The catalytic steam gasification of one Australian and three Japanese coals using potassium and sodium carbonates

The catalytic steam gasification of four different coals using potassium and sodium carbonates as catalysts was carried out in a semi-flow type fixed-bed reactor. The coal was gasified with or without the catalyst under a steam—argon atmosphere at a heating rate of 50°C/s at 700–800°C. The catalytic activity of carbonates for gasification was remarkable for Japanese high-volatile coals (Miike and Takashima coals), and moderate for Australian medium-volatile coal (New Lithgow coal); however, the carbonates had little effect on gasification of Japanese lignite (Taiheiyo coal). It is assumed that Miike and Takashima coals soften and melt during the heating process to make the contact between char and catalyst better. New Lithgow and Taiheiyo coals do not have this property. Gasification was promoted significantly at lower temperatures when the catalyst was used. In both catalyzed and uncatalyzed runs the main products were hydrogen and carbon dioxide; the reaction temperature did not affect the composition of the gases much. A water—gas shift reaction occurred during gasification resulting in a large amount of carbon dioxide under a large excess of steam flow.     

Reaction property of diffused H2with defect Centers in GeO2-doped fiber

This paper presents the reaction property of diffused molecular hydrogen (H2) with irradiation-induced defect centers in a GeO2-doped fiber. When H2diffuses into an irradiated fiber, an OH loss increases even at room temperature. This loss increase is thought to be caused by chemical reaction between diffused H2and irradiation-induced nonbridging oxygen hole centers (NBOHC's). The hydrogen-associated defect centers having 11.9-mT hyperfine structure are formed by chemical reaction between diffused H2and irradiation-induced Ge-defect centers. Moreover, the irradiated fiber shows an OH loss increase at high temperatures even after diffused H2is removed from the fiber. The hydrogen-associated defect centers are considered to be the hydrogen source for the OH formation.     

Recurrence of thyrotoxicosis after attack of allergic rhinitis in patients with Graves' disease

Graves' disease is frequently aggravated during antithyroid drug therapy; however, little is known of its aggravating factors. We studied 83 patients with Graves' disease who were euthyroid for at least 6 months under antithyroid maintenance therapy, and we examined the relationship between thyrotoxicosis relapse, attack of allergic rhinitis, and peripheral eosinophil increase. Forty-one patients showed thyrotoxicosis relapse; of these, 22 (54%) showed peripheral eosinophil increase, and 14 (34%) had attacks of allergic rhinitis. In the remaining 42 patients without thyrotoxicosis relapse, only 4 (10%, P < 0.001) showed an increase in peripheral eosinophils, and only 3 (7%, P < 0.01) had allergic rhinitis. Recurrence of thyrotoxicosis was observed with the increase in serum levels of TSH-receptor antibodies and increase in eosinophils 2 months after the attack of allergic rhinitis. Three patients with seasonal allergic rhinitis showed thyrotoxicosis relapse at the same time of year within 2 consecutive years. Our findings indicate that allergic rhinitis can be an aggravating factor of Graves' disease and suggest that the preceding increase in peripheral eosinophils can be a predictive indicator of recurrence of thyrotoxicosis during antithyroid drug therapy.     

Full-wave modeling of coplanar waveguide discontinuities withfinite conductor thickness

An extended version of the spectral domain approach (SDA) is developed to analyze discontinuities in open coplanar waveguide with finite metallization thickness. By making use of the exact Green's function in the spectral domain, the effects of surface wave and radiation phenomena are accurately accounted for. Both longitudinal and transverse components of the aperture electric fields are used in the analysis to allow modelling of structures with large transverse dimensions at high frequencies. The procedure also includes mode conversion near the discontinuities. As an illustration of the method, analytical steps and computed scattering parameters of the coplanar waveguide short-circuits and transitions are provided and compared against measured data     

Inexpensive short-range microwave telemetry transponder

A microwave transponder is described which is suitable for short-range telemetry applications requiring an inexpensive transmitter. Two antiparallel beam-lead diodes at the terminals of a bow-tie antenna produce double-sideband suppressed-carrier modulation centred about the second harmonic of an externally supplied fundamental carrier. A simple theory predicting performance of the device is confirmed by experiment.     

