The production of an electrochemical capacitor electrode using holey single-wall carbon nanohorns with high specific surface area

We prepared single-wall carbon nanohorns (SWCNHs) with a high specific surface area and fabricated an electrochemical capacitor electrode with good performance from them. Carbon impurities involved in the as-grown SWCNHs were thoroughly removed and the purified SWCNHs were oxidized to produce holes in them (SWCNHox). The specific surface area was estimated as 1720 m²/g, the largest surface area of SWCNHs ever reported. Capacitive properties were also investigated using the obtained SWCNHox. We found that an electrochemical device with SWCNHox showed an excellent specific capacitance of about 100 F/g, accelerating industrial progress for their uses in energy and environmental fields.     

Deodorisation of off-odour during sweet potato juice production by employing physical and chemical deodorants

The mechanism and efficiency of three types of deodorants, namely activated carbon (AC), maltosyl cyclodextrin (MCD) and apple polyphenol (AP), in reducing the “boiled heavy odour” of saccharified sweet potato juice was investigated. The highest deodorising efficiency of AC, followed by MCD and AP, was confirmed by using the electronic nose and sensory analysis. Furthermore, flavour compounds in the sweet potato juice were identified by GC–MS analysis. While AC decreased the peak intensities of all the compounds to below the minimum detection limit, MCD, which eliminated the odour components by the formation of enclosure compounds, did not reduce the peak intensities to a similar extent. The mechanisms of adsorption with AC and envelopment with MCD for the identified odour components of sweet potato juice was also clarified.     

Rapid growth of thick particulate film of crystalline ZnO in an aqueous solution

Thick particulate films of crystalline ZnO were developed in an aqueous solution. ZnO crystallized in the solution of zinc nitrate hexahydrate and ethylenediamine at 60 °C. ZnO crystalline particles were then gradually deposited on a glass substrate to form thick particulate films. The thick films were constructed of multi-needle ZnO particles having an ultrafine surface relief structure, and thus had high specific surface area. The thick films can be applied to dye-sensitized solar cells supported by low-heat-resistant polymer films.     

Neck electrical impedance for measurement of swallowing

Recently, videofluorography has been used for evaluation of swallowing function in the rehabilitation field. But it is not easy to evaluate swallowing disorders simply. In addition, there are problems of exposure for daily use. We have proposed a measurement method of swallowing using bioelectrical impedance (impedance pharyngography, IPG) which has advantages of easy handling and noninvasive measurement. Appropriate electrode position have been determined. The waveforms of IPG can be obtained with some extent reproducibility. The change of neck electrical impedance in the pharyngeal phase is mainly caused by the changes of equivalent cross sectional area near the epiglottis. The possibilities of applications for clinical diagnosis have been shown. © 2000 Scripta Technica, Electr Eng Jpn, 130(4): 35–44, 2000     

Fabrication of Blanket-Like Assembled ZnO Nanowhiskers Using an Aqueous Solution

Blanket-like assembled ZnO nanowhiskers were fabricated using a freestanding ZnO nanoparticle layer by an aqueous solution deposition. X-ray diffraction and field emission scanning electron microscopy clarified the crystalline phase, orientation, morphology, and microstructure. Thermal treatment of the zinc acetate dihydrate layer resulted in the formation and delamination of the ZnO nanoparticle layer on the glass substrate. The growth habits of ZnO crystals resulted in the growth of ZnO nanowhiskers preferentially orientated along the direction of the c -axis on the whole surface of the freestanding ZnO nanoparticle layer by heterogeneorous nucleation and growth. The hierarchical-structured blanket-like ZnO nanowhisker assemblies can be utilized for dye-sensitive solar cells and gas sensors because of their high surface-to-volume ratio.     

