• Title/Summary/Keyword: $J_c$ (B)

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Progress in $MgB_2$ Superconductor Wires and Tapes

  • Kim, Jung-Ho;Kumakura, Hiroaki;Rindflesich, Matthew;Dou, Shi Xue;Hwang, Soo-Min;Joo, Jin-Ho
    • Progress in Superconductivity
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    • v.12 no.2
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    • pp.75-81
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    • 2011

  • We report on the progress that has been made in developing $MgB_2$ superconducting wires and tapes for commercialization and research efforts. A number of techniques have been developed to overcome the obstacle posed by the poor critical current density ($J_c$) of pristine $MgB_2$. Chemical doping has proved to be the effective way to modify and enhance the superconducting properties, such as the $J_c$ and the irreversibility field ($B_{irr}$). More than 100 different types of dopants have been investigated over the past 8 years. Among these, the most effective dopants have been identified to be SiC and malic acid ($C_4H_6O_5$). The best results, viz. a $B_{irr}$ of 22 T and $J_c$ of $30,000\;A{\cdot}cm^{-2}$ at 4.2 K and 10 T, were reported for malic acid doped $MgB_2$ wires, which matched the benchmark performance of commercial low temperature superconductor wires. In this work, we discuss the progress made in $MgB_2$ conductors over the past few years at the University of Wollongong, Hyper Tech Research, Inc., and Ohio State University.

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Synthesis and Properties of 1,4-Diboracyclohexene-2 Derivatives (1,4-Dibora-2-cyclohexene 유도체들의 합성과 그 성질)

  • Uhm, Jae-Kook;Hu D.;Zenneek U.;Pritzkow H.;Siebert W.
    • Journal of the Korean Chemical Society
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    • v.34 no.5
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    • pp.490-497
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    • 1990

  • Two synthetic routes for the 1,4-diboracyclohexene-2 ring 8 have been developed. Method i) starts with 1,2-bis(dichloroaluminyl)ethane, in which the AlCl$_2$ group is replaced by BCl$_2$. Exchange of the chlorine with BI$_3$ in 1,2-bis-(dichloroboryl)ethane yields the corresponding iodo compound, which reacts with the alkynes to heterocycles 8a, b in good yield. In method ii) B$_2$Cl$_4$ is added to alkenes, replacement of chlorine with BI$_3$ yields the bis(diiodoboryl)ethane derivatives which undergo redox reactions with alkynes to give 8c, d. The diiodo derivative 8a forms the pyridine adduct 9a, and reacts with ether to give the ethoxy derivative 8f. 8a-d react with AlMe$_3$ to yield the corresponding dimethyl derivatives 8g-j, which give unstable radical anions when treated with potassium in THF. The ESR parameters are reported. In electrochemical experiments irreversible reductions of 8g-j are observed. 8g-j react with (C$_5$H$_5$)Co(C$_2$H$_4$)$_2$ to give the intermediate 16 VE complexes (C$_5$H$_5$)Co(8), in which C-H activation occurs with formation of the corresponding red 1,4-diboracyclohexadiene complexes 10. The X-ray structure analyses of 10h and 10j are reported.

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cSNP Identification and Genotyping from C4B and BAT2 Assigned to the SLA Class III Region (돼지 SLA class III 영역 내 C4B 및 BAT2의 cSNP 동정 및 이를 이용한 유전자형 분석)

  • Kim, J.H.;Lim, H.T.;Seo, B.Y.;Lee, S.H.;Lee, J.B.;Yoo, C.K.;Jung, E.J.;Jeon, J.T.
    • Journal of Animal Science and Technology
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    • v.49 no.5
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    • pp.549-558
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    • 2007

  • C4B and BAT2, assigned to the SLA class III region, were recently reported on relation with human diseases. The primers for RT-PCR and RACE-PCR for CDS analysis of these genes of pig were designed by aligning the CDSs of humans and mice from GenBank. After we amplified and sequenced with these primers and cDNAs, the full-length CDSs of pig were determined. The CDS lengths of C4B and BAT2 were shown as 5226 bp and 6501 bp. In addition, the identities of nucleotide sequences with human and mouse were 76% to 87%, and the identities of amino acids were 72% to 90%. After we carried out the alignment with determined CDSs in this study and pig genomic sequences from GenBank, the primers for cSNP detection in genome were designed in intron regions that flanked one or more exons. Then, we amplified and directly sequenced with genomic DNAs of six pig breeds. Four cSNPs from C4B and three 3 cSNPs from BAT2 were identified. In addition, amino acid substitution occurred in six cSNP positions except for C4248T of C4B. By the Multiplex-ARMS method, we genotyped seven cSNPs with DNA samples used for direct sequencing. We verified that this result was the same as that analyzed using direct sequencing. To demonstrate recrudescence, we performed both direct sequencing and Multiplex-ARMS on two randomly selected DNA samples. The genotype of each sample showed the same result from both methods. Therefore, seven cSNPs were identified from C4B and BAT2 and could be used as the basic data for haplotype analysis of SLA class III region. Moreover, the Multiplex-ARMS method should be powerful for genotyping of genes assigned to the whole SLA region for the xenograft study.

  • https://doi.org/10.5187/JAST.2007.49.5.549 인용 PDF KSCI