A high-gain 50-GHz-band monolithic balanced gate mixer with anexternal IF balun

This paper presents a 90-GHz-band high-gain monolithic balanced gate mixer. IF impedance of the balanced gate mixer is approximated from a small-signal equivalent circuit, and conversion gain of the mixer is improved by using an external IF balun with high impedance-transforming ratio. The maximum conversion gain of 8.2 dB is achieved at LO power of 0 dBm. Effectiveness of the described mixer is confirmed experimentally     

Isolation and identification of styrene-degrading Corynebacterium strains, and their styrene metabolism

By supplying styrene in the gas phase as the sole carbon and energy source, styrene-degrading aerobic microorganisms were readily isolated from soil samples. They were identified as Corynebacterium pseudodiphtheriticum and similar species, or Pseudomonas sp. Growth experiments on some aromatic compounds, resting-cell reactions with them, and the measurement of degrading enzyme activities suggest that Corynebacterium sp. AC-5 and St-5 strains metabolize styrene through styrene oxidation into styrene oxide, then convert it into phenylacetaldehyde by a reaction using styrene oxide isomerase, and phenylacetaldehyde is reduced to 2-phenylethanol. The Corynebacterium sp. ST-10 strain did not have styrene oxide isomerase, and metabolized styrene oxide by an unknown enzymatic reaction. Possible metabolism of styrene was proposed for the Corynebacterium strains.     

Surgical treatment for acute aortic arch dissection

The authors describe 2 patients with Takayasu's arteritis in whom lupus anticoagulant was positive and the titer of anticardiolipin antibody was elevated. One patient developed diffusely stenotic and occlusive changes in the multiple larger arteries. Histology of the small-sized arteries in another patient showed occlusive vasculitis without thrombosis, in addition to the findings in large-sized arteries compatible with Takayasu's disease. These findings are uncommon in Takayasu's arteritis. These findings suggest that antiphospholipid antibodies may have contributed to the pathogenesis of the extensive vasculopathy and may have triggered vasculitis in these patients.     

High-quality 1.3-/spl mu/m GaInAsP-BH-lasers fabricated by MOVPE and dry-etching technique

High-quality and high-reliability GaInAsP-InP Fabry-Perot-type buried heterostructure strained-multi-quantum-well lasers operating at 1.3 pm have been produced by metalorganic vapor phase epitaxy growth and the dry-etching technique. We compare two types of chemical treatments to slightly etch damaged mesa-walls before regrowth after dry-etching. Slight chemical etching prevents Zn in the p-type buried layer from diffusing to the active layer during regrowth of buried hetero layers. Two step treatment using the combination of selective and unselective wet chemical etching produces a superior mesa-wall which has limited Zn-diffusion to the active layer. BH laser fabricated by MOVPE and the dry-etching technique is also confirmed as having high-reliability in practical usage.     

The conversion process from polydimethylsilane to polycarbosilane in the presence of polyborodiphenylsiloxane

The pyrolytic reaction of polydimethylsilane to polycarbosilane in the presence of polyborodiphenylsiloxane have been studied by the use of organosilicon intermediates obtained during the initial pyrolytic stage of polydimethylsilane. In this reaction, the cleavage of the framework of Si-Si bonds occurred. Si-CH₂-Si and Si-H bonds were subsequently formed by the rearrangement reaction between radicals formed and Si-CH₃ bonds. The formation of Si-Si bonds by dehydrogenation between Si-H bonds then proceeded simultaneously or stepwise. It is assumed that polyborodiphenylsilane plays a role in accelerating the polycondensation reaction, that is, the propagation reaction occurred by dehydrogenation between the Si-H bonds, but takes no part in the radical rearrangement reaction from Si-Si bonds to Si-CH₂-Si bonds.