Temperature programmed desorption study of adsorbed species formed by the decomposition of N2O on ion-exchanged copper zeolite catalysts

The nature of the adsorbed species on Cu-ZSM-5 (Cu-Z), Cu-Mordenite (Cu-M), and Cu-Y-zeolite (Cu-Y) was investigated by means of temperature programmed desorption (TPD). When dinitrogen monoxide (N₂O) came into contact with Cu-zeolites above 573 K, the decomposition of N₂O occurred accompanied by the formation of adsorbed oxygen species and adsorbed nitrogen oxide species. In the TPD runs, three O₂ desorption peaks appeared at temperatures of 623, 673, and 753 K and were named -, β-, and γ-peaks, respectively. The O₂ desorption at the - and γ-peaks became quickly saturated after contacting N₂O at 598 K, while the amount of O₂ desorbed at the β-peak increased with time, not reaching a constant level until 120 min of exposure. The activity for the decomposition of N₂O decreased with the accumulation of β-oxygen over the catalyst. The rate of N₂O decomposition depended upon the nature and amount of the copper zeolite catalysts available, as determined by the formation of - and/or β-oxygen.     

Comparative study on corpora for speech translation

This paper investigates issues in preparing corpora for developing speech-to-speech translation (S2ST). It is impractical to create a broad-coverage parallel corpus only from dialog speech. An alternative approach is to have bilingual experts write conversational-style texts in the target domain, with translations. There is, however, a risk of losing fidelity to the actual utterances. This paper focuses on balancing a tradeoff between these two kinds of corpora through the analysis of two newly developed corpora in the travel domain: a bilingual parallel corpus with 420 K utterances and a collection of in-domain dialogs using actual S2ST systems. We found that the first corpus is effective for covering utterances in the second corpus if complimented with a small number of utterances taken from monolingual dialogs. We also found that characteristics of in-domain utterances become closer to those of the first corpus when more restrictive conditions and instructions to speakers are given. These results suggest the possibility of a bootstrap-style of development of corpora and S2ST systems, where an initial S2ST system is developed with parallel texts, and is then gradually improved with in-domain utterances collected by the system as restrictions are relaxed.     

Low excess losses in a Y-branching plastic optical waveguide formed through injection molding

We have demonstrated low excess losses (1.9 dB at 660-nm wavelength) in a Y-branching plastic optical waveguide (POWG) that was fabricated using an injection-molding method. The waveguide had an amorphous vinyl polymer as the core and transparent polyolefin as the cladding. We then studied a method for isolating the excess loss in the Y-branching POWG, and with that method we estimated the lower limit of the loss to be 1.41 dB at 660 nm. The sample had a heat-resistant plastic optical fiber (POF) with a core composed of crosslinked poly (methyl methacrylate) (PMMA) copolymer, and a cladding composed of poly (tetrafluoroethylene-co-hexafluoropropylene). The POWG has sufficient reliability for ordinary uses below 100 °C. A model for a bidirectional wavelength-division multiplexing opticalcommunication system with the developed Y-branching POWG and the POF was also demonstrated.     

Heat Shock-Induced Three-Dimensional-Like Proliferation of Normal Human Fibroblasts Mediated by Pressed Silk

The aim of this study was to determine the optimal heat treatment conditions for enhancement of pressed silk-mediated 3D-like proliferation of normal human dermal fibroblasts, as well as to determine the responses to heat shock of cells and intracellular signaling pathways. The beginning of 3D-like pattern formation of cells was observed in the second week after the start of the experiment. The mean rates of beginning of 3D-like pattern formation by cells heat-treated at 40 ºC and 43 ºC for 10 min were significantly higher (3.2- and 8.6-fold, respectively) than that of untreated cells. We found that apoptosis had occurred in 7.5% and 50.0% of the cells at one week after heat treatment for 10 min at 43 ºC and 45 ºC, respectively. Western blot analysis demonstrated that phosphorylation of p38 MAPK and that of Hsp27 were markedly increased by heat treatment at 43 ºC for 10 min. The results of an experiment using a p38 MAPK inhibitor and Hsp27 inhibitor suggest that activation of p38 MAPK by heat shock is associated with 3D-like cell proliferation and that Hsp27 contributes to the inhibition of apoptosis. The results of this study should be useful for further studies aimed at elucidation of the physiologic mechanisms underlying thermotherapy.     

