Characterization and electrochemical properties of CF4 plasma-treated boron-doped diamond surfaces

The effect of CF₄ plasma etching on diamond surfaces, with respect to treatment time, was investigated using scanning electron microscopy (SEM), Raman spectroscopy, X-ray photoelectron spectroscopy (XPS), and electrochemical measurements. SEM observations and Raman spectra indicated an increase in surface roughening on a scale of 10–20 nm, and an increase in crystal defect density was apparent with treatment time in the range of 10 s to 30 min. In contrast, alteration of the diamond surface terminations from oxygen to fluorine was found to be rather rapid, with saturation of the F/C atomic ratio estimated from XPS analysis after treatment durations of 1 min and more. The redox kinetics of Fe(CN)₆^3−/4− was also found to be significantly modified after 10 s of CF₄ plasma treatment. This behavior shows that C–F terminations predominantly affect the redox kinetics compared to the effect on the surface roughness and crystal defects. The double-layer capacitance (C_dl) of the electrolyte/CF₄ plasma-treated boron-doped diamond interface was found to show a minimum value at 1 min of treatment. These results indicate that a short-duration CF₄ plasma treatment is effective for the fabrication of fluorine-terminated diamond surfaces without undesirable surface damage.     

Excessive closure of the right eye: a new sign of infarction in the territory of the ipsilateral right middle cerebral artery

In right middle cerebral territory infarction a new sign, excessive closure of the right eye ipsilateral to the lesion and mild closure of the left eye on command, was noted. The excessive ipsilateral eye closure was not observed on spontaneous eye closure.     

Some characteristics of a sparged agitated vessel under foaming — Mechanical control of foaming —

Foam-breaking with a rotating disk mechanical foam-breaker (MFRD) was studied for a foaming system containing a diluted detergent solution in a laboratory sparged agitated vessel. The change of the foam-breaking capacity of the MFRD by varying the air sparge rate, the working volume and the impeller speed or the disk diameter was measured. Based on these measurements, empirical equations are presented for predicting the critical foam-breaking regions of the MFRD fitted with the agitated vessel. The operational range where foam-breaking with the MFRD can be carried out effectively and economically is also discussed.     

Changes in liquid hold-up in foam and size of foam by perforated plates and contribution to mechanical foam-breaking

Changes in the liquid hold-up, ?, and the diameter of d, of a foam that are induced by perforated plates (PPs) and the contribution of PPs to foam-breaking were studied. A foaming system containing a dilute detergent solution in a column with mechanical agitation fitted with a rotating-disk foam-breaker (MFRD) was used. After the foam passed through the PPs, ? and d decreased and increased, respectively. The use of PPs to achieve a maximum reduction in ? and a maximum increase in d is confirmed. It is also demonstrated that use of PPs contributes not only to improving the foam-breaking performance of the MFRD, but also to power savings.     

A GaAs FET-IC mixer achieving high receiver sensitivity for coherent optical heterodyne detection at 2.5 Gb/s

A FET-IC mixer that uses a Gilbert-cell multiplier with a single-to-balance conversion input buffer is proposed. The key point in the FET-IC mixer design is that a single-to-balance conversion input buffer is used to improve the amplitude and phase balance of signals output from the input buffer stage. Excellent squaring characteristics were achieved in the range from 0 to -25 dBm. The FET-IC mixer was successfully tested in a 2.5 Gb/s CPFSK demodulator for optical heterodyne reception. Compared to the best diode passive double-balanced diode mixers, receiver sensitivity was improved by 1 dB at +10 dBm electrical input power. Very small degradation in receiver sensitivity, less than 3 dB, was achieved at electrical input power levels ranging from +10 to -10 dBm.<>     

Fabrication of long length Bi-2223 superconductor tape using continuous electrophoretic deposition on round and flat substrates

We have developed a continuous fabrication process for producing long lengths of Bi-2223 superconductor tapes. The process involves sequentially electrophoretically depositing and sintering superconductor and then silver layers on a substrate, followed by rolling and thermal processing. Both round and flat silver substrates have been used. Bi-2223 tapes made using flat silver substrates require only a few processing steps. Transport critical current densities at 77K in zero applied magnetic field exceeding 20000 A/cm² have been obtained.     

A 98 mm2 die size 3.3-V 64-Mb flash memory with FN-NORtype four-level cell

In order to realize high-capacity and low-cost flash memory, we have developed a 64-Mb flash memory with multilevel cell operation scheme. The 64-Mb flash memory has been achieved in a 98 mm² die size by using four-level per cell operation scheme, NOR type cell array, and 0.4-μm CMOS technology. Using an FN type program/erase cell allows a single 3.3 V supply voltage. In order to establish fast programming operation using Fowler-Nordheim (FN)-NOR type memory cell, we have developed a highly parallel multilevel programming technology. The drain voltage controlled multilevel programming (DCMP) scheme, the parallel multilevel verify (PMV) circuit, and the compact multilevel sense-amplifier (CMS) have been implemented to achieve 128 b parallel programming and 6.3 μs/Byte programming speed     

High-Speed TDM–WDM Techniques for Long-Haul Submarine Optical Amplifier Systems

Optical amplifier techniques have led to the installation of large-capacity submarine systems and further capacity increases seem likely. This paper reviews the FSA submarine system, which flexibly operates at both 2.5 and 10 Gb/s and offers maximum transmission capacity of 60 Gb/s for commercial use. The system configuration as well as its characteristics and upgradability will be introduced, including measurement results on time-division-multiplexing/wavelength-division-multiplexing (TDM–WDM) transmission at bit rates of 10 and 20 Gb/s using non-return-to-zero or soliton pulses. To further increase transmission capacity, TDM–WDM techniques that permit more than 10 Gb/s signal transmission in each data channel should be developed. Thus, pulse formats, which include non-return-to-zero, return-to-zero, or soliton pulses, and dispersion allocation in transmission fibers are significant issues. We introduce and discuss our recent results from high-speed (10 to 40 Gb/s) TDM–WDM signal transmission experiments with regard to the above aspects.     

Boundary element method for electromagnetic scattering from cylinders

The computation of low frequency scattering of electromagnetic fields by solid/hollow dielectric or conducting cylinders using the boundary element method (BEM) is considered. A general computer program has been developed for both transverse electric and magnetic cases. Numerical examples are given for conducting circular cylinders, and solid and hollow dielectric cylinders. The computational accuracy is checked by comparing the results with the analytic solution or computing an error defined from the optical theorem. In addition some problems at an interior resonance of the scatterer are discussed. The method can be directly applied to more complicated geometries.     

Structural chirality of cholesteric liquid crystal produces atropisomerism: Chiroptical polyisocyanides from achiral monomer in cholesteric liquid crystal matrix

1-Naphthyl isocyanide was polymerized with Ni(II) catalyst in a cholesteric matrix at the liquid crystal (LC) temperature range. The resultant polymers showed optical activity. In this reaction, the structural chirality of cholesteric LC effectively functions to impart one-handed helicity on the corresponding polymers as an optically active atropisomer.