Electrical characterization of wafer-bonded Ge(111)-on-insulator substrates using four-point-probe pseudo-metal-oxide-semiconductor field-effect transistor method

The electrical properties of wafer-bonded n-type Ge(111)-on-insulator (Ge(111)-OI) substrates were characterized using a four-point-probe pseudo-metal-oxide-semiconductor field-effect transistor (pseudo-MOSFET) method. Average electron and hole mobilities in the Ge(111)-OI channel were measured to be ~ 1000 cm²/V s in accumulation mode and ~ 310 cm²/V s in inversion mode, respectively. The measured mobility strongly depended on the sample position, due to the spatially inhomogeneous distribution of the interface states. Despite the existence of interface states, the carrier mobility exhibited a high value demonstrating the prospect of wafer-bonded Ge(111)-OI as a channel material in MOSFETs.     

Impulse partial discharge characteristics and their mechanisms under non-uniform electric field in N/sub 2//SF/sub 6/ gas mixtures

We have investigated impulse partial discharge (PD) and breakdown (BD) characteristics of a needle-plane gap in N/sub 2//SF/sub 6/ gas mixtures under positive lightning impulse voltage application, and discussed their physical mechanisms. The 50% probability PD inception voltage (PDIV/sub 50/), leader discharge onset voltage (LOV) and BD voltage (BDV/sub 50/) were measured and analyzed as a function of gas pressure and SF/sub 6/ content. Experimental results revealed the stepwise propagation process of the impulse PD and enabled us to classify the impulse PD in N/sub 2//SF/sub 6/ gas mixtures into two types, the streamer discharge and the leader discharge. We also discussed the impulse PD propagation mechanisms in terms of PD parameters such as propagation length, time interval and current pulse magnitude, and suggested a sequential relationship in the PD propagation process under non-uniform electric field.     

Experimental validation of a linear model for data reduction in chirp-pulse microwave CT

Chirp-pulse microwave computerized tomography (CP-MCT) is an imaging modality developed at the Department of Biocybernetics, University of Niigata (Niigata, Japan), which intends to reduce the microwave-tomography problem to an X-ray-like situation. We have recently shown that data acquisition in CP-MCT can be described in terms of a linear model derived from scattering theory. In this paper, we validate this model by showing that the theoretically computed response function is in good agreement with the one obtained from a regularized multiple deconvolution of three data sets measured with the prototype of CP-MCT. Furthermore, the reliability of the model as far as image restoration in concerned, is tested in the case of space-invariant conditions by considering the reconstruction of simple on-axis cylindrical phantoms.     

Solid-phase crystallization of β-FeSi2 thin film in Fe/Si structure

Dependence of solid-phase growth of β-FeSi₂ thin films on the crystal orientation of Si substrates has been investigated by using a-Fe (thickness: 20 nm)/c-Si(100), (110) and (111) stacked structures. X-ray diffraction (XRD) measurements suggested that the substrate orientation dependence of the formation rate of β-FeSi₂ was as follows: (100)>(111)>(110). This dependence can be explained on the basis of the lattice mismatch between β-FeSi₂ and Si substrates, i.e., the lattice mismatch between β-FeSi₂(100) and Si(100), β-FeSi₂(110) or (101) and Si(111), and β-FeSi₂(010) or (001) and Si(110) of 1.4-2.0%, 5.3-5.5% and 9.2%, respectively. The substrate orientation dependence of solid-phase growth becomes relatively remarkable for very thin films.     

Preparation of KTiOPO4 thin films on different substrates by pulsed laser deposition

Pulsed laser deposition (PLD) technique is applied in fabrication of thin films of KTiOPO₄ (KTP) material, which possesses electro-optic and nonlinear optical properties. Thin film fabrication of optically functional KTP on fused silica and different sapphire substrates by changing an ambient oxygen pressure and a substrate temperature during PLD is investigated. Highly oriented KTP thin films could be grown on sapphire $ {\left( {11\overline{2} 0} \right)} $ in an oxygen atmosphere by PLD using a composite target whose stoichiometry is nearly same as KTP. Although the film contained polycrystalline crystallites, predominant crystallites seemed to be epitaxially grown.