Electrochemical and surface studies on the passivity of a dental Pd-based casting alloy in alkaline sulphide solution

The corrosion and tarnish behavior of a dental casting Pd-25Ag-18Cu-12Au alloy in 0.1% Na₂S solution at 37 °C was investigated using potentiodynamic polarization and spectrocolorimetric techniques. The surface film was characterized by X-ray photoelectron spectroscopy (XPS).This alloy exhibited markedly higher resistance to corrosion and tarnish than did the Ag-20Pd-18Cu-12Au alloy in current clinical use. XPS spectra indicated the presence of a thin sulphide film composed of PdS. It was found that the PdS film is very protective and is responsible for the passivity of the Pd-25Ag-18Cu-12Au alloy in 0.1% Na₂S solution.     

Construction of large cross-section double-tier Metropolitan Inter-city Highway (Ken-O-Do) Ome Tunnel by NATM

Ome Tunnel is a double-tier highway tunnel with large cross-section of 220–260 m² excavated at a shallow depth in unconsolidated ground. The tunnel was excavated by NATM. Since the tunnel passes under a road in dense residential area, surface settlement due to tunneling was restricted. Therefore, various auxiliary construction method such as long span steel pipe fore-piling with injection was adopted based on monitoring and analyzing ground behavior during construction. A total of 1060 m of tunneling work was successfully completed without major interruption of work excessive damage on surface residents and other facilities.     

Stereospecific analysis of fish oil triacyl-sn-glycerols

Stereospecific analysis of fish oil triacyl-sn-glycerols was carried out by novel high-performance liquid chromatography on a chiral stationary phase. The positional distributions of fatty acids were determined without accumulation of errors in a particular position and preferential hydrolysis for a particular fatty acid. High-resolution gas-liquid chromatography on an open tubular column detailed the distribution of unsaturated fatty acid isomers having olefinic bonds in different positions. The distribution of fatty acids was not independent of other fatty acids. The distribution of long-chain highly unsaturated fatty acids 22:6(n-3), 22:5(n-3) and 20:5(n-3) was governed by total amounts of 20:1 and 22:1 in triacyl-sn-glycerols. Long-chain monounsaturated acids 20:1 and 22:1 were influenced by the position of the olefinic bond in 20:1 occurring in triacyl-sn-glycerols. Shorter-chain C14-C18 fatty acids seemed to be influenced by total fatty acid composition. These results introduce a concept of mutual interaction between fatty acids to the investigation of positional distribution of fatty acids.     

DSP-based real time output waveform synthesis for three-phase PWM inverter

A new digital control technique is proposed to synthesize an arbitrary three-phase PWM inverter output. Sensing two line-to-line voltages, the required pulse patterns for deadbeat response are computed in a real time manner based on the predicted voltage by an observer at 18-kHz sampling frequency. When used for the uninterruptible power supply, this closed-loop voltage control inherently results in a very low THD and a very quick transient response with less filter capacity. Also, with the repetitive compensator, the proposed scheme has advantages in improving the output waveform for nonlinear load. This paper describes the modeling technique, theoretical analysis, simulations and experimental results.     

Effects of silicate and phosphate ions on the formation of ferric oxide hydroxide particles

The effects of silicate and phosphate ions on the formation of α- and β-FeOOH particles were studied. The formation and crystallization of α-FeOOH particles were inhibited by both the anions, and their particle size decreased with increasing concentration of the anions added. This inhibition was caused not only by complexing with ferric ions but also by adsorption on the particle surface. For α-FeOOH the amorphous particles were formed at a higher concentration of these anions. On the other hand, in the case of β-FeOOH the effects of both the anions were little, especially for silicate ions. This difference between α- and β-FeOOH particles could be explained by the difference between their preparation pH. The α-FeOOH particles prepared in the presence of these anions showed a microporosity.     

Water Impervious URD Cable Having Lead Foil on Conductor and on Core

This paper describes the mechanical properties of the lead foil laminated with semi-conductive plastic on both sides. This lead composite tape is quite useful to medium voltage water impervious cable because the tape can follow the thermal expansion and contraction of the cable core. Some important properties of 15KV URD cable which has water impervious layers over the conductor and over the core are also shown in this paper. The test result proved that the lead composite tape worked well as the water impervious barrier for the medium voltage URD cable.