Spatial charge cloud size of microchannel plates

We examine the spatial evolution of charge clouds emitted by microchannel plates (MCPs). A model of this evolution is presented, along with a comparison to experimental results. We also present an experimental method to measure the charge cloud radius in which the radial charge cloud distribution is assumed to be Gaussian. When a charge cloud is released from the MCP, its initial size is determined by the number and distribution of excited channels. The size of the charge cloud is examined as a function acceleration voltage, distance between MCP and anode, and MCP bias voltage. Since electrons released from the MCP have various initial energies and angular divergence, the charge cloud size increases as it travels away from the MCP. Space charge effects also contribute to the growth of the charge cloud. The experimental results are in close agreement with our model, which includes these effects. From experiment, we also derive an approximate expression for charge cloud radius as a function of acceleration voltage and distance between MCP and anode. This expression can be used for the practical design and optimization of a position sensing system comprised of multiple anodes.     

Air Entrapment in Nanometer-Thick Lubricant Films and its Effect on Slider Flying Height in a Hard Disk Drive

Experimental data are presented, showing that the flying height of a slider in a hard disk drive can be altered by the chemical nature of the molecularly-thin lubricant film on the disk surface. It is suggested that this effect is likely due to entrapment of the air molecules, both nitrogen and oxygen, within the lubricant film, which results in pressurization loss within the air bearing gap, and lower slider flying height. For the two advanced multidentate lubricants reported in this study, the amount of flying height change is almost insignificant for one of them, but amount to about 0.7?nm, i.e. a significant fraction of the magnetic spacing budget for the other. Bulk air solubility data suggest that the magnitude of this effect is diminished for lubricant molecules with a lower density of backbone ether linkages.     

Fast magneto-optical spectrometry by spectrometer

Time efficient measurement of the spectroscopic magneto-optical (MO) activity of materials has always been desirable. In conventional MO systems, the monochromator produces quasi-monochromatic light in a narrow wavelength window. Therefore, to measure the spectroscopic MO activity, a large number of measurements over the full spectra is required to obtain satisfactory wavelength resolution and thus is very time consuming. Here, we develop a novel system that is capable of fast measurement of the MO activity by only one white light source, two polarizers, one achromatic quarter-wave plate, and one spectrometer. This system is flexible from UV to IR region, only depending on the power spectra of light source and sensitivity of the detector at the corresponding wavelengths. As examples, we measured the intriguing optic and MO activity in glass, ferromagnetic thin film, and bulk GaAs in the visible to near infrared region. The results of glass demonstrated a minimum resolvable Faraday rotation angle of 0.004° by the currently equipped system.     

Apertureless near-field Raman spectroscopy

We report on the tip‐enhanced Raman spectra of C60 obtained on a custom‐built apertureless scanning near‐field optical microscope. A commercial atomic force microscope tip coated with 100 nm thickness of gold was used to enhance locally the Raman signal and permit topographic and spectral information to be acquired simultaneously. We present preliminary data which demonstrate the tip enhancement effect using C60 as a test sample.     

The development of simplified ultrasonic CT system and its application to the evaluation of weld metal

In this paper, as a new measurement method to estimate the change of material condition, the simplified ultrasonic CT system, which uses the information of three directions, that is, 90°, + 45° and −45° about inspection plane is proposed. Use of simplified CT system has two merits: Firstly, the measurement time is very short compared with general CT. Secondly, it can detect sensitively small defect in vertical or slant direction about inspection plane because the obtained image is CT image calculated from three directions. From these merits, this method can be considered as an effective method to evaluate material conditions. The basic performance of the proposed method was confirmed through several specimens with several simple defects. In order to confirm the applicability of actual NDT, several kinds of welded specimens are investigated. The result showed that the CT image obtained had good agreement with actual defect of specimens.     

Development of high performance Raney Cu-based catalysts for methanol synthesis from CO2 and H2

Catalytic hydrogenation of CO₂ into methanol has been investigated over Raney Cu-based catalysts. The Raney catalysts leached in NaOH/ZnO solutions showed high activities and selectivities for methanol synthesis. The deposition of Zn on the surface of Cu particles increased the surface area and the specific activity of Raney Cu–M. Raney Cu–Zr developed was significantly more active than a commercial catalyst.     

Multi-component granulation in a fast fluidized bed

The granulation of multi-component particles was conducted in a fast fluidized bed with an atomizing binder solution. The effects of gas velocity and binder droplet diameter on granulation rate, granule size distribution and granule composition were studied. The granulation rate and granule yield were determined by the balance between the agglomeration rate of feed particles and the disintegration rate of granules because there was no secondary granulation. With the increase in gas velocity and the reduction in binder droplet size, the agglomeration rate of feed particles decreased but the disintegration rate of granules increased, resulting in a reduced granule yield. Despite the larger fraction of small particles in the granules, the homogenous granulation of multi-component particles was achieved.     

Fatty acid composition of the cellular slime mold Polysphondylium pallidum

The cellular slime mold Polysphondylium pallidum was grown upon Escherichia coli B/r, and the fatty acid compositions of total lipids obtained from vegetative amebae and aggregation-competent cells were compared. Fatty acids isolated from vegetative cells included C-17 and C-19 cyclopropane fatty acids and also straight-chain, saturated fatty acids. The cyclopropane fatty acids were derived from the ingested bacteria. Development of amebae to aggregation-competent cells was accompanied by a substantial decrease in saturated cyclopropane fatty acids and a concomitant increase in unsaturated fatty acids and unsaturated cyclopropane fatty acids, mostly as 18∶3 (5,9,12). We report here the fatty acid composition and identify the occurrence of Δ5 desaturation of cyclopropane fatty acids, namely, 9,10-methylene 5-hexadecenoic acid and 11,12-methylene 5-octadecenoic acid. These fatty acids have not been reported previously in the related species Dictyostelium discoideum, which also feeds on E. coli B/r and has Δ5-desaturation activity.     

Monte Carlo simulation of phase separation in iron-based ternary alloys

Numerical simulations of phase separation in Fe–Cr–Mo ternary alloys were performed with use of a model based on the Monte Carlo simulation, in order to investigate mechanisms of phase separation in Fe-based ternary alloys. Cr-rich regions were formed in an Fe–40at.%Cr–5at%Mo alloy. Mo atoms enrich into the Cr-rich region and/or boundaries of Cr/Fe rich regions. Behaviors of Mo and Cr in an Fe 40at.%Mo–5at.%Cr alloy were similar to those in the Fe–40at.%Cr–5at.%Mo alloy. The first peak position of the structure factor moves on to the shorter side of the wave number with the increase of temperature. Analysis of the static structure factor of a minor element indicates that the bifurcation formation of concentration profile of the minor element occurs at peak positions of the major element which is predicted by a theory based on the Cahn-Hilliard equation.     

Analysis of main pigments and other ingredients in lac color product

The contents of the main pigments and other ingredients in commercial lac color products were determined by HPLC using an RP-18 column with 0.1 mol/L citric acid buffer solution-methanol (16:5) as the mobile phase, and a photodiode array (PDA) detector set at 280 nm and 490 nm. The main pigments were confirmed by PDA and electrospray ionization mass spectrometry. Laccaic acids A, B, C and E were detected in all lac color products, and the ratio of content of laccaic acid A in all products was over 50%. The total contents of laccaic acids A, B and C in lac color food additive products and reagent products were 775-858, 797 and 779 g/kg, respectively. As for the contents of ingredients except pigments in commercial food additive products, the maximum moisture content was about 10%, and ether-soluble substances amounted to 0.5-3.6%.