Zirconia Coating on Stainless Steel Sheets from Organozirconium Compounds

The stability and the coating characteristics of a variety of organozirconium compounds have been investigated to coat ZrO₂ films on stainless steets for the improvement of heat resistance against oxidation. Zirconium tetraoctylate and zirconium tetrakis(acetylacetonate) were found to be more stable than zirconium alkoxides in an ambient atmosphere. The ZrO₂ films from zirconium alkoxides became white and discontinuous when the thickness of the films exceeded about 200 Å (20 nm). On the other hand, transparent ZrO₂ films were obtained from zirconium tetraoctylate and zirconium tetrakis(acetylacetonate). The IR spectra of the films showed that the heat treatment at 400°C for 5 min produced organic-free ZrO₂ films. The heat resistance of stainless steel sheets against oxidation was improved by the ZrO₂ coating, depending on the film thickness.     

Preparation of flexible transparent acryl/alumina nano-hybrid materials exhibiting low thermal expansion coefficient

In this study, flexible transparent hybrid films with low thermal expansion coefficient were prepared by combination of alumina fillers and polymerizable/non-polymerizable surface modifiers with carboxyl group. Four types of alumina fillers with different shape and size were used in this study, and could modify with surface modifiers containing carboxyl groups by electrostatic interaction and disperse homogeneously in resulting hybrid films regardless of the shape and size. So the hybrid films obtained showed high transmittance around 90%T, and it was considered, from transmission electron microscopic analysis, alumina fillers were dispersed at near original filler size, without aggregation. Moreover, thermal mechanical analysis cleared that the use of pillar or fiber type filler is more effective to reduce CTE compared with plate type fillers, especially CTE of hybrid film prepared with fiber type filler was drastically decreased to 17 ppm/K, while the influence by the difference of filler shape/size was not observed on tensile properties, surface hardness. By use of fiber type alumina filler and combination of polymerizable surface modifier and non-polymerizable surface modifier which seems to interact with matrix, for optimizing of the crosslink density, it was possible to reduce CTE, while the good mechanical properties was kept. Finally, hybrid film indicating low CTE value as 19 ppm/K, high flexibility (windable against 0.4 mm radius steel bar), and good tensile properties and surface hardness which were equal to or higher than those of matrix could prepared.     

Production of extracellular bifidogenic growth stimulator by anaerobic and aerobic cultivations of several propionibacterial strains

Production of a bifidogenic growth stimulator (BGS) by propionic acid bacteria was investigated under anaerobic and aerobic culture conditions. To measure the concentration of extracellular BGS produced by propionic acid bacteria, we evaluated the effects of bioassay conditions using Bifidobacterium longum as a test microorganism on the formation of a growth-stimulation zone. The diameter of the growth-stimulation zone was significantly affected by both the component concentrations and the pH of a bioassay medium. The optimum component concentrations and pH of a bioassay medium were one-half of the normal values and 8.5, respectively. Using the bioassay method, we can measure the concentration of BGS produced by propionic acid bacteria ranging in concentrations from 0.1 microg/l to 1 mg/l using 1,4-dihydroxy-2-naphthoic acid (DHNA) and 2-amino-3-carboxy-1,4-naphthoquinone (ACNQ) as standards. Of six dairy propionic acid bacterial strains tested, the four strains (Propionibacterium freudenreichii ET-3, P. shermanii PZ-3, P. acidipropionici JCM 6432, and P. jensenii JCM 6433) produced BGS at a concentration range of 4-23 mg/l under the anaerobic culture conditions. Analysis of high performance liquid chromatography (HPLC) showed that more than 70% of total BGS produced in supernatant samples was DHNA and no ACNQ was produced by the strains. The effect of oxygen supply on BGS production was investigated for the four BGS-producing strains. The aerobic conditions exerted in positive effects on BGS production by only P. acidipropionici JCM 6432. The concentration of BGS obtained in the aerobic cultivation of P. acidipropionici JCM 6432 was 1.3-fold than that in anaerobic cultivation. Different properties (BGS production as well as cell growth and glucose metabolism) occurring in response to the aerobic conditions were observed, depending on the propionic acid bacterial strain used. This paper is the first report on BGS production by propionibacterial strains except for P. freudenreichii.     

Carboxylated polysulfone membranes having a chiral recognition site induced by an alternative molecular imprinting technique

SUMMARY Molecularly imprinted polymeric membranes were prepared from carboxylated polysulfone. Membranes imprinted by Z-D-Glu recognize the D-isomer in preference to the corresponding L-isomer, and vice versa. The amino acid preferentially adsorbed by the membrane was also selectively permeated by electrodialysis. Received: 22 January 1998/Accepted: 20 February 1998     

Diffusion of low molecular weight siloxane from bulk to surface

Silicone-based materials for outdoor insulators have the advantage that low molecular weight (LMW) components migrate through the material and coat the surface, thereby restoring hydrophobicity over a period of hours. By measuring the IR absorption of siloxane migrating to the silicone surface through a thin carbon coating, the time constant for migration was calculated. According to the time dependence of IR-absorbance, the time constant for migration ranged from 1.6 to 5.3 h depending on alumina trihydrate (ATH) filler concentration     

