• Title/Summary/Keyword: fine chemicals

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Surface Modification of TiO2 Thin Films by N2 Atmospheric Plasma and Evaluation of Photocatalytic Activity (질소 상압플라즈마를 이용한 TiO2 박막의 표면개질 및 광활성 평가)

  • Lim, Gyeong-Taek;Kim, Kyung Hwan;Park, Jun;Kim, Kyoung Seok;Park, Yu Jeoung;Song, Sun-Jung;Kim, Jong-Ho;Cho, Dong Lyun
    • Applied Chemistry for Engineering
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    • v.20 no.4
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    • pp.402-406
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    • 2009
  • $TiO_2$ thin films were surface-modified with atmospheric plasma and their photocatalytic activities were evaluated. The films were deposited on glass plates by dip-coating in a $TiO_2$ sol-gel solution and sintered at various temperatures for various times. Nitrogen plasma was used for the modification and the experiments were carried out varying operational parameters such as discharge power and treatment time. Photocatalytic activity was evaluated based on the degradation efficiency of methylene blue (MB) under irradiation of UV-A and fluorescent light. According to XPS analysis, a little amount of nitrogen was found to be doped in the film surface after the modification. As a result, photocatalytic activity increased under irradiation of UV-A and fluorescent light, especially fluorescent light.

Development of Recombinant Human $Interferon-{\beta}-1a$ Analogs using Serum Free Suspension Culture of CHO Cell

  • Lee, Jong-Min;Oh, Han-Kyu;So, Moon-Kyoung;Yang, Ji-Hye;Yoon, Ho-Chul;Ahn, Ji-Soo;Kim, Ji-Tai;Yoo, Ji-Uk;Byun, Tae-Ho
    • 한국생물공학회:학술대회논문집
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    • 2005.04a
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    • pp.35-35
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    • 2005
  • Recombinant human $interferon-{\beta}-1a(rIFN-{\beta})$ is a single glycosylated protein (at N80, 1N) with anti-viral activity. However, present drugs have a relatively short serum half-life of $rIFN-{\beta}$, thus patients suffer from frequent $infections.^{1)}$ To improve its half-life, eight glycosylation analogs were prepared, which have additional N-linked glycosylation consensus sequences (N-X-T/S) within the $IFN-{\beta}$ molecule and/or at C-terminal. Each $rIFN-{\beta}$ analog was examined for the presence of additional N-linked glycosylation and the maintenance of anti-viral activity in CHO cells. The molecular weights of five analogs were not changed. However, two analogs, R27T within $rIFN-{\beta}$ (27 kDa, 2N) and GNITVNITV at C-terminal (29kDa, 2N), showed a clear increase in molecular weights, compared to native $rIFN-{\beta}$ (23 kDa, 1N). And another combined analog of R27T+GNITVNITV showed increased molecular weight (33 kDa, 3N). It was confimed that the molecular weight increment of analogs was caued by the N-linked glycosylation with the treatment of N-glycansae. In the case of anti-viral activity, the analog GNITVNITV showed a reduction in activity compared to native $IFN-{\beta}$, whereas the analogs R27T and R27T+GNITVNITV were found to have distinctly increased activities. Pharmacokinetic study in rats also disclosed that the analogs R27T and R27T+GNITVNITV had 2 3 fold increased serum half-life, respectively. In conclusion, the addition of N-linked glycosylation in $rIFN-{\beta}$ increased serum half-life, thereby its less frequent administration will be expected.

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Improved Cycle Performance of Sulfur-Doped LiFePO4 Material at High Temperatures

  • Lee, Seung-Byung;Cho, Seung-Hyun;Aravindan, Vanchiappan;Kim, Hyun-Soo;Lee, Yun-Sung
    • Bulletin of the Korean Chemical Society
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    • v.30 no.10
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    • pp.2223-2226
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    • 2009
  • Pristine and sulfur-doped (LiFe$PO_{3.98}S_{0.03}$) lithium iron phosphates were synthesized by a sol-gel method. The XRD pattern of the prepared materials suggested an orthorhombic structure with a Pnma space group and an absence of impurities. The Li/LiFe$PO_4$ or LiFe$PO_{3.98}S_{0.03}$ cells were employed for cycling studies at various temperatures (25, 50 and $60\;{^{\circ}C}$). In all cases, the Li/LiFe$PO_{3.98}S_{0.03}$ cell showed an improved performance with a stable discharge behavior of ~155 mA$hg^{-1}$. Nevertheless, pristine LiFeP$O_4$ cells presented poor discharge behavior at elevated temperatures, especially $60\;{^{\circ}C}$.