Influence of alloy composition on fillet-lifting phenomenon in tin binary alloys

The influence of alloy composition on the fillet-lifting phenomenon was investigated for Sn−Bi, Sn−Pb, and Sn−In binary alloys. Fillet-lifting occurs in Sn-(1–30%)Bi, Sn-(1–5%)Pb, Sn-(2–15%)In, but does not occur in pure Sn, Sn-(40–62%)Bi, Sn-(10–45%)Pb, and Sn-43 In. Fillet-lifting does not correlate with the formation of a Bi-concentrated layer at the solder/Cu land interface, previously thought to cause fillet-lifting. The solidification temperature range also does not necessarily correlate with fillet-lifting. Fillet-lifting was found to be related to the retention time (t_r) for which solidus temperature (the final solidification temperature) remains by latent heat released during eutectic solidification in the cooling curve. The released latent heat contributes to the alleviation of the temperature gradient causing fillet-fifting in the solder joint. A fillet-fifting resistant index (FRI) is proposed as a new index for fillet-lifting, and correlates well with fillet-lifting occurrence rate in each of the studied tin binary alloys.     

Characteristics and control of a bidirectional axial gap combinedmotor-bearing

Introduces the design characteristics of a bidirectional axial gap combined motor-bearing where the flat disc motor has both rotation and axial position control capability. This motor consists of a disc rotor with a stator on each side of the rotor. The axial motion of the rotor is actively controlled while the other axes are constrained by additional passive or active radial magnetic bearings. Each stator produces a rotating magnetic flux in the air gap, to generate the motor torque. The axial force is controlled by changing the amplitude of the rotating flux. Both permanent-magnet motor and induction motor versions were analyzed theoretically and tested experimentally. The results demonstrated the capability of providing both the functions of a motor and a magnetic bearing     

Online generation and control of quasi-static multi-contact motion by PWT Jacobian matrix with contact wrench estimation and joint load reduction*

In this paper, we propose a generic method of online motion generation and control that realizes quasi-static multi-contact motion for real position-controlled humanoids. The proposed system calculates command joint angle online by prioritized inverse kinematics that realizes the target contact states and the target position/orientation of interaction end-effectors feasibly. In order to enable control of contact wrench and joint torque with position-controlled robots, Jacobian matrixes (PWT Jacobian matrix) focusing on relationships between command joint angle and actual joint position, contact wrench, and joint torque are introduced. In addition, contact wrench is estimated at the body parts where force sensors are not mounted to enable contacts there, and joint load reduction based on the motor temperature is taken into account to enable long-term motions with real humanoids. The proposed method was verified by a real life-size position-controlled humanoid HRP2-JSKNTS, and various multi-contact motions such as desk climbing using the right knee and both arms were realized.     

Binding of Bifidobacterium bifidum and Lactobacillus reuteri to the carbohydrate moieties of intestinal glycolipids recognized by peanut agglutinin

We examined binding of Bifidobacterium bifidum and Lactobacillus reuteri to the carbohydrate moieties of glycolipids extracted from human enterocyte-like Caco-2 cells in this study. In binding assays to reference glycolipids of different carbohydrate compositions, B. bifidum EB102 bound strongly to gangliotetraosylceramide (asialo-GM1) and less strongly to gangliotriaosylceramide (asialo-GM2), lactosylceramide and sulfatide. The binding profile of B. bifidum EB102 was almost identical to that of L. reuteri JCM1081 described previously [Lett. Appl. Microbiol. 27 (1998) 130]. When we examined binding to neutral glycolipids extracted from Caco-2 cells, the binding profiles of B. bifidum EB102 and L. reuteri JCM1081 were very similar to that shown by peanut agglutinin (PNA). Binding of both strains to periodate-treated intestinal glycolipids was completely abolished, suggesting that the bacterial cells bind to carbohydrate moieties of the glycolipids. Furthermore, B. bifidum EB102 was found to express multiple glycolipid-binding proteinaceaous components on the cell surface. These results strongly suggested involvement of cell-surface proteinaceous components of B. bifidum in binding to the carbohydrate moieties of intestinal glycolipids recognized by PNA. Binding ability of B. bifidum and L. reuteri to intestinal glycolipids may play a crucial role for colonization on the mucosal surface of the intestine.     

Analysis of long-term internal stress and film structure of SiO2 optical thin films

Recently, the demand for durability of optical thin films, which have long been used, has been growing as the performance of optical components improves. The stress of a film is an important parameter that is related to its adhesion. The electron beam (EB) and ion-assisted deposition (IAD) methods are widely used to fabricate optical thin films. However, there are few reports on long-term internal stress, despite the importance of this issue. Here we discuss the time dependence of the stress of SiO2 optical thin films in terms of optical characteristics in the infrared region. It was found that SiO2 thin films prepared by the EB and IAD methods exhibited compression stress. The Si-OH molecular bond was observed at around 930?cm(-1) in the Fourier transform infrared spectroscopy spectrum of the sample prepared by the EB method, which exhibited a large change in internal stress after an elapsed time. It is considered that this change in bonding was related to the decrease in the stress of the films.     

