Earth‐Abundant and Durable Nanoporous Catalyst for Exhaust‐Gas Conversion

Precious metals (Pt and Pd) and rare earth elements (Ce in the form of CeO₂) are typical materials for heterogeneous exhaust‐gas catalysts in automotive systems. However, their limited resources and high market‐driven prices are principal issues in realizing the path toward a more sustainable society. In this regard, herein, a nanoporous NiCuMnO catalyst, which is both abundant and durable, is synthesized by one‐step free dealloying. The catalyst thus developed exhibits catalytic activity and durability for NO reduction and CO oxidation. Microstructure characterization indicates a distinct structural feature: catalytically active Cu/CuO regions are tangled with a stable nanoporous NiMnO network after activation. The results obtained by in situ transmission electron microscopy during NO reduction clearly capture the unique reaction‐induced self‐transformation of the nanostructure. This finding can possibly pave the way for the design of new catalysts for the conversion of exhaust gas based on the element strategy.     

S/N and error rate performance in AlGaAs semiconductor laser preamplifier and linear repeater systems

The applications of AlGaAs semiconductor laser preamplifier and linear repeaters in single mode optical fiber transmission systems were studied through the baseband signal-to-noise ratio and bit error rate performance measurement. Experiments were carried out with the Fabry-Perot cavity laser amplifiers whose characteristics are improved by reducing the input mirror reflectivity to 6 percent. The use of a preamplifier improves the minimum detectable power by 7.4 dB over the Si-APD direct detection level when the received signal is amplified by 30 dB before photodetection. The use of two linear repeaters increases the regenerative repeater gain by 37 dB. These experimental results are in good agreement with theoretical predictions based on the photon statistic master equation analysis.     

S/N performance of an AlGaAs laser preamplifier and a linear repeater system

Baseband signal-to-noise-ratio characteristics in an AlGaAs laser preamplifier and a linear repeater system were studied theoretically and experimentally. The AlGaAs laser preamplifier improved the minimum detectable power by 1.6 dB over the level achieved by direct detection with an Si APD. 37 dB regenerative repeater gain was experimentally obtained in the system with two optical repeaters at 100 Mbit/s data rate.     

Oxygen influence on drawing-induced defect centres and radiation-induced loss in pure silica optical fibres

Drawing-induced defect centres are investigated in pure silica optical fibres drawn from the preforms consolidated in O2-including atmospheres. The drawing-induced E? centres decrease while the peroxy radicals increase with increasing flow rate of O2 into the consolidation furnance. The ?-ray-induced loss of these fibres is also examined.     

Polarisation characteristics of fused-fibre coupler as quarter-wave device in 1.55?m-wavelength region

Polarisation characteristics of the fused-taper-twisted single-mode-fibre coupler as a quarter-wave device are reported for the first time. In the case that circular polarisation is launched into the input port of the fused-fibre coupler, linear polarisation was observed at two output ports of the coupler, and an extinction ratio of about 30dB was obtained.     

Field test results of multi-channel digital tv transmission at 15 and 30 Mb/s through an intelsat satellite using a PSK/FDMA system

This paper describes field test results of multi-channel digital TV transmission using a PSK/FDMA system and the related subjective test results of received TV pictures. The picture quality of the multi-channel 15 or 30 Mb/s transmission for both NTSC and PAL systems through the INTELSAT POR satellite are subjectively evaluated for various bit-error rates. In addition, subjective evaluations were made at various values of earth-station e.i.r.p. to compare the picture quality of digital transmissions with that of current half-transponder FM transmission.     

