Morphology of CuO through precipitation process under 2.45 GHz microwave irradiation

The morphology of CuO powders formed by a homogeneous precipitation process from aqueous copper precursor complex was investigated. The effect of 2.45 GHz microwave irradiation appeared in the characteristic morphology of the CuO microcrystal with comparison of an ordinal synthesis process. The crystallographic orientation of CuO microcrystals in the particle was examined by HRTEM. Using microwave irradiation, it was demonstrated that the morphology of the particles was kept through the decomposition of the precursor. Also the rapid transformation of a precursor to CuO in aqueous solution under microwave irradiation condition was discussed.     

Estimation of compound classes in coal hydrogenation liquids by thin-layer chromatography

Compound classes in coal liquids were investigated by thin-layer chromatography coupled with a flame ionization detector (t.l.c.-f.i.d.). Individual t.l.c. peaks for coal liquids were identified as paraffins, aromatics, polar compounds and more strongly polar compounds or asphaltenes in order of increasing R_f values by comparison with specific compounds separated previously by conventional liquid chromatography. Concentrations of compound classes for a series of samples obtained by varying the hydrogenation time were estimated and good agreement was found with the results obtained by the USBM-API 60 liquid chromatography procedure. By using the t.l.c.-f.i.d. method, the relation of distribution of compound classes to the reaction conditions of coal hydrogenation could be derived quantitatively with relative ease.     

Electric transfer function model of switched reluctance motors and model‐based current control design

This paper presents a current control design for switched reluctance motors (SRMs). The electric transfer characteristic of the motors is studied first. Their transfer function is shown to be expressible by a pure resistive component, which is not constant but varies depending on the motor current and speed. The current control design for SRMs follows the classical design technique used for DC machines, where the zeros of the PI controller cancel the poles of Ls+R. Because the transfer function of SRMs does not have any poles, an I controller is suitable for them. The integral gain should be adjusted in order to compensate the nonlinearity, that is, the variation in the equivalent resistor of the SRMs' transfer function. The values of the integral gain are tuned and tabulated for the motor speed and current. Simulation and experiment demonstrate that the current and speed of the SRMs present good responses without dependence on the motor speed and current. © 2010 Wiley Periodicals, Inc. Electr Eng Jpn, 173(1): 51–59, 2010; Published online in Wiley InterScience ( www.interscience.wiley.com ). DOI 10.1002/eej.20987     

Analysis of a coal-derived liquid using highpressure liquid chromatography and synchronous fluorescence spectrometry

Synchronous fluorescence spectra of model polycondensed aromatic hydrocarbon molecules were recorded and used to identify the number of condensed rings in the aromatic molecules. A coal-derived liquid from Yubarishinko coal was initially separated into fractions having different number of condensed aromatic rings, and each fraction was further divided into narrow fractions having different numbers of carbon atoms. These fractions were studied using synchronous fluorescence spectroscopy. Results indicate the potential usefulness of synchronous fluorescence spectroscopy as a method of analysis of complex mixtures as coal-derived liquids despite the limitation of the method that some molecules give only weak peaks. Several components in some fractions were identified by a combination of synchronous fluorescence spectra and conventional excitation and emission fluorescence spectra.     

Enhancement by ganglioside GT1b of annexin I phosphorylation in bovine mammary gland in the presence of phosphatidylserine and Ca2+

Ganglioside GT1b and, to a lesser extent, GD3, enhanced phosphorylation of a 36 kDa protein (the substrate of protein kinase C) in the particulate fraction from bovine mammary gland. Sialic acids, asialogangliosides, and GM3 were without effect, and GD1a conversely inhibited phosphorylation of the 36 kDa protein. The enhanced phosphorylation by GT1b required the simultaneous presence of phosphatidylserine (PS) and Ca²⁺. The 36 kDa protein reacted with anti-annexin I in Western blot analysis. Addition of purified annexin I to the reaction mixture containing the particulate fraction increased the extent of phosphorylated 36 kDa protein, and the phosphorylation was further enhanced by GT1b. The enhanced phosphorylation of annexin I by GT1b was also dependent on PS and Ca²⁺. When annexin I was phosphorylated by purified protein kinase C, GT1b inhibited the annexin I phosphorylation. Addition of epidermal growth factor or insulin to the particulate fraction had little effect on the enhancement. These results suggest that an enzyme or enzymes other than protein kinase C, epidermal growth factor receptor kinase, or insulin receptor kinase is responsible for the GT1b- and GD3-enhanced phosphorylation of annexin I in the presence of PS and Ca²⁺.     

