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Hajimahmoodi M.,Tehran University of Medical Sciences | Mohammadi N.,Tehran University of Medical Sciences | Soltani N.,Research Institute of Applied Science | Oveisi M.R.,Tehran University of Medical Sciences | Nafissi-Varcheh N.,Tehran University of Medical Sciences
Journal of Applied Phycology | Year: 2010

Antioxidant activities of both cells and extracellular substances were evaluated in 12 soil-isolated strains of microalgae according to FRAP and DPPH-HPLC assays. Their total phenolic contents were also determined by Folin-Ciocalteu method. Extractions were performed with hexane, ethyl acetate, and water. The results of FRAP assay showed that algal cells contained considerable amounts of antioxidants from 0.56 ± 0.06 to 31.06 ± 4.00 μmol Trolox g-1 for Microchaete tenera hexane extract and Chlorella vulgaris water extract, respectively. In water fractions of extracellular substances, the antioxidants were from 1.30 ± 0.15 μmol Trolox g-1 for Fischerella musicola to 73.20 ± 0.16 μmol Trolox g-1 for Fischerella ambigua. Also, DPPH-HPLC assay represented high antioxidant potential of water fractions. The measured radical-scavenging activities of the studied microalgae were at least 0.15 ± 0.02 in Nostoc ellipsosporum cell mass to a maximum of 109.02 ± 8.25 in C. vulgaris extracellular substance. The amount of total phenolic contents varied in different strains of microalgae and ranged from zero in hexane extract to 19.15 ± 0.04 mg GAE g-1 in C. vulgaris extracellular water fraction. Significant correlation coefficients between two measured parameters indicated that phenolic compounds were a major contributor to the microalgal antioxidant capacities. © Springer Science+Business Media B.V. 2009. Source


Naruse H.,Kyoto University | Yamamoto O.,Research Institute of Applied Science
2015 3rd International Conference on Electric Power Equipment - Switching Technology, ICEPE-ST 2015 | Year: 2015

A secondary electron emission avalanche occurring on a surface of an insulator of a bridged gap, along with the resultant charging phenomena of the surface, plays a decisive role in the progress of the flashover in a vacuum. This paper reports a method developed to derive a constant that is necessary for calculating the distribution of charge accumulated on the surface due to the secondary electron emission avalanche based on a calculation and a measurement. © 2015 IEEE. Source


Osamura K.,Research Institute of Applied Science | MacHiya S.,Daido University | Tsuchiya Y.,Japan National Institute of Materials Science | Suzuki H.,Japan Atomic Energy Agency
Superconductor Science and Technology | Year: 2010

The stress/strain behavior of the surround Cu stabilized YBCO coated conductors and its influence on critical current were precisely investigated. The internal strain exerted on the superconducting YBCO layer was determined at 77K by using a neutron diffraction technique at JAEA. The initial compressive strain decreased during tensile loading and changed to a tensile component at the force free strain (Aff), where the internal uniaxial stress becomes zero in the YBCO layer. The Aff was evaluated to be 0.19-0.21% at 77K. The critical current measurements were carried out under a uniaxial tensile load at 77K. The strain dependence revealed a characteristic behavior, where a maximum was observed at 0.035%. Thus it was made clear that the strain at the critical current maximum does not correlate with A ff for YBCO coated conductors. © 2010 IOP Publishing Ltd. Source


Osamura K.,Research Institute of Applied Science | MacHiya S.,Daido University | Tsuchiya Y.,Japan National Institute of Materials Science | Suzuki H.,Japan Atomic Energy Agency
IEEE Transactions on Applied Superconductivity | Year: 2010

The mechanical properties of surround Cu stabilized YBCO coated conductor were assessed at 5.7, 77 and 298 K. The internal strain exerted on the superconducting YBCO layer was directly evaluated under tensile load at low temperatures down to 9.8 K by neutron diffraction techniques. The compressive internal strain, present in the YBCO layer without external load, is the thermally induced residual strain. When the external tensile load was applied, the compressive component of internal strain decreased and changed into tensile. The force-free strain, Aff , was determined as the strain at which the internal strain becomes zero. The Aff estimated from (200) diffraction data depended weakly on temperatures between 298 and 9.8 K. However, the Aff estimated from (020) data decreased prominently with decreasing temperature. © 2006 IEEE. Source


Osamura K.,Research Institute of Applied Science | MacHiya S.,Daido University | Tsuchiya Y.,Japan National Institute of Materials Science | Suzuki H.,Japan Atomic Energy Agency | And 3 more authors.
IEEE Transactions on Applied Superconductivity | Year: 2012

The elastic properties of REBCO tape (i.e., REBa 2Cu 3O 7-d, RE = Y, Sm and Gd) have been investigated by means of diffraction techniques using synchrotron radiation. Total local strain A hkl l, which consists of thermal strain A hkl T and lattice strain A hkl, was analyzed using a microscopic structure model, with two types of microtwin configuration along the tensile axis, i.e., with the [100] or [110] crystal axis oriented parallel to the longitudinal direction of the tape. Experimental results were: (a) slope dA h00l/dA is larger than dA 0k0l/dA (where A is the external tensile strain), which is attributed to the elastic modulus E a along the a-axis being smaller than E b along the b-axis; (b) both dA h00l/dA and dA 0k01/dA are smaller than unity, but dA 110l/dA is almost unity depending on the configuration of microtwin; (c) the thermal strain for different planes is different as A h00 T ≠ A 0k0 T due to the elastic behavior of the superconducting layer being modified because it is constrained by the substrate and the outer metallic layer; and (d) a large Poisson ratio is attributed to this constraint state. It is suggested that the microtwin structure is critical to understand and model this unusual stress/strain behavior. © 2006 IEEE. Source

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