Wind energy activities in Japan

This paper describes recent activities on wind energy in Japan. The national “Sunshine Project” conducted by the Ministry of International Trade and Industry, was reviewed in 1990 to map out a new energy strategy in the Age of Global Environment. As a result, a new 500kW WECS R&D project has started in FY1991 and the operation started in FY1996. A number of basic and applied studies have been undertaken at the NEDO, the MEL and many universities. Interests in utilization of wind energy have spread gradually among power company. From FY1991, the Tohoku Electric Power Company has operated a 2,875kW Windpark(5 units of 275kW machine and 5 units of 300kW machine) at Tappi, where the annual wind speed is as strong as 10m/s.Researches and demonstrations are also conducted by some other power companies. MHI has developed middle-sized commercial WTGs. More than 800 units were exported to the United States and UK. IHI also developed 300kW machines. Fuji Heavy Industry is developing new concept machine of small to medium size.     

Myofibril-Bound Serine Proteinase (MBP) and its Degradation of Myofibrillar Proteins

Proteolysis of a myofibril-bound serine proteinase (MBP) from carp Cyprinus carpio on myofibrillar proteins and their gel formation ability were investigated. MBP readily decomposed myosin heavy chain as indicated by SDS-PAGE. In the preparation of kamaboko, the gel formation ability was diminished by addition of MBP. The optimum degradation temperatures of MBP to myosin heavy chain in myofibril and kamaboko gel were 55°C and 60°C, respectively. The degradation effects of MBP on actin, α-actinin and tropomyosin were studied by the immunoblotting method. Because of its myofibril-bound and myofibrillar protein degradation characteristics, MBP was regarded as the proteinase most probably involved in the modori effect.     

LMI-based controller synthesis: A unified formulation and solution

This paper proposes a unified approach to linear controller synthesis that employs various LMI conditions to represent control specifications. We define a comprehensive class of LMIs and consider a general synthesis problem described by any LMI of the class. We show a procedure that reduces the synthesis problem, which is a BMI problem, to solving a certain LMI. The derived LMI condition is equivalent to the original BMI condition and also gives a convex parametrization of all the controllers that solve the synthesis problem. The class contains many of widely-known LMIs (for H_∞ norm, H₂ norm, etc.), and hence the solution of this paper unifies design methods that have been proposed depending on each LMI. Further, the class also provides LMIs for multi-objective performance measures, which enable a new formulation of controller design through convex optimization. © 1998 John Wiley & Sons, Ltd.     

Development of a 400 kJ Nb3Sn superconducting magnet for an SMES system

An Nb₃Sn superconducting magnet to store 400 kJ was developed as a unit magnet for a 2.4-MJ SMES system used for stabilization studies of electrical power systems. The superconducting magnet consists of a cryostat and an Nb₃Sn coil. The dimensions of the coil are: 340 mm inner diameter, 700 mm outer diameter and 177 mm axial length. The pool-cooled coil is a stack of 20 Nb₃Sn double pancakes, and the cooling channels are aligned between pancake coils. To reduce Joule loss in electrical power converters, the maximum operating current of the coil is designed to be 350 A, which is one order of magnitude less than the operating currents of similar scale coils for pulse use. The conductor is an Nb₃Sn monolithic conductor with cross section 1.50 × 2.38 mm. For good superconducting stability and high dielectric strength of the coil, the Nb₃Sn double pancakes were wound by the react-and-wind technique. Operation of dc current to 105% (367.5 A) of the design operating current was achieved without quench. After the whole of the coil was exposed out of liquid helium, the coil did not quench under 120 A current operation for more than 2 hours. It was verified that the coil was stable for the SMES system. © 1998 Scripta Technica, Inc. Electr Eng Jpn, 121(3): 44–52, 1997     

A generalized method of controlled voltage source-fed induction motor vector control using the observer theory

Vector control of induction motors is widely used for industrial applications. On-line parameter identification and speed sensorless control are being studied actively. A representative method for these problems is the application of an adaptive full-order observer. The rotor flux for vector control is estimated by a full-order observer and machine parameters, or the rotor speed is determined by an adaptive algorithm. In this paper, a new vector control scheme with parameter identification is proposed. This method is based on the adaptive full-order observer. However, the observed currents which are usually estimated in the voltage model are considered as command currents and the voltage model is used for the current controller. As a result, the proposed system is simpler than the conventional adaptive full-order observer system. Since the proposed system is composed of an induction motor model in a synchronously rotating reference frame, the well-known slip frequency control block is contained. The arrangement of the poles which are related to the torque transfer function is discussed. A linear model is derived taking into account the effects of the change of the stator and rotor resistances. The trajectories of poles and zeros of the torque transfer function are computed and discussed for various system parameters. Identification of stator and rotor resistances is confirmed by simulation using a nonlinear system model. The proposed idea is applied to a speed sensorless system; this system has a similar configuration to those of existing systems under some assumptions. © 1997 Scripta Technica, Inc. Electr Eng Jpn, 119(4): 66–76, 1997