We report the optical and electrical properties of Cu-TCNQ (TCNQ = 7,7 0 ,8,8 0 -tetracyanoquinodimethane) nanocrystals (NCs) fabricated by previously reported chemical reduction reprecipitation methods. The size of the resulting NCs ranges from 50 nm to 10 mm along the long axis. Raman experiment, X-ray photoelectron spectroscopic experiment, and elemental analysis reveal that these NCs have few TCNQ dianions due to the excess amount of Cu. The absorption of interband transition in the near-infrared region shows a blue shift, and the band gap increases with decreasing NC size. The obtained NCs show high electric conductivity, compared with typical Cu-TCNQ microcrystals, and multistep switching due to the existence of TCNQ dianions. #

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Abstract-A magnetically levitated superconducting coil system is being developed using high temperature superconductors for examining a new magnetic confinement of high-beta plasmas. A miniature double-pancake coil was fabricated with a Bi-2223 Ag-sheathed tape for the purpose of developing a floating control using laser displacement gauges. The coil was inductively excited with liquid nitrogen cooling and successfully levitated in the air. A persistent current switch is also being developed with a Bi-2223 Ag-0.3wt%Mn-sheathed tape, and a prototype model was successfully tested.Index Terms-Bi-2223, high temperature superconductor, magnetic levitation, persistent current switch, plasma confinement.

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To improve the stability of superconducting magnets cooled by He II, it is considered that the utilization of the porous media enhances the heat transport capability of He II. In the present studies, the thermal hydraulic characteristics of He II through porous media have been investigated experimentally and numerically. Experimental results are presented about 6 porous media with various porosity, thickness and average pore diameters. Numerical results are reported about 4 porous media among them. In the present numerical analysis, the two-dimensional calculations have been performed for the turbulent Gorter-Mellink regime to understand the heat and mass transfer of the He II through the porous media in the case of the large heat input. The present numerical model was based on the two-fluid model with the Gorter-Mellink mutual friction and dealt with the classical friction loss and the tortuosity in the porous media. This paper discusses the influence of these additional terms on the heat and mass flow of He II through the porous media at the turbulent Gorter-Mellink regime. KEYWORDS:He II, heat and mass flow, porous media, turbulent two fluid model and tortuosity PACS: 44.30,+v Heat flow in porous media 105 This article is copyrighted as indicated in the article. Reuse of AIP content is subject to the terms at: http://scitation.aip.org/termsconditions. Downloaded