Hydrodynamics of a spouted bed with an impermeable draft tube for binary particle systems

A spouted bed with an impermeable draft tube was employed to obtain fundamental data of binary mixtures of glass beads for both the operating conditions and the design factors. These data were compared with those for the coarser particle system only. From this view point, minimum spouting velocity, pressure drop, hold-up of solid particles within a draft tube, upward gas flow rate within the annulus and solids circulation rate were determined by changing the total gas flow rate and mass fraction of finer particles as operating parameters and by changing distance of entrainment zone and draft tube diameter as geometric parameters.     

Bi-based electrochromic cell with mediator for white/black imaging

We studied electrochemical properties of bismuth deposit, which showed reversible color change from colorless clear to black by electrochemical reaction, toward paper-like electronic imaging device. Bismuth salt in an electrolyte solution is colorless clear, but turned to black by the electrodeposition on an electrode. Namely, bismuth ion (Bi³⁺) dissolved in the electrolyte solution (colorless clear) is electrochemically reduced on the electrode to deposit the Bi metal showing black color. The Bi deposit on the electrode is electrochemically oxidized to dissolve the deposit into the solution. These processes enable the color change between colorless clear and black. However, the stability of the switching between colorless and black state is not sufficient due to less electroactivity of bismuth deposit. To improve the switching stability of the present electrochromic cell, various mediators were employed to add into the electrolyte solution. Reversible white/black display cell has been successfully demonstrated.     

Electrochemical study on Mn-substitution in LiFePO4 olivine compound

Olivine compounds LiFe_1−xMn_xPO₄ (0.0 < x < 0.4) were prepared by the solid-state reaction, and the electrochemical properties were studied in order to examine the effects of Mn²⁺-substitution. The substitution led to the modification of the electrochemical performance, such as initial capacity, capacity fading and polarization. From the cyclic voltammetry, it was found that the effective Li⁺ ionic diffusion coefficient was always larger in the charging process than in the discharging process and that it became larger with an appropriate amount substitution. The structural analysis on the chemical-delithiated compounds exhibited anomalous expansion of the unit cell along c-axis with the substitution, while the lattice parameters of the pristine compounds obeyed Vegard's law. The relationship between the Li⁺ ion diffusion and the bottle-neck area of (0 1 0) zigzag path was discussed. From the results, it was considered that Mn²⁺ had no direct contribution on the electrochemical reaction but influenced both electronic and ionic conductivities, which led to some modifications in the electrochemical performance.     

Flow characteristics of gas–liquid two phase plunging jet absorber–gas holdup and bubble penetration depth

A gas-liquid two phase plunging jet is formed through a gas sucking type multi-jet ejector nozzle. In this study, the effects of various conditions in the multi-jet ejector nozzle, the column diameter, and the liquid jet length on penetration depth of air bubblesl _B and gas holdup h_G in a gas-liquid two phase plunging jet absorber were studied experimentally. Consequently, empirical equations concerningl _B and h_G were obtained, respectively. These equations agree with the experimental data with an accuracy of ±20% forl _B and ±25% for h_G.     

Propagation of Weak Pressure Waves against Two Parallel Subsonic Streams

In this paper, the characteristics of a pressure wave propagating against two parallel subsonic streams in a constant-area straight duct are investigated by one-dimensional analysis, two-dimensional numerical simulation, and experiments. Computations have been carried out by the two-dimensional Euler Equations using the Chakravarthy-Osher-type TVD scheme. Optical observations by the schlieren method as well as wall pressure measurements have been performed to clarify both the structure and the propagation velocity of pressure waves. The results show that the pressure wave propagating against the streams changes into a bifurcated pressure wave and the bifurcation occurs in the low speed streams. It is also found that the propagation velocity of the pressure wave obtained by the analysis and computation agrees well with the present experimental data.     

H+-ATPase activity in Bifidobacterium with special reference to acid tolerance

The acid tolerance of 17 strains of nine species of bifidobacteria was compared using brief exposures to acidic conditions (pH 2-5). In addition, because it has been hypothesized that the acid tolerance of bifidobacteria depends on H+-ATPase activity, the activity of this enzyme in various strains and species was compared. In general, the acid tolerance of bifidobacteria was found to be weak, with the exception of Bifidobacterium lactis and Bifidobacterium animalis. High numbers of all strains of B. lactis and B. animalis survived exposure to pH 3-5 for 3 h. The H+-ATPase activity of the acid-tolerant strains B. lactis LKM512 and JCM 10602T, and B. animalis JCM 1190T, JCM 1253, JCM 7117, and JCM 7124 was higher at pH 4 than at pH 5. In contrast, the H+-ATPase activity of nonacid-tolerant strains was lower at pH 4 than at pH 5.     

Flow regimes and vertical solids conveying in a spout‐fluid bed with a draft tube

Pressure fluctuation data were obtained in a semi‐cylindrical spout‐fluid bed with draft tube, and statistical analyses of them were employed to recognise flow regimes. Also, the effects of spouting‐gas and auxiliary‐gas velocities, and length of entrainment zone on solids loading ratio in a draft tube were examined. As a result, five flow regimes appeared by changing spouting‐gas and auxiliary‐gas velocities and it was found that the simplest method to determine flow regime is to measure pressure fluctuations in a draft tube. Moreover, solids loading ratio could be controlled flexibly by auxiliary‐gas velocity and length of entrainment zone.     

Microwave dielectric properties of mixed phase ceramics, Ba(Zn1/3Ta2/3)O3–xCaTiO3 and xMgTiO3–yCaTiO3–z(Nd2O3,wTiO2)

The effect of different chemical compositions on the microwave dielectric properties of Ba(Zn_1/3Ta_2/3)O₃–xCaTiO₃ and xMgTiO₃–yCaTiO₃–z(Nd₂O₃,wTiO₂) was studied. High fQ dielectrics were designed by optimizing composition and firing conditions. Adding up to 1 mol % CaTiO₃ to Ba(Zn_1/3Ta_2/3)O₃ increased ε_r from 25 to 30 at a firing temperature of 1450 °C, and produced very high fQ values of more than 100 000 GHz at a firing temperature of 1550 °C. EPMA and XRD suggested that ceramics based on Ba(Zn_1/3Ta_2/3)O₃ with CaTiO₃ had mixed phases of Ba(Zn_1/3Ta_2/3)O₃ and Ca–Ti–Zn–O. Addition of CaTiO₃ increased the Ba(Zn_1/3Ta_2/3)O₃ peak observed in XRD and decreased the Ba₃Ta₂O₈ peak. Prolonged sintering of Ba(Zn_1/3Ta_2/3)O₃ with CaTiO₃ increased the fQ value but kept ε_r constant. 0.5MgTiO₃–0.5CaTiO₃–z(Nd₂O₃,wTiO₂) showed a high dielectric constant ε_r>40 and fQ>20 000 GHz. When w=1, τ_f decreased linearly with z around 0 ppm/ °C in 0.5MgTiO₃–0.5CaTiO₃–z(Nd₂O₃,TiO₂) (0.25≤z≤0.5). X-ray and EDX analysis revealed a mixed phase matrix of MgTiO₃ and (Ca_1?αNd_2α/3)Ti_βO₃. It was concluded that ε_r of the high fQ materials Ba(Zn_1/3Ta_2/3)O₃–xCaTiO₃ and xMgTiO₃–yCaTiO₃–z(Nd₂O₃,wTiO₂) would be increased by varying their chemical compositions, x, y, z, and w, and that their fQ value would be improved by appropriate choices of heating temperature and time.