Extraction of uranium from simulated ore by the supercritical carbon dioxide fluid extraction method with nitric acid-TBP complex.

The supercritical fluid extraction (SFE) method using CO(2) as a medium with an extractant of HNO(3)-tri-n-butyl phosphate (TBP) complex was applied to extract uranium from several uranyl phosphate compounds and simulated uranium ores. An extraction method consisting of a static extraction process and a dynamic one was established, and the effects of the experimental conditions, such as pressure, temperature, and extraction time, on the extraction of uranium were ascertained. It was found that uranium could be efficiently extracted from both the uranyl phosphates and simulated ores by the SFE method using CO(2). It was thus demonstrated that the SFE method using CO(2) is useful as a pretreatment method for the analysis of uranium in ores.     

63Cu, 35Cl, and 1H NMR in the S=1/2 Kagome lattice ZnCu3(OH)6Cl2

ZnCu(3)(OH)(6)Cl(2) (S=1/2) is a promising new candidate for an ideal Kagome Heisenberg antiferromagnet, because there is no magnetic phase transition down to approximately 50 mK. We investigated its local magnetic and lattice environments with NMR techniques. We demonstrate that the intrinsic local spin susceptibility decreases toward T=0, but that slow freezing of the lattice near approximately 50 K, presumably associated with OH bonds, contributes to a large increase of local spin susceptibility and its distribution. Spin dynamics near T=0 obey a power-law behavior in high magnetic fields.     

Application of ToF-SIMS to the study on heartwood formation in Cryptomeria japonica trees

Influence of gold- and carbon-coating on ToF-SIMS analysis of Cryptomeria japonica (Sugi) wood has been investigated to apply the samples after observing water distribution by cryo-scanning electron microscopy (cryo-SEM) or analyzing distribution of metal elements by SEM with energy dispersive X-ray spectrometer (SEM/EDX) to ToF-SIMS analysis to study the mechanism of heartwood formation of woody plants. The intensities of peaks at the m/z 285 ion in positive mode and the m/z 283 ion in negative mode from gold- and carbon-coated samples were compared with from those of non-coated samples. Those peaks were apparently attributable to ferruginol, a typical heartwood compounds in Sugi tree. From both gold- and non-coated samples, positive m/z 285 ions were generated. On the other hand, in negative mode, the intensity of m/z 283 ion was decreased after coating with gold. From carbon-coated samples, intensities of both positive m/z 285 ion and negative m/z 283 ion were decreased. These results suggest that the samples coated with gold for cryo-SEM could be applied to ToF-SIMS analysis directly to investigate the relation between water distribution and distribution of heartwood substances in heartwood-forming Sugi trees. However, non-coated samples should be used for SEM/EDX before analyzing by ToF-SIMS.     

Design theory and experiment of acousto-optical tunable filter by use of flexural waves applied to thin optical fiber

Spectral response of acoustically induced microbending through thin optical fiber is discussed from mode-coupling of core and cladding modes. The thin fiber is analyzed in three-layered structure (core-cladding-air) to gain insights into acousto-optic modulation. We explained the dependence of core and/or cladding diameters on acoustic source parameters from numerical calculations. According to the calculations, we successfully fabricated all-optical tunable filter using this thin fiber that yields an efficient mode-coupling at flexural wave frequencies less than 1MHz. To increase the acousto-optic effect, we used a specially designed thin optical fiber (80 μm of cladding diameter) in the section where flexural wave is produced, and spliced both ends of the thin fiber to the tapered 125 μm fibers. The frequency and voltage tuning of fabricated filter is also confirmed by changing the driven frequency and applied voltage of the PZT, respectively. This result suggests a possibility of fiber-optic device application as all-optical tunable filter at 1.55 μm.     

Fabrication of highly porous and micropatterned SnO2 films by oxygen bubbles generated on the anode electrode

The fabrication process of highly porous SnO(2) thick film by reaction between tin ions and oxygen gas generated by an anodic applied potential on substrates in SnCl(2) aqueous solution is reported; moreover, we succeeded in forming porous SnO(2) micropatterns through site-selective deposition on a Pt-patterned F-doped SnO(2)(FTO) coated substrate .     

Crystal growth of metastable rutile-type TixSn1-xO2 solid solutions in an aqueous system

Nanoscale grains of crystalline TixSn1-xO2 were directly grown over the whole range of [Ti]/([Ti] + [Sn]) ratio (x = 0.00-1.00) in aqueous solutions at near room temperature.     

Achromatically injection-seeded terahertz-wave parametric generator

An achromatically injection-seeded terahertz-wave parametric generator was constructed with MgO:LiNbO (3) crystals and a tunable seeder in a stationary dispersion-compensated optical arrangement. Without readjusting the mirrors, we obtained smooth tuning of the terahertz wave over the 0.6-2.6 THz range by adjusting the seeder wavelength alone. We have successfully demonstrated the feasibility of this system for terahertz-wave absorption measurements over a wide frequency range by using low-pressure water vapor.     

Asymmetry measurement of the polarized Σ+p elastic scattering and the hyperon-nucleon spin-orbit interaction

In order to study the hyperon-nucleon spin-orbit interaction, asymmetries of the polarized Σ⁺ elastic scattering on protons have been measured. The polarized hyperons were produced through the p(π⁺, K⁺) Σ⁺ reaction in a liquid-scintillator active target, and tracks of Σ⁺p scattering events were recorded with a newly developed track detector named SCITIC (scintillating track image camera). Although analyses of 10 times more data with more sophisticated data-taking systems and more elaborated analyzing tools are under way, data from an early stage of this experiment indicate a large Σ⁺p spin-orbit interaction in contrast to the case of the small ΛN spin-orbit interaction. Received: 27 May 2002 / Accepted: 23 July 2002 / Published online: 19 November 2002 RID="a" ID="a"e-mail: nakai@post.kek.jp Communicated by Th. Walcher