Decomposition of Mullite by Silica Volatilization

Thermal decomposition of mullite into corundum was investigated using a high-temperature X-ray single-crystal camera equipped with a gas-flame furnace and by scanning electron microscopy and electron probe microanalysis (EPMA). When heated to ∼1750°C, mullite decomposed to corundum by the liberation of the SiO₂ component with topotaxial relations of:

• (1) 

  (310)_mull∥(001)_cor; [001]_mull∥[110]_cor
• (2) 

  (130)_mull∥(001)_cor; [001]_mull∥[110]_cor
• (3) 

  (110)_mull∥(001)_cor; [001]_mull∥[110]_cor

Thus, it was considered that, when mullite decomposed into corundum, their oxygen close-packed planes were almost preserved. The SEM photographs showed that the crystals of the developed corundum are prismatic and ∼5 μm wide. The EPMA showed that the phase boundary between mullite and developed corundum is discontinuous.     

PHYTOCYSTATINS AND THEIR TARGET ENZYMES: FROM MOLECULAR BIOLOGY TO PRACTICAL APPLICATION: A REVIEW

Cystatins are protein inhibitors of cysteine proteinases. Oryzacystatin I (OC-I) has been cloned and is apparently the first well-defined cystatin of plant origin (phytocystatin). Besides OC-I, various other phytocystatins occur in rice, corn, wheat and soybean. Phytocystatins have endogenous target enzymes whose expression is induced by gibberellin, and also exogenous target enzymes from viruses and insects. It is thus likely that phytocystatins are involved in the regulation of intracellular protein catabolism as well as in the defense from infection. Better understanding of this phenomenon and cloning of appropriate genes will facilitate the creation of transgenic crops with enhanced resistance to viruses and insects.     

SCREENING OF RESISTANT TRIACYLGLYCEROLS TO THE PANCREATIC LIPASE AND THEIR POTENTIALITIES AS A DIGESTIVE RETARDANT

A gradual retarding of lipid digestion and absorption might contribute to preventing the visceral fat accumulation and obesity in humans. The lipolysis rates of different triacylglycerols (TAGs) by pancreatic lipase in vitro were studied in order to find suitable components as a retardant for lipolysis. Several TAGs containing longer acyl chains than stearic acid or containing unsaturated fatty acids whose double bonds are located closely to the carboxyl group like petroserinic and γ-linolenic acid showed significantly lower lipolysis rates as compared with triolein (OOO) control. Most of these resistant TAGs contributed to decelerating the lipolysis rate when replaced at 10% into the OOO control. Especially, 1-behenoyl-2,3-dioleoyl- rac -glycerol (BOO) was comprehensively thought to be a suitable TAG as a digestive retardant among them. Each 10% replacement of edible oils by BOO gave 15% to 30% reduction of the lipolysis rate in vitro . Resistant TAGs that are able to melt or solubilize into liquid oil at body temperature have some potential as a digestive retardant for lipids.

PRACTICAL APPLICATIONS

Visceral fat accumulation and obesity in humans are thought to be correlated with the rate of lipid digestion and absorption. The entire rate of lipid absorption is controlled by their partial replacement with some digestive retardant. Resistant triacylglycerols may have some potential as a digestive retardant of lipids. Results of the present study propose a new fat system for foods with antiobesity effect.     

Simulataneous analysis of reactivity of anilines in the hydrogen-isotope exchange reaction

In order to reveal the reactivity of a functional group in an aromatic compound having two substituents in the aromatic ring, the hydrogen-isotope exchange reaction （T-H exchange reaction） between tritiated water vapor （HTO vapor） and 4-amino-2-methylbenzenesulfonic acid （and 5-amino-2-methylphenol） were dynamically observed at 50℃ （and 70℃） in a gas-solid system. Consequently, the fact that the specific activity of the acid increased with time was obtained, and the T-for-H exchange reaction occurred. By applying the A＂-McKay plot method to the data observed, the rate constant of each functional group for the reaction was obtained. After the additive property of the Hammett＇s rule was applied to this work, the new substituent constants were obtained. From the above-mentioned, the following four items have been confirmed： （1） the reactivity of the functional groups can be dynamically analyzed, and the A＂-McKay plot method is useful to analyze the reactivity; （2） the additive property of the Hammett＇s rule is applicable to quantitative comparison of the reactivity of the functional groups; （3） the reactivity of the functional groups can be simultaneously analyzed by using the A ＂-McKay plot method in the T-H exchange reaction; and （4） the method used in this work is also useful for analyzing the reactivity of a certain material having some kinds of func- tional groups.     

