Acetylene Vacuum Carburizing

Almost 30 years has passed since the publication of materials on vacuum carburizing technology, and is attracting a great deal of attention as a technology capable of being used as a substitute for gas carburizing technology.However, the technology was not popular except in specific fields. The main reason for this is due to a variety of harmful influences accompanying the sooting problems caused by CH4 or C3H8. We have succeeded in that the occurrence of sooting was suppressed by utilizing acetylene, at extremely low pressure for carburizing (below 1 kPa). This process is now showing the excellent quality and prospects for this technology in terms of quality, economy and safety. At present almost 70 practical mass production furnaces are used in production lines, in Japan and abroad. At this time, we will report summary of the present acetylene vacuum carburizing process and the actual results obtained by these acetylene vacuum carburizing furnaces for mass production.     

Antinuclear antibody screening by an enzyme-linked immunosorbent assay using multiple nuclear antigens

The oxidation of aminopyrine, an N-alkyl aromatic amine, by the hydroperoxidase activity of lipoxygenase was studied. Aminopyrine gave rise to a purple color in the presence of H2O2 and lipoxygenase, the color being proportional to the aminopyrine radical cation. The H2O2/aminopyrine radical cation molar ratio was 0.5. The overall reaction was considered as an enzymic-chemical second order mechanism with substrate regeneration. From the equations, the apparent constant of the radical cation's decomposition (k'app) was evaluated under different experimental conditions. It was found to be inversely proportional to the proton concentration but unaffected by the concentration of aminopyrine. These results suggest a new comprehensive mechanism for N-demethylation, which takes into account the described presence of both nitrogen- and carbon-centered radicals and the marked effect of pH on the stability of the radical cation.     

Transoceanic WDM System with More Than 100 Gb/s Capacity

This paper reviews several key technologies to realize a transoceanic wavelength-division-multiplexing (WDM) system with more than 100 Gb/s capacity. The key technologies include a novel gain equalization scheme, a broadband erbium-doped fiber amplifier, a chromatic dispersion compensation technique at a transmitter, and a RZ modulation format. Employing these new technologies, we successfully demonstrated a 32 channel 5.3 Gb/s (total capacity of 170 Gb/s) WDM signal transmission over 9879 km.     

Characterization of the ubiquinone reduction site of mitochondrial complex I using bulky synthetic ubiquinones

A wide variety of alkyl derivatives of Q2 (6-geranyl-2, 3-dimethoxy-5-methyl-1,4-benzoquinone) and DB (6-n-decyl-2, 3-dimethoxy-5-methyl-1,4-benzoquinone), in which methoxy groups of the 2- and/or 3-positions of the quinone ring were replaced by other bulky alkoxy groups from ethoxy to butoxy, were prepared by novel synthetic procedures. Electron-accepting activities of the bulky quinones were investigated with bovine heart mitochondrial complex I and its counterpart of Paracoccus denitrificans(NDH-1) to elucidate structural and functional features of the quinone reduction site of the enzymes. The bulky quinone analogues served as sufficient electron acceptors from the physiological quinone reduction site of bovine complex I. Considering the very poor activities of even the ethoxy derivatives as substrates for other respiratory enzymes such as mitochondrial complexes II and III [He, D. Y., Gu, L. Q., Yu, L., and Yu, C. A. (1994) Biochemistry 33, 880-884], this result indicated that the quinone reduction site of bovine complex I is spacious enough to accommodate bulky exogenous substrates. In contrast to bovine complex I, bulky quinone analogues served as poor electron acceptors with Paracoccus NDH-1. These observations indicated that bovine complex I recognizes the substrate structure with poor specificity. The substituent effects in the 2- and 3-positions of the quinone ring on the electron-transfer activity with bovine complex I differed significantly between Q2 and DB series despite having the same total number of carbon atoms in the side chain. The inhibitory effect involving Q2 due to its geranyl side chain was markedly diminished by structural modifications of the quinone ring moiety. These findings indicate that the side chain plays a specific role in the redox reaction and that the quinone ring and side-chain moieties contribute interdependently to binding interaction. Moreover, structural dependency of the proton-pumping activity of the quinone analogues was comparable to that of the electron-transfer activity with bovine complex I, indicating that the mechanism of redox-driven proton-pumping does not differ depending upon the substrate structure.     

Fragment detection system for studies of exotic neutron-rich nuclei

We have developed a fragment detection system for use in studies of exotic, neutron-rich nuclei. Using a C-shaped dipole magnet, the system sweeps charged fragments and un-reacted beam particles through an angle before stopping them in an array of plastic scintillator detectors, recording time-of-flight and total energy. The system also includes a pair of silicon strip detectors to measure fragment angle of emergence from the target and energy loss for particle identification.     

High performance double-doped InAlAs/InGaAs/InP heterojunction FET with potential for millimetre-wave power applications

Lattice matched InAlAs/InGaAs/InP heterojunction field-effect transistors (HJFETs), which have carrier supplying layers on and beneath the undoped InGaAs channel layer, have been successfully fabricated. A selective recess of the InGaAs channel edge at a mesa sidewall together with the use of a wide recess gate structure leads to a 5.7 V gate-drain breakdown voltage without kink effects. The fabricated HJFET with a 0.15*100 mu m/sup 2/ T-shaped gate exhibits a 700 mA/mm maximum drain current, a voltage gain of 14, and a 345 GHz maximum frequency of oscillation.<>     

Effects of viscosities on the transient current in homeotropic nematic liquid crystal cells

Effects of the Leslie viscosity coefficients α_i (i = 1, 2, …, 5) of nematic liquid crystals (NLCs) with negative dielectric anisotropy (Δε < 0) on the electric-field-induced director reorientation in homeotropic NLC cells have been studied from the analysis of the transient current induced by step voltage application. The transient current in a homeotropic NLC cell with Δε < 0 was well reproduced by computer simulation, based on the theory of NLCs in which the flow effects and the free-slip boundary condition are taken into account. It is found that the response time of vertical alignment NLC displays is dominantly governed by α₂ and α₄ + α₅ of NLCs with Δε < 0.     

Some properties of thin aluminium nitride films formed in a glow discharge

The formation of thin AlN films and some of their electrical properties have been investigated. The films were prepared by exposing the surface of evaporated aluminium films to a glow discharge in pure nitrogen gas. It has been confirmed by transmission electron diffraction that the structure of the film is of the wurtzite type, as is that of the bulk material. It was observed that the thickness of the AlN films depends on the voltage of the glow discharge, the distance from the discharge electrode to the films and the treatment time. The electrical properties were measured in the form of a sandwich diode, i.e. Al-AlN-Au. The voltage-controlled negative resistance, which was first discovered in Al-Al₂O₃-metal diodes, has also been observed in this nitride film diode and shows very good reproducibility and stability.     

Ion irradiation effects in EuBa2Cu3Oy thin film

The effect of He ion irradiation on the pinning potential in EuBa₂Cu₃O _y , thin film was investigated by measuring the temperature dependence of resistivity in magnetic fields. The pinning potential decreased as the ion fluence increased. A slower decrease of pinning potential was observed in higher magnetic field in the fluence region <3.5×10¹⁵ cm^–2.