Proposal of Design Criteria for Gas Entrainment from Vortex Dimples Based on a Computational Fluid Dynamics Method

Design criteria for gas entrainments (GE) from the liquid surface in a fast breeder reactor system were proposed in this paper for the two types of GE phenomena from a vortex dimple based on a computational fluid dynamics (CFD) method. The first gas entrainment phenomenon is a gas core extension directly to the outlet piping level, which induces large amount of GE to the flow system. The second is continuous bubble detachments from the tip of the vortex dimple. Based on CFD calculations for elemental experiments of the surface vortex, local CFD non-dimensional numbers were defined as the design criteria to prevent GE. In conclusion, it was found that the CFD non-dimensional numbers are useful for the design parameters of GE prevention.     

Ionic liquid enables simple and rapid sample preparation of human culturing cells for scanning electron microscope analysis

Ionic liquid is a kind of salt that stays in a molten state even at room temperature. It does not vaporize at all in vacuum and facilitates electrical conductivity to the sample surfaces for observations with a scanning electron microscope (SEM). In this study, we used an ionic liquid in SEM for the first time to observe fixed human culture cells. The condition for the cell culture using wrapping sheets and SEM settings were varied to elucidate the optimized protocol. Compared to samples prepared by the conventional way, the ionic liquid‐treatment of samples gave SEM images of the cellular ultra structures in more detail, enabling observation of microvilli that made bridges between separated cells. In addition, the ionic liquid treatment is less time consuming as well as less laborious compared with the conventional way that includes dehydration, drying, and conductivity treatments. Totally, we concluded the ionic liquid is a useful reagent for SEM sample preparation. Microsc. Res. Tech., 2011. © 2010 Wiley‐Liss, Inc.     

Experimental study on latent heat storage characteristics of W/O emulsion -Supercooling rate of dispersed water drops by direct contact heat exchange-

Recently, much attention has been paid to investigate the latent heat storage system. Using of ice heat storage system brings an equalization of electric power demand, because it will solved the electric -power-demand-concentration on day-time of summer by the air conditioning. The flowable latent heat storage material, Oil/Water type emulsion, microencapsulated latent heat material-water mixture or ice slurry, etc., is enable to transport the latent heat in a pipe. The flowable latent heat storage material can realize the pipe size reduction and system efficiency improvement. Supercooling phenomenon of the dispersed latent heat storage material in continuous phase brings the obstruction of latent heat storage. The latent heat storage rates of dispersed water drops in W/O (Water/Oil) emulsion are investigated experimentally in this study. The water drops in emulsion has the diameter within 3 ～ 25μm, the averaged water drop diameter is 7.3μm and the standard deviation is 2.9μm. The direct contact heat exchange method is chosen as the phase change rate evaluation of water drops in W/O emulsion. The supercooled temperature and the cooling rate are set as parameters of this study. The evaluation is performed by comparison between the results of this study and the past research. The obtained experimental result is shown that the 35K or more degree from melting point brings 100% latent heat storage rate of W/O emulsion. It was clarified that the supercooling rate of dispersed water particles in emulsion shows the larger value than that of the bulk water.     

Three-layer flow membrane system on a microchip for investigation of molecular transport

A stable three-layer flow system, water/organic solvent/water, has been successfully applied for the first time in a microchannel to get rapid transport through an organic liquid membrane. In the continuous laminar flow region, the analyte (methyl red) was rapidly extracted across the microchannel from the donor to the acceptor phase through the organic solvent phase (cyclohexane). Thermal lens microscopy was used to monitor the process. The thickness of the organic phase, sandwiched by the two aqueous phases, was approximately 64 microm, and it was considered as a thin liquid organic membrane. Permeability studies showed the effects of molecular diffusion, layer thickness, and organic solvent-water partition coefficient on the molecular transport. In the microchip, complete equilibration was achieved in several seconds, in contrast to a conventionally used apparatus, where it takes tens of minutes. The thickness of the organic and aqueous boundary layers was defined as equal to the microchannel dimensions, and the organic solvent-water partition coefficient was determined on a microchip using the liquid/liquid extraction system. Experimental data on molecular transport across the organic membrane were in agreement with the calculated permeability based on the three-compartment water/organic solvent/water model. This kind of experiment can be performed only in a microspace, and the system can be considered as a potential biological membrane for future in vitro study of drug transport.     

Motion of an antiviral compound in a rhinovirus capsid under rotational symmetry boundary conditions

A molecular dynamics (MD) simulation of a complex of a rhinovirus protein shell referred to as a "capsid" and an anti-rhinovirus drug, WIN52084s, was performed under the rotational symmetry boundary conditions. For the simulation, the energy parameters of WIN52084s in all-atom approximations were determined by ab initio calculations using a 6-31G* basis set and the two-conformational two-stage restricted electrostatic potential fit method. The motion of WIN52084s and the capsid was focused on in the analysis of the trajectory of the simulation. The root mean square deviations of WIN52084s from the X-ray structure were decomposed to conformational, translational, and rotational components. The translation was further decomposed to radial, longitudinal, and lateral components. The conformation of WIN52084s was rigid, but moving in the pocket. The easiest path of motion for WlN52084s was on the longitudinal line, providing a track for the binding process required of the anti-rhinovirus drug to enter the pocket. The conformation of the pocket was also preserved in the simulation, although the position of the pocket in the capsid fluctuated in the lateral and radial directions.     

