Identification of factor determining strength under compressive loads of steel members corrected by heating/pressing

By using cruciform columns, factors dominating behavior under compressive loads of steel structural members, whose locally buckled part was corrected by heating/pressing, have been elucidated. They were geometric residual imperfection resulted from incomplete correction and increase of yield stress due to large plastic deformation caused by local buckling and its correction process. For soundness diagnosis of the corrected member, the importance of these factors was investigated based on the results of the numerical simulation. Although the increase of yield stress did not affect the ultimate strength, that changed the deformation mode of the member after the ultimate situation. As the result, it was elucidated that the increase of yield stress was not important in the soundness diagnosis. The residual imperfection affected the buckling and ultimate strength of the corrected member. Rather the size of the region than the absolute value in the out-of-plane direction of the residual imperfection should be controlled as small as possible for ensuring the soundness of the corrected member.     

Spintronics based random access memory: a review

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Fatigue characteristics of patch plate joints by fillet welding assisted with bonding

A series of fatigue experiments and elastic analysis were carried out for investigating fatigue characteristics of patch plate joints assembled by fillet welding assisted with bonding. In the case that fatigue cracks occurred at the weld toe by the four-point bending fatigue experiment, the fatigue life of joints assembled by welding and bonding (WB) specimens were almost the same as those by only welding (W) specimens. The elastic analysis simulating the four-point bending loaded situation on W and WB specimens was performed for elucidating its reason. The stress concentration at the weld toe was even high in the WB specimens. Therefore, the fatigue life of WB specimens was not longer than that of W specimens. On the other hand, the stress around the weld root of WB specimen was around 30% of that of W specimen. The possibility of stress reduction effect by bonding was indicated around the weld root rather than around the weld toe. In order to verify this possibility, the four-point bending fatigue experiment was performed by setting the specimens so that the tensile stress was applied on the weld root. It was confirmed that the fatigue cracks occurred from the weld root in both W and WB specimens. The fatigue life defined in this study of WB specimens was from 4 to 8 times longer than that of W specimens when the applied nominal stress range was under 175 MPa. The fatigue life defined in this study of WB specimens was from 2 to 3 times longer than that of W specimens when the applied nominal stress range was over 200 MPa. The results indicated the fatigue life improvement of patch plate joints by fillet welding assisted with bonding when the fatigue cracks occurred at the weld root.     

Effects of shear flow on a semidilute polymer solution under phase-separating condition

We studied the effects of a step-up shear flow from zero shear rate to the given shear rate, , on formation of shear-induced structures for a semidilute polystyrene (PS)/diethyl malonate (DEM) solution below its cloud point temperature where the solution undergoes phase separation via spinodal decomposition (SD) in quiescent state. We elucidated that the effects of step-up shear can be divided into two regions: below and above a critical shear rate, . At , growing phase-separated domains via SD are found to be deformed under the flow, so that FFT spectra of the shear-microscopy images become elliptical with the wave number q_mx at the maximum intensity parallel to the flow being smaller than the corresponding wave number q_mz parallel to the neutral axis. However, strikingly enough, the aspect ratio q_mz/q_mx of the elliptic spinodal ring observed for this system was much smaller than that observed for binary fluids. The unique feature was proposed to be the elastic effect inherent in this system. When is larger than , however, initially phase-separating structures via SD are strongly deformed and distorted. Interestingly enough, the light scattering pattern was transformed from the isotropic ring pattern into the butterfly pattern. This is interpreted as follows: when , there may not be enough time for the domains composed of elastically deformed swollen-network chains to relax, and consequently the domains are cooperatively disrupted. The disrupted domains tend to squeeze solvent in order to release the elastic free energy stored in the deformed swollen-network chains, resulting in anisotropic domain more extended to neutral axis than flow direction and hence giving rise to the butterfly pattern.     

Charge Transfer in Fullerene-Conducting Polymer Compositex: Electronic and Excitonic Properties

C₆₀ doping into conducting polymer with highly extended π-electron system in the main chain induces remarkable quenching of photoluminescence in conducting polymer and drastic enhancement of photoconductivity. These results can be explained in terms of photo-induced charge transfer between conducting polymer and C₆₀. That is, photoexcited excitons or exciton-polarons on conducting polymer are effectively dissociated at C₆₀ molecules transferring electrons to C₆₀. Photoexcitation of C₆₀ results in the transfer of hole from C₆₀ to conducting polymer. These novel C₆₀ doping effects have been observed not only in conducting polymers with non-degenerated ground state structures but also those with degenerated ground state structure such as di-substituted acetylene polymers with solitonic electronic systems.

