Catalytic reduction of NO by hydrocarbons over a mechanical mixture of spinel Ni–Ga oxide and manganese oxide

NO reduction with propylene over Mn₂O₃, spinel Ni–Ga oxide and their mechanical mixtures has been investigated. Mn₂O₃ has no activity to NO reduction, but has a high activity for NO oxidation to NO₂. Spinel Ni–Ga oxide showed an apparent activity to NO reduction only at temperatures above 400°C. Mixing of Mn₂O₃ to the Ni–Ga oxide resulted in a significant enhancement of NO reduction in the temperature range of 250–450°C. The optimal Mn₂O₃ content in the mixture catalyst was about 10–20 wt%. It is suggested that the synergetic effect of Mn₂O₃ and Ni–Ga oxide plays an important role in the catalysis of NO reduction. The Ni–Ga oxide and Mn₂O₃ mixture catalyst is superior to Pt/Al₂O₃ and Cu-ZSM-5 by showing a higher NO reduction conversion, resistance to water and negligible harmful by-product formation. Other lower hydrocarbons C₂H₄, C₂H₆ and C₃H₈ also give a maximum NO reduction conversion as high as 50%. The difference from using C₃H₆ is that the temperature at the maximum NO reduction is higher than it is with C₃H₆. This revised version was published online in July 2006 with corrections to the Cover Date.     

Expression of the CGTase Gene of Alkalophilic Bacillus No. 38-2 in Various Hosts

We compared the expression level of cyclomaltodextrin glucanotransferase (CGTase) gene of alkalophilic Bacillus species No. 38-2 in various hosts. Plasmid pEAP85, a new excretion vector, containing tac promoter for expression was constructed. CGTase gene was introduced into a new excretion vector pEAP85 and a shuttle vector pHY300PLK and plasmids pCS8, pEAP85-CGT and pKG-1 were constructed. Escherichia coli carrying pEAP85-CGT excretes 70% (350 U/ml culture) of total CGTase (500 U/ml) into the culture broth. This amount was higher than that produced by the original Bacillus species. Bacillus subtilis carrying pGK-1 produced very low level of CGTase(< 0.1 U/ml).     

Effects of epoxy resin on mechanical and thermal characteristics of poly(propylene oxide)/poly(butyl acrylate) networks

We report mechanical and thermal characteristics of a network composed of poly(propylene oxide) (PPG) and poly(butyl acrylate) crosslinked with tolylene diisocyanate. It was found that addition of about 4 wt % of an epoxy resin resulted in a higher mechanical toughness and less discoloration. Furthermore, it was found that the epoxy has a self‐restoration function against thermal degradation of the network. The reaction mechanism between the network and the epoxy was investigated with infrared spectroscopy and ¹³C‐NMR and the effect of the epoxy resin on the thermal stability and physical properties is discussed. © 2000 John Wiley & Sons, Inc. J Appl Polym Sci 77: 1886–1893, 2000     

HITTM cells—high‐efficiency crystalline Si cells with novel structure

Our unique, high‐efficiency c‐Si solar cell, named the HIT cell, has shown considerable potential to improve junction properties and surface passivation since it was first developed. The improved properties in efficiency and temperature dependence compared to conventional p – n diffused c‐Si solar cells are featured in HIT power 21^TM solar cell modules and other applications which are now on the market. In the area of research, further improvement in the junction properties of the a‐Si/c‐Si heterojunction has been examined, and the highest efficiency to date of 20.1% has recently been achieved for a cell size of 101 cm². The high open circuit voltage exceeding 700 mV, due to the excellent surface passivation of the HIT structure, is responsible for this efficiency. In this paper, recent progress in HIT cells by Sanyo will be introduced. Copyright © 2000 John Wiley & Sons, Ltd.     

Analysis of an adjustable speed rotary condenser for power system stabilization

Over the last five to ten years, significant progress has been made in high‐power semiconductor devices and in their practical applications to power systems. This comes not only from sophisticated semiconductor technology but also from the demand for a higher degree of frequency and voltage stability, and for greater reliability in power systems. This paper deals with an adjustable speed rotary condenser capable of not only reactive power control but also active power control based on a flywheel effect of the rotor. The behavior of a power system consisting of the adjustable speed rotary condenser, a synchronous generator, and a transmission line is subjected to a set of nonlinear differential equations. The set of nonlinear equations can be linearized by limiting attention to small perturbations around a reference state, thus leading to the so‐called Heffron–Phillips model of the power system. The Heffron–Phillips model derived is effective in analyzing effects of the adjustable speed rotary condenser on power system stabilization. The validity of the analysis is confirmed by computer simulation based on EMTDC. Finally, it is discussed how well power system stabilization is achieved by the rotary condenser. As a result, the rotary condenser has the function of decoupling reactive power control from active power control, thus producing a good effect on power system stabilization which would not be achieved by a conventional inverter‐based static var compensator. © 2000 Scripta Technica, Electr Eng Jpn, 133(1): 31–42, 2000     

