Removal kinetic model of oil droplet from o/w emulsion by adding methylated milk casein in flotation

In this study, o/w emulsion flotation experiments were conducted by adding methylated milk casein (MeSC). Emulsion used in this study was prepared by ultrasonic emulsification of heavy oil (bunker-A) and sodium dodecyl sulfate (SDS) solution. A simple kinetic model was proposed to estimate the removal rate of the oil droplets within the column. The model was based on main assumption that adsorption of single droplet adsorbed MeCS or floc onto bubble surface within flotation column. Removal rate constant, K, was defined by k_aX_s (S_bτ/V), where k_a and X_s are overall adsorption rate and saturated adsorption density of oil droplet or floc, S_b, τ and V are bubble surface production rate, retention time of bubble swarms and emulsion volume within the column, respectively. The experiments were conducted with varying operating conditions; superficial gas velocity, column dimension and emulsion volume. K was evaluated from slope value of obtained straight line by plotting time versus ln (T/T₀), where T/T₀ is relative turbidity. K was mostly proportional to (S_bτ/V), which corresponds to specific surface area of bubble swarms per unit volume within the column, in the present experimental region. This result suggested that efficiency of this removal process was mainly controlled by the specific surface area of bubble swarms, and proposed model was fundamentally verified.     

Forced oscillations,optimal forcing and resonance of thermal convection under small,time-varying forcing

This study proposes a method to obtain forced oscillation induced by arbitrary small time-varying forcing on a stable thermal convection field, and a framework for finding universal and inherent resonance modes on the field, independent of the ways of forced vibration, indicators of resonance and other information. It is based on an eigenvalue analysis of a Hermitian matrix relating to the frequency response function, and the typical forced oscillation at a resonance is given by the response to the optimal forcing as the eigenvector corresponding to the largest eigenvalue of the matrix. The method also provides indicators to quantify the efficiency in realizing a given resonance mode by a specific forced vibration. We can find thereby that heat-flux vibration not on the bottom wall but on the left-hand sidewall is preferred for realizing the internal gravity wave resonance.     

Reinvestigation of Thermoelectric Properties of n- and p-Type Ba8−d Au x Si46−x−y Clathrate

We have synthesized n- and p-type clathrates Ba_8?d Au _x Si_46?x?y with various Au contents (4.6 < x < 6.0) by arc-melting, annealing at 1173 K, and spark plasma sintering at 1073 K. The Au compositions found by wavelength-dispersive x-ray spectrometry for the synthesized samples were slightly lower than the nominal compositions. Ba_7.8Au_4.6Si_41.4 and Ba_7.7Au_4.9Si_41.1 samples showed n- and p-type conduction, respectively. According to the electron count (Ba²⁺)₈Au(^3?)_5.33Si_40.67, the clathrate composition with x = 5.33 is expected to be an intrinsic semiconductor. Our experimental results show that increase of the Au composition causes a transition from n-type to p-type conduction between x = 4.6 and 4.9. We have also calculated the band structures of the Ba₈Au _x Si_46?x clathrate including a vacancy by ab initio calculation based on density functional theory with structure optimization. It was found that the vacancy behaves like an electron acceptor and the numbers of vacancies at 24k sites for the synthesized Ba₈Au _x Si_46?x?y clathrates can be estimated as ～0.4 in a unit cell.     

Proposal of earthing resistance measurement method without auxiliary electrodes

This paper proposes an earthing resistance measurement method for a simple earthing electrode without two auxiliary electrodes. The proposed method can measure the earthing resistance by evaluating loop impedance of an earth return circuit composed of an earth electrode of the under test and a lead wire, a return wire, and the earth soil. The return wire is placed on the soil surface without any terminations. The earthing resistance of the electrode of the under test can be given by the earth return circuit impedance at a resonant frequency design between 100 kHz and 1 MHz. The measurement conditions for the proposed method are determined by numerical calculations. Earthing resistance deviations between the proposed method and the existing method are ?13% to +22% for earthing resistance values with 50, 100, or 300Ω. It is found that the proposed method can be used to evaluate an earthing resistance around 100Ω for a simple earthing electrode. © 2005 Wiley Periodicals, Inc. Electr Eng Jpn, 154(3): 16–26, 2006; Published online in Wiley InterScience ( www.interscience.wiley.com ). DOI 10.1002/eej.20196     

Thermoelectric Properties of Ga-Doped Ba8Al x Si46−x Clathrate

Single-crystalline Ba₈Al _x Ga _y Si_46?x?y clathrates were synthesized by the arc melting method and Czochralski method without subsequent treatment, and their thermoelectric properties were compared with those of Ba₈Al _x Ga _y Si_46?x?y and Ba₈Al _x Si_46?x clathrates with almost the same carrier concentration as estimated from the similar Seebeck coefficient and the Zintl concept. The resistivity of Ba_7.8Al_5.3Ga_7.4Si_33.3 was lower than that of Ba_7.9Al_12.6Si_33.4. The specific electrical resistance of Ba_7.9Al_12.6Si_33.4 and Ba_7.8Al_5.3Ga_7.4Si_33.3 was 0.573 mΩ cm and 0.282 mΩ cm at 750 K, respectively. The band structure of Ba₈Al₈Ga₈Si₃₀ and Ba₈Al₁₆Si₃₀ was estimated by first-principle calculations using density functional theory with the local density approximation. Based on these calculations, it was found that the shape of the bottom of the conduction band for Ba₈Al _x Si_46?x clathrate changed slightly on Ga doping and the radius of curvature of the bottom of the conduction band for Ba₈Al₈Ga₈Si₃₀ clathrate was lower than that for Ba₈Al₁₆Si₃₀ clathrate. These results indicate that the mobility was enhanced by Ga doping of Ba₈Al _x Si_46?x clathrate. We also synthesized single-crystalline Ga-doped Ba₈Al _x Si_46?x clathrate. The electrical resistivity decreased dramatically due to the single-crystallization because of reduced electron scattering on grain boundaries. These results suggest that Ga doping and single-crystallization are effective for improvement of the thermoelectric properties of Ba₈Al _x Si_46?x clathrate.     

