferroelectric polarization and strong magnetoelectric coupling are preferred. However, these two properties have not been found to be compatible in the single‐phase multiferroic materials discovered as yet. Here, it is shown that superior multiferroic properties exist in the A‐site ordered perovskite BiMn₃Cr₄O₁₂ synthesized under high‐pressure and high‐temperature conditions. The compound experiences a ferroelectric phase transition ascribed to the 6s² lone‐pair effects of Bi³⁺ at around 135 K, and a long‐range antiferromagnetic order related to the Cr³⁺ spins around 125 K, leading to the presence of a type‐I multiferroic phase with huge electric polarization. On further cooling to 48 K, a type‐II multiferroic phase induced by the special spin structure composed of both Mn‐ and Cr‐sublattices emerges, accompanied by considerable magnetoelectric coupling. BiMn₃Cr₄O₁₂ thus provides a rare example of joint multiferroicity, where two different types of multiferroic phases develop subsequently so that both large polarization and significant magnetoelectric effect are achieved in a single‐phase multiferroic material.     

Photo-carrier transport in microcrystalline silicon films prepared by hot-wire CVD

Electronic transport properties of hydrogenated microcrystalline silicon films prepared by hot-wire CVD have been discussed. Near room temperature, the photo-transport occurs by thermionic emission of electrons over potential barriers between grain boundaries. The potential barrier height, which dominates the carrier mobility, decreases with increasing illumination intensity. The mobility-lifetime product (10^− 7-10^− 8 cm² V^− 1) at 300 K obtained experimentally is comparable with those obtained in films prepared by plasma enhanced CVD.     

Photosynthetic Linear Electron Flow Drives CO2 Assimilation in Maize Leaves

Photosynthetic organisms commonly develop the strategy to keep the reaction center chlorophyll of photosystem I, P700, oxidized for preventing the generation of reactive oxygen species in excess light conditions. In photosynthesis of C₄ plants, CO₂ concentration is kept at higher levels around ribulose 1,5-bisphosphate carboxylase/oxygenase (Rubisco) by the cooperation of the mesophyll and bundle sheath cells, which enables them to assimilate CO₂ at higher rates to survive under drought stress. However, the regulatory mechanism of photosynthetic electron transport for P700 oxidation is still poorly understood in C₄ plants. Here, we assessed gas exchange, chlorophyll fluorescence, electrochromic shift, and near infrared absorbance in intact leaves of maize (a NADP-malic enzyme C₄ subtype species) in comparison with mustard, a C₃ plant. Instead of the alternative electron sink due to photorespiration in the C₃ plant, photosynthetic linear electron flow was strongly suppressed between photosystems I and II, dependent on the difference of proton concentration across the thylakoid membrane (ΔpH) in response to the suppression of CO₂ assimilation in maize. Linear relationships among CO₂ assimilation rate, linear electron flow, P700 oxidation, ΔpH, and the oxidation rate of ferredoxin suggested that the increase of ΔpH for P700 oxidation was caused by the regulation of proton conductance of chloroplast ATP synthase but not by promoting cyclic electron flow. At the scale of intact leaves, the ratio of PSI to PSII was estimated almost 1:1 in both C₃ and C₄ plants. Overall, the photosynthetic electron transport was regulated for P700 oxidation in maize through the same strategies as in C₃ plants only except for the capacity of photorespiration despite the structural and metabolic differences in photosynthesis between C₃ and C₄ plants.     

Irradiation test of component for radiation-resistant small sized motor

A small-sized motor with a resistance to radiation was developed. This motor has been able to operate at a gamma-ray dose of a value 700 times as high as the specification of a commercial motor. The present work describes results of post-irradiation examinations (PIEs) to evaluate effects of neutron irradiation on the lifetime of some major components of the motor such as a bearing, a magnet and a fixation agent for a field coil wire. It became clear from the results of PIEs that the radiation-resistance dose of the motor using a Sm–Co magnet will be expected to be one order of magnitude higher than that of the motor using a Nb–Fe–B magnet.     

Rapid detection of Shiga-like toxin gene in feces with rapid-cycle polymerase chain reaction

A rapid detection for Shiga-like toxin in feces was developed with the nucleic acid extraction method by silicondioxide-guanidine thiothianate and rapid-cycle polymerase chain reaction by RapidCycler (model 1002; Idaho Technology, RC-PCR here after). Twenty-two fecal samples that were collected from patients with diarrhoea caused by E. coli O157:H7 and frozen for 6 months were examined directly by RC-PCR, conventional PCR assay using by ThermalCycler 9600-R (Roche, TC-PCR here after) and by the culture method using tellurite-cefixime sorbitol MacConkey (direct method). These examinations were done also after being injected into TCV-TSB and incutated at 35 degrees C overnight (indirect method). The sensitivity of RC-PCR and TC-PCR using a diluted suspension of broth enriched at 35 degrees C overnight were 4.1 pg and 410 fg, respectively. Positive results in the direct method were obtained in 7 for RC-PCR, 10 for TC-PCR and 5 for culture. Positive results on indirect assay were obtained in 9 for RC-PCR, 9 for TC-PCR and 7 for culture. It was demonstrated that the RC-PCR assay was able to detect Shiga-like toxin gene in feces in less than 90 minutes after being received at the laboratory.