Preparation, morphology and electrochemical characteristics of LiNi1/3Mn1/3Co1/3O2 with LiF addition

LiNi_1/3Mn_1/3Co_1/3O₂ with LiF additives was prepared by a spray dry process, and characterized by XRD, SEM, TEM, ICP, XPS, EIS and charge-discharge testing. Although some of the LiF was lost during the preparation, the remaining LiF existed on the surface of the LiNi_1/3Mn_1/3Co_1/3O₂ particles and had little influence on its structure. The LiF addition could not only promote the combine of the particles and increase the tap density of the material, but also effectively improve the cyclic performance of LiNi_1/3Mn_1/3Co_1/3O₂ at high cutoff voltages (up to 4.7 V) and at a high current density. The EIS results suggest that the LiF presence could significantly suppress the increase in the charge transfer resistance that occurred during the charged storage state or after long cycling, which should be related to the improvement on the electrochemical properties.     

Effects of Cosolvents on the Folding and Catalytic Activities of the Hammerhead Ribozyme

The RNA cleavage activity of the hammerhead ribozyme has been compared in various mixed aqueous solutions containing cosolvents. Kinetic analysis revealed that the tested cosolvents enhanced the ribozyme activity, particularly at low MgCl₂ concentrations. These enhancements, in some cases of more than tenfold, resulted from a reduction in the Mg²⁺ concentration required for substrate cleavage. An inverse correlation was found between the MgCl₂ concentration essential for efficient catalysis and the dielectric constant values. In contrast, FRET measurements showed no substantial influence of cosolvents on the Mg²⁺‐induced structural transitions. The results suggest that the solution environment has various effects on the Mg²⁺ interactions involved in the catalysis and global folding of the ribozyme.     

Experimental evidence for direct insulator-quantum Hall transition in multi-layer graphene

We have performed magnetotransport measurements on a multi-layer graphene flake. At the crossing magnetic field B_c, an approximately temperature-independent point in the measured longitudinal resistivity ρ_xx, which is ascribed to the direct insulator-quantum Hall (I-QH) transition, is observed. By analyzing the amplitudes of the magnetoresistivity oscillations, we are able to measure the quantum mobility μ_q of our device. It is found that at the direct I-QH transition, μ_qB_c ≈ 0.37 which is considerably smaller than 1. In contrast, at B_c, ρ_xx is close to the Hall resistivity ρ_xy, i.e., the classical mobility μB_c is ≈ 1. Therefore, our results suggest that different mobilities need to be introduced for the direct I-QH transition observed in multi-layered graphene. Combined with existing experimental results obtained in various material systems, our data obtained on graphene suggest that the direct I-QH transition is a universal effect in 2D.     

Study on stochastic optimal electric power procurement strategies with uncertain market prices

The player in deregulated electricity markets can be categorized into three groups of GENCO (Generator Companies), TRANSCO (Transmission Companies), and DISCO (Distribution Companies). This research focuses on the role of Distribution Companies, which purchase electricity from the market at randomly fluctuating prices, and provide it to their customers at given fixed prices. Therefore, Distribution Companies have to take the risk stemming from price fluctuation of electricity instead of the customers. This entails the necessity of developing a certain method to make an optimal strategy for electricity procurement. In such a circumstance, this research has the purpose of proposing a mathematical model based on stochastic dynamic programming to evaluate the value of a long‐term bilateral contract for electricity trade, and also a project of combination of the bilateral contract and power generation with their own generators for procuring electric power in a deregulated market. © 2006 Wiley Periodicals, Inc. Electr Eng Jpn, 156(2): 32–42, 2006; Published online in Wiley InterScience ( www.interscience.wiley.com ). DOI 10.1002/eej.20105     

Catalytic Methanol Decomposition Over Palladium Deposited on Mesoporous Cerium Oxide

Ultrafine palladium particles can be deposited on mesoporous cerium oxide by a deposition–precipitation method. After reduction with hydrogen at 300 °C, palladium on the mesoporous compound is cationic with a valence close to +1 whereas the particles have a metallic structure. The catalytic activity in selective methanol decomposition to hydrogen and carbon monoxide at 180 °C is significantly higher than that of palladium supported on non-porous cerium oxide, suggesting that the mesoporous structure is advantageous to the reaction. When the palladium content is high, part of mesopores are probably choked with large palladium particles, which will cause saturation of the activity.     

Flow analysis of aqueous solution of silk fibroin in the spinneret of Bombyx mori silkworm by combination of viscosity measurement and finite element method calculation

Bombyx mori silk fibers possess outstanding mechanical properties in spite of being spun at room temperature and from the aqueous solution. Therefore, the mechanism of the structural transition has been studied with great attention, but still not be well understood. In this study the flow simulation of the silk fibroin aqueous solution using finite element method was performed on the basis of both the relationship between the viscosity and shear rate of the silk fibroin solution prepared from the silk gland, and the detailed structure of the spinneret including silk press part of the silkworm obtained from the optical micrographs. The viscosity of the silk fibroin solution decreased with power-law till the shear rate, about 1.5 s⁻¹ with increasing shear rate. Then the viscosity increased reversely which is speculated due to the fiber formation as a result of aggregation of the molecules. In the flow simulation analysis, the initiation site of the fiber formation was calculated by regulating the extrusion pressure. The fiber formation occurs in 550 μm from the spigot at 1 MPa and in 600 μm from the spigot at 50 MPa. The extrusion pressure in the range from 1 MPa to 50 MPa induces the fiber formation in the stiff plates (550-600 μm from the spigot), that is, the silk press part in the spinneret.     

Focusing of radially and azimuthally polarized beams through a uniaxial crystal

We calculated and measured the difference between focal positions of radially and azimuthally polarized beams after passing through a uniaxial crystal. Calculations were carried out on the basis of the ray optics and the vector diffraction theory. The results of the calculations were in good agreement with those of the experiment. In addition, we discussed the polarization selection in a hemispherical laser cavity that was used for the generation of a radially polarized beam by use of the birefringence of a c-cut Nd:YVO4 laser crystal [Opt. Lett. 31, 2151 (2006)]. The stability range of the laser cavity length for the generation of a radially polarized beam was also in good agreement with the differences mentioned above.     

Novel Core Structure and Iron‐Loss Modeling for Contactless Power Transfer System of Electric Vehicle

A contactless power transfer system for electric vehicles must have high efficiency, a large air gap, good tolerance to misalignment in the lateral direction, compactness, and light weight. In this paper, a new 1.5‐kW transformer has been developed using a novel H‐shaped core which is more efficient, more robust to misalignment, and lighter than previous rectangular cores, to satisfy these criteria, and its characteristics are described. An efficiency of 95% was achieved across a 70‐mm mechanical gap. Iron‐loss modeling of the equivalent circuit is also presented. The calculated efficiency using this model shows good agreement with experimental results. © 2013 Wiley Periodicals, Inc. Electr Eng Jpn, 184(2): 61–70, 2013; Published online in Wiley Online Library (wileyonlinelibrary.com). DOI 10.1002/eej.22377