Emerging cell array based on reaction–diffusion

This article demonstrates the self-replication and self-organization phenomena based on a reaction–diffusion mechanism by computer simulation. The simulation model consists of a one-dimensional cell array. Each cell contains two kinds of chemical substances, activator u and inhibitor v, that can generate a reaction–diffusion wave, which is a spatial concentration pattern. The cells are supposed to be divided or deleted depending on the concentrations of chemical substances. We tried several kinds of diffusion coefficient in the model, and in some simulations, a self-replication process and a generating cell array with a metabolic process were observed. By applying the division rule and the apoptosis rule, cell arrays duplicate in two oscillating states, i.e., self-replication processes were observed. By applying a division rule and an annihilation rule, a cell array that has a stable length is generated by changing the cell components, i.e., generating a cell array by a metabolic process was observed. Surprisingly, these two phenomena are realized independently of the initial number of cells. This work was presented in part at the 11th International Symposium on Artificial Life and Robotics, Oita, Japan, January 23–25, 2006     

Shape oscillation of bubbles in a row excited by ultrasonic vibration

Behaviors of bubble(s) exposed to an ultrasonic vibration are focused. Size of the bubbles interested in the present study is of O(1 mm) in diameter. The bubbles were injected through the micro syringe to the test fluid (water or water/surfactant mixture) filled in the rectangular tank. Ultrasonic vibration was irradiated to the bubble(s) after the detachment of the bubble from the tip of the syringe; thus the bubbles were exposed to the periodic oscillation in rising the test fluid. The authors clearly detect radial and shape oscillations under the large-amplitude vibration by use of high-speed camera. Preferable mode number of the shape oscillation, and the transition process from the radial to the shape oscillation are discussed.     

Densification of magnesia-based inert matrix fuels using asbestos waste-derived materials as a sintering additive

A new concept for densification of minor actinide-containing inert matrix fuels (IMFs) using asbestos waste-derived materials was proposed for the effective utilization of resources and health protection of the general public. In this concept, magnesium silicates, which are mainly generated by the decomposition of asbestos in low temperature heat-treatments, are used as a sintering additive to achieve high density magnesia (MgO) -based IMFs at relatively low sintering temperature. In the present study, preliminary fabrication tests of MgO-based IMFs with magnesium silicates were carried out using cerium oxide (CeO₂) as a representative of minor actinide oxides. The sintered densities of MgO-based IMFs increased with use of the additives. The sintering behavior of MgO-based IMFs with magnesium silicate additives was discussed from the viewpoints of the effects of magnesium silicates on the densification of the MgO and CeO₂.     

A novel method for induction and detection of anaphylactic reaction using the mouse abdominal wall (AW method)

We found that an antigen-specific anaphylaxis was induced by antigen challenge to the abdominal wall, ear auricle, or subcutaneous tissue in mice sensitized 9 days previously with antigen and adjuvant. The anaphylactic reaction was detected by vascular permeability at the injected site 7 minutes after challenge, which was the best time for estimation. A novel method (AW method) for induction and detection of the anaphylactic reaction in mice was established using the abdominal wall as the challenge site. This method could detect the anaphylactic response in mice 1 to 3 weeks after sensitization. The increase in vascular permeability was completely inhibited by administration of diphenhydramine.     

Kink and power saturation of 660-nm AlGaInP laser diodes

We analyze kink and power saturation phenomena of high power 660-nm laser diodes for DVD-R/RW experimentally. Power-current (P-I) and voltage-current (V-I) characteristics of laser diodes with different cavity lengths were measured. Using these results and thermal resistances, temperature rises caused by self-heating (/spl Delta/T) and the dependence of slope efficiencies on the temperature rise (Se-/spl Delta/T) were calculated. The slope efficiencies decreased linearly with /spl Delta/T and their gradients showed the same value regardless of the cavity length, while they had no systematic dependence on the current. The kinks occurred at the same /spl Delta/T of 30/spl deg/C regardless of the cavity length, while they occurred at different currents. These results indicate that the temperature rise caused by the self-heating is a key parameter for the kink and the saturation power. A method is proposed to calculate the kink and the saturation power using the gradient (Se-/spl Delta/T) and the kink temperature.     

Effect of catalyst combination on growth of single-walled carbon nanotubes

A new effective catalysts combination of iron — nickel for alcohol CVD technique was found. This catalyst catalyzed well as well as the typical catalyst of iron — cobalt catalysts, but gave a different diameter distribution. Calculating their electrical density of states under the assumption of their solid lattice structures, the result was fairly consistent with experimental results. The number of electrical states near Fermi level that is considered to be important for catalytic reaction is enough and the DOS of iron – nickel catalyst was quite similar to that of cobalt unlike manganese – copper catalyst. Consequently, a blend of catalysts that has a similar DOS to cobalt and has enough states near the Fermi level can be a good catalyst for alcohol CVD.     

Synthesis and characterization of fluorene-carbazole and fluorene-phenothiazine copolymers with carbazole and oxadiazole pendants for organic light emitting diodes

We report the synthesis and characterization of new series of the fluorene based polymers with carbazole and oxadiazole pendants for the generation of the white emission out of the EL device. In the fluorene backbone, hole transporting units such as carbazole or phenothiazine were incorporated to improve the EL brightness and efficiency. The PFCzOxd-co-PCzs and PFCzOxd-co-PPTZs in EL spectra showed maximum peaks at around 430 nm and additional large peaks at around 530 and 500 nm, respectively. In case of PFCzOxd-alt-PCz and PFCzCzPCz-co-PFOxdOxdPCz, the EL spectra of the polymers showed two distinct peaks comprising the maximum at 427 nm, which corresponds to the EL spectra of the conjugated backbone, and additional broad peaks at around 540 and 530 nm, respectively. The CIE coordinates of the devices from PFCzOxd-alt-PCz and PFCzCzPCz-co-PFOxdOxdPCz were (0.28, 0.33) and (0.25, 0.32), respectively, approaching the value of the standard white of National Television System Committee (NTSC) (0.33, 0.33).     

Effect of operating factors on liquid–liquid mass transfer and dispersion pattern of sedimentary liquid in a mechanically stirred vessel

Liquid–liquid dispersion and mass transfer were investigated in mechanically stirred vessels without baffles by changing operation factors such as an impeller rotation speed, off-bottom clearance, volumetric liquid ratio, etc. The dispersion regime was categorized into five groups: the sedimentary liquid was kept at the vessel bottom (I), partially elevated without any collision (II), partially dispersed by colliding with the impeller bottom (III), both liquids were partially dispersed by collisions with impeller blades (III’), and the sedimentary liquid was completely dispersed (IV). The dispersion switched to I → II → III → IV with the increasing rotation speed and decreasing off-bottom clearance. The liquid–liquid mass transfer rate was significantly enhanced with the collision of the sedimentary liquid with the impeller bottom, and subsequently increased with the increasing rotation speed, volumetric liquid ratio, and vessel diameter and with the decreasing off-bottom clearance. A multiple regression analysis method was applied to determine the mass transfer rates of III and III’.