As a result of the vertical elongation of dee-shaped plasmas, natural single-null poloidal-divertor equilibria have been stably obtained in the upper half of the Doublet III vacuum chamber with a plasma current of 320 kA, a major radius of 140 cm, an average minor radius of ∼45 cm, and a vertical elongation of 1.3–1.4 in the plasma cross-section. Without employing any particular divertor chamber, this simple divertor reduces the influx of metallic impurities to the main plasma and the re-cycling of charged particles in the periphery of the main plasma. The divertor reduces the radiation loss power and improves the energy confinement time.

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Neutral beam injection has been the most successful scheme used to heat magnetically confined plasmas studied in controlled nuclear fusion research, and neutral beams are a candidate to heat to ignition the International Tokamak Experimental Reactor (ITER). This article describes the system which is presently being designed in Europe, Japan, and Russia, with coordination by the Joint Central Team of ITER at Naka, Japan. The proposed system consists of three negative ion based neutral injectors, delivering a total of 50 MW of 1 MeV D0 to the ITER plasma for pulse length of ≳1000 s. The proposed injectors each use a single caesiated volume arc discharge negative ion source, and a multigrid, multiaperture accelerator, to produce about 40 A of 1 MeV D−. This will be neutralized in a subdivided gas neutralizer, which has a conversion efficiency of about 60%. The charged fraction of the beam emerging from the neutralizer is dumped onto the water-cooled surfaces making up the electrostatic residual ion dump. A water-cooled calorimeter can be moved into the beam path to intercept the neutral beam, allowing commissioning of the injector independent of ITER.

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Hinokitiol (a-thujaplicin, 2-hydroxy-4-isopropyl-2,4,6-cycloheptatrien-1-one), one of the tropolone compounds purified from the woods of Chamaecyparis and Thujopsis (hinoki and hiba), produced reactive oxygen species as a complex with transition metals. Hinokitiol/iron complex inactivated aconitase, the most sensitive enzyme to reactive oxygen, whereas it did not affect aldolase and glyceraldehyde 3-phosphate dehydrogenase. The inactivation of aconitase was irondependent, and prevented by TEMPOL, a scavenger of reactive oxygen species and superoxide dismutase, suggesting that the hinokitiol/iron-mediated generation of superoxide anion is responsible for the inactivation of aconitase. Addition of hinokitiol effectively enhanced the ascorbate/copper-mediated formation of 8-hydroxy-2ø-deoxyguanosine in DNA. Cytotoxic effect of hinokitiol can be explained by its prooxidant properties: hinokitiol/transition metal complex generates reactive oxygen species causing inactivation of aconitase and production of hydroxyl radical resulting in the formation of DNA base adduct.Hinokitiol (b-thujaplicin, 2-hydroxy-4-isopropyl-2,4,6-cycloheptatrien-1-one), one of the tropolone compounds purified from the woods of Chamaecyparis and Thujopsis (hinoki and hiba), shows antimicrobial (Inamori et al. 1999), antifungal (Diouf et al. 2002 and antitumour activities (Yasumoto et al. 2004), and is used as cosmetics and skin care products due to its anti-microbial activity (Arima et al. 2003). The cytotoxicity of hinokitiol with the hydroxyketone structure is considered to depend on the potent ironchelating activity (Yasumoto et al. 2004), which inhibits a respiratory chain dependent on the number of iron-containing enzyme and ribonucleotide reductase with iron at the active sites. In this communication we demonstrate that hinokitiol generates reactive oxygen species thereby causing cytotoxicity. Production of reactive oxygen species was demonstrated by inactivation of aconitase (EC 4.2.1.3), the sensitive enzyme to active oxygen, and further by the enhancement of ascorbate/copper dependent formation of 8-hydroxy-2ø-deoxyguanosine in DNA. Hinokitiol-dependent generation of reactive oxygen species may explain the antimicrobial and antitumoural properties of this compound. Materials and MethodsMaterials. Hinokitiol was obtained from, JCS corp. (Kyoto, Japan); quercetin, threo-Ds-isocitrate, superoxide dismutase, TEMPOL (4-hydroxy-2, 2, 6, 6-tetramethylpiperidine-1-oxyl), 8-hydroxy-2ø-deoxgyguanosine, and enzymes for DNA hydrolysis, from Sigma-Aldrich Japan (Tokyo, Japan) and NADP-isocitrate dehydrogenase from Oriental Yeast Co. (Tokyo, Japan). Baker's yeast was purchased locally.Author for correspondence: Masataka Yoshino, Department of Biochemistry, Aichi Medical University School of Medicine, Nagakute, Aichi 480-1195, Japan (fax π81 561 61 4056, e-mail yoshino/aichi-med-u.ac.jp). et al. 1980) were treated with hinokitiol plus FeSO 4 in the absence and presence of TEMPOL or superoxide dismutase, and used for determination of enzym...