Preparation and application of methacrylate-based cation-exchange monolithic columns for capillary ion chromatography

Polymer-based strong cation-exchange monolithic capillary columns with different capacities were constructed for ion chromatography by radical polymerization of glycidyl methacrylate (GMA) and ethylene dimethacrylate in a 250-microm-i.d. fused-silica capillary and its subsequent sulfonation based on ring opening of epoxides with 1 M Na(2)SO(3). The cation-exchange capacities can easily and reproducibly be controlled in the range of up to 300 microequiv/mL by changing the immersion time of the epoxy-containing polymer in the Na(2)SO(3) solution. The chromatographic performance of the produced monolithic capillary columns was evaluated through the separation of a model mixture of common cations such as Na(+), NH(4)(+), K(+), Mg(2+), and Ca(2+). As an example, these cations could be well separated from one another on a 15-cm-long cation-exchange monolithic column (column volume, 7.4 microL) with a capacity of 150 microequiv/mL by elution with 10 mM CuSO(4). The pressure drop of this 15-cm column was approximately 1 MPa at a normal linear velocity of 1 mm/s (a flow rate of 3 microL/min), and the numbers of theoretical plates for the cations were above 3000 plates/15 cm. This GMA-based cation-exchange monolithic column could withstand high linear velocities of at least 10 mm/s. Over a period of at least two weeks of continuous use, no significant changes in the selectivity and resolution were observed. The applicability of a flow rate gradient elution and the feasibility of direct injection determination of major cations in human saliva sample were also presented.     

Infrared absorption enhancement of C60 by overlaying thin silver island films

Normal-incidence infrared absorption has been observed for silver overlaid C(60) thin films formed on surface-oxidized Si(111) substrates as a function of the silver or C(60) film thickness. The absorption spectra exhibit bands at 1429 and 1180 cm(-1) due, respectively, to the infrared active T(lu) (4) and T(lu) (3) modes of C(60) in multi-layers. Additionally, two bands appear at 1442 and 1370 cm(-1). The former band is caused by activation of the infrared inactive (Raman active) A(g) (2) mode via electron transfer from the silver to adsorbed C(60), and the latter is assigned to the T(1u) (4) mode red-shifted by the charge transfer. These bands are all enhanced in intensity dependent either upon the silver or C(60) thickness, i.e., the largest absorption enhancement is obtained for 25-monolayers-thick silver and 12-nm-thick C(60). Under atomic force microprobe inspection, the average size and height of the islands in the overlaid 25-monolayers-thick silver change with underlying C(60) film thickness. The influence of the C(60) film structure upon the silver film and in turn the absorption intensity is strongly suggested.     

Optical Burst Switching Router With 40-,10-Gb/s Bit-Rate Transparent Contention Resolution

We report a bit-rate transparent optical burst switching (OBS) router prototype using a fast 5 times 5 PLZT [(Pb,La)(Zr,Ti)O₃ ] optical matrix switch. Dynamic switching in a two-wavelength, 2 times 2 OBS switch is demonstrated. Contention resolution using a tunable Mach-Zehnder interferometer wavelength converter for both 40- and 10-Gb/s bursts is demonstrated for the first time. Error-free operation was achieved for both bit rates under the same settings, as required in autonomous networks     

Polarization-Insensitive Monolithic 40-Gbps SOA–MZI Wavelength Converter With Narrow Active Waveguides

A polarization-insensitive monolithic 40-Gbps semiconductor optical amplifier (SOA)-Mach-Zehnder interferometer wavelength converter has been developed. Based on the photon-electron rate equation, we optimized the dimensions of the waveguide structure to maximize the field confinement in the active layer. An InGaAsP active layer with narrow SOA waveguide effectively enables polarization-insensitive high-speed wavelength conversion. High-precision wafer processing technique enabled the fabrication of submicrometer-wide active waveguides with low current leakage. Input waveguide arrays were fabricated at intervals of 25 mum and mounted in a module with two-lens aspherical lens optics. The 40-Gbps nonreturn-to-zero wavelength conversion experiment demonstrates a clear eye opening over full C-band operation     

A simple approach to plane strain extrusion with dead metal zone using upper-bound theorem

This paper treats the upper-bound approach to the problem of rigid-plastic deformation in case where the configuration of the deformation zone is previously unknown. The plane strain forward extrusion process with the so-called dead metal zone is analysed by assuming a simple velocity field. The calculations are carried out for the material with or without strain hardening or strain rate sensitivity and for various reduction ratios. The numerical results show that the region of the dead metal zone becomes smaller with the increase in the reduction ratio. The calculated punch forces agree with the experimental ones fairly well. Furthermore, it is found that the dead metal zone becomes larger with increasing the strain hardening as well as the strain rate sensitivity of the material.     

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.     

Identification of a novel all-cis-5,9,12-Heptadecatrienoic acid in the cellular slime moldPolysphondylium pallidum

The all-cis-5,9,12-heptadecatrienoic acid was identified in the cellular slime moldPolysphondylium pallidum. The structural elucidation was accomplished by capillary gas chromatography, argentation thin-layer chromatography, and gas chromatography/mass spectrometry. This fatty acid has not been reported previously. Dedicated to Professors Tadao Yoshida and Masakazu Tatewaki on the occasion of their academic retirement.     

Prediction of mill load in hot strip mill rolling

It has been ascertained whether or not the model capable of predicting the stress-strain relation of plain carbon steels, previously proposed, is applicable to the estimation of mill loads in the finishing process (consisting of six mill stands) of a hot strip mill. An appreciably good agreement with the predicted and measured mill load values has been obtained in the earlier passes where the strip microstructure is regarded to have completed static recrystallization, and the predicted mill loads in the later passes have been far less than the measured load owing to the effect of the strain accumulated in the previous rolling process. Then, a simple model to predict the accumulated strain has been constructed and introduced into the calculation of mill loads. As a result, the predicted mill loads have been fairly improved over the whole passes in the finishing process.