Langmuir-temkin-pyzhev rate models for ammonia decomposition reaction

Existing rate data of ammonia decomposition were correlated using the Langmuir-Temkin-Pyzhev models and the applicability of those models was examined. Conventional statistical tests indicated that the Langmuir-Temkin-Pyzhev model was adequate, but the physico-chemical examination of parameter estimates showed that the model was not feasible. The Temkin-Pyzhev model was also employed to describe the decomposition data and discussed.     

Zero-Point Energy of the Proton Motions and Its Effect on the Pressure of Molecular Dissociation in Dense Hydrogen

Zero-point motion energy of the protons is evaluated in the quasi-harmonic approximation for both atomic and molecular phases of highly compressed hydrogen. The results are in good agreement with Kagan et al.'s. In the calculation, the phonon frequencies all over the Brillouin zone are obtained using force constants calculated by the first-principles band theoretical treatments. In the atomic phase, the Cs-IV structure, which is one of the low energy structures in the tetragonal diamond family, is found to be stable with real frequencies all over the Brillouin zone, while the -Sn structure is unstable with imaginary frequencies near zone-boundaries. In the molecular phase, taking the Cmca structure which is one of the candidate structures above 200 GPa, we have studied phonons and the stability of the lattice. We have evaluated the effect of the zero-point energy on the pressure of the molecular dissociation, assuming that it occurs between the Cs-IV and the Cmca structures. With inclusion of the zero-point energy the dissociation pressure is reduced by 90–120 GPa from that estimated by the static energy. The equation of state is in good agreement with the extrapolated one of Loubeyre et al.'s.     

Design of transmission line filters and matching circuits using genetic algorithms

A method for designing microwave filters and impedance matching circuits using transmission lines is presented. Transmission line filters with shunt‐connected open circuit stubs and continuously varying transmission line matching circuits are described in detail. The proposed method is based on genetic algorithms and can effectively be applied to various filter and matching circuit design problems without increasing theoretical and computational complexity. Design examples are provided, and the proposed method is demonstrated to be effective in designing transmission line filters and matching circuits. Copyright © 2007 Institute of Electrical Engineers of Japan. Published by John Wiley & Sons, Inc.     

Reliability-guided Rayleigh backscattering spectrum correlation method for distributed strain measurements in optical fibres

We present a method of reliability-guided Rayleigh backscattering correlation for distributed strain measurements in optical fibres. In this method, a reference Rayleigh-backscattering-spectrum (RBS) range that is larger than the measurement RBS range is defined to extend the matching range. To obtain the best match between reference and measurement spectra, the zero-mean normalized cross correlation (ZNCC) is employed to evaluate the degree of similarity. The path for searching the maximum similarity matching pattern is guided using Newton’s iteration method. The reliability of the computed RBS shift is identified by the ZNCC coefficient distribution. The experiments show that the proposed method has high reliability in computing the RBS shift. Even at a relatively large strain (e.g. 5000?µ?), the proposed method can stably demodulate the strain within a relative error of ?1% and a spatial resolution of 1.6?cm over a 22-meter-long single-mode fibre. This shows that the proposed method has an advantage in regard to relatively large strain measurements.     

The effect of pretreatment in a fluidized bed upon diamond synthesis on particles by chemical vapour deposition

Diamond synthesis was carried out on non-diamond particles (single- and poly-crystal silicon, quartz and SiC) by microwave plasma-enhanced chemical vapour deposition. Fine diamond particles were deposited on the non-diamond particle surface. The particle deposition density on the untreated particle substrates was strongly dependent on the surface characteristics of the particle substrates. The value ranged from 10–10⁵ mm^–2 for each particle. Particle substrates were pretreated in a gas-solid fluidized bed, and these were then used for the deposition of diamond. The pretreatment of the surface of the particle substrate in the fluidized bed greatly enhanced the nucleation of diamond. A deposition density of about 10⁷ mm^–2 was obtained on single-crystal silicon particles pretreated for 15 h. The effectiveness of the fluidized bed pretreatment on the deposition density was observed to be appreciable for the four kinds of particle examined.