To clarify the behavior of ZnO fine particles in an electric field in the presence of sodium hexamethaphosphate, we studied the effect of temperature, pH and concentration of electrolyte on the electrophoretic mobility and zeta potential of fine particles of different sizes.
The absolute value of zeta potential of ZnO particles was found to be a maximum at pH 9 and to decrease in the high pH range, because the electric double layer is compressed by increasing NaOH concentration. Electrophoretic mobility was found to increase with increasing temperature, due to a decrease in viscosity of the solvent and the accompanying decrease in the resistance against the motion of particles. Electrophoretic mobility also decreased with decreasing particle size because of strongly acting asymmetric and electrophoretic effects. On the other hand, electrophoretic mobility decreased with increasing particle size above a critical value at which resistance due to viscosity is controlling.

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Particle size distributions of isopycnic floating particles were measured by use of a solid-liquid tapered fluidized bed. Experiments were conducted with a Glassbubbles K1–water system with a solid-liquid density ratio of 0.125, and a paraffin–24 wt% sodium chloride solution system with a solid-liquid density ratio of 0.760. Particle size distributions measured by the present method agreed with those measured by the laser diffraction/scattering method. The tapered shape of the fluidized bed suppresses the spilling of small particles. The ranges of particle sizes which can be measured are approximately 5 : 1 or 6 : 1 in terms of the ratio between the maximum and the minimum particle sizes. By controlling the solid–liquid tapered fluidized bed in a state of uniform fluidization, the particle size distribution of floating particles can be measured.

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The adsorption of histidine-containing dipeptides (HCDPs) such as carnosine (Car) onto a Cu(II)-immobilized cellulosic chelating adsorbent (Cu-CF) was investigated with a view to recovering HCDPs from extracts of food waste. Car was effectively recovered using Cu-CF on the basis of metal affinity interactions. The adsorption rate onto Cu-CF was faster than that onto Cu(II)-immobilized polystyrene chelating adsorbent. The percentage of Car adsorbed onto Cu-CF was maximal under neutral or weakly basic conditions, without interference from coexisting salt, and histidine and HCDPs were selectively adsorbed over other amino acids. Car was selectively adsorbed onto Cu-CF from a model solution of the extract of eel guts, and Car adsorbed on Cu-CF was recovered using eluents such as acetic acid.

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Pore structures of microporous silica membranes, and the relationship between membrane structural characteristics and gas permeation properties were studied by molecular dynamics (MD) simulation. Virtual SiO₂ membranes were prepared by the melt-quench procedure utilizing Born–Mayer–Huggines (BMH) pair potential and Stillinger–Weber (SW) three-body interactions. In this study, two types of virtual SiO₂ membrane models were prepared: a network pore model formed by silica polymers; and a bimodal pore model consisting of network pores and penetrating pores, which simulated an inter-particle pore. Gas permeation simulations were conducted using a dual control plane non-equilibrium molecular dynamics (DCP-NEMD) method. Helium and CO₂ were adopted as permeating gas species, and their permeabilities were calculated at temperatures from 300 to 800 K. In the case of the network model, permeation of CO₂ could not be observed, and helium permeation characteristics were in good agreement with experimental data. These results showed the qualitative validity of the network pore model prepared in this study. In the case of bimodal pore model, permeation of CO₂ could be observed, so this result indicated the existence of an inter-particle pore effect on gas permeation properties. In addition, CO₂ permeation characteristics were in agreement with experimental data, thus indicating the qualitative validity of the network pore model and penetrating pore model.
However, the simulated permeabilities of helium and CO₂ by the bimodal pore model were larger than those previously reported for actual silica membranes. The bimodal pore model prepared in this study underestimates the ratio of network pore area per inter-particle pore, since the simulated permeability of each gas through the bimodal pore model could be approximated to experimental data by increasing the ratio of network pore area per inter-particle pore. Optimization of the virtual silica membrane area showed that one inter-particle pore existed per square with side length of about 8–11.5 nm. Such a valuable finding about the microstructure of a silica membrane as the ratio of “network pore area/inter-particle pore” could be obtained by using molecular dynamics simulation.

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A new method is proposed to separate oil from natural materials. The method separates the natural materials, into a liquid that passes through an ice-filter layer and a highly-viscous solution and/or solids that are captured in the ice-filter layer. Fundamental tests of the method with squid viscera (oil emulsion) yielded a separation (oil capture) efficiency of as high as 87%. The practical equipment comprises a filter crystal process, a separating process and a melting process.

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Spirulina platensis was cultured at 278–323 K to investigate the effects of temperature on its specific growth rate and specific autolysis rate. The specific growth rate of S. platensis was maximal at around 305 K, zero or negative at temperatures of 288 K or 313 K, but in both cases growth was observed when the cultivation temperature was returned to 303 K. The specific autolysis rate constant of S. platensis increased with decreasing temperature.

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To examine the possibility of using an inorganic electro-luminescence sheet as a cultivation light source, we conducted cultivation experiments of Spirulina platensis and measured its illumination intensity profile. We found that the illumination intensity profile on the inorganic electro-luminescence sheet was uniform, and that in the horizontal direction it obeys the Lambert.Beer equation. We also found it possible to use the inorganic electro-luminescence sheet to cultivate Spirulina platensis.

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