Contrasting effects of water-soluble and water-insoluble dietary fibers on bile acid conjugation and taurine metabolism in the rat

The effect of the type of dietary fiber on the bile acid and taurine metabolism was examined in rats. Diets containing 10% of various water-soluble fibers (citrus pectin, konjak mannan, guar gum) as compared to a fiber-free diet increased biliary excretion of total bile acids. In contrast, water-insoluble dietary fibers (cellulose, corn bran, chitin; 10% in the diets) as well as cholestyramine (5% in the diet) considerably, decreased bile acid excretion. Water-soluble dietary fibermediated increases in bile acid excretion were totally attributable to increases in glycine-conjugates. Thus, these fibers greatly increased by the bile acid glycine-to-taurine ratio (G/T). Excretio of glycine conjugates decreased more than that of taurine conjugates in rats fed various water-insoluble dietary fibers. As a results, G/T in rats fed water-insoluble fibers was significantly lowered as compared to G/T in animals fed a fiber-free diet. Cholestyramine did not affect the G/T ratio of bile acids. Fecal bile acid excretion and the activities of hepatic cholesterol 7α-hydroxylase (EC 1.14.13.17) in rats fed various water-soluble dietary fibers approximately doubled as compared to the respective values for rats fed a fiber-free diet. Whereas cholestyramine greatly increased these parameters, water-insoluble fibers did not significantly affect them. Various water-soluble fibers decreased hepatic concentration and urinary excretion of taurine as well as the activity of hepatic cysteine dioxygenase (EC 1.13.11.20). In contrast, water-insoluble fibers considerably increased hepatic taurine concentrations and enzyme activities. The parameters for taurine metabolism were unaffected by cholestyramine. It was suggested that the types of dietary fiber affected hepatic taurine synthesis and thus modified bile acid glycine/taurine ratios.     

CW operation at - 10°C for InGaAlP visible light laser diodes grown by MOCVD

CW operation at - 10°C for InGaP/InGaAlP double heterostructure (DH) laser diodes has been achieved for the first time. The DH wafers were grown by low-pressure metalorganic chemical vapour deposition using methyl metalorganics as the source of group III elements. Under room-temperature pulsed operation, the lasing wavelength was 663 nm and the lowest threshold current density was 7.8 kA/cm2. The CW characteristic temperature T0 was 63 K at around -30°C.     

Heat Transfer & Thermal Stress Analysis of Plastic-Encapsulated ICs

Analytic approaches of thermal stress in plastic-encapslated ICs reliability have been studied using a simple, 2-dimensional model of the cross section of ICs by the finite-element method. To test the validity of the model, the actual stress within the silicon chip was measured using piezoresistive devices. The calculated stress in the silicon chip agreed with the experimental values. The stress distributions were changed by lead-frame properties. Package cracking, and delamination between the molding plastic and the lead-frame were qualitatively explained. We estimated the effect of the plastic properties on stress quantitatively. Furthermore, to test the validity of this model, the temperature change at the silicon chip was measured using the Vf temperature dependency of a diode. The calculated temperature change at the silicon chip agreed with the observed values. A very high temperature gradient was observed near the surface of the plastic immediately after solder dipping. The non-uniform temperature distributions produced different thermal stress distributions than those observed in the steady-state. This result indicated that rapid thermal shock could delaminate the plastic from the lead-frame. We believe that these results can guide the development of an optimum low-stress plastic.     

Operation Assist by Vibration Suppression Control Using Impulse‐Shaped Signals for Power Assist Conveyance System

This paper presents an assist control method for a flexible parts conveyance task using a power assist conveyance system. The assist control method should be designed so as not only to suppress vibration but also to reduce the degradation of operating feel. For this purpose, multiple impulse‐shaped signals are used as feedforward signals in order to reduce the vibration of flexible parts during conveyance. In addition, the adjustment time is introduced to adjust the input timing of the impulse‐shaped signal and to suppress vibration. In order to improve the degradation of operating feel, the smaller amplitudes of the three impulse‐shaped signals are used and input repeatedly. The effectiveness of the proposed system was verified experimentally. © 2013 Wiley Periodicals, Inc. Electr Eng Jpn, 186(2): 31–39, 2014; Published online in Wiley Online Library ( wileyonlinelibrary.com ). DOI 10.1002/eej.22476