Showing papers by "Waseda University published in 1981"

A Load Flow Calculation Method for III-Conditioned Power Systems

Abstract: In this paper, a load flow calculation method for ill-conditioned power systems is developed. The proposed method is very simple, has no mathematical approximations, and requires almost no additional storage and computation time when incorporated into the normal Newton-Raphson program. Using the method, the load flow solution never diverges, and also the existence of the solution from the initial estimate can be easily judged. To examine the effectivenesst two ill-conditioned power systems, i.e., 11 and 43 bus systems are studied by the method, and it is found that the solution does not exist for the 11 bus system though the given data are said to be operational, and also that the solution does exist for the 43 bus system but does not converge with the single precision due to the precision deficiency of the computer.

Effect of hydrophilic and hydrophobic microdomains on mode of interaction between block polymer and blood platelets.

Abstract: ABA-type block copolymers composed of 2-hydroxyethyl methacrylate (HEMA), a hydrophilic monomer, and styrene (St), a hydrophobic monomer, were synthesized by the coupling reaction of telechelic oligomers used as prepolymers. These block copolymers may be represented as microphase-separated structures. It is therefore possible to change the balance between hydrophilicity and hydrophobicity in the level of an assembled order of macromolecules. In response to the relative composition of the copolymers, three typical morphological patterns were observed in electron microscopic photographs: dispersed domains of continuous St chains in the region of HEMA chains, alternate HEMA and St lamellae and finally, dispersed phases of continuous HEMA chains in the region of St chains. The effect of the hydrophilic and hydrophobic microdomains of the copolymers on the mode of interaction between polymers and platelets was studied by the microsphere column method. In the case of homopolymers and random copolymers, a significant degree of platelet adhesion and aggregation was observed. However, the degree of platelet adhesion and deformation was suppressed on the surfaces of the block copolymers containing 0.608 and 0.347 mole fractions of HEMA whose microdomains were hydrophilic-hydrophobic lamellae and isolated hydrophilic islands in hydrophobic areas, respectively. These results show that the microphase-separated structures were antithrombogenic and prevented platelet adhesion and deformation. On the basis of the results obtained, the interaction between platelets and polymer surfaces was described in terms of the effect of hydrophilic and hydrophobic microdomains.

Ferroelectric phase transition in a copolymer of vinylidene fluoride and trifluoroethylene

Abstract: The phase transition in a copolymer of 55% vinylidene fluoride and 45% trifluoroethylene near 70°C has been investigated by measuring the temperature dependence of fundamental properties. The remanent polarization disappeared near 70°C. The dielectric relaxation strength showed a peak indicating an anomaly and the dielectric relaxation time showed a critical slowing down phenomenon. A change in crystal lattice spacing associated with remanent strain and an anomalous specific heat were observed. These results are consistent with a ferroelectric phase transition. Comparison is made between observation and prediction by phenomenological and simple dipolar theories for a order-disorder type transition.

Preparation and electrical properties of quaternary ammonium montmorillonite-polystyrene complexes

Abstract: Intercalation compounds of styrene and quaternary ammonium montmorillonite were prepared by immersion of the clay in styrene monomer. The intercalation of stearyltrimethylammonium (CHa(CH~)lTN(CHs)a+)-montmorillonite and styrene showed an expansion of the basal spacing to a constant value of ~32 ,~ after immersion for 10 days. After polymerization, the amount of polystyrene in the inter- layer region was determined by thermal gravimetric analysis. Styrene adsorption initially increased with increasing quaternary ammonium cation and then became approximately constant when loading of the quaternary ammonium cation exceeded 100 meq/100 g clay. The volume resistivity of the stearyltrimethyl- ammonium-montmorilionite-polystyrene complex, which was determined with a high resistance meter, was greater than that of both the quaternary ammonium-montmorillonite and the montmorillonite, and increased in proportion to the amount of polymer adsorbed. These data indicate that polystyrene improved the insulating properties of the clay films.

Wake-Oscillator Model of Vortex-Induced Oscillation of Circular Cylinder

Abstract: The Birkhoff type wake-oscillator whose length varies is proposed for a stationary cylinder. The motion of the wake-oscillator is expressed approximately in a nonlinear equation. The system consisting of the oscillator and an elastically mounted cylinder is considered as a binary system in simultaneous equations. The periodic solutions and their rough explanations are obtained and examined for their variation with mechanical damping. The numerical solutions of the model by Runge-Kutta method are calculated and compared with many experimental results. It is found that the proposed model can simulate the vortex-induced oscillation of a two dimensional circular cylinder not only in quality but also in quantity.

Low-temperature redistribution of As in Si during Pd2Si formation

Abstract: We have investigated the change in depth compositional profiles of implanted As in Si due to Pd2Si formation by using anodic oxidation and neutron activation analysis. We found that a high concentration (∼1×1021/cm3) of implanted As was snowplowed by the moving silicide‐Si interface into the substrate Si during Pd2Si formation at 250 °C. In other words, we have found a very low temperature process of doping As into Si. The amount of snowplowed As was found to be greater in samples which were preannealed at 900 °C—30 min before silicide formation than those without the preannealing.

Purification and properties of bullfrog prolactin.

Abstract: Prolactin was purified from bullfrog adenohypophyses by extraction of acetone-dried powder with acid acetone and chromatography on DEAE-cellulose and Sephadex G100. The bullfrog prolactin had a molecular weight of 23,000 as determined by SDS gel electrophoresis. The isoelectric point was 5.76 when determined by electrofocussing. The amino acid composition of the purified prolactin closely resembles that of mammalian prolactin. The prolactin was found to be 3.6 times as potent as bovine prolactin in promoting collagen synthesis in the tadpole tail fin.