A modified Wells turbine for wave energy conversion

The method of wave energy conversion utilises an oscillating water column (OWC). The OWC converts wave energy into low-pressure pneumatic energy in the form of bi-directional airflow. Wells turbine with its zero blade pitch setting has been used to convert this pneumatic power into uni-directional mechanical shaft power. Measurements in OWC based wave energy plants in India and Japan show that the airflow velocity is not equal in both directions. The velocity is more when the airflows out to the atmosphere (exhalation) than in the reverse direction. It may be advantageous to set the rotor blade pitch asymmetrically at a positive pitch so as to achieve a higher mean efficiency in a wave cycle. Towards this objective, performance characteristics of a turbine with different blade setting angles in steady flow were found by experimentation. Quasi-steady analysis was then used to predict the mean efficiency for a certain variation of air velocity with time. This variation with time was taken as pseudo-sinusoidal wherein the positive part of the cycle was taken as a half sine-wave whose amplitude is greater than that of the negative half sine-wave. Such a variation is representative of what happens in reality. For exhalation velocity amplitude to inhalation velocity ratios 0.8 and 0.6, a rotor blade setting angle of 2° was found to be optimum.     

Study of electron irradiation-induced defects in and by electron spin resonance

Electron irradiation effects in CuInSe₂ and CuInGaSe₂ were investigated using electron spin resonance (ESR) method. ESR signal caused by electron irradiation was found in irradiated samples. The ESR spectra of irradiated samples were well reproduced by a computer simulation of powder spectrum assuming Cu²⁺ ion. Electron irradiation effects in CuInSe₂ and CuInGaSe₂ are discussed based on present ESR study together with previous deep level transient spectroscopy (DLTS) and Hall effect measurements.     

Radical-initiator-Induced solid-state polymerization of butadiyne nanocrystals in water and their dispersion stabilization

Butadiyne nanocrystals in water are usually polymerized by UV or gamma-ray irradiation to give polydiacetylene (PDA) nanocrystals. In this study, we confirmed that solid-state polymerization of 1,6-di(N-carbazolyl)-2,4-hexadiyne (DCHD) and 5,7-dodecadiyn-1,12-diyl bis[N-(butoxycarbonyl-methyl)carbamate] (4BCMU) could be stimulated by water-soluble radical initiators. The radical initiators used were potassium peroxodisulfate, three kinds of azo-type compounds and a redox initiator. In all cases, the solid-state polymerization was confirmed by color change into blue indicating that PDA modified by the radical residues at the end was formed. However, nanocrystal cohesion occurred especially when the concentration of the initiators was high or the dispersion was kept for a long time. In order to improve the dispersion stability, two kinds of surfactants, i.e., sodium dodecyl sulfate (SDS) or dodecyltrimethylammonium chloride (DTMAC), were added to the DCHD nanocrystal aqueous dispersion. As a result, when anionic SDS was added, the solid-state polymerization of nanocrystals proceeded without coagulation and quantitative conversion was confirmed for all initiators. Cationic DTMAC has no effect on dispersion stabilization. PDA nanocrystal surfaces in water are negatively charged in nature and electric interaction of nanocrystals with the cations results in decrease of surface charge and aggregation of nanocrystals.     

NMR Study Under Pressure on the La1111 Pnictides,LaFeAsO<Subscript>1−<Emphasis Type="Italic">x</Emphasis></Subscript>F<Subscript><Emphasis Type="Italic">x</Emphasis></Subscript>

The relationship between antiferromagnetic (AF) fluctuation and superconductivity was investigated in the La1111 series, LaFeAsO_1−x F _x (x=0.05, 0.08, and 0.14) by examining nuclear relaxation rates (1/T ₁) at both ambient pressure and 3.0 GPa. Although the AF fluctuation is enhanced by applying pressure in the underdoped regime (x=0.05, and 0.08), the increase in critical transition temperature (T _c) is small, whereas T _c increases remarkably in the overdoped regime (x=0.14) where the AF fluctuation is absent, suggesting that high T _c above 40 K originates not from the AF fluctuation but from the density of states at the electron pocket.     

Magnetic and magnetoelectric properties of self-assembled Fe₂.₅Mn₀.₅O₄ nanocrystals

We report magnetoresistance of -40%, corresponding to 80% spin polarization, at magnetic field of 0.5 T and 200 K for oleic acid-coated Fe(2.5)Mn(0.5)O(4) nanocrystals (FMO NCs) self-assembled on a SiO(2)/Si substrate by drop casting fabrication. The FMO NCs exhibited spin glass transition around 150 K and nonlinear current-voltage (I-V) characteristics. Fowler-Nordheim plot of the I-V characteristics indicated that electrons tunnel directly barriers between the FMO NCs. Transmission electron microscopy revealed that the FMO NCs are elongated hexagon in shape with size of ～15 × 20 nm. The FMO NCs self-assembled in two-dimension hexagonal networks of collinear ferromagnetic moments. The [111] easy magnetization axis of each FMO NC was parallel to each other in the hexagonal arrays. Geometrically frustrated lattice of collinear ferromagnetic moments supports both a low and a high intergranular tunneling conductance for the self-assembled FMO NCs without and with magnetic fields, respectively.