Finite element analysis of the magnetomechanical behavior of a toroidal coil with magnetic mirrors

A toroidal simulator is used to study the magnetomechanical behavior of a superconducting D-shaped coil set at the center between sectored ferromagnetic plates. Since the magnetic field distribution between the two plates is expected to be almost the same as that created by toroidal field coils arrayed in a torus, the toroidal simulator may be expected to show almost the same magnetomechanical behavior as that of the full torus coils. To verify its validity experimentally, buckling and vibration tests were carried out in a liquid helium cryostat. In addition numerical analyses were performed for the magnetic field distribution to reveal its similarity and for the experimental results from the toroidal simulator to confirm its validity. Its validity is fully demonstrated in the present study.     

Mechanochemical block copolymerization in heterogeneous systems of the solid poly(vinyl chloride) with styrene by ultrasonic irradiation

Summary Mechanochemical block copolymerization in heterogeneous systems of the solid poly(vinyl chloride)-styrene-sodium dodecyl sulfate aqueous solutions has been studied by ultrasonic irradiation at 65 °C. The block copolymerization of styrene was initiated by free radicals produced from the poly(vinyl chloride) particles by ultrasonic waves. The initial rate of the block copolymerization Rp was given by Rp α [Styrene] [Sodium dodecyl sulfate]^1/2. Both copolymer and homopolymer were obtained. For example, when 2.506 g of the poly(vinyl chloride) particles, 24.23 g of styrene, and 54.00 g of sodium dodecyl sulfate aqueous solution (0.500 wt%) were added in the reaction system, the weight proportions of the block copolymer and polystyrene after 60 min were approximately 50 and 20%.     

Thermodynamic properties for the quaternary system H2O + CH3OH + LiBr + ZnCl2

The thermodynamic properties (solubility, vapour pressure, density, viscosity, heat capacity and heat of mixing) of the H₂O + CH₃OH + LiBr + ZnCl₂ (9:1 H₂O:CH₃OH and 1:1 LiBr:ZnCl₂ by mass) system using H₂O + CH₃OH as the working media and LiBr + ZnCl₂ as the absorbents were measured. The solubility data were obtained in the temperature range from 270.35 to 389.55 K. The measurements of vapour pressure, density, viscosity and heat capacity were carried out at various temperatures and absorbent concentrations. The differential heat of dilution and differential heat of solution at 298.15 K were measured for solutionw with absorbent concentrations from 0 to 75.2 wt%. The integral heat of mixing data at 298.15 K were obtained from both sets of experimental data. The integral heats of mixing for this quaternary system showed exothermic behaviour. The vapour pressure data were correlated with an Antoine-type equation. An empirical formula for the heat capacity was obtained from experimental data. The experimental data for the basic thermodynamic properties of this quaternary system were compared with those of the basic H₂O + LiBr system.     

GaAs varactor diode for u.h.f. t.v. tuners

The design and fabrication of a GaAs varactor diode for u.h.f. t.v. tuners were carried out using a GaAs double epitaxial layer. The capacitance ratio of diode. C3/C25, is 6.0 and the series resistance at 470 MHz is 0.24 ?. These characteristics are much better than those of an Si diode and well satisfy the requirements for t.v. tuners.     

Comparison of Antifungal and Antioxidant Activities of <Emphasis Type="Italic">Acacia mangium</Emphasis> and <Emphasis Type="Italic">A. auriculiformis</Emphasis> Heartwood Extracts

The effect of heartwood extracts from Acacia mangium (heartrot-susceptible) and A. auriculiformis (heartrot-resistant) was examined on the growth of wood rotting fungi with in vitro assays. A. auriculiformis heartwood extracts had higher antifungal activity than A. mangium. The compounds 3,4,7,8-tetrahydroxyflavanone and teracacidin (the most abundant flavonoids in both species) showed antifungal activity. A. auriculiformis contained higher levels of these flavonoids (3.5- and 43-fold higher, respectively) than A. mangium. This suggests that higher levels of these compounds may contribute to heartrot resistance. Furthermore, both flavonoids had strong 1,1-diphenyl-2-picrylhydrazyl (DPPH) radical scavenging activity and laccase inhibition. This suggests that the antifungal mechanism of these compounds may involve inhibition of fungal growth by quenching of free radicals produced by the extracellular fungal enzyme laccase.     