High-dose,intermediate-temperature neutron irradiation effects on silicon carbide composites with varied fiber/matrix interfaces

SiC/SiC composites are promising structural candidate materials for various nuclear applications over the wide temperature range of 300–1000 °C. Accordingly, irradiation tolerance over this wide temperature range needs to be understood to ensure the performance of these composites. In this study, neutron irradiation effects on dimensional stability and mechanical properties to high doses (11–44 dpa) at intermediate irradiation temperatures (?600 °C) were evaluated for Hi-Nicalon Type-S or Tyranno-SA3 fiber–reinforced SiC matrix composites produced by chemical vapor infiltration. The influence of various fiber/matrix interfaces, such as a 50–120 nm thick pyrolytic carbon (PyC) monolayer interphase and 70–130 nm thick PyC with a subsequent PyC (?20 nm)/SiC (?100 nm) multilayer, was evaluated and compared with the previous results for a thin-layer PyC (?20 nm)/SiC (?100 nm) multilayer interphase. Four-point flexural tests were conducted to evaluate post-irradiation strength, and SEM and TEM were used to investigate microstructure. Regardless of the fiber type, monolayer composites showed considerable reduction of flexural properties after irradiation to 11–12 dpa at 450–500 °C; and neither type showed the deterioration identified at the same dose level at higher temperatures (>750 °C) in a previous study. After further irradiation to 44 dpa at 590–640 °C, the degradation was enhanced compared with conventional multilayer composites with a PyC thickness of ?20 nm. Multilayer composites have shown comparatively good strength retention for irradiation to ?40 dpa, with moderate mechanical property degradation beginning at 70–100 dpa. Irradiation-induced debonding at the F/M interface was found to be the major cause of deterioration of various composites.     

Response of isotopically tailored titanium diboride to neutron irradiation

The response of polycrystalline TiB₂ to neutron irradiation was investigated. The material was fabricated using isotopically enriched ¹¹B powders to minimize helium production via the ¹⁰B(n, α)⁷Li reaction. Neutron irradiation was conducted at temperatures of ~200°C and ~600°C to a fast fluence of 2.4 × 10²⁵ n/m² (>0.1 MeV). The material exhibited some swelling, but less swelling at the higher irradiation temperature. No macroscopic damage was observed in the irradiated material, although moderate irradiation-induced micro-cracking was found in the irradiated TiB₂. This study demonstrated improved radiation resistance of isotopically tailored TiB₂ compared with natural boron TiB₂, which exhibited macroscopic fracture by irradiation.     

High‐brightness electron sources for a next‐generation light source based on an energy recovery linac

A high‐brightness electron source of ultrasmall emittance and high average current is one of the most important components for next‐generation light sources based on an energy‐recovery linac (ERL). Such a high‐brightness electron source can be realized by a DC photocathode gun driven by laser pulses tailored in the temporal and spatial dimensions. We propose a novel photocathode based on a quantum cascade laser (QCL). Since the ultrafast response of photoelectron emission from QCL is compatible with the tailored laser pulses, it is a candidate electron source for ERLs. © 2011 Wiley Periodicals, Inc. Electr Eng Jpn, 177(3): 46–53, 2011; Published online in Wiley Online Library ( wileyonlinelibrary.com ). DOI 10.1002/eej.21154     

Group Symmetry in Interior-Point Methods for Semidefinite Program

A class of group symmetric Semi-Definite Program (SDP) is introduced by using the framework of group representation theory. It is proved that the central path and several search directions of primal-dual interior-point methods are group symmetric. Preservation of group symmetry along the search direction theoretically guarantees that the numerically obtained optimal solution is group symmetric. As an illustrative example, we show that the optimization problem of a symmetric truss under frequency constraints can be formulated as a group symmetric SDP. Numerical experiments using an interior-point algorithm demonstrate convergence to strictly group symmetric solutions.     

Spin doping of individual molecules by using single-atom manipulation

Being able to control the spin of magnetic molecules at the single-molecule level will make it possible to develop new spin-based nanotechnologies. Gate-field effects and electron and photon excitations have been used to achieve spin switching in molecules. Here, we show that atomic doping of molecules can be used to change the molecular spin. Furthermore, a scanning tunneling microscope was used to place or remove the atomic dopant on the molecule, allowing us to change the molecular spin in a controlled way. Bis(phthalocyaninato)yttrium (YPc(2)) molecules deposited on an Au (111) surface keep their spin-1/2 magnetic moment due to the small molecule-substrate interaction. However, when Cs atoms were carefully placed onto YPc(2) molecules, the spin of the molecule vanished as shown by our conductance measurements and corroborated by the results of density functional theory calculations.