Effect of anisotropic scattering in neutronics analysis of BWR assembly

The anisotropic scattering effect to keff is studied for UO₂ and MOX fueled BWR assemblies. The anisotropic scattering effect increases the assembly k_∞ by 0.44% Δk for the UO₂ assembly with 0% void fraction, and by 0.21% Δk for the MOX assembly with 0% void fraction. This is because the anisotropic scattering effect flattens the intra-assembly thermal flux, and the absorption rate in the surrounding water gap is decreased, but the absorption rates in the MOX fuel rods are increased compared to the UO₂ rods. Therefore, the total decrease in absorption rates in the UO₂ assembly is relatively large, and the k_∞ is increased in the UO₂ assembly. The dependence of the anisotropic scattering effect on the void fraction is investigated, and the significant difference of 0.62% Δk/k is found for the 0% and the 80% void fractions. The BWR assemblies with Gd rods are also considered. Furthermore, the usefulness of the transport cross section is investigated, and it is found that the transport cross section gives reasonable anisotropic scattering effect, though not satisfactory.     

Preparation of Lanthanum Nickel Oxide-Coated Ni Sheet Anodes and Their Application to Electrolytic Production of (CF3)3N in (CH3)4NF·4.0HF Melt

A new process for electrolytic production of a perfluorinated compound, (CF₃)₃N, using lanthanum nickel oxide-coated Ni sheet anode in the (CH₃)₄NF·4.0HF melt at room temperature, was developed. Thin films of the lanthanum nickel oxides were prepared on Ni sheets by sol-gel coating method using polyvinlylpyrrolidone(PVP). The main components of the thin films were La₂O₃, LaNiO₃, and La₂NiO₄ at 500, 750 and 1000 °C, respectively. The anode performance in the (CH₃)₄NF·4.0HF melt depends greatly on the main component of the thin film, and the LaNiO₃-coated Ni sheet anode gives the best anode performance. The potential of LaNiO₃-coated Ni sheet anode remains constant at 5.9 V during electrolysis at 20 mA·cm⁻² in the (CH₃)4NF·4.0HF melt for 100 h. This is because LaNiO₃ and NiF₃, and/or Ni₂F₅, the latter of which was formed during electrolysis, in the film give a high electronic conductivity to the surface film during electrolysis. The maximum mole fraction of (CF₃)₃N (21.4%) was obtained at 20 mA·cm⁻² in (CH₃)₄NF·4.0HF melt using the LaNiO₃-coated Ni sheet.     

Grain-growth-inhibiting effects of primary inclusion particles of ZrO2 and MgO in Fe-10 mass pct Ni alloy

Grain-growth inhibition in an Fe-10 mass pct Ni alloy, which was continuously cooled from a melt, was studied at 1673 K in the presence of primary deoxidation products of ZrO₂ or MgO particles. The mean grain size and grain-size distribution in a cross section were measured as a function of holding time for up to 240 minutes. The grain growth was strongly inhibited by the inclusion particles and was influenced by the dissolved Zr. In the Zr deoxidation, the number of particles per unit area (N _A) ranged from 80 to 650 mm⁻², the ZrO₂ particle size ( ) varied from 1.1 to 1.6 μm, and the dissolved Zr level was below 1800 mass ppm. In the Mg deoxidation, the particle-number density was 90 to 270 mm⁻², the MgO particle size was 1.1 to 1.7 μm, and the dissolved Mg level was below 20 mass ppm. In a logarithmic plot of the ratio of limiting mean grain diameter ( ) to the mean particle diameter ( ) against the volume fraction of particles (f _V), both the value for a given f _V value, which ranged from 0.014 to 0.074 pct, and the slope were significantly lower than that predicted from the two-dimensional relation =(4/π) · f _V ^/−1 , i.e., Zener’s limit. This discrepancy is discussed in light of the fraction of particles at the grain boundaries measured experimentally. Normal grain growth was confirmed from the grain-size distribution observed as a function of holding time, which was best described by the log-normal distribution.     

Surface Effects of 4He Coating on the Viscosity and the Slip Length of Normal and Superfluid 3He

We have measured the viscosity, , and the slip length, , of normal and superfluid ³ He using a torsional oscillator with a thick sample space. We coated the oscillating surface with 2.5 layers of ⁴ He film to study how the ⁴ He thin film changes the scattering mechanism of ³ He quasiparticles at the cell wall at 5 bar and 21 bar. In the normal phase, the temperature dependence of the viscosity was changed a little by the ⁴ He film at 21 bar but no change was observed at 5 bar. The slip length was enhanced by ⁴ He coating at 5 bar. This enhancement indicates the increase of specularity of ³ He quasiparticles scattering at the oscillating surface. On the other hand, a reduction of the slip length was observed at 21 bar. In the superfluid phase, the temperature dependence of supports the existence of Andreev reflection even with ⁴ He film on the surface at 5 bar and 21 bar.