Development of Molecular Sieves‐Supported Palladium Catalyst and Chemoselective Hydrogenation of Unsaturated Bonds in the Presence of Nitro Groups

The chemoselective hydrogenation of unsaturated bonds and azide functionalities is achieved in the presence of nitro groups by a heterogeneous palladium catalyst supported on molecular sieves (MS3A). The present method shows a wide‐range of applicability with regard to substrates and the catalyst can be easily prepared and reused at least three times without any loss of activity.     

Analysis of glycosyl bond cleavage and related isotope effects in collision-induced dissociation quadrupole-time-of-flight mass spectrometry of isomeric trehaloses

The configuration isomers alpha,alpha-, alpha,beta-, and beta,beta-trehalose are distinguishable by a relative ion abundance analysis using collision-induced dissociation MS/MS measurements in electrospray ionization quadrupole-time-of-flight mass spectrometry. The relative abundance of the Y-type fragment ion of alpha,alpha-trehalose is the highest and that of beta,beta-trehalose is the lowest, indicating that alpha-glycosyl bonds cleave more easily than beta-glycosyl bonds. The relative ion abundance depends on both the alpha- and beta-glycosyl linkage type and the number of alpha-glycosyl bonds. The reaction path of glycosyl bond cleavage is calculated computationally using the molecular orbital method in the form of Hartree-Fock theory in conjunction with the 6-31G(d) basis set. The results are consistent with the experimental data. Isotope effects on the fragmentation of the glycosyl bonds are detected in the experiments of the H2O/D2O solvent systems. Furthermore, the isotope effect regarding beta,beta-trehalose is larger than those of alpha,alpha- and alpha,beta-trehalose, indicating that the isotope effect on the beta-glycosyl bond cleavage is larger than that on the alpha-glycosyl bond cleavage. The thermal energy increase in trehalose-d8 molecules over the corresponding trehalose molecules is calculated from the vibrational modes.     

Thermal degradation characteristics of oil‐filled cable joint with extremely degraded tan δ oil

Much of oil‐filled (OF) cable has been used for a long time as 66‐ to 500‐kV extrahigh‐voltage cable. Sometimes we can see extremely degraded tan δ oil (several tens of percent of tan δ, for example) in joint boxes, etc. The values of tan δ calculated by a simple combination model of paper/oil show that the oil‐impregnated paper with such a high tan δ oil likewise has an extremely high tan δ, which must result in thermal breakdown. However, such an event has not taken place up to the present in actually operated transmission lines. This fact suggests that some mechanism for the suppression of tan δ has acted in the paper insulation impregnated with degraded tan δ oil. Therefore, we investigated in detail the tan δ characteristics of paper impregnated with extremely high tan δ oil. In addition, based on the investigation results, we developed a method for simulation of heat generation by dielectric loss in an OF cable joint (which has degraded tan δ oil). © 2011 Wiley Periodicals, Inc. Electr Eng Jpn, 178(1): 1–10, 2012; Published online in Wiley Online Library ( wileyonlinelibrary.com ). DOI 10.1002/eej.21184     

A New Hybrid Phosphine Ligand for Palladium‐Catalyzed Amination of Aryl Halides

A new hybrid phosphine was designed. The phosphine combines two common structural characteristics found among the effective phosphine ligands reported recently, namely, three tert‐alkyl substituents binding to the phosphorus and an aryl group at an appropriate position. A hybrid phospine/palladium system is versatile and effective for the coupling reaction of various aryl halides with primary and secondary amines including carbazole.     

Effect of texture on oxidation resistance of Ti3AlC2

Oxidation resistance of textured Ti₃AlC₂ ceramics was measured in the temperature range 1273–1573?K. It was found that the oxidation was markedly anisotropic and the samples exhibited a better oxidation resistance when tested along a direction transverse to the c-axis. This behavior was attributed to the rapid diffusion of Al within its basal planes to form a passivating Al₂O₃ scale and it respected Ellingham diagrams. The scales formed had different compositions depending on the testing direction; this response was clearly resulting from the crystallographic orientation. Even at 1473?K after 20?h exposure, the samples tested in a direction transverse to the c-axis showed a reduced weight gain which was 45 times lower than one seen on a basal plane.