Aggregation of poly(methacrylic acid)-poly(ethylene oxide) complex in aqueous medium†

Abstract: It is known that poly(methacrylic acid) and poly(ethylene oxide) interact with each other through hydrogen bonds and form polymer complexes in an aqueous medium. The initially formed polymer complexes were considered to exist in a semi-stable state, and they aggregated through desolvation and hydrophobic interaction. A successive aggregation of polymer complexes was observed following the rapid initial complexation. The aggregation was affected by some chemical factors e.g., polymer concentration, temperature, pH and so on. These effects were measured as the changes of the molecular shape by means of laser-light scattering, turbidity measurements, and scanning electron microscopy. It was observed that lower pH and higher temperature made the aggregation faster within such experimental conditions as pH 2–7, 20–50°C. The aggregates were nearly spherical with almost the same diameter (200 nm), and spontaneously grew larger with time.

Complexation of metal ion with poly(1-vinylimidazole) resin prepared by radiation-induced polymerization with template metal ion

Abstract: Poly(1-vinylimidazole) (PVI) resin was prepared with Ni/sup 2 +/, CO/sup 2 +/, or Zn/sup 2 +/ as a template to study the adsorption of metal ions. The metal-1-vinylimidazole complex was copolymerized and cross-linked with 1-vinyl-2-pyrrolidone by ..gamma..-ray irradiation and the template metal ion was removed by treating the polymer complex with an acid. These PVI resins adsorbed metal ions more effectively than the PVI resin prepared without the template. The number of adsorption sites (As) and the stability constant (K) of Ni/sup 2 +/ complex were larger for the PVI resin prepared with the Ni ion template caused by the smaller dissociation rate constant of Ni ion from the resin. The composition of the Ni/sup 2 +/ complex in the resin remained constant. This suggests that the complexation proceeded via a one-step mechanism.

Stimulation of protein synthesis in round spermatids from rat testes by lactate.

Abstract: Lactate markedly increased the rate of [3H]leucine incorporation into the protein of isolated round spermatids (steps 1-8) from rat testes. Four kinds of hexoses, glucose, fructose, galactose, and monnose, also stimulated [3H]leucine incorporation, but to much lesser extents than lactate. Ribose had no effect. The glucose-induced stimulation of protein synthesis was entirely suppressed by iodoacetate and NaF, whereas iodoacetate and NaF were without effect on the lactate-induced increase in protein synthesis. Lactate stimulated both protein synthesis and ATP production in the spermatids. However, both of these stimulatory effects of lactate were completely blocked by DNP and rotenone. Rotenone entirely blocked oxygen consumption, as expected, whilst DNP enhanced it additively with lactate. Moreover, lactate was without influence on either transport of alpha-[3H]AIB into spermatids or incorporation of [3H]leucine into protein of a cell-free system of spermatids. These findings suggest that lactate may increase the protein synthesis of spermatids in the same fashion as glucose, and that the effect of lactate in increasing the level of ATP during incubation in vitro may be a major factor in the mechanism of stimulation of protein synthesis in the spermatids.

A structural model for the interface between amorphous and (100) crystalline silicon

Abstract: A structural model for the interface between amorphous and (100) crystalline Si has been constructed by building a model of a continuous random network (CRN) on a crystalline substrate. In relaxing the atomic coordinates to minimize the elastic energy, the Keating Potential was used for the interatomic interactions. The interface consists of 121 atoms on the amorphous and 230 atoms on the crystalline side. In the 121-atom CRN model, the r.m.s. deviations of the bond lengths and bond angles are 1·05% and 6·86° respectively, and the bond-angle distribution, dihedral-angle distribution, and reduced intensity function F(s) are similar to a bulk CRN model. The principal results characterizing the interface are (a) the r.m.s. bond-angle deviation in the crystal is 3·52° (not zero), and (b) the r.m.s. bond-angle deviation on the boundary surface between the amorphous and crystalline sections is 9·05° indicating a larger distortion than in the bulk CRN model.

Stroop phenomena in the japanese language: the case of ideographic characters (kanji) and syllabic characters ( kana)

Abstract: Utilizing a unique feature of the Japanese languages--that besides two syllabic orthographies, which have identical pronunciations, words with the same pronunciation may also be written in an orthography composed of ideographic characters--we have conducted an investigation of Stroop phenomena. The fact that pronunciations of the three Japanese orthographies are identical means that, if there are any differences between them in the Stroop phenomena observed, we can place the locus of this interference effect in the perceptual process. Five color names were written in the ideographic characters (kanji) and the two syllabic orthographies (hiragana and katakana). Color-congruent cards and incongruent cards were utilized in a color-naming task and a word-reading task. Mean required times for the color-naming condition and the word-reading conditions were compared with those for control conditions. Stroop phenomena were observed in both ideographic and syllabic orthographies. Significant differences in mean required times were observed between the ideographic and syllabic orthographies but not between the two syllabic orthographies. Interferences in comparisons of Japanese orthographies and color patch control conditions were much smaller than in the case of Stroop's (1935) experiment. A "Reverse Stroop Phenomenon" was observed only in the case of kanji on incongruent cards in the word-reading condition. The results support the hypothesis that both ideographic characters (in this case, kanji) and colors are processed in a parallel fashion in the non-dominant right cerebral hemisphere, while syllabic or phonetic characters are processed in the dominant left cerebral hemisphere.