Impact of Retailer and Consumer Behavior on Voltage in Distribution Network Under Liberalization of Electricity Retail Market

The liberalization movement in Japan will be expanded to the residential sector and full liberalization of the retail market will be achieved in the near future. Against this background, it is expected that transactions in a distribution network (DN), which has many consumers of the residential sector, will be activated. Furthermore, consumers can control their loads depending on the selling prices offered by retailers with the introduction of demand response (DR) technologies such as home energy management systems (HEMS). Due to the variation of load by DR, however, the voltage profile in DN may be changed compared to the present situation. This may make voltage management difficult and cause problems such as voltage deviation from an adequate range. In this paper, the impact of DR in a liberalized electricity market on DN is evaluated for efficient voltage management. In order to evaluate the behavior of the retailer and consumers, this paper proposes a bi‐level programming approach based on the Stackelberg game model. Solving the bi‐level programming problem including the power flow equation for a DN model based on the IEEE 13‐bus test feeder, we analyze the impact of the retailer and consumers on the voltage in the DN in order to account for transactions between these market players.     

Object oriented programming in production management—two pilot systems

This paper discusses AI-oriented production management systems using object oriented programming. The two pilot systems described here are both implemented using the Smalltalk-80 programming environment. One of the systems concerns production planning in dairy industries, while the other is a simulation tool for production flow analysis. The merits of object oriented programming in the design of the user interfaces are emphasised. The flexibility of the object oriented approach for stepwise development has been observed. Simulation method as a communication tool is used in both systems and the applicability of Smalltalk in simulation is demonstrated. Design effectiveness and efficiency has proven surprisingly good. The experiences introduced in the paper are based on two geographically disjoint research groups, having thus impact on the generality of the observations made.     

PMSM Sensorless Control Based on Position Estimation Correction Using All‐Pass Filters

This paper proposes a novel flux estimation method for the position sensorless control of permanent magnet synchronous motors (PMSMs). In general, the stator flux linkage for position estimation in PMSMs is obtained using the pure integration of voltages. The infinite dc gain of the pure‐integrator, however, causes numerical drifts in the obtained stator flux linkage due to the dc offset in the input of this integrator. To address this problem, a quasi‐integrator is often substituted instead of the pure integrator to restrict the dc gain, leading to another problem in which the phase characteristics vary according to the operating frequency. As a result, the ideal phase characteristics (?90° constant) cannot be held, and the position estimation performance deteriorates. Therefore, this paper proposes a phase characteristic correction method for quasi‐integrators using all‐pass filters, which achieves extremely precise estimation under transient conditions as well as in steady state.     

Comparison of the characteristics of electric double-layer capacitors with an activated carbon powder and an activated carbon fiber

The characteristics of electric double-layer capacitors (EDLCs) with activated carbon powder (ACP), pulverized activated carbon fiber (ACF), and ACF-cloth have been compared. The BET surface areas of the ACP and ACF were estimated to be 1740 and 1970 m² g⁻¹, respectively. In the pore-size distribution curve of the ACP and ACF, the most dominant pore diameter was 1.8 and 1.1 nm for the ACP and ACF, respectively. Disc- and cloth-type of electrodes were fabricated using ACP and ACF. The electrical resistance of the ACF-disc and ACF-cloth electrodes was four orders of magnitudes lower than that of the ACP-disc electrodes. In accordance with the lower electrical resistance of the ACF-disc and ACF-cloth, the d.c. resistance of the EDLC with the ACF-disc and with ACF-cloth was lower than that of the EDLC with the ACP-disc. The highest specific volume capacitance of 28.3 F cm⁻³ (capacitance / volume of total ACF in the EDLC) was achieved with the ACF-disc. In the cyclic voltammograms of the ACF-disc, the stable electric double-layer charging and discharging behavior was observed.     

Light-Focusing Glass Fibers and Rods

Glass fibers and rods with radially parabolic refractive-index distributions were produced by exchanging potassium ions from a salt bath or a lower-index cladding glass for thallium ions in the glass composition. A fiber 1 m long and 0.25 mm in diameter could be bent around a curve of radius 10 cm without deforming the Gaussian mode pattern; the depolarization of a laser beam was < −20 dB. The resolution of a rod 3.14 mm long and 1.0 mm in diameter with a focal length of 1.64 mm was of the order of 450 lines/mm. Attenuation (caused primarily by absorption induced by trace impurities) was 100 to 250 dB/km at 6328 Å; since further improvement with respect to loss is expected, these fiber guides are promising materials for use in long-distance optical communications.