Anion-exchange properties of nickel–aluminum layered double hydroxide prepared by liquid phase deposition

The optimum coordination structure of Ni–fluoro complexes for the preparation of Ni–Al LDH by LPD process and the diverse anion-exchange properties of as-deposited Ni–Al on α-alumina powder were quantitatively evaluated for the industrial application of new positive material for alkali secondary batteries. The [NiF_6−x−y(NH₃)_x(OH⁻)_y]ⁿ⁺ was more suitable than [NiF₆]⁴⁻ as the precursor of the deposition of Ni–Al LDH in the LPD reaction, and the improved LPD reaction achieved the synthesis of high purity and high crystallinity Ni–Al LDH. All anion-exchanged Ni–Al LDHs for OH⁻–, Cl⁻–, SO₄²⁻–, and CH₃COO⁻–forms kept the high crystallinity and showed the enlargement of interlayer distances. The tilting angle of the intercalated CH₃COO⁻ anions was about 15°. Anion-exchange capacity remained constant at a minimum of 0.8 meq g⁻¹ in pH >10, increased as pH decreased, and reached a maximum of 8 meq g⁻¹ at pH 2. Anion-exchange of OH⁻–form of Ni–Al LDH was accelerated by the neutralization of hydroxide ions in interlayers, in addition, the anion-exchange capacity and the crystallinity of Ni–Al LDH could be controlled by the amount of doped aluminum ions.     

Effects of Na Addition, Pyridine Preadsorption, and Water Preadsorption on the Hydrogen Adsorption Property of Pt/SO4 2--ZrO2

Hydrogen adsorption was studied for Pt/SO₄ ^2--ZrO₂ samples modified with Na addition, pyridine preadsorption, and water preadsorption to elucidate the relation between the rate and capacity of hydrogen adsorption and the surface state. The surface states were monitored by XRD, IR, ammonia TPD, and measurement of catalytic activity for cyclohexane isomerization. All the modifications suppressed the hydrogen uptake. It was suggested that Lewis acid sites promote the hydrogen uptake by stabilizing spiltover hydrogen atoms.     

Single-pass desalination of high salinity sea water with reverse osmosis

Two types of new “HOLLOSEP” have been developed for single-pass desalination of high salinity seawater. One is a high pressure and high temperature module, type “HPT”. The performance of this new type HOLLOSEP is analyzed in the case of desalination of high salinity seawater under a high pressure Of 75Kg/cm² G at high temperature of 40°C. It has been found that the operation costs can be reduced by this high pressure and high temperature operation system.The other is a large size module containing five elements of 12 inches diameter, type “JM-12”. This module has been developed to reduce the water cost by enlarging the diameter and the length of a vessel coupled with the improvement in water flux rate of the hollow fiber membranes. The fresh water productivity of this module is 150m³/day under the conditions of 3.5% NaCl feed water, 30% product water recovery at 55kg/cm²G.     

Contribution of Asian dust to atmospheric deposition of radioactive cesium ((137)Cs)

Both Asian dust (kosa) transported from the East Asian continent and locally suspended dust near monitoring sites contribute to the observed atmospheric deposition of (137)Cs in Japan. To estimate the relative contribution of these dust phenomena to the total (137)Cs deposition, we monitored weekly deposition of mineral particles and (137)Cs in spring. Deposition of (137)Cs from a single Asian dust event was 62.3 mBq m(-2) and accounted for 67% of the total (137)Cs deposition during the entire monitoring period. Furthermore, we found high (137)Cs specific activity in the Asian dust deposition sample. Although local dust events contributed to (137)Cs deposition, their contribution was considerably smaller than that of Asian dust. We conclude that the primary source of atmospheric (137)Cs in Japan is dust transported from the East Asian continent.     

Decrease in hydrogen sulfide content during the final stage of beer fermentation due to involvement of yeast and not carbon dioxide gas purging

We observed a rapid decrease in hydrogen sulfide content in the final stage of beer fermentation that was attributed to yeast and not to the purging of carbon dioxide (CO(2)) gas. The well known immature off-flavor in beer due to hydrogen sulfide (H(2)S) behavior during beer fermentation was closely investigated. The H(2)S decrease occurred during the final stage of fermentation when the CO(2)-evolution rate was extremely small and there was a decrease in the availability of fermentable sugars, suggesting that the exhaustion of fermentable sugars triggered the decrease in H(2)S. An H(2)S-balance analysis suggested that the H(2)S decrease might have been caused due to sulfide uptake by yeast. Further investigation showed that the time necessary for H(2)S to decrease below the sensory threshold was related to the number of suspended yeast cells. This supported the hypothesis that yeast cells contributed to the rapid decrease in H(2)S during the final stage of beer fermentation.