Highly effective photo-induced charge transfer has been also observed in conducting polymer/C₆₀ heterojunctions, which are interpreted as donor (D)-acceptor (A) photocell. Based on this finding we have demonstrated an organic photovoltaic cell with D-A double heterojunction, Al/C₆₀/OEP/conducting polymer/TTO, in which OEP is octaethylporphine as an light absorbing antenna molecule. Novel characteristics have also been observed in various other junction devices utilizing C₆₀ doped conducting polymer.

Granular and multiphase superconductivity has been found in C₆₀-conducting polymer-alkali metal composites.

Effect of other type of fullerenes such as C₇₀, modified C₆₀ and C₆₀ polymers, and also effect of C₆₀ doping in polysilanes and their derivatives have also been studied.     

Substantial reduction of critical current for magnetization switching in an exchange-biased spin valve

Great interest in current-induced magnetic excitation and switching in a magnetic nanopillar has been caused by the theoretical predictions of these phenomena. The concept of using a spin-polarized current to switch the magnetization orientation of a magnetic layer provides a possible way to realize future 'current-driven' devices: in such devices, direct switching of the magnetic memory bits would be produced by a local current application, instead of by a magnetic field generated by attached wires. Until now, all the reported work on current-induced magnetization switching has been concentrated on a simple ferromagnet/Cu/ferromagnet trilayer. Here we report the observation of current-induced magnetization switching in exchange-biased spin valves (ESPVs) at room temperature. The ESPVs clearly show current-induced magnetization switching behaviour under a sweeping direct current with a very high density. We show that insertion of a ruthenium layer between an ESPV nanopillar and the top electrode effectively decreases the critical current density from about 10(8) to 10(7) A cm(-2). In a well-designed 'antisymmetric' ESPV structure, this critical current density can be further reduced to 2 x 10(6) A cm(-2). We believe that the substantial reduction of critical current could make it possible for current-induced magnetization switching to be directly applied in spintronic devices, such as magnetic random-access memory.     

Water Treatment Using Discharge Generated in Cavitation Field with Micro Bubble Cloud

A new method of wastewater treatment using electric discharge in the water cavitation field formed by a large number of micro bubbles generated by high‐speed water flow is proposed in this paper. Indigo carmine solution, which is a type of dye, with a concentration of 9 mg/liter was used as the specimen solution for demonstration of water treatment. The total volume of solution and the average speed of solution in the cavitation field were 20 liters and about 7.4 m/s, respectively. An absorbance decrease rate of 96% was obtained in 50 min of treatment time at the electrode distance of 2 mm and discharge power of 16 W. It was also found that the efficiency of decolorization was improved by changing the electrode location. © 2013 Wiley Periodicals, Inc. Electr Eng Jpn, 186(4): 1–10, 2014; Published online in Wiley Online Library ( wileyonlinelibrary.com ). DOI 10.1002/eej.22483     

Observation of Magnetic‐Switching and Multiferroic‐Like Behavior of Co Nanoparticles in a C60 Matrix

A novel magnetoelectric effect is found to appear in a C₆₀‐Co nanocomposite. Although Co is well‐known as a ferromagnet, its nanoparticles embedded in a C₆₀ matrix can exhibit multiferroic‐like behavior, i.e., an electric field controls magnetic alignment of the nanoparticles and a magnetic field controls their charged states. This novel effect enables a strong magnetic switching effect for which the on/off ratio is ca. 10⁴. Such an effect has been expected to exist and these findings show this magnetoelectric coupling for the first time.     

Stimulatory effects of vanadate on amylase release from isolated rat pancreatic acini

Mechanical forces are important modulators of cellular function in many tissues and are particularly important in the cardiovascular system. The endothelium, by virtue of its unique location in the vessel wall, responds rapidly and sensitively to the mechanical conditions created by blood flow and the cardiac cycle. In this study, we examine data which suggest that steady laminar shear stress stimulates cellular responses that are essential for endothelial cell function and are atheroprotective. We explore the ability of shear stress to modulate atherogenesis via its effects on endothelial-mediated alterations in coagulation, leukocyte and monocyte migration, smooth muscle growth, lipoprotein uptake and metabolism, and endothelial cell survival. We also propose a model of signal transduction for the endothelial cell response to shear stress including possible mechanotransducers (integrins, caveolae, ion channels, and G proteins), intermediate signaling molecules (c-Src, ras, Raf, protein kinase C) and the mitogen activated protein kinases (ERK1/2, JNK, p38, BMK-1), and effector molecules (nitric oxide). The endothelial cell response to shear stress may also provide a mechanism by which risk factors such as hypertension, diabetes, hypercholesterolemia, and sedentary lifestyle act to promote atherosclerosis.