Quantitative determination of butylated hydroxyanisole, butylated hydroxytoluene, and tert-butyl hydroquinone in oils, foods, and biological fluids by high-performance liquid chromatography with fluorometric detection

Concentrations of synthetic antioxidants butylated hydroxyanisole, butylated hydroxytoluene, and tert-butyl hydroquinone were quantified using a high-performance liquid chromatograph with spectrofluorometric detector. The antioxidants were separated and eluted on a reversed-phase column by gradient of a mixture of H₂O/acetonitrile/acetic acid (66.5: 28.5∶5, by vol) and a mixture of acetonitrile/acetic acid (95∶5, vol/vol). The eluants were monitored at emission and excitation wavelengths of 310 and 280 nm, respectively. Calibration curves obtained using peak areas against concentration showed ligh coefficients of multiple determination (R ²>0.99) for all antioxidants. Known concentrations of added antioxidant standards were recoverable within 98–99% from oils and over 93% from mouse blood. This method requires minimum sample extraction and purification before analysis and provides a relatively high percentage recovery. The method has been applied successfully for the measurement of antioxidant concentrations in oils, dried foods, and biological fluids.     

Effect of inlet guide vanes on the performance of small axial flow fan

Effects of the inlet guide vanes on the static characteristics, aerodynamic noise and internal flow characteristics of a small axial flow fan are studied in this work. The inlet guide vanes with different outlet angle are designed,which are mounted on the casing and located at the upstream of the impeller of the prototype fan. Both steady and unsteady flow simulations are performed. The steady flow is simulated by the calculations of Navier-Stokes equations coupled with RNG k-epsilon turbulence model, while the unsteady flow is computed with large eddy simulation. According to the theoretical analysis, the inlet guide vanes with outlet angle of 60° are regarded as the optimal inlet guide vanes. The static characteristic experiment is carried out in a standard test rig and the aerodynamic noise is tested in a semi-anechoic room. Then, performances of the fan with optimal inlet guide vanes are compared with those of the prototype fan. The results show that there is reasonable agreement between the simulation results and the experimental data. It is found that the static characteristics of small axial flow fan is improved obviously after installing the optimal inlet guide vanes. Meanwhile, the optimal inlet guide vanes have effect on reducing noise at the near field, but have little effect on the noise at the far field.     

Characteristics of lightning surges observed at 77 kV substations

In order to improve power supply reliability, it is necessary to prevent lightning faults in transmission lines and substation apparatus. However, faults are caused occasionally in lower-voltage power systems, particularly at the 77 kV level. The governing factor for insulation strength of substation apparatus is the lightning impulse voltage, and it is necessary to know the voltage level and distribution in a substation caused by lightning surges in order to investigate rational insulation coordination. For this purpose, the authors measured lightning surges at two 77 kV conventional substations from 1990 to 1993. In this paper, the characteristics of induced lightning surges and back flashover lightning surges are described. Comparisons of related surge voltages at two substations, the power line phases in grounding faults, and the equivalent capacitance of the substations are also discussed.     

Macrolayer formation and mechanisms of nucleate boiling,critical heat flux,and transition boiling

The drying process of a macrolayer on a 15 mm diameter boiling surface was observed with high speed video in the region of nucleate and of transition boiling close to the critical heat flux (CHF). It was found that the macrolayer rests beneath a large vapor mass. It partially dries in nucleate boiling and completely dries in transition boiling at the detachment of the vapor mass. The macrolayer thickness at CHF and in transition boiling was determined on the basis of the energy balance relation proposed by Katto and Yokoya. The macrolayer thickness at low heat flux was obtained by decreasing CHF with downward-facing heating surfaces and agreed well with the correlation proposed previously by the present authors. The macrolayer thickness in transition boiling with a vertical surface also agrees fairly well with the correlation, when the heat flux at macrolayer formation, given on the nucleate boiling curve, is extrapolated to surface superheat of transition boiling and when the surface temperature at macrolayer formation is equal to a time-averaged value. © 1998 Scripta Technical, Heat Trans Jpn Res, 27(2): 155–168, 1998     

Studies on pool boiling heat transfer: Macrolayer thickness in transition boiling

Macrolayer thicknesses in transition boiling were determined from the energy balance relation q_tr = ρ_lH_fgδ_l·f , based on measurements of q_tr (the time-averaged heat flux in transition boiling) and f (the detachment frequency of vapor masses) for water and ethanol boiling on vertical and horizontal 15-mm-diameter surfaces under atmospheric pressure. The macrolayer thickness for the vertical surface, designed to prevent liquid contact with the periphery of the surface during the vapor mass hovering, agreed well with the correlation proposed previously by the present authors, when the heat flux at macrolayer formation is obtained from a nucleate boiling curve extrapolated to the superheat of transition boiling. The macrolayer on the horizontal surface was apparently thickened due to the inflow of bulk liquid beneath the growing vapor masses. © 1999 Scripta Technica, Heat Trans Jpn Res, 27(8): 568–583, 1998