• Title/Summary/Keyword: MgB2

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Desmutagenic Effect of Legumes and Plants Crude Saponins in Salmonella typhimurium TA 98 (콩과 식물에서 추출한 사포닌의 돌연변이원성 억제효과)

  • Ryu, Beung-Ho;Lee, Beung-Ho;Ha, Mi-Suck;Kim, Dong-Seuk;Sin, Dong-Bun;Nam, Ki-Du
    • Korean Journal of Food Science and Technology
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    • v.18 no.5
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    • pp.345-350
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    • 1986
  • Crude saponins of soybean and Azuki bean (2.0 mg/plate)were most effective against Trp-p-2, and also all of legume saponins (2.0 mg/plate)were excellent effective against aflatoxin $B_1$. Crude saponins of taro, burdock and ginseng were remarkably effective at ranging from 1.0 mg to 2.0 mg per plate against MeIQ. Especially ginseng saponin was excellent effective and arrow root saponins was remarkably effective against MeIQ, respectively. Plant saponins of taro, lotus burdock, arrow root and ginseng except for dodok were most effective activities against aflatoxin $B_1$.

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Effect of thermal annealing on low-energy C-ion irradiated MgB2 thin films

  • Jung, Soon-Gil;Son, Seung-Ku;Pham, Duong;Lim, W.C.;Song, J.;Kang, W.N.;Park, T.
    • Progress in Superconductivity and Cryogenics
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    • v.21 no.3
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    • pp.13-17
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    • 2019
  • We investigate the effect of thermal annealing on $MgB_2$ thin films with thicknesses of 400 and 800 nm, irradiated by 350 keV C-ions with a dose of $1{\times}10^{15}atoms/cm^2$. Irradiation by low-energy C-ions produces atomic lattice displacement in $MgB_2$ thin films, improving magnetic field performance of critical current density ($J_c$) while reducing the superconducting transition temperature ($T_c$). Interestingly, the lattice displacement and the $T_c$ are gradually restored to the original values with increasing thermal annealing temperature. In addition, the magnetic field dependence of $J_c$ also returns to that of the pristine state together with the restoration of $T_c$. Because $J_c$(H) is sensitive to the type and density of the disorder, i.e. vortex pinning, the recovery of $J_c$(H) in irradiated $MgB_2$ thin films by thermal annealing indicates that low-energy C-ion irradiation on $MgB_2$ thin films primarily causes lattice displacement. These results provide new insights into the application of low-energy irradiation in strategically engineering critical properties of superconductors.

Enhancement of a mechanical property of metal sheaths (Cu and Nb) of MgB2 superconducting wires by E-beam irradiation

  • Kim, C.J.;Lee, T.R.;Jun, B.H.
    • Progress in Superconductivity and Cryogenics
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    • v.24 no.3
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    • pp.30-34
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    • 2022
  • Effects of electron beam (EB) irradiation on the mechanical strength of Cu (conducting sheath) and Nb (diffusion barrier) of Cu/Nb/MgB2 superconducting was investigated. Wire- and tape-type Cu/Nb/MgB2 samples were irradiated at E-beam energy of 2.5 MeV and 5 mA and a maximum E-beam dose was 5×1017 e/m2. The hardness value of Cu and Nb region was measured by the Vickers micro-hardness method. In the case of the wire sample, the hardness of Cu and Nb increased proportionally as the dose was increased up to 5×1017 e/m2, whereas in the case of the tape sample, the hardness increased up to a dose of 0.5×1017 e/m2, and decreased slightly 5×1017 e/m2. The hardness increase of Cu and Nb is believed to be due to the decrease of the deformability of Cu and Nb due to the defects formed inside the materials by E-beam irradiation.

Relationship between Particle Density and Electrochemical Properties of Spherical LiMn2-xMxO4 (M = Al, Mg, B) Spinel Cathode Materials (구형 스피넬계 LiMxMn2-xO4 (M = Al, Mg, B) 양극소재의 입자치밀도와 전지성능간의 상관관계에 대한 연구)

  • Kim, Kyoung-Hee;Jung, Tae-Gyu;Song, Jun-Ho;Kim, Young-Jun
    • Journal of the Korean Electrochemical Society
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    • v.15 no.2
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    • pp.67-73
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    • 2012
  • Spherical lithium manganese oxide spinel, $LiMn_{2-x}M_xO_4$ (M = Al, Mg, B) prepared by wet-milling, spray-drying, and sintering process has been investigated as a cathode material for lithium ion batteries. As-prepared powders exhibit various surface morphologies and internal density in terms of boron (B) doping level. It is found that the dopant B drives the growth of the primary particle and minimizes the surface area of the powder. As a result, the dopant enhances the internal density of the particles. Electrochemical tests demonstrated that the capacity of the synthesized material at 5 C could be maintained up to 90% of that at 0.2 C. The cycle performance of the material showed that the initial capacity was retained up to 80% even after 500 cycles under the high temperature of $60^{\circ}C$.