A totally enclosed traction motor using a permanent magnet synchronous motor

Ventilated‐type traction motors are widely used for railway vehicles. However, they require overhauls to clean inside them. In addition, they are a major noise source in railway vehicles. To solve these problems, we propose a totally enclosed‐type traction motor using a permanent magnet synchronous motor that has the same weight power ratio as that of a conventional ventilated‐type traction motor. In this paper, we report the test results of the proposed motor. The test results demonstrate that the temperature rise values are within its limit and the noise level is decreased by 10 dB compared to conventional motors. © 2005 Wiley Periodicals, Inc. Electr Eng Jpn, 151(3): 71–80, 2005; Published online in Wiley InterScience ( www.interscience.wiley.com ). DOI 10.1002/eej.20079     

Synthesis of biocompatible dendrimers with a peripheral network formed by linking of polymerizable groups

Toward the production of unimolecular nanocapsules with biocompatible surface, we prepared a fourth generation polyamidoamine dendrimer having both a poly(ethylene glycol) (PEG) with the number average molecular weight of 2000 and a methacryloyl group at every chain end of the dendrimer through an l-lysine residue. The introduced methacryloyl groups of the dendrimer were successfully polymerized by using free radical initiators, such as azobisisobutyronitrile and dibenzoyl peroxide, as judged by ¹H NMR. GPC revealed that the molecular weight of the dendrimers having the polymerizable groups did not change after their polymerization, indicating that the polymerization of the methacryloyl groups took place within the single dendrimer. Polymerization of the methacryloyl groups resulted in a significant reduction of the affinity of the dendrimer to a guest molecule, rose bengal, suggesting that the peripheral network formed by the linking of methacryloyl groups hides the dendrimer interior. In addition, when the methacryloyl groups of the dendrimer were polymerized in the presence of rose bengal, the guest molecule was found to be tightly associated with the dendrimer.     

Synthesis and structure-activity relationships of novel 2',2'-difluoro analogues of docetaxel

To investigate the role of the 2'-hydroxy group at the C-13 side chain of docetaxel in the antitumor activity, we prepared several 2',2'-difluoro derivatives of docetaxel and evaluated their cytotoxicity against mouse leukemia and human tumor cell lines and their microtubule disassembly-inhibitory activity. These analogues were prepared by esterification of protected 10-deacetylbaccatin III (21) with appropriate alpha, alpha-difluorinated carboxylic acids (Charts 1 and 2). Among these 2',2'-difluorodocetaxel derivatives, 2',2'-difluorodocetaxel (23b) was approximately 3-10 times as active as 2'-fluorodocetaxel (29a) in terms of cytotoxicity. In addition, the 3'-(2-furyl) (23h) and 3'-(2-pyrrolyl) (23p) analogues showed activity comparable or superior to that of docetaxel (2).     

Direct measurement of lightning current through a wind turbine generator structure

The development of a wind turbine generator system in Japan is regarded as a promising source of clean energy, and its popularization is rapidly increasing. In Japan, there are many wind turbine generator systems installed on the Sea of Japan coast, with large wind capacity. However, since the Sea of Japan coast is a region with abundant winter lightning, a phenomenon peculiar to Japan, the wind turbine generator systems are subject to damage from winter lightning. Thus, it is important to observe the lightning currents striking wind turbine generator systems in order to provide lightning protection. The authors therefore installed currents sensors (Rogowski coils) on wind turbine generators installed in Hokkaido and Kagoshima Prefectures, and performed waveform observation of lightning stroke current in the winter of 2002 and the summer of 2003. These observations yielded a few current waveforms for lightning striking wind turbine generators. This paper describes the investigation and presents the observation results. © 2006 Wiley Periodicals, Inc. Electr Eng Jpn, 157(4): 40– 47, 2006; Published online in Wiley InterScience ( www.interscience.wiley.com ). DOI 10.1002/eej.20250     

Kinetics of absorption of hydrogen sulfide into aqueous Fe(III) solutions

In our recent studies, absorption of H₂S into the aqueous Fe₂(SO₄)₃ and FeCl₃ solutions with various values of ionic strength and pH was investigated in an agitated vessel with a flat interface. The experimental results for both systems revealed that the species which reacts with H₂S is FeOH²⁺. The absorption rates were explained by the theory of gas absorption with an irreversible (l,l)-th order reaction between H₂S and FeOH₂₊. The reaction rate constants were independent of the ionic strength of the solution and correlated as a function of temperature. In this paper, kinetics and mechanism of these absorption reactions are reviewed and the identity for both systems is emphasized.     

Photoacoustic spectra of Sb-doped ZnSe

Photoacoustic (PA) spectra were made on Sb-doped ZnSe samples grown by metalorganic vapor phase epitaxy (MOVPE). The samples deposited at a low temperature under irradiation show the PA spectrum with a sharp edge near the band gap and with three distinct peaks. From the Sb flow rate dependence of PA peaks, two of them seem to be related to Sb impurities. Non-doped sample shows only one peak, which is tentatively ascribed to